http://git-wip-us.apache.org/repos/asf/hadoop/blob/cb5ba73b/hadoop-hdfs-project/hadoop-hdfsdb/src/main/native/snappy/snappy-test.cc ---------------------------------------------------------------------- diff --git a/hadoop-hdfs-project/hadoop-hdfsdb/src/main/native/snappy/snappy-test.cc b/hadoop-hdfs-project/hadoop-hdfsdb/src/main/native/snappy/snappy-test.cc new file mode 100644 index 0000000..4619410 --- /dev/null +++ b/hadoop-hdfs-project/hadoop-hdfsdb/src/main/native/snappy/snappy-test.cc @@ -0,0 +1,606 @@ +// Copyright 2011 Google Inc. All Rights Reserved. +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are +// met: +// +// * Redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer. +// * Redistributions in binary form must reproduce the above +// copyright notice, this list of conditions and the following disclaimer +// in the documentation and/or other materials provided with the +// distribution. +// * Neither the name of Google Inc. nor the names of its +// contributors may be used to endorse or promote products derived from +// this software without specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. +// +// Various stubs for the unit tests for the open-source version of Snappy. + +#include "snappy-test.h" + +#ifdef HAVE_WINDOWS_H +#define WIN32_LEAN_AND_MEAN +#include <windows.h> +#endif + +#include <algorithm> + +DEFINE_bool(run_microbenchmarks, true, + "Run microbenchmarks before doing anything else."); + +namespace snappy { + +string ReadTestDataFile(const string& base, size_t size_limit) { + string contents; + const char* srcdir = getenv("srcdir"); // This is set by Automake. + string prefix; + if (srcdir) { + prefix = string(srcdir) + "/"; + } + file::GetContents(prefix + "testdata/" + base, &contents, file::Defaults() + ).CheckSuccess(); + if (size_limit > 0) { + contents = contents.substr(0, size_limit); + } + return contents; +} + +string ReadTestDataFile(const string& base) { + return ReadTestDataFile(base, 0); +} + +string StringPrintf(const char* format, ...) { + char buf[4096]; + va_list ap; + va_start(ap, format); + vsnprintf(buf, sizeof(buf), format, ap); + va_end(ap); + return buf; +} + +bool benchmark_running = false; +int64 benchmark_real_time_us = 0; +int64 benchmark_cpu_time_us = 0; +string *benchmark_label = NULL; +int64 benchmark_bytes_processed = 0; + +void ResetBenchmarkTiming() { + benchmark_real_time_us = 0; + benchmark_cpu_time_us = 0; +} + +#ifdef WIN32 +LARGE_INTEGER benchmark_start_real; +FILETIME benchmark_start_cpu; +#else // WIN32 +struct timeval benchmark_start_real; +struct rusage benchmark_start_cpu; +#endif // WIN32 + +void StartBenchmarkTiming() { +#ifdef WIN32 + QueryPerformanceCounter(&benchmark_start_real); + FILETIME dummy; + CHECK(GetProcessTimes( + GetCurrentProcess(), &dummy, &dummy, &dummy, &benchmark_start_cpu)); +#else + gettimeofday(&benchmark_start_real, NULL); + if (getrusage(RUSAGE_SELF, &benchmark_start_cpu) == -1) { + perror("getrusage(RUSAGE_SELF)"); + exit(1); + } +#endif + benchmark_running = true; +} + +void StopBenchmarkTiming() { + if (!benchmark_running) { + return; + } + +#ifdef WIN32 + LARGE_INTEGER benchmark_stop_real; + LARGE_INTEGER benchmark_frequency; + QueryPerformanceCounter(&benchmark_stop_real); + QueryPerformanceFrequency(&benchmark_frequency); + + double elapsed_real = static_cast<double>( + benchmark_stop_real.QuadPart - benchmark_start_real.QuadPart) / + benchmark_frequency.QuadPart; + benchmark_real_time_us += elapsed_real * 1e6 + 0.5; + + FILETIME benchmark_stop_cpu, dummy; + CHECK(GetProcessTimes( + GetCurrentProcess(), &dummy, &dummy, &dummy, &benchmark_stop_cpu)); + + ULARGE_INTEGER start_ulargeint; + start_ulargeint.LowPart = benchmark_start_cpu.dwLowDateTime; + start_ulargeint.HighPart = benchmark_start_cpu.dwHighDateTime; + + ULARGE_INTEGER stop_ulargeint; + stop_ulargeint.LowPart = benchmark_stop_cpu.dwLowDateTime; + stop_ulargeint.HighPart = benchmark_stop_cpu.dwHighDateTime; + + benchmark_cpu_time_us += + (stop_ulargeint.QuadPart - start_ulargeint.QuadPart + 5) / 10; +#else // WIN32 + struct timeval benchmark_stop_real; + gettimeofday(&benchmark_stop_real, NULL); + benchmark_real_time_us += + 1000000 * (benchmark_stop_real.tv_sec - benchmark_start_real.tv_sec); + benchmark_real_time_us += + (benchmark_stop_real.tv_usec - benchmark_start_real.tv_usec); + + struct rusage benchmark_stop_cpu; + if (getrusage(RUSAGE_SELF, &benchmark_stop_cpu) == -1) { + perror("getrusage(RUSAGE_SELF)"); + exit(1); + } + benchmark_cpu_time_us += 1000000 * (benchmark_stop_cpu.ru_utime.tv_sec - + benchmark_start_cpu.ru_utime.tv_sec); + benchmark_cpu_time_us += (benchmark_stop_cpu.ru_utime.tv_usec - + benchmark_start_cpu.ru_utime.tv_usec); +#endif // WIN32 + + benchmark_running = false; +} + +void SetBenchmarkLabel(const string& str) { + if (benchmark_label) { + delete benchmark_label; + } + benchmark_label = new string(str); +} + +void SetBenchmarkBytesProcessed(int64 bytes) { + benchmark_bytes_processed = bytes; +} + +struct BenchmarkRun { + int64 real_time_us; + int64 cpu_time_us; +}; + +struct BenchmarkCompareCPUTime { + bool operator() (const BenchmarkRun& a, const BenchmarkRun& b) const { + return a.cpu_time_us < b.cpu_time_us; + } +}; + +void Benchmark::Run() { + for (int test_case_num = start_; test_case_num <= stop_; ++test_case_num) { + // Run a few iterations first to find out approximately how fast + // the benchmark is. + const int kCalibrateIterations = 100; + ResetBenchmarkTiming(); + StartBenchmarkTiming(); + (*function_)(kCalibrateIterations, test_case_num); + StopBenchmarkTiming(); + + // Let each test case run for about 200ms, but at least as many + // as we used to calibrate. + // Run five times and pick the median. + const int kNumRuns = 5; + const int kMedianPos = kNumRuns / 2; + int num_iterations = 0; + if (benchmark_real_time_us > 0) { + num_iterations = 200000 * kCalibrateIterations / benchmark_real_time_us; + } + num_iterations = max(num_iterations, kCalibrateIterations); + BenchmarkRun benchmark_runs[kNumRuns]; + + for (int run = 0; run < kNumRuns; ++run) { + ResetBenchmarkTiming(); + StartBenchmarkTiming(); + (*function_)(num_iterations, test_case_num); + StopBenchmarkTiming(); + + benchmark_runs[run].real_time_us = benchmark_real_time_us; + benchmark_runs[run].cpu_time_us = benchmark_cpu_time_us; + } + + string heading = StringPrintf("%s/%d", name_.c_str(), test_case_num); + string human_readable_speed; + + nth_element(benchmark_runs, + benchmark_runs + kMedianPos, + benchmark_runs + kNumRuns, + BenchmarkCompareCPUTime()); + int64 real_time_us = benchmark_runs[kMedianPos].real_time_us; + int64 cpu_time_us = benchmark_runs[kMedianPos].cpu_time_us; + if (cpu_time_us <= 0) { + human_readable_speed = "?"; + } else { + int64 bytes_per_second = + benchmark_bytes_processed * 1000000 / cpu_time_us; + if (bytes_per_second < 1024) { + human_readable_speed = StringPrintf("%dB/s", bytes_per_second); + } else if (bytes_per_second < 1024 * 1024) { + human_readable_speed = StringPrintf( + "%.1fkB/s", bytes_per_second / 1024.0f); + } else if (bytes_per_second < 1024 * 1024 * 1024) { + human_readable_speed = StringPrintf( + "%.1fMB/s", bytes_per_second / (1024.0f * 1024.0f)); + } else { + human_readable_speed = StringPrintf( + "%.1fGB/s", bytes_per_second / (1024.0f * 1024.0f * 1024.0f)); + } + } + + fprintf(stderr, +#ifdef WIN32 + "%-18s %10I64d %10I64d %10d %s %s\n", +#else + "%-18s %10lld %10lld %10d %s %s\n", +#endif + heading.c_str(), + static_cast<long long>(real_time_us * 1000 / num_iterations), + static_cast<long long>(cpu_time_us * 1000 / num_iterations), + num_iterations, + human_readable_speed.c_str(), + benchmark_label->c_str()); + } +} + +#ifdef HAVE_LIBZ + +ZLib::ZLib() + : comp_init_(false), + uncomp_init_(false) { + Reinit(); +} + +ZLib::~ZLib() { + if (comp_init_) { deflateEnd(&comp_stream_); } + if (uncomp_init_) { inflateEnd(&uncomp_stream_); } +} + +void ZLib::Reinit() { + compression_level_ = Z_DEFAULT_COMPRESSION; + window_bits_ = MAX_WBITS; + mem_level_ = 8; // DEF_MEM_LEVEL + if (comp_init_) { + deflateEnd(&comp_stream_); + comp_init_ = false; + } + if (uncomp_init_) { + inflateEnd(&uncomp_stream_); + uncomp_init_ = false; + } + first_chunk_ = true; +} + +void ZLib::Reset() { + first_chunk_ = true; +} + +// --------- COMPRESS MODE + +// Initialization method to be called if we hit an error while +// compressing. On hitting an error, call this method before returning +// the error. +void ZLib::CompressErrorInit() { + deflateEnd(&comp_stream_); + comp_init_ = false; + Reset(); +} + +int ZLib::DeflateInit() { + return deflateInit2(&comp_stream_, + compression_level_, + Z_DEFLATED, + window_bits_, + mem_level_, + Z_DEFAULT_STRATEGY); +} + +int ZLib::CompressInit(Bytef *dest, uLongf *destLen, + const Bytef *source, uLong *sourceLen) { + int err; + + comp_stream_.next_in = (Bytef*)source; + comp_stream_.avail_in = (uInt)*sourceLen; + if ((uLong)comp_stream_.avail_in != *sourceLen) return Z_BUF_ERROR; + comp_stream_.next_out = dest; + comp_stream_.avail_out = (uInt)*destLen; + if ((uLong)comp_stream_.avail_out != *destLen) return Z_BUF_ERROR; + + if ( !first_chunk_ ) // only need to set up stream the first time through + return Z_OK; + + if (comp_init_) { // we've already initted it + err = deflateReset(&comp_stream_); + if (err != Z_OK) { + LOG(WARNING) << "ERROR: Can't reset compress object; creating a new one"; + deflateEnd(&comp_stream_); + comp_init_ = false; + } + } + if (!comp_init_) { // first use + comp_stream_.zalloc = (alloc_func)0; + comp_stream_.zfree = (free_func)0; + comp_stream_.opaque = (voidpf)0; + err = DeflateInit(); + if (err != Z_OK) return err; + comp_init_ = true; + } + return Z_OK; +} + +// In a perfect world we'd always have the full buffer to compress +// when the time came, and we could just call Compress(). Alas, we +// want to do chunked compression on our webserver. In this +// application, we compress the header, send it off, then compress the +// results, send them off, then compress the footer. Thus we need to +// use the chunked compression features of zlib. +int ZLib::CompressAtMostOrAll(Bytef *dest, uLongf *destLen, + const Bytef *source, uLong *sourceLen, + int flush_mode) { // Z_FULL_FLUSH or Z_FINISH + int err; + + if ( (err=CompressInit(dest, destLen, source, sourceLen)) != Z_OK ) + return err; + + // This is used to figure out how many bytes we wrote *this chunk* + int compressed_size = comp_stream_.total_out; + + // Some setup happens only for the first chunk we compress in a run + if ( first_chunk_ ) { + first_chunk_ = false; + } + + // flush_mode is Z_FINISH for all mode, Z_SYNC_FLUSH for incremental + // compression. + err = deflate(&comp_stream_, flush_mode); + + *sourceLen = comp_stream_.avail_in; + + if ((err == Z_STREAM_END || err == Z_OK) + && comp_stream_.avail_in == 0 + && comp_stream_.avail_out != 0 ) { + // we processed everything ok and the output buffer was large enough. + ; + } else if (err == Z_STREAM_END && comp_stream_.avail_in > 0) { + return Z_BUF_ERROR; // should never happen + } else if (err != Z_OK && err != Z_STREAM_END && err != Z_BUF_ERROR) { + // an error happened + CompressErrorInit(); + return err; + } else if (comp_stream_.avail_out == 0) { // not enough space + err = Z_BUF_ERROR; + } + + assert(err == Z_OK || err == Z_STREAM_END || err == Z_BUF_ERROR); + if (err == Z_STREAM_END) + err = Z_OK; + + // update the crc and other metadata + compressed_size = comp_stream_.total_out - compressed_size; // delta + *destLen = compressed_size; + + return err; +} + +int ZLib::CompressChunkOrAll(Bytef *dest, uLongf *destLen, + const Bytef *source, uLong sourceLen, + int flush_mode) { // Z_FULL_FLUSH or Z_FINISH + const int ret = + CompressAtMostOrAll(dest, destLen, source, &sourceLen, flush_mode); + if (ret == Z_BUF_ERROR) + CompressErrorInit(); + return ret; +} + +// This routine only initializes the compression stream once. Thereafter, it +// just does a deflateReset on the stream, which should be faster. +int ZLib::Compress(Bytef *dest, uLongf *destLen, + const Bytef *source, uLong sourceLen) { + int err; + if ( (err=CompressChunkOrAll(dest, destLen, source, sourceLen, + Z_FINISH)) != Z_OK ) + return err; + Reset(); // reset for next call to Compress + + return Z_OK; +} + + +// --------- UNCOMPRESS MODE + +int ZLib::InflateInit() { + return inflateInit2(&uncomp_stream_, MAX_WBITS); +} + +// Initialization method to be called if we hit an error while +// uncompressing. On hitting an error, call this method before +// returning the error. +void ZLib::UncompressErrorInit() { + inflateEnd(&uncomp_stream_); + uncomp_init_ = false; + Reset(); +} + +int ZLib::UncompressInit(Bytef *dest, uLongf *destLen, + const Bytef *source, uLong *sourceLen) { + int err; + + uncomp_stream_.next_in = (Bytef*)source; + uncomp_stream_.avail_in = (uInt)*sourceLen; + // Check for source > 64K on 16-bit machine: + if ((uLong)uncomp_stream_.avail_in != *sourceLen) return Z_BUF_ERROR; + + uncomp_stream_.next_out = dest; + uncomp_stream_.avail_out = (uInt)*destLen; + if ((uLong)uncomp_stream_.avail_out != *destLen) return Z_BUF_ERROR; + + if ( !first_chunk_ ) // only need to set up stream the first time through + return Z_OK; + + if (uncomp_init_) { // we've already initted it + err = inflateReset(&uncomp_stream_); + if (err != Z_OK) { + LOG(WARNING) + << "ERROR: Can't reset uncompress object; creating a new one"; + UncompressErrorInit(); + } + } + if (!uncomp_init_) { + uncomp_stream_.zalloc = (alloc_func)0; + uncomp_stream_.zfree = (free_func)0; + uncomp_stream_.opaque = (voidpf)0; + err = InflateInit(); + if (err != Z_OK) return err; + uncomp_init_ = true; + } + return Z_OK; +} + +// If you compressed your data a chunk at a time, with CompressChunk, +// you can uncompress it a chunk at a time with UncompressChunk. +// Only difference bewteen chunked and unchunked uncompression +// is the flush mode we use: Z_SYNC_FLUSH (chunked) or Z_FINISH (unchunked). +int ZLib::UncompressAtMostOrAll(Bytef *dest, uLongf *destLen, + const Bytef *source, uLong *sourceLen, + int flush_mode) { // Z_SYNC_FLUSH or Z_FINISH + int err = Z_OK; + + if ( (err=UncompressInit(dest, destLen, source, sourceLen)) != Z_OK ) { + LOG(WARNING) << "UncompressInit: Error: " << err << " SourceLen: " + << *sourceLen; + return err; + } + + // This is used to figure out how many output bytes we wrote *this chunk*: + const uLong old_total_out = uncomp_stream_.total_out; + + // This is used to figure out how many input bytes we read *this chunk*: + const uLong old_total_in = uncomp_stream_.total_in; + + // Some setup happens only for the first chunk we compress in a run + if ( first_chunk_ ) { + first_chunk_ = false; // so we don't do this again + + // For the first chunk *only* (to avoid infinite troubles), we let + // there be no actual data to uncompress. This sometimes triggers + // when the input is only the gzip header, say. + if ( *sourceLen == 0 ) { + *destLen = 0; + return Z_OK; + } + } + + // We'll uncompress as much as we can. If we end OK great, otherwise + // if we get an error that seems to be the gzip footer, we store the + // gzip footer and return OK, otherwise we return the error. + + // flush_mode is Z_SYNC_FLUSH for chunked mode, Z_FINISH for all mode. + err = inflate(&uncomp_stream_, flush_mode); + + // Figure out how many bytes of the input zlib slurped up: + const uLong bytes_read = uncomp_stream_.total_in - old_total_in; + CHECK_LE(source + bytes_read, source + *sourceLen); + *sourceLen = uncomp_stream_.avail_in; + + if ((err == Z_STREAM_END || err == Z_OK) // everything went ok + && uncomp_stream_.avail_in == 0) { // and we read it all + ; + } else if (err == Z_STREAM_END && uncomp_stream_.avail_in > 0) { + LOG(WARNING) + << "UncompressChunkOrAll: Received some extra data, bytes total: " + << uncomp_stream_.avail_in << " bytes: " + << string(reinterpret_cast<const char *>(uncomp_stream_.next_in), + min(int(uncomp_stream_.avail_in), 20)); + UncompressErrorInit(); + return Z_DATA_ERROR; // what's the extra data for? + } else if (err != Z_OK && err != Z_STREAM_END && err != Z_BUF_ERROR) { + // an error happened + LOG(WARNING) << "UncompressChunkOrAll: Error: " << err + << " avail_out: " << uncomp_stream_.avail_out; + UncompressErrorInit(); + return err; + } else if (uncomp_stream_.avail_out == 0) { + err = Z_BUF_ERROR; + } + + assert(err == Z_OK || err == Z_BUF_ERROR || err == Z_STREAM_END); + if (err == Z_STREAM_END) + err = Z_OK; + + *destLen = uncomp_stream_.total_out - old_total_out; // size for this call + + return err; +} + +int ZLib::UncompressChunkOrAll(Bytef *dest, uLongf *destLen, + const Bytef *source, uLong sourceLen, + int flush_mode) { // Z_SYNC_FLUSH or Z_FINISH + const int ret = + UncompressAtMostOrAll(dest, destLen, source, &sourceLen, flush_mode); + if (ret == Z_BUF_ERROR) + UncompressErrorInit(); + return ret; +} + +int ZLib::UncompressAtMost(Bytef *dest, uLongf *destLen, + const Bytef *source, uLong *sourceLen) { + return UncompressAtMostOrAll(dest, destLen, source, sourceLen, Z_SYNC_FLUSH); +} + +// We make sure we've uncompressed everything, that is, the current +// uncompress stream is at a compressed-buffer-EOF boundary. In gzip +// mode, we also check the gzip footer to make sure we pass the gzip +// consistency checks. We RETURN true iff both types of checks pass. +bool ZLib::UncompressChunkDone() { + assert(!first_chunk_ && uncomp_init_); + // Make sure we're at the end-of-compressed-data point. This means + // if we call inflate with Z_FINISH we won't consume any input or + // write any output + Bytef dummyin, dummyout; + uLongf dummylen = 0; + if ( UncompressChunkOrAll(&dummyout, &dummylen, &dummyin, 0, Z_FINISH) + != Z_OK ) { + return false; + } + + // Make sure that when we exit, we can start a new round of chunks later + Reset(); + + return true; +} + +// Uncompresses the source buffer into the destination buffer. +// The destination buffer must be long enough to hold the entire +// decompressed contents. +// +// We only initialize the uncomp_stream once. Thereafter, we use +// inflateReset, which should be faster. +// +// Returns Z_OK on success, otherwise, it returns a zlib error code. +int ZLib::Uncompress(Bytef *dest, uLongf *destLen, + const Bytef *source, uLong sourceLen) { + int err; + if ( (err=UncompressChunkOrAll(dest, destLen, source, sourceLen, + Z_FINISH)) != Z_OK ) { + Reset(); // let us try to compress again + return err; + } + if ( !UncompressChunkDone() ) // calls Reset() + return Z_DATA_ERROR; + return Z_OK; // stream_end is ok +} + +#endif // HAVE_LIBZ + +} // namespace snappy
http://git-wip-us.apache.org/repos/asf/hadoop/blob/cb5ba73b/hadoop-hdfs-project/hadoop-hdfsdb/src/main/native/snappy/snappy-test.h ---------------------------------------------------------------------- diff --git a/hadoop-hdfs-project/hadoop-hdfsdb/src/main/native/snappy/snappy-test.h b/hadoop-hdfs-project/hadoop-hdfsdb/src/main/native/snappy/snappy-test.h new file mode 100644 index 0000000..0f18bf1 --- /dev/null +++ b/hadoop-hdfs-project/hadoop-hdfsdb/src/main/native/snappy/snappy-test.h @@ -0,0 +1,582 @@ +// Copyright 2011 Google Inc. All Rights Reserved. +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are +// met: +// +// * Redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer. +// * Redistributions in binary form must reproduce the above +// copyright notice, this list of conditions and the following disclaimer +// in the documentation and/or other materials provided with the +// distribution. +// * Neither the name of Google Inc. nor the names of its +// contributors may be used to endorse or promote products derived from +// this software without specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. +// +// Various stubs for the unit tests for the open-source version of Snappy. + +#ifndef UTIL_SNAPPY_OPENSOURCE_SNAPPY_TEST_H_ +#define UTIL_SNAPPY_OPENSOURCE_SNAPPY_TEST_H_ + +#include <iostream> +#include <string> + +#include "snappy-stubs-internal.h" + +#include <stdio.h> +#include <stdarg.h> + +#ifdef HAVE_SYS_MMAN_H +#include <sys/mman.h> +#endif + +#ifdef HAVE_SYS_RESOURCE_H +#include <sys/resource.h> +#endif + +#ifdef HAVE_SYS_TIME_H +#include <sys/time.h> +#endif + +#ifdef HAVE_WINDOWS_H +#define WIN32_LEAN_AND_MEAN +#include <windows.h> +#endif + +#include <string> + +#ifdef HAVE_GTEST + +#include <gtest/gtest.h> +#undef TYPED_TEST +#define TYPED_TEST TEST +#define INIT_GTEST(argc, argv) ::testing::InitGoogleTest(argc, *argv) + +#else + +// Stubs for if the user doesn't have Google Test installed. + +#define TEST(test_case, test_subcase) \ + void Test_ ## test_case ## _ ## test_subcase() +#define INIT_GTEST(argc, argv) + +#define TYPED_TEST TEST +#define EXPECT_EQ CHECK_EQ +#define EXPECT_NE CHECK_NE +#define EXPECT_FALSE(cond) CHECK(!(cond)) + +#endif + +#ifdef HAVE_GFLAGS + +#include <gflags/gflags.h> + +// This is tricky; both gflags and Google Test want to look at the command line +// arguments. Google Test seems to be the most happy with unknown arguments, +// though, so we call it first and hope for the best. +#define InitGoogle(argv0, argc, argv, remove_flags) \ + INIT_GTEST(argc, argv); \ + google::ParseCommandLineFlags(argc, argv, remove_flags); + +#else + +// If we don't have the gflags package installed, these can only be +// changed at compile time. +#define DEFINE_int32(flag_name, default_value, description) \ + static int FLAGS_ ## flag_name = default_value; + +#define InitGoogle(argv0, argc, argv, remove_flags) \ + INIT_GTEST(argc, argv) + +#endif + +#ifdef HAVE_LIBZ +#include "zlib.h" +#endif + +#ifdef HAVE_LIBLZO2 +#include "lzo/lzo1x.h" +#endif + +#ifdef HAVE_LIBLZF +extern "C" { +#include "lzf.h" +} +#endif + +#ifdef HAVE_LIBFASTLZ +#include "fastlz.h" +#endif + +#ifdef HAVE_LIBQUICKLZ +#include "quicklz.h" +#endif + +namespace { + +namespace File { + void Init() { } +} // namespace File + +namespace file { + int Defaults() { } + + class DummyStatus { + public: + void CheckSuccess() { } + }; + + DummyStatus GetContents(const string& filename, string* data, int unused) { + FILE* fp = fopen(filename.c_str(), "rb"); + if (fp == NULL) { + perror(filename.c_str()); + exit(1); + } + + data->clear(); + while (!feof(fp)) { + char buf[4096]; + size_t ret = fread(buf, 1, 4096, fp); + if (ret == 0 && ferror(fp)) { + perror("fread"); + exit(1); + } + data->append(string(buf, ret)); + } + + fclose(fp); + } + + DummyStatus SetContents(const string& filename, + const string& str, + int unused) { + FILE* fp = fopen(filename.c_str(), "wb"); + if (fp == NULL) { + perror(filename.c_str()); + exit(1); + } + + int ret = fwrite(str.data(), str.size(), 1, fp); + if (ret != 1) { + perror("fwrite"); + exit(1); + } + + fclose(fp); + } +} // namespace file + +} // namespace + +namespace snappy { + +#define FLAGS_test_random_seed 301 +typedef string TypeParam; + +void Test_CorruptedTest_VerifyCorrupted(); +void Test_Snappy_SimpleTests(); +void Test_Snappy_MaxBlowup(); +void Test_Snappy_RandomData(); +void Test_Snappy_FourByteOffset(); +void Test_SnappyCorruption_TruncatedVarint(); +void Test_SnappyCorruption_UnterminatedVarint(); +void Test_Snappy_ReadPastEndOfBuffer(); +void Test_Snappy_FindMatchLength(); +void Test_Snappy_FindMatchLengthRandom(); + +string ReadTestDataFile(const string& base, size_t size_limit); + +string ReadTestDataFile(const string& base); + +// A sprintf() variant that returns a std::string. +// Not safe for general use due to truncation issues. +string StringPrintf(const char* format, ...); + +// A simple, non-cryptographically-secure random generator. +class ACMRandom { + public: + explicit ACMRandom(uint32 seed) : seed_(seed) {} + + int32 Next(); + + int32 Uniform(int32 n) { + return Next() % n; + } + uint8 Rand8() { + return static_cast<uint8>((Next() >> 1) & 0x000000ff); + } + bool OneIn(int X) { return Uniform(X) == 0; } + + // Skewed: pick "base" uniformly from range [0,max_log] and then + // return "base" random bits. The effect is to pick a number in the + // range [0,2^max_log-1] with bias towards smaller numbers. + int32 Skewed(int max_log); + + private: + static const uint32 M = 2147483647L; // 2^31-1 + uint32 seed_; +}; + +inline int32 ACMRandom::Next() { + static const uint64 A = 16807; // bits 14, 8, 7, 5, 2, 1, 0 + // We are computing + // seed_ = (seed_ * A) % M, where M = 2^31-1 + // + // seed_ must not be zero or M, or else all subsequent computed values + // will be zero or M respectively. For all other values, seed_ will end + // up cycling through every number in [1,M-1] + uint64 product = seed_ * A; + + // Compute (product % M) using the fact that ((x << 31) % M) == x. + seed_ = (product >> 31) + (product & M); + // The first reduction may overflow by 1 bit, so we may need to repeat. + // mod == M is not possible; using > allows the faster sign-bit-based test. + if (seed_ > M) { + seed_ -= M; + } + return seed_; +} + +inline int32 ACMRandom::Skewed(int max_log) { + const int32 base = (Next() - 1) % (max_log+1); + return (Next() - 1) & ((1u << base)-1); +} + +// A wall-time clock. This stub is not super-accurate, nor resistant to the +// system time changing. +class CycleTimer { + public: + CycleTimer() : real_time_us_(0) {} + + void Start() { +#ifdef WIN32 + QueryPerformanceCounter(&start_); +#else + gettimeofday(&start_, NULL); +#endif + } + + void Stop() { +#ifdef WIN32 + LARGE_INTEGER stop; + LARGE_INTEGER frequency; + QueryPerformanceCounter(&stop); + QueryPerformanceFrequency(&frequency); + + double elapsed = static_cast<double>(stop.QuadPart - start_.QuadPart) / + frequency.QuadPart; + real_time_us_ += elapsed * 1e6 + 0.5; +#else + struct timeval stop; + gettimeofday(&stop, NULL); + + real_time_us_ += 1000000 * (stop.tv_sec - start_.tv_sec); + real_time_us_ += (stop.tv_usec - start_.tv_usec); +#endif + } + + double Get() { + return real_time_us_ * 1e-6; + } + + private: + int64 real_time_us_; +#ifdef WIN32 + LARGE_INTEGER start_; +#else + struct timeval start_; +#endif +}; + +// Minimalistic microbenchmark framework. + +typedef void (*BenchmarkFunction)(int, int); + +class Benchmark { + public: + Benchmark(const string& name, BenchmarkFunction function) : + name_(name), function_(function) {} + + Benchmark* DenseRange(int start, int stop) { + start_ = start; + stop_ = stop; + return this; + } + + void Run(); + + private: + const string name_; + const BenchmarkFunction function_; + int start_, stop_; +}; +#define BENCHMARK(benchmark_name) \ + Benchmark* Benchmark_ ## benchmark_name = \ + (new Benchmark(#benchmark_name, benchmark_name)) + +extern Benchmark* Benchmark_BM_UFlat; +extern Benchmark* Benchmark_BM_UIOVec; +extern Benchmark* Benchmark_BM_UValidate; +extern Benchmark* Benchmark_BM_ZFlat; + +void ResetBenchmarkTiming(); +void StartBenchmarkTiming(); +void StopBenchmarkTiming(); +void SetBenchmarkLabel(const string& str); +void SetBenchmarkBytesProcessed(int64 bytes); + +#ifdef HAVE_LIBZ + +// Object-oriented wrapper around zlib. +class ZLib { + public: + ZLib(); + ~ZLib(); + + // Wipe a ZLib object to a virgin state. This differs from Reset() + // in that it also breaks any state. + void Reinit(); + + // Call this to make a zlib buffer as good as new. Here's the only + // case where they differ: + // CompressChunk(a); CompressChunk(b); CompressChunkDone(); vs + // CompressChunk(a); Reset(); CompressChunk(b); CompressChunkDone(); + // You'll want to use Reset(), then, when you interrupt a compress + // (or uncompress) in the middle of a chunk and want to start over. + void Reset(); + + // According to the zlib manual, when you Compress, the destination + // buffer must have size at least src + .1%*src + 12. This function + // helps you calculate that. Augment this to account for a potential + // gzip header and footer, plus a few bytes of slack. + static int MinCompressbufSize(int uncompress_size) { + return uncompress_size + uncompress_size/1000 + 40; + } + + // Compresses the source buffer into the destination buffer. + // sourceLen is the byte length of the source buffer. + // Upon entry, destLen is the total size of the destination buffer, + // which must be of size at least MinCompressbufSize(sourceLen). + // Upon exit, destLen is the actual size of the compressed buffer. + // + // This function can be used to compress a whole file at once if the + // input file is mmap'ed. + // + // Returns Z_OK if success, Z_MEM_ERROR if there was not + // enough memory, Z_BUF_ERROR if there was not enough room in the + // output buffer. Note that if the output buffer is exactly the same + // size as the compressed result, we still return Z_BUF_ERROR. + // (check CL#1936076) + int Compress(Bytef *dest, uLongf *destLen, + const Bytef *source, uLong sourceLen); + + // Uncompresses the source buffer into the destination buffer. + // The destination buffer must be long enough to hold the entire + // decompressed contents. + // + // Returns Z_OK on success, otherwise, it returns a zlib error code. + int Uncompress(Bytef *dest, uLongf *destLen, + const Bytef *source, uLong sourceLen); + + // Uncompress data one chunk at a time -- ie you can call this + // more than once. To get this to work you need to call per-chunk + // and "done" routines. + // + // Returns Z_OK if success, Z_MEM_ERROR if there was not + // enough memory, Z_BUF_ERROR if there was not enough room in the + // output buffer. + + int UncompressAtMost(Bytef *dest, uLongf *destLen, + const Bytef *source, uLong *sourceLen); + + // Checks gzip footer information, as needed. Mostly this just + // makes sure the checksums match. Whenever you call this, it + // will assume the last 8 bytes from the previous UncompressChunk + // call are the footer. Returns true iff everything looks ok. + bool UncompressChunkDone(); + + private: + int InflateInit(); // sets up the zlib inflate structure + int DeflateInit(); // sets up the zlib deflate structure + + // These init the zlib data structures for compressing/uncompressing + int CompressInit(Bytef *dest, uLongf *destLen, + const Bytef *source, uLong *sourceLen); + int UncompressInit(Bytef *dest, uLongf *destLen, + const Bytef *source, uLong *sourceLen); + // Initialization method to be called if we hit an error while + // uncompressing. On hitting an error, call this method before + // returning the error. + void UncompressErrorInit(); + + // Helper function for Compress + int CompressChunkOrAll(Bytef *dest, uLongf *destLen, + const Bytef *source, uLong sourceLen, + int flush_mode); + int CompressAtMostOrAll(Bytef *dest, uLongf *destLen, + const Bytef *source, uLong *sourceLen, + int flush_mode); + + // Likewise for UncompressAndUncompressChunk + int UncompressChunkOrAll(Bytef *dest, uLongf *destLen, + const Bytef *source, uLong sourceLen, + int flush_mode); + + int UncompressAtMostOrAll(Bytef *dest, uLongf *destLen, + const Bytef *source, uLong *sourceLen, + int flush_mode); + + // Initialization method to be called if we hit an error while + // compressing. On hitting an error, call this method before + // returning the error. + void CompressErrorInit(); + + int compression_level_; // compression level + int window_bits_; // log base 2 of the window size used in compression + int mem_level_; // specifies the amount of memory to be used by + // compressor (1-9) + z_stream comp_stream_; // Zlib stream data structure + bool comp_init_; // True if we have initialized comp_stream_ + z_stream uncomp_stream_; // Zlib stream data structure + bool uncomp_init_; // True if we have initialized uncomp_stream_ + + // These are used only with chunked compression. + bool first_chunk_; // true if we need to emit headers with this chunk +}; + +#endif // HAVE_LIBZ + +} // namespace snappy + +DECLARE_bool(run_microbenchmarks); + +static void RunSpecifiedBenchmarks() { + if (!FLAGS_run_microbenchmarks) { + return; + } + + fprintf(stderr, "Running microbenchmarks.\n"); +#ifndef NDEBUG + fprintf(stderr, "WARNING: Compiled with assertions enabled, will be slow.\n"); +#endif +#ifndef __OPTIMIZE__ + fprintf(stderr, "WARNING: Compiled without optimization, will be slow.\n"); +#endif + fprintf(stderr, "Benchmark Time(ns) CPU(ns) Iterations\n"); + fprintf(stderr, "---------------------------------------------------\n"); + + snappy::Benchmark_BM_UFlat->Run(); + snappy::Benchmark_BM_UIOVec->Run(); + snappy::Benchmark_BM_UValidate->Run(); + snappy::Benchmark_BM_ZFlat->Run(); + + fprintf(stderr, "\n"); +} + +#ifndef HAVE_GTEST + +static inline int RUN_ALL_TESTS() { + fprintf(stderr, "Running correctness tests.\n"); + snappy::Test_CorruptedTest_VerifyCorrupted(); + snappy::Test_Snappy_SimpleTests(); + snappy::Test_Snappy_MaxBlowup(); + snappy::Test_Snappy_RandomData(); + snappy::Test_Snappy_FourByteOffset(); + snappy::Test_SnappyCorruption_TruncatedVarint(); + snappy::Test_SnappyCorruption_UnterminatedVarint(); + snappy::Test_Snappy_ReadPastEndOfBuffer(); + snappy::Test_Snappy_FindMatchLength(); + snappy::Test_Snappy_FindMatchLengthRandom(); + fprintf(stderr, "All tests passed.\n"); + + return 0; +} + +#endif // HAVE_GTEST + +// For main(). +namespace snappy { + +static void CompressFile(const char* fname); +static void UncompressFile(const char* fname); +static void MeasureFile(const char* fname); + +// Logging. + +#define LOG(level) LogMessage() +#define VLOG(level) true ? (void)0 : \ + snappy::LogMessageVoidify() & snappy::LogMessage() + +class LogMessage { + public: + LogMessage() { } + ~LogMessage() { + cerr << endl; + } + + LogMessage& operator<<(const std::string& msg) { + cerr << msg; + return *this; + } + LogMessage& operator<<(int x) { + cerr << x; + return *this; + } +}; + +// Asserts, both versions activated in debug mode only, +// and ones that are always active. + +#define CRASH_UNLESS(condition) \ + PREDICT_TRUE(condition) ? (void)0 : \ + snappy::LogMessageVoidify() & snappy::LogMessageCrash() + +class LogMessageCrash : public LogMessage { + public: + LogMessageCrash() { } + ~LogMessageCrash() { + cerr << endl; + abort(); + } +}; + +// This class is used to explicitly ignore values in the conditional +// logging macros. This avoids compiler warnings like "value computed +// is not used" and "statement has no effect". + +class LogMessageVoidify { + public: + LogMessageVoidify() { } + // This has to be an operator with a precedence lower than << but + // higher than ?: + void operator&(const LogMessage&) { } +}; + +#define CHECK(cond) CRASH_UNLESS(cond) +#define CHECK_LE(a, b) CRASH_UNLESS((a) <= (b)) +#define CHECK_GE(a, b) CRASH_UNLESS((a) >= (b)) +#define CHECK_EQ(a, b) CRASH_UNLESS((a) == (b)) +#define CHECK_NE(a, b) CRASH_UNLESS((a) != (b)) +#define CHECK_LT(a, b) CRASH_UNLESS((a) < (b)) +#define CHECK_GT(a, b) CRASH_UNLESS((a) > (b)) + +} // namespace + +using snappy::CompressFile; +using snappy::UncompressFile; +using snappy::MeasureFile; + +#endif // UTIL_SNAPPY_OPENSOURCE_SNAPPY_TEST_H_ http://git-wip-us.apache.org/repos/asf/hadoop/blob/cb5ba73b/hadoop-hdfs-project/hadoop-hdfsdb/src/main/native/snappy/snappy.cc ---------------------------------------------------------------------- diff --git a/hadoop-hdfs-project/hadoop-hdfsdb/src/main/native/snappy/snappy.cc b/hadoop-hdfs-project/hadoop-hdfsdb/src/main/native/snappy/snappy.cc new file mode 100644 index 0000000..f8d0d23 --- /dev/null +++ b/hadoop-hdfs-project/hadoop-hdfsdb/src/main/native/snappy/snappy.cc @@ -0,0 +1,1306 @@ +// Copyright 2005 Google Inc. All Rights Reserved. +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are +// met: +// +// * Redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer. +// * Redistributions in binary form must reproduce the above +// copyright notice, this list of conditions and the following disclaimer +// in the documentation and/or other materials provided with the +// distribution. +// * Neither the name of Google Inc. nor the names of its +// contributors may be used to endorse or promote products derived from +// this software without specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +#include "snappy.h" +#include "snappy-internal.h" +#include "snappy-sinksource.h" + +#include <stdio.h> + +#include <algorithm> +#include <string> +#include <vector> + + +namespace snappy { + +// Any hash function will produce a valid compressed bitstream, but a good +// hash function reduces the number of collisions and thus yields better +// compression for compressible input, and more speed for incompressible +// input. Of course, it doesn't hurt if the hash function is reasonably fast +// either, as it gets called a lot. +static inline uint32 HashBytes(uint32 bytes, int shift) { + uint32 kMul = 0x1e35a7bd; + return (bytes * kMul) >> shift; +} +static inline uint32 Hash(const char* p, int shift) { + return HashBytes(UNALIGNED_LOAD32(p), shift); +} + +size_t MaxCompressedLength(size_t source_len) { + // Compressed data can be defined as: + // compressed := item* literal* + // item := literal* copy + // + // The trailing literal sequence has a space blowup of at most 62/60 + // since a literal of length 60 needs one tag byte + one extra byte + // for length information. + // + // Item blowup is trickier to measure. Suppose the "copy" op copies + // 4 bytes of data. Because of a special check in the encoding code, + // we produce a 4-byte copy only if the offset is < 65536. Therefore + // the copy op takes 3 bytes to encode, and this type of item leads + // to at most the 62/60 blowup for representing literals. + // + // Suppose the "copy" op copies 5 bytes of data. If the offset is big + // enough, it will take 5 bytes to encode the copy op. Therefore the + // worst case here is a one-byte literal followed by a five-byte copy. + // I.e., 6 bytes of input turn into 7 bytes of "compressed" data. + // + // This last factor dominates the blowup, so the final estimate is: + return 32 + source_len + source_len/6; +} + +enum { + LITERAL = 0, + COPY_1_BYTE_OFFSET = 1, // 3 bit length + 3 bits of offset in opcode + COPY_2_BYTE_OFFSET = 2, + COPY_4_BYTE_OFFSET = 3 +}; +static const int kMaximumTagLength = 5; // COPY_4_BYTE_OFFSET plus the actual offset. + +// Copy "len" bytes from "src" to "op", one byte at a time. Used for +// handling COPY operations where the input and output regions may +// overlap. For example, suppose: +// src == "ab" +// op == src + 2 +// len == 20 +// After IncrementalCopy(src, op, len), the result will have +// eleven copies of "ab" +// ababababababababababab +// Note that this does not match the semantics of either memcpy() +// or memmove(). +static inline void IncrementalCopy(const char* src, char* op, ssize_t len) { + assert(len > 0); + do { + *op++ = *src++; + } while (--len > 0); +} + +// Equivalent to IncrementalCopy except that it can write up to ten extra +// bytes after the end of the copy, and that it is faster. +// +// The main part of this loop is a simple copy of eight bytes at a time until +// we've copied (at least) the requested amount of bytes. However, if op and +// src are less than eight bytes apart (indicating a repeating pattern of +// length < 8), we first need to expand the pattern in order to get the correct +// results. For instance, if the buffer looks like this, with the eight-byte +// <src> and <op> patterns marked as intervals: +// +// abxxxxxxxxxxxx +// [------] src +// [------] op +// +// a single eight-byte copy from <src> to <op> will repeat the pattern once, +// after which we can move <op> two bytes without moving <src>: +// +// ababxxxxxxxxxx +// [------] src +// [------] op +// +// and repeat the exercise until the two no longer overlap. +// +// This allows us to do very well in the special case of one single byte +// repeated many times, without taking a big hit for more general cases. +// +// The worst case of extra writing past the end of the match occurs when +// op - src == 1 and len == 1; the last copy will read from byte positions +// [0..7] and write to [4..11], whereas it was only supposed to write to +// position 1. Thus, ten excess bytes. + +namespace { + +const int kMaxIncrementCopyOverflow = 10; + +inline void IncrementalCopyFastPath(const char* src, char* op, ssize_t len) { + while (op - src < 8) { + UnalignedCopy64(src, op); + len -= op - src; + op += op - src; + } + while (len > 0) { + UnalignedCopy64(src, op); + src += 8; + op += 8; + len -= 8; + } +} + +} // namespace + +static inline char* EmitLiteral(char* op, + const char* literal, + int len, + bool allow_fast_path) { + int n = len - 1; // Zero-length literals are disallowed + if (n < 60) { + // Fits in tag byte + *op++ = LITERAL | (n << 2); + + // The vast majority of copies are below 16 bytes, for which a + // call to memcpy is overkill. This fast path can sometimes + // copy up to 15 bytes too much, but that is okay in the + // main loop, since we have a bit to go on for both sides: + // + // - The input will always have kInputMarginBytes = 15 extra + // available bytes, as long as we're in the main loop, and + // if not, allow_fast_path = false. + // - The output will always have 32 spare bytes (see + // MaxCompressedLength). + if (allow_fast_path && len <= 16) { + UnalignedCopy64(literal, op); + UnalignedCopy64(literal + 8, op + 8); + return op + len; + } + } else { + // Encode in upcoming bytes + char* base = op; + int count = 0; + op++; + while (n > 0) { + *op++ = n & 0xff; + n >>= 8; + count++; + } + assert(count >= 1); + assert(count <= 4); + *base = LITERAL | ((59+count) << 2); + } + memcpy(op, literal, len); + return op + len; +} + +static inline char* EmitCopyLessThan64(char* op, size_t offset, int len) { + assert(len <= 64); + assert(len >= 4); + assert(offset < 65536); + + if ((len < 12) && (offset < 2048)) { + size_t len_minus_4 = len - 4; + assert(len_minus_4 < 8); // Must fit in 3 bits + *op++ = COPY_1_BYTE_OFFSET + ((len_minus_4) << 2) + ((offset >> 8) << 5); + *op++ = offset & 0xff; + } else { + *op++ = COPY_2_BYTE_OFFSET + ((len-1) << 2); + LittleEndian::Store16(op, offset); + op += 2; + } + return op; +} + +static inline char* EmitCopy(char* op, size_t offset, int len) { + // Emit 64 byte copies but make sure to keep at least four bytes reserved + while (len >= 68) { + op = EmitCopyLessThan64(op, offset, 64); + len -= 64; + } + + // Emit an extra 60 byte copy if have too much data to fit in one copy + if (len > 64) { + op = EmitCopyLessThan64(op, offset, 60); + len -= 60; + } + + // Emit remainder + op = EmitCopyLessThan64(op, offset, len); + return op; +} + + +bool GetUncompressedLength(const char* start, size_t n, size_t* result) { + uint32 v = 0; + const char* limit = start + n; + if (Varint::Parse32WithLimit(start, limit, &v) != NULL) { + *result = v; + return true; + } else { + return false; + } +} + +namespace internal { +uint16* WorkingMemory::GetHashTable(size_t input_size, int* table_size) { + // Use smaller hash table when input.size() is smaller, since we + // fill the table, incurring O(hash table size) overhead for + // compression, and if the input is short, we won't need that + // many hash table entries anyway. + assert(kMaxHashTableSize >= 256); + size_t htsize = 256; + while (htsize < kMaxHashTableSize && htsize < input_size) { + htsize <<= 1; + } + + uint16* table; + if (htsize <= ARRAYSIZE(small_table_)) { + table = small_table_; + } else { + if (large_table_ == NULL) { + large_table_ = new uint16[kMaxHashTableSize]; + } + table = large_table_; + } + + *table_size = htsize; + memset(table, 0, htsize * sizeof(*table)); + return table; +} +} // end namespace internal + +// For 0 <= offset <= 4, GetUint32AtOffset(GetEightBytesAt(p), offset) will +// equal UNALIGNED_LOAD32(p + offset). Motivation: On x86-64 hardware we have +// empirically found that overlapping loads such as +// UNALIGNED_LOAD32(p) ... UNALIGNED_LOAD32(p+1) ... UNALIGNED_LOAD32(p+2) +// are slower than UNALIGNED_LOAD64(p) followed by shifts and casts to uint32. +// +// We have different versions for 64- and 32-bit; ideally we would avoid the +// two functions and just inline the UNALIGNED_LOAD64 call into +// GetUint32AtOffset, but GCC (at least not as of 4.6) is seemingly not clever +// enough to avoid loading the value multiple times then. For 64-bit, the load +// is done when GetEightBytesAt() is called, whereas for 32-bit, the load is +// done at GetUint32AtOffset() time. + +#ifdef ARCH_K8 + +typedef uint64 EightBytesReference; + +static inline EightBytesReference GetEightBytesAt(const char* ptr) { + return UNALIGNED_LOAD64(ptr); +} + +static inline uint32 GetUint32AtOffset(uint64 v, int offset) { + assert(offset >= 0); + assert(offset <= 4); + return v >> (LittleEndian::IsLittleEndian() ? 8 * offset : 32 - 8 * offset); +} + +#else + +typedef const char* EightBytesReference; + +static inline EightBytesReference GetEightBytesAt(const char* ptr) { + return ptr; +} + +static inline uint32 GetUint32AtOffset(const char* v, int offset) { + assert(offset >= 0); + assert(offset <= 4); + return UNALIGNED_LOAD32(v + offset); +} + +#endif + +// Flat array compression that does not emit the "uncompressed length" +// prefix. Compresses "input" string to the "*op" buffer. +// +// REQUIRES: "input" is at most "kBlockSize" bytes long. +// REQUIRES: "op" points to an array of memory that is at least +// "MaxCompressedLength(input.size())" in size. +// REQUIRES: All elements in "table[0..table_size-1]" are initialized to zero. +// REQUIRES: "table_size" is a power of two +// +// Returns an "end" pointer into "op" buffer. +// "end - op" is the compressed size of "input". +namespace internal { +char* CompressFragment(const char* input, + size_t input_size, + char* op, + uint16* table, + const int table_size) { + // "ip" is the input pointer, and "op" is the output pointer. + const char* ip = input; + assert(input_size <= kBlockSize); + assert((table_size & (table_size - 1)) == 0); // table must be power of two + const int shift = 32 - Bits::Log2Floor(table_size); + assert(static_cast<int>(kuint32max >> shift) == table_size - 1); + const char* ip_end = input + input_size; + const char* base_ip = ip; + // Bytes in [next_emit, ip) will be emitted as literal bytes. Or + // [next_emit, ip_end) after the main loop. + const char* next_emit = ip; + + const size_t kInputMarginBytes = 15; + if (PREDICT_TRUE(input_size >= kInputMarginBytes)) { + const char* ip_limit = input + input_size - kInputMarginBytes; + + for (uint32 next_hash = Hash(++ip, shift); ; ) { + assert(next_emit < ip); + // The body of this loop calls EmitLiteral once and then EmitCopy one or + // more times. (The exception is that when we're close to exhausting + // the input we goto emit_remainder.) + // + // In the first iteration of this loop we're just starting, so + // there's nothing to copy, so calling EmitLiteral once is + // necessary. And we only start a new iteration when the + // current iteration has determined that a call to EmitLiteral will + // precede the next call to EmitCopy (if any). + // + // Step 1: Scan forward in the input looking for a 4-byte-long match. + // If we get close to exhausting the input then goto emit_remainder. + // + // Heuristic match skipping: If 32 bytes are scanned with no matches + // found, start looking only at every other byte. If 32 more bytes are + // scanned, look at every third byte, etc.. When a match is found, + // immediately go back to looking at every byte. This is a small loss + // (~5% performance, ~0.1% density) for compressible data due to more + // bookkeeping, but for non-compressible data (such as JPEG) it's a huge + // win since the compressor quickly "realizes" the data is incompressible + // and doesn't bother looking for matches everywhere. + // + // The "skip" variable keeps track of how many bytes there are since the + // last match; dividing it by 32 (ie. right-shifting by five) gives the + // number of bytes to move ahead for each iteration. + uint32 skip = 32; + + const char* next_ip = ip; + const char* candidate; + do { + ip = next_ip; + uint32 hash = next_hash; + assert(hash == Hash(ip, shift)); + uint32 bytes_between_hash_lookups = skip++ >> 5; + next_ip = ip + bytes_between_hash_lookups; + if (PREDICT_FALSE(next_ip > ip_limit)) { + goto emit_remainder; + } + next_hash = Hash(next_ip, shift); + candidate = base_ip + table[hash]; + assert(candidate >= base_ip); + assert(candidate < ip); + + table[hash] = ip - base_ip; + } while (PREDICT_TRUE(UNALIGNED_LOAD32(ip) != + UNALIGNED_LOAD32(candidate))); + + // Step 2: A 4-byte match has been found. We'll later see if more + // than 4 bytes match. But, prior to the match, input + // bytes [next_emit, ip) are unmatched. Emit them as "literal bytes." + assert(next_emit + 16 <= ip_end); + op = EmitLiteral(op, next_emit, ip - next_emit, true); + + // Step 3: Call EmitCopy, and then see if another EmitCopy could + // be our next move. Repeat until we find no match for the + // input immediately after what was consumed by the last EmitCopy call. + // + // If we exit this loop normally then we need to call EmitLiteral next, + // though we don't yet know how big the literal will be. We handle that + // by proceeding to the next iteration of the main loop. We also can exit + // this loop via goto if we get close to exhausting the input. + EightBytesReference input_bytes; + uint32 candidate_bytes = 0; + + do { + // We have a 4-byte match at ip, and no need to emit any + // "literal bytes" prior to ip. + const char* base = ip; + int matched = 4 + FindMatchLength(candidate + 4, ip + 4, ip_end); + ip += matched; + size_t offset = base - candidate; + assert(0 == memcmp(base, candidate, matched)); + op = EmitCopy(op, offset, matched); + // We could immediately start working at ip now, but to improve + // compression we first update table[Hash(ip - 1, ...)]. + const char* insert_tail = ip - 1; + next_emit = ip; + if (PREDICT_FALSE(ip >= ip_limit)) { + goto emit_remainder; + } + input_bytes = GetEightBytesAt(insert_tail); + uint32 prev_hash = HashBytes(GetUint32AtOffset(input_bytes, 0), shift); + table[prev_hash] = ip - base_ip - 1; + uint32 cur_hash = HashBytes(GetUint32AtOffset(input_bytes, 1), shift); + candidate = base_ip + table[cur_hash]; + candidate_bytes = UNALIGNED_LOAD32(candidate); + table[cur_hash] = ip - base_ip; + } while (GetUint32AtOffset(input_bytes, 1) == candidate_bytes); + + next_hash = HashBytes(GetUint32AtOffset(input_bytes, 2), shift); + ++ip; + } + } + + emit_remainder: + // Emit the remaining bytes as a literal + if (next_emit < ip_end) { + op = EmitLiteral(op, next_emit, ip_end - next_emit, false); + } + + return op; +} +} // end namespace internal + +// Signature of output types needed by decompression code. +// The decompression code is templatized on a type that obeys this +// signature so that we do not pay virtual function call overhead in +// the middle of a tight decompression loop. +// +// class DecompressionWriter { +// public: +// // Called before decompression +// void SetExpectedLength(size_t length); +// +// // Called after decompression +// bool CheckLength() const; +// +// // Called repeatedly during decompression +// bool Append(const char* ip, size_t length); +// bool AppendFromSelf(uint32 offset, size_t length); +// +// // The rules for how TryFastAppend differs from Append are somewhat +// // convoluted: +// // +// // - TryFastAppend is allowed to decline (return false) at any +// // time, for any reason -- just "return false" would be +// // a perfectly legal implementation of TryFastAppend. +// // The intention is for TryFastAppend to allow a fast path +// // in the common case of a small append. +// // - TryFastAppend is allowed to read up to <available> bytes +// // from the input buffer, whereas Append is allowed to read +// // <length>. However, if it returns true, it must leave +// // at least five (kMaximumTagLength) bytes in the input buffer +// // afterwards, so that there is always enough space to read the +// // next tag without checking for a refill. +// // - TryFastAppend must always return decline (return false) +// // if <length> is 61 or more, as in this case the literal length is not +// // decoded fully. In practice, this should not be a big problem, +// // as it is unlikely that one would implement a fast path accepting +// // this much data. +// // +// bool TryFastAppend(const char* ip, size_t available, size_t length); +// }; + +// ----------------------------------------------------------------------- +// Lookup table for decompression code. Generated by ComputeTable() below. +// ----------------------------------------------------------------------- + +// Mapping from i in range [0,4] to a mask to extract the bottom 8*i bits +static const uint32 wordmask[] = { + 0u, 0xffu, 0xffffu, 0xffffffu, 0xffffffffu +}; + +// Data stored per entry in lookup table: +// Range Bits-used Description +// ------------------------------------ +// 1..64 0..7 Literal/copy length encoded in opcode byte +// 0..7 8..10 Copy offset encoded in opcode byte / 256 +// 0..4 11..13 Extra bytes after opcode +// +// We use eight bits for the length even though 7 would have sufficed +// because of efficiency reasons: +// (1) Extracting a byte is faster than a bit-field +// (2) It properly aligns copy offset so we do not need a <<8 +static const uint16 char_table[256] = { + 0x0001, 0x0804, 0x1001, 0x2001, 0x0002, 0x0805, 0x1002, 0x2002, + 0x0003, 0x0806, 0x1003, 0x2003, 0x0004, 0x0807, 0x1004, 0x2004, + 0x0005, 0x0808, 0x1005, 0x2005, 0x0006, 0x0809, 0x1006, 0x2006, + 0x0007, 0x080a, 0x1007, 0x2007, 0x0008, 0x080b, 0x1008, 0x2008, + 0x0009, 0x0904, 0x1009, 0x2009, 0x000a, 0x0905, 0x100a, 0x200a, + 0x000b, 0x0906, 0x100b, 0x200b, 0x000c, 0x0907, 0x100c, 0x200c, + 0x000d, 0x0908, 0x100d, 0x200d, 0x000e, 0x0909, 0x100e, 0x200e, + 0x000f, 0x090a, 0x100f, 0x200f, 0x0010, 0x090b, 0x1010, 0x2010, + 0x0011, 0x0a04, 0x1011, 0x2011, 0x0012, 0x0a05, 0x1012, 0x2012, + 0x0013, 0x0a06, 0x1013, 0x2013, 0x0014, 0x0a07, 0x1014, 0x2014, + 0x0015, 0x0a08, 0x1015, 0x2015, 0x0016, 0x0a09, 0x1016, 0x2016, + 0x0017, 0x0a0a, 0x1017, 0x2017, 0x0018, 0x0a0b, 0x1018, 0x2018, + 0x0019, 0x0b04, 0x1019, 0x2019, 0x001a, 0x0b05, 0x101a, 0x201a, + 0x001b, 0x0b06, 0x101b, 0x201b, 0x001c, 0x0b07, 0x101c, 0x201c, + 0x001d, 0x0b08, 0x101d, 0x201d, 0x001e, 0x0b09, 0x101e, 0x201e, + 0x001f, 0x0b0a, 0x101f, 0x201f, 0x0020, 0x0b0b, 0x1020, 0x2020, + 0x0021, 0x0c04, 0x1021, 0x2021, 0x0022, 0x0c05, 0x1022, 0x2022, + 0x0023, 0x0c06, 0x1023, 0x2023, 0x0024, 0x0c07, 0x1024, 0x2024, + 0x0025, 0x0c08, 0x1025, 0x2025, 0x0026, 0x0c09, 0x1026, 0x2026, + 0x0027, 0x0c0a, 0x1027, 0x2027, 0x0028, 0x0c0b, 0x1028, 0x2028, + 0x0029, 0x0d04, 0x1029, 0x2029, 0x002a, 0x0d05, 0x102a, 0x202a, + 0x002b, 0x0d06, 0x102b, 0x202b, 0x002c, 0x0d07, 0x102c, 0x202c, + 0x002d, 0x0d08, 0x102d, 0x202d, 0x002e, 0x0d09, 0x102e, 0x202e, + 0x002f, 0x0d0a, 0x102f, 0x202f, 0x0030, 0x0d0b, 0x1030, 0x2030, + 0x0031, 0x0e04, 0x1031, 0x2031, 0x0032, 0x0e05, 0x1032, 0x2032, + 0x0033, 0x0e06, 0x1033, 0x2033, 0x0034, 0x0e07, 0x1034, 0x2034, + 0x0035, 0x0e08, 0x1035, 0x2035, 0x0036, 0x0e09, 0x1036, 0x2036, + 0x0037, 0x0e0a, 0x1037, 0x2037, 0x0038, 0x0e0b, 0x1038, 0x2038, + 0x0039, 0x0f04, 0x1039, 0x2039, 0x003a, 0x0f05, 0x103a, 0x203a, + 0x003b, 0x0f06, 0x103b, 0x203b, 0x003c, 0x0f07, 0x103c, 0x203c, + 0x0801, 0x0f08, 0x103d, 0x203d, 0x1001, 0x0f09, 0x103e, 0x203e, + 0x1801, 0x0f0a, 0x103f, 0x203f, 0x2001, 0x0f0b, 0x1040, 0x2040 +}; + +// In debug mode, allow optional computation of the table at startup. +// Also, check that the decompression table is correct. +#ifndef NDEBUG +DEFINE_bool(snappy_dump_decompression_table, false, + "If true, we print the decompression table at startup."); + +static uint16 MakeEntry(unsigned int extra, + unsigned int len, + unsigned int copy_offset) { + // Check that all of the fields fit within the allocated space + assert(extra == (extra & 0x7)); // At most 3 bits + assert(copy_offset == (copy_offset & 0x7)); // At most 3 bits + assert(len == (len & 0x7f)); // At most 7 bits + return len | (copy_offset << 8) | (extra << 11); +} + +static void ComputeTable() { + uint16 dst[256]; + + // Place invalid entries in all places to detect missing initialization + int assigned = 0; + for (int i = 0; i < 256; i++) { + dst[i] = 0xffff; + } + + // Small LITERAL entries. We store (len-1) in the top 6 bits. + for (unsigned int len = 1; len <= 60; len++) { + dst[LITERAL | ((len-1) << 2)] = MakeEntry(0, len, 0); + assigned++; + } + + // Large LITERAL entries. We use 60..63 in the high 6 bits to + // encode the number of bytes of length info that follow the opcode. + for (unsigned int extra_bytes = 1; extra_bytes <= 4; extra_bytes++) { + // We set the length field in the lookup table to 1 because extra + // bytes encode len-1. + dst[LITERAL | ((extra_bytes+59) << 2)] = MakeEntry(extra_bytes, 1, 0); + assigned++; + } + + // COPY_1_BYTE_OFFSET. + // + // The tag byte in the compressed data stores len-4 in 3 bits, and + // offset/256 in 5 bits. offset%256 is stored in the next byte. + // + // This format is used for length in range [4..11] and offset in + // range [0..2047] + for (unsigned int len = 4; len < 12; len++) { + for (unsigned int offset = 0; offset < 2048; offset += 256) { + dst[COPY_1_BYTE_OFFSET | ((len-4)<<2) | ((offset>>8)<<5)] = + MakeEntry(1, len, offset>>8); + assigned++; + } + } + + // COPY_2_BYTE_OFFSET. + // Tag contains len-1 in top 6 bits, and offset in next two bytes. + for (unsigned int len = 1; len <= 64; len++) { + dst[COPY_2_BYTE_OFFSET | ((len-1)<<2)] = MakeEntry(2, len, 0); + assigned++; + } + + // COPY_4_BYTE_OFFSET. + // Tag contents len-1 in top 6 bits, and offset in next four bytes. + for (unsigned int len = 1; len <= 64; len++) { + dst[COPY_4_BYTE_OFFSET | ((len-1)<<2)] = MakeEntry(4, len, 0); + assigned++; + } + + // Check that each entry was initialized exactly once. + if (assigned != 256) { + fprintf(stderr, "ComputeTable: assigned only %d of 256\n", assigned); + abort(); + } + for (int i = 0; i < 256; i++) { + if (dst[i] == 0xffff) { + fprintf(stderr, "ComputeTable: did not assign byte %d\n", i); + abort(); + } + } + + if (FLAGS_snappy_dump_decompression_table) { + printf("static const uint16 char_table[256] = {\n "); + for (int i = 0; i < 256; i++) { + printf("0x%04x%s", + dst[i], + ((i == 255) ? "\n" : (((i%8) == 7) ? ",\n " : ", "))); + } + printf("};\n"); + } + + // Check that computed table matched recorded table + for (int i = 0; i < 256; i++) { + if (dst[i] != char_table[i]) { + fprintf(stderr, "ComputeTable: byte %d: computed (%x), expect (%x)\n", + i, static_cast<int>(dst[i]), static_cast<int>(char_table[i])); + abort(); + } + } +} +#endif /* !NDEBUG */ + +// Helper class for decompression +class SnappyDecompressor { + private: + Source* reader_; // Underlying source of bytes to decompress + const char* ip_; // Points to next buffered byte + const char* ip_limit_; // Points just past buffered bytes + uint32 peeked_; // Bytes peeked from reader (need to skip) + bool eof_; // Hit end of input without an error? + char scratch_[kMaximumTagLength]; // See RefillTag(). + + // Ensure that all of the tag metadata for the next tag is available + // in [ip_..ip_limit_-1]. Also ensures that [ip,ip+4] is readable even + // if (ip_limit_ - ip_ < 5). + // + // Returns true on success, false on error or end of input. + bool RefillTag(); + + public: + explicit SnappyDecompressor(Source* reader) + : reader_(reader), + ip_(NULL), + ip_limit_(NULL), + peeked_(0), + eof_(false) { + } + + ~SnappyDecompressor() { + // Advance past any bytes we peeked at from the reader + reader_->Skip(peeked_); + } + + // Returns true iff we have hit the end of the input without an error. + bool eof() const { + return eof_; + } + + // Read the uncompressed length stored at the start of the compressed data. + // On succcess, stores the length in *result and returns true. + // On failure, returns false. + bool ReadUncompressedLength(uint32* result) { + assert(ip_ == NULL); // Must not have read anything yet + // Length is encoded in 1..5 bytes + *result = 0; + uint32 shift = 0; + while (true) { + if (shift >= 32) return false; + size_t n; + const char* ip = reader_->Peek(&n); + if (n == 0) return false; + const unsigned char c = *(reinterpret_cast<const unsigned char*>(ip)); + reader_->Skip(1); + *result |= static_cast<uint32>(c & 0x7f) << shift; + if (c < 128) { + break; + } + shift += 7; + } + return true; + } + + // Process the next item found in the input. + // Returns true if successful, false on error or end of input. + template <class Writer> + void DecompressAllTags(Writer* writer) { + const char* ip = ip_; + + // We could have put this refill fragment only at the beginning of the loop. + // However, duplicating it at the end of each branch gives the compiler more + // scope to optimize the <ip_limit_ - ip> expression based on the local + // context, which overall increases speed. + #define MAYBE_REFILL() \ + if (ip_limit_ - ip < kMaximumTagLength) { \ + ip_ = ip; \ + if (!RefillTag()) return; \ + ip = ip_; \ + } + + MAYBE_REFILL(); + for ( ;; ) { + const unsigned char c = *(reinterpret_cast<const unsigned char*>(ip++)); + + if ((c & 0x3) == LITERAL) { + size_t literal_length = (c >> 2) + 1u; + if (writer->TryFastAppend(ip, ip_limit_ - ip, literal_length)) { + assert(literal_length < 61); + ip += literal_length; + // NOTE(user): There is no MAYBE_REFILL() here, as TryFastAppend() + // will not return true unless there's already at least five spare + // bytes in addition to the literal. + continue; + } + if (PREDICT_FALSE(literal_length >= 61)) { + // Long literal. + const size_t literal_length_length = literal_length - 60; + literal_length = + (LittleEndian::Load32(ip) & wordmask[literal_length_length]) + 1; + ip += literal_length_length; + } + + size_t avail = ip_limit_ - ip; + while (avail < literal_length) { + if (!writer->Append(ip, avail)) return; + literal_length -= avail; + reader_->Skip(peeked_); + size_t n; + ip = reader_->Peek(&n); + avail = n; + peeked_ = avail; + if (avail == 0) return; // Premature end of input + ip_limit_ = ip + avail; + } + if (!writer->Append(ip, literal_length)) { + return; + } + ip += literal_length; + MAYBE_REFILL(); + } else { + const uint32 entry = char_table[c]; + const uint32 trailer = LittleEndian::Load32(ip) & wordmask[entry >> 11]; + const uint32 length = entry & 0xff; + ip += entry >> 11; + + // copy_offset/256 is encoded in bits 8..10. By just fetching + // those bits, we get copy_offset (since the bit-field starts at + // bit 8). + const uint32 copy_offset = entry & 0x700; + if (!writer->AppendFromSelf(copy_offset + trailer, length)) { + return; + } + MAYBE_REFILL(); + } + } + +#undef MAYBE_REFILL + } +}; + +bool SnappyDecompressor::RefillTag() { + const char* ip = ip_; + if (ip == ip_limit_) { + // Fetch a new fragment from the reader + reader_->Skip(peeked_); // All peeked bytes are used up + size_t n; + ip = reader_->Peek(&n); + peeked_ = n; + if (n == 0) { + eof_ = true; + return false; + } + ip_limit_ = ip + n; + } + + // Read the tag character + assert(ip < ip_limit_); + const unsigned char c = *(reinterpret_cast<const unsigned char*>(ip)); + const uint32 entry = char_table[c]; + const uint32 needed = (entry >> 11) + 1; // +1 byte for 'c' + assert(needed <= sizeof(scratch_)); + + // Read more bytes from reader if needed + uint32 nbuf = ip_limit_ - ip; + if (nbuf < needed) { + // Stitch together bytes from ip and reader to form the word + // contents. We store the needed bytes in "scratch_". They + // will be consumed immediately by the caller since we do not + // read more than we need. + memmove(scratch_, ip, nbuf); + reader_->Skip(peeked_); // All peeked bytes are used up + peeked_ = 0; + while (nbuf < needed) { + size_t length; + const char* src = reader_->Peek(&length); + if (length == 0) return false; + uint32 to_add = min<uint32>(needed - nbuf, length); + memcpy(scratch_ + nbuf, src, to_add); + nbuf += to_add; + reader_->Skip(to_add); + } + assert(nbuf == needed); + ip_ = scratch_; + ip_limit_ = scratch_ + needed; + } else if (nbuf < kMaximumTagLength) { + // Have enough bytes, but move into scratch_ so that we do not + // read past end of input + memmove(scratch_, ip, nbuf); + reader_->Skip(peeked_); // All peeked bytes are used up + peeked_ = 0; + ip_ = scratch_; + ip_limit_ = scratch_ + nbuf; + } else { + // Pass pointer to buffer returned by reader_. + ip_ = ip; + } + return true; +} + +template <typename Writer> +static bool InternalUncompress(Source* r, Writer* writer) { + // Read the uncompressed length from the front of the compressed input + SnappyDecompressor decompressor(r); + uint32 uncompressed_len = 0; + if (!decompressor.ReadUncompressedLength(&uncompressed_len)) return false; + return InternalUncompressAllTags(&decompressor, writer, uncompressed_len); +} + +template <typename Writer> +static bool InternalUncompressAllTags(SnappyDecompressor* decompressor, + Writer* writer, + uint32 uncompressed_len) { + writer->SetExpectedLength(uncompressed_len); + + // Process the entire input + decompressor->DecompressAllTags(writer); + return (decompressor->eof() && writer->CheckLength()); +} + +bool GetUncompressedLength(Source* source, uint32* result) { + SnappyDecompressor decompressor(source); + return decompressor.ReadUncompressedLength(result); +} + +size_t Compress(Source* reader, Sink* writer) { + size_t written = 0; + size_t N = reader->Available(); + char ulength[Varint::kMax32]; + char* p = Varint::Encode32(ulength, N); + writer->Append(ulength, p-ulength); + written += (p - ulength); + + internal::WorkingMemory wmem; + char* scratch = NULL; + char* scratch_output = NULL; + + while (N > 0) { + // Get next block to compress (without copying if possible) + size_t fragment_size; + const char* fragment = reader->Peek(&fragment_size); + assert(fragment_size != 0); // premature end of input + const size_t num_to_read = min(N, kBlockSize); + size_t bytes_read = fragment_size; + + size_t pending_advance = 0; + if (bytes_read >= num_to_read) { + // Buffer returned by reader is large enough + pending_advance = num_to_read; + fragment_size = num_to_read; + } else { + // Read into scratch buffer + if (scratch == NULL) { + // If this is the last iteration, we want to allocate N bytes + // of space, otherwise the max possible kBlockSize space. + // num_to_read contains exactly the correct value + scratch = new char[num_to_read]; + } + memcpy(scratch, fragment, bytes_read); + reader->Skip(bytes_read); + + while (bytes_read < num_to_read) { + fragment = reader->Peek(&fragment_size); + size_t n = min<size_t>(fragment_size, num_to_read - bytes_read); + memcpy(scratch + bytes_read, fragment, n); + bytes_read += n; + reader->Skip(n); + } + assert(bytes_read == num_to_read); + fragment = scratch; + fragment_size = num_to_read; + } + assert(fragment_size == num_to_read); + + // Get encoding table for compression + int table_size; + uint16* table = wmem.GetHashTable(num_to_read, &table_size); + + // Compress input_fragment and append to dest + const int max_output = MaxCompressedLength(num_to_read); + + // Need a scratch buffer for the output, in case the byte sink doesn't + // have room for us directly. + if (scratch_output == NULL) { + scratch_output = new char[max_output]; + } else { + // Since we encode kBlockSize regions followed by a region + // which is <= kBlockSize in length, a previously allocated + // scratch_output[] region is big enough for this iteration. + } + char* dest = writer->GetAppendBuffer(max_output, scratch_output); + char* end = internal::CompressFragment(fragment, fragment_size, + dest, table, table_size); + writer->Append(dest, end - dest); + written += (end - dest); + + N -= num_to_read; + reader->Skip(pending_advance); + } + + delete[] scratch; + delete[] scratch_output; + + return written; +} + +// ----------------------------------------------------------------------- +// IOVec interfaces +// ----------------------------------------------------------------------- + +// A type that writes to an iovec. +// Note that this is not a "ByteSink", but a type that matches the +// Writer template argument to SnappyDecompressor::DecompressAllTags(). +class SnappyIOVecWriter { + private: + const struct iovec* output_iov_; + const size_t output_iov_count_; + + // We are currently writing into output_iov_[curr_iov_index_]. + int curr_iov_index_; + + // Bytes written to output_iov_[curr_iov_index_] so far. + size_t curr_iov_written_; + + // Total bytes decompressed into output_iov_ so far. + size_t total_written_; + + // Maximum number of bytes that will be decompressed into output_iov_. + size_t output_limit_; + + inline char* GetIOVecPointer(int index, size_t offset) { + return reinterpret_cast<char*>(output_iov_[index].iov_base) + + offset; + } + + public: + // Does not take ownership of iov. iov must be valid during the + // entire lifetime of the SnappyIOVecWriter. + inline SnappyIOVecWriter(const struct iovec* iov, size_t iov_count) + : output_iov_(iov), + output_iov_count_(iov_count), + curr_iov_index_(0), + curr_iov_written_(0), + total_written_(0), + output_limit_(-1) { + } + + inline void SetExpectedLength(size_t len) { + output_limit_ = len; + } + + inline bool CheckLength() const { + return total_written_ == output_limit_; + } + + inline bool Append(const char* ip, size_t len) { + if (total_written_ + len > output_limit_) { + return false; + } + + while (len > 0) { + assert(curr_iov_written_ <= output_iov_[curr_iov_index_].iov_len); + if (curr_iov_written_ >= output_iov_[curr_iov_index_].iov_len) { + // This iovec is full. Go to the next one. + if (curr_iov_index_ + 1 >= output_iov_count_) { + return false; + } + curr_iov_written_ = 0; + ++curr_iov_index_; + } + + const size_t to_write = std::min( + len, output_iov_[curr_iov_index_].iov_len - curr_iov_written_); + memcpy(GetIOVecPointer(curr_iov_index_, curr_iov_written_), + ip, + to_write); + curr_iov_written_ += to_write; + total_written_ += to_write; + ip += to_write; + len -= to_write; + } + + return true; + } + + inline bool TryFastAppend(const char* ip, size_t available, size_t len) { + const size_t space_left = output_limit_ - total_written_; + if (len <= 16 && available >= 16 + kMaximumTagLength && space_left >= 16 && + output_iov_[curr_iov_index_].iov_len - curr_iov_written_ >= 16) { + // Fast path, used for the majority (about 95%) of invocations. + char* ptr = GetIOVecPointer(curr_iov_index_, curr_iov_written_); + UnalignedCopy64(ip, ptr); + UnalignedCopy64(ip + 8, ptr + 8); + curr_iov_written_ += len; + total_written_ += len; + return true; + } + + return false; + } + + inline bool AppendFromSelf(size_t offset, size_t len) { + if (offset > total_written_ || offset == 0) { + return false; + } + const size_t space_left = output_limit_ - total_written_; + if (len > space_left) { + return false; + } + + // Locate the iovec from which we need to start the copy. + int from_iov_index = curr_iov_index_; + size_t from_iov_offset = curr_iov_written_; + while (offset > 0) { + if (from_iov_offset >= offset) { + from_iov_offset -= offset; + break; + } + + offset -= from_iov_offset; + --from_iov_index; + assert(from_iov_index >= 0); + from_iov_offset = output_iov_[from_iov_index].iov_len; + } + + // Copy <len> bytes starting from the iovec pointed to by from_iov_index to + // the current iovec. + while (len > 0) { + assert(from_iov_index <= curr_iov_index_); + if (from_iov_index != curr_iov_index_) { + const size_t to_copy = std::min( + output_iov_[from_iov_index].iov_len - from_iov_offset, + len); + Append(GetIOVecPointer(from_iov_index, from_iov_offset), to_copy); + len -= to_copy; + if (len > 0) { + ++from_iov_index; + from_iov_offset = 0; + } + } else { + assert(curr_iov_written_ <= output_iov_[curr_iov_index_].iov_len); + size_t to_copy = std::min(output_iov_[curr_iov_index_].iov_len - + curr_iov_written_, + len); + if (to_copy == 0) { + // This iovec is full. Go to the next one. + if (curr_iov_index_ + 1 >= output_iov_count_) { + return false; + } + ++curr_iov_index_; + curr_iov_written_ = 0; + continue; + } + if (to_copy > len) { + to_copy = len; + } + IncrementalCopy(GetIOVecPointer(from_iov_index, from_iov_offset), + GetIOVecPointer(curr_iov_index_, curr_iov_written_), + to_copy); + curr_iov_written_ += to_copy; + from_iov_offset += to_copy; + total_written_ += to_copy; + len -= to_copy; + } + } + + return true; + } + +}; + +bool RawUncompressToIOVec(const char* compressed, size_t compressed_length, + const struct iovec* iov, size_t iov_cnt) { + ByteArraySource reader(compressed, compressed_length); + return RawUncompressToIOVec(&reader, iov, iov_cnt); +} + +bool RawUncompressToIOVec(Source* compressed, const struct iovec* iov, + size_t iov_cnt) { + SnappyIOVecWriter output(iov, iov_cnt); + return InternalUncompress(compressed, &output); +} + +// ----------------------------------------------------------------------- +// Flat array interfaces +// ----------------------------------------------------------------------- + +// A type that writes to a flat array. +// Note that this is not a "ByteSink", but a type that matches the +// Writer template argument to SnappyDecompressor::DecompressAllTags(). +class SnappyArrayWriter { + private: + char* base_; + char* op_; + char* op_limit_; + + public: + inline explicit SnappyArrayWriter(char* dst) + : base_(dst), + op_(dst) { + } + + inline void SetExpectedLength(size_t len) { + op_limit_ = op_ + len; + } + + inline bool CheckLength() const { + return op_ == op_limit_; + } + + inline bool Append(const char* ip, size_t len) { + char* op = op_; + const size_t space_left = op_limit_ - op; + if (space_left < len) { + return false; + } + memcpy(op, ip, len); + op_ = op + len; + return true; + } + + inline bool TryFastAppend(const char* ip, size_t available, size_t len) { + char* op = op_; + const size_t space_left = op_limit_ - op; + if (len <= 16 && available >= 16 + kMaximumTagLength && space_left >= 16) { + // Fast path, used for the majority (about 95%) of invocations. + UnalignedCopy64(ip, op); + UnalignedCopy64(ip + 8, op + 8); + op_ = op + len; + return true; + } else { + return false; + } + } + + inline bool AppendFromSelf(size_t offset, size_t len) { + char* op = op_; + const size_t space_left = op_limit_ - op; + + // Check if we try to append from before the start of the buffer. + // Normally this would just be a check for "produced < offset", + // but "produced <= offset - 1u" is equivalent for every case + // except the one where offset==0, where the right side will wrap around + // to a very big number. This is convenient, as offset==0 is another + // invalid case that we also want to catch, so that we do not go + // into an infinite loop. + assert(op >= base_); + size_t produced = op - base_; + if (produced <= offset - 1u) { + return false; + } + if (len <= 16 && offset >= 8 && space_left >= 16) { + // Fast path, used for the majority (70-80%) of dynamic invocations. + UnalignedCopy64(op - offset, op); + UnalignedCopy64(op - offset + 8, op + 8); + } else { + if (space_left >= len + kMaxIncrementCopyOverflow) { + IncrementalCopyFastPath(op - offset, op, len); + } else { + if (space_left < len) { + return false; + } + IncrementalCopy(op - offset, op, len); + } + } + + op_ = op + len; + return true; + } +}; + +bool RawUncompress(const char* compressed, size_t n, char* uncompressed) { + ByteArraySource reader(compressed, n); + return RawUncompress(&reader, uncompressed); +} + +bool RawUncompress(Source* compressed, char* uncompressed) { + SnappyArrayWriter output(uncompressed); + return InternalUncompress(compressed, &output); +} + +bool Uncompress(const char* compressed, size_t n, string* uncompressed) { + size_t ulength; + if (!GetUncompressedLength(compressed, n, &ulength)) { + return false; + } + // On 32-bit builds: max_size() < kuint32max. Check for that instead + // of crashing (e.g., consider externally specified compressed data). + if (ulength > uncompressed->max_size()) { + return false; + } + STLStringResizeUninitialized(uncompressed, ulength); + return RawUncompress(compressed, n, string_as_array(uncompressed)); +} + + +// A Writer that drops everything on the floor and just does validation +class SnappyDecompressionValidator { + private: + size_t expected_; + size_t produced_; + + public: + inline SnappyDecompressionValidator() : produced_(0) { } + inline void SetExpectedLength(size_t len) { + expected_ = len; + } + inline bool CheckLength() const { + return expected_ == produced_; + } + inline bool Append(const char* ip, size_t len) { + produced_ += len; + return produced_ <= expected_; + } + inline bool TryFastAppend(const char* ip, size_t available, size_t length) { + return false; + } + inline bool AppendFromSelf(size_t offset, size_t len) { + // See SnappyArrayWriter::AppendFromSelf for an explanation of + // the "offset - 1u" trick. + if (produced_ <= offset - 1u) return false; + produced_ += len; + return produced_ <= expected_; + } +}; + +bool IsValidCompressedBuffer(const char* compressed, size_t n) { + ByteArraySource reader(compressed, n); + SnappyDecompressionValidator writer; + return InternalUncompress(&reader, &writer); +} + +void RawCompress(const char* input, + size_t input_length, + char* compressed, + size_t* compressed_length) { + ByteArraySource reader(input, input_length); + UncheckedByteArraySink writer(compressed); + Compress(&reader, &writer); + + // Compute how many bytes were added + *compressed_length = (writer.CurrentDestination() - compressed); +} + +size_t Compress(const char* input, size_t input_length, string* compressed) { + // Pre-grow the buffer to the max length of the compressed output + compressed->resize(MaxCompressedLength(input_length)); + + size_t compressed_length; + RawCompress(input, input_length, string_as_array(compressed), + &compressed_length); + compressed->resize(compressed_length); + return compressed_length; +} + + +} // end namespace snappy +