On Wed, Mar 19, 2014 at 12:30 AM, Duy Nguyen <pclo...@gmail.com> wrote: > On Wed, Mar 19, 2014 at 7:46 AM, <sza...@chromium.org> wrote: >> This adds a Windows implementation of pread. Note that it is NOT >> safe to intersperse calls to read() and pread() on a file >> descriptor. According to the ReadFile spec, using the 'overlapped' >> argument should not affect the implicit position pointer of the >> descriptor. Experiments have shown that this is, in fact, a lie. > > If I understand it correctly, new pread() is added because > compat/pread.c does not work because of some other read() in between? > Where are those read() (I can only see one in index-pack.c, but there > could be some hidden read()..)
I *think* it's the call to fixup_pack_header_footer(), but I'm not 100% sure. I suppose it would be possible to fix the immediate problem just by using one fd per thread, without a new pread implementation. But it seems better overall to have a pread() implementation that is thread-safe as long as read() and pread() aren't interspersed; and then convert all existing read() calls to pread(). That would be a good follow-up patch... > >> >> To accomodate that fact, this change also incorporates: >> >> http://article.gmane.org/gmane.comp.version-control.git/196042 >> >> ... which gives each index-pack thread its own file descriptor. >> --- >> builtin/index-pack.c | 21 ++++++++++++++++----- >> compat/mingw.c | 31 ++++++++++++++++++++++++++++++- >> compat/mingw.h | 3 +++ >> config.mak.uname | 1 - >> 4 files changed, 49 insertions(+), 7 deletions(-) >> >> diff --git a/builtin/index-pack.c b/builtin/index-pack.c >> index 2f37a38..c02dd4c 100644 >> --- a/builtin/index-pack.c >> +++ b/builtin/index-pack.c >> @@ -51,6 +51,7 @@ struct thread_local { >> #endif >> struct base_data *base_cache; >> size_t base_cache_used; >> + int pack_fd; >> }; >> >> /* >> @@ -91,7 +92,8 @@ static off_t consumed_bytes; >> static unsigned deepest_delta; >> static git_SHA_CTX input_ctx; >> static uint32_t input_crc32; >> -static int input_fd, output_fd, pack_fd; >> +static const char *curr_pack; >> +static int input_fd, output_fd; >> >> #ifndef NO_PTHREADS >> >> @@ -134,6 +136,7 @@ static inline void unlock_mutex(pthread_mutex_t *mutex) >> */ >> static void init_thread(void) >> { >> + int i; >> init_recursive_mutex(&read_mutex); >> pthread_mutex_init(&counter_mutex, NULL); >> pthread_mutex_init(&work_mutex, NULL); >> @@ -141,11 +144,17 @@ static void init_thread(void) >> pthread_mutex_init(&deepest_delta_mutex, NULL); >> pthread_key_create(&key, NULL); >> thread_data = xcalloc(nr_threads, sizeof(*thread_data)); >> + for (i = 0; i < nr_threads; i++) { >> + thread_data[i].pack_fd = open(curr_pack, O_RDONLY); >> + if (thread_data[i].pack_fd == -1) >> + die_errno("unable to open %s", curr_pack); >> + } >> threads_active = 1; >> } >> >> static void cleanup_thread(void) >> { >> + int i; >> if (!threads_active) >> return; >> threads_active = 0; >> @@ -155,6 +164,8 @@ static void cleanup_thread(void) >> if (show_stat) >> pthread_mutex_destroy(&deepest_delta_mutex); >> pthread_key_delete(key); >> + for (i = 0; i < nr_threads; i++) >> + close(thread_data[i].pack_fd); >> free(thread_data); >> } >> >> @@ -288,13 +299,13 @@ static const char *open_pack_file(const char >> *pack_name) >> output_fd = open(pack_name, O_CREAT|O_EXCL|O_RDWR, >> 0600); >> if (output_fd < 0) >> die_errno(_("unable to create '%s'"), pack_name); >> - pack_fd = output_fd; >> + nothread_data.pack_fd = output_fd; >> } else { >> input_fd = open(pack_name, O_RDONLY); >> if (input_fd < 0) >> die_errno(_("cannot open packfile '%s'"), pack_name); >> output_fd = -1; >> - pack_fd = input_fd; >> + nothread_data.pack_fd = input_fd; >> } >> git_SHA1_Init(&input_ctx); >> return pack_name; >> @@ -542,7 +553,7 @@ static void *unpack_data(struct object_entry *obj, >> >> do { >> ssize_t n = (len < 64*1024) ? len : 64*1024; >> - n = pread(pack_fd, inbuf, n, from); >> + n = pread(get_thread_data()->pack_fd, inbuf, n, from); >> if (n < 0) >> die_errno(_("cannot pread pack file")); >> if (!n) >> @@ -1490,7 +1501,7 @@ static void show_pack_info(int stat_only) >> int cmd_index_pack(int argc, const char **argv, const char *prefix) >> { >> int i, fix_thin_pack = 0, verify = 0, stat_only = 0; >> - const char *curr_pack, *curr_index; >> + const char *curr_index; >> const char *index_name = NULL, *pack_name = NULL; >> const char *keep_name = NULL, *keep_msg = NULL; >> char *index_name_buf = NULL, *keep_name_buf = NULL; >> diff --git a/compat/mingw.c b/compat/mingw.c >> index 383cafe..6cc85d6 100644 >> --- a/compat/mingw.c >> +++ b/compat/mingw.c >> @@ -329,7 +329,36 @@ int mingw_mkdir(const char *path, int mode) >> return ret; >> } >> >> -int mingw_open (const char *filename, int oflags, ...) >> + >> +ssize_t mingw_pread(int fd, void *buf, size_t count, off64_t offset) >> +{ >> + HANDLE hand = (HANDLE)_get_osfhandle(fd); >> + if (hand == INVALID_HANDLE_VALUE) { >> + errno = EBADF; >> + return -1; >> + } >> + >> + LARGE_INTEGER offset_value; >> + offset_value.QuadPart = offset; >> + >> + DWORD bytes_read = 0; >> + OVERLAPPED overlapped = {0}; >> + overlapped.Offset = offset_value.LowPart; >> + overlapped.OffsetHigh = offset_value.HighPart; >> + BOOL result = ReadFile(hand, buf, count, &bytes_read, &overlapped); >> + >> + ssize_t ret = bytes_read; >> + >> + if (!result && GetLastError() != ERROR_HANDLE_EOF) >> + { >> + errno = err_win_to_posix(GetLastError()); >> + ret = -1; >> + } >> + >> + return ret; >> +} >> + >> +int mingw_open(const char *filename, int oflags, ...) >> { >> va_list args; >> unsigned mode; >> diff --git a/compat/mingw.h b/compat/mingw.h >> index 08b83fe..377ba50 100644 >> --- a/compat/mingw.h >> +++ b/compat/mingw.h >> @@ -174,6 +174,9 @@ int mingw_unlink(const char *pathname); >> int mingw_rmdir(const char *path); >> #define rmdir mingw_rmdir >> >> +ssize_t mingw_pread(int fd, void *buf, size_t count, off64_t offset); >> +#define pread mingw_pread >> + >> int mingw_open (const char *filename, int oflags, ...); >> #define open mingw_open >> >> diff --git a/config.mak.uname b/config.mak.uname >> index e8acc39..b405524 100644 >> --- a/config.mak.uname >> +++ b/config.mak.uname >> @@ -474,7 +474,6 @@ ifeq ($(uname_S),NONSTOP_KERNEL) >> endif >> ifneq (,$(findstring MINGW,$(uname_S))) >> pathsep = ; >> - NO_PREAD = YesPlease >> NEEDS_CRYPTO_WITH_SSL = YesPlease >> NO_LIBGEN_H = YesPlease >> NO_POLL = YesPlease >> -- >> 1.9.0.279.gdc9e3eb >> >> -- >> To unsubscribe from this list: send the line "unsubscribe git" in >> the body of a message to majord...@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > -- > Duy -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
