Edit report at http://bugs.php.net/bug.php?id=35090&edit=1
ID: 35090 Comment by: surfchen at gmail dot com Reported by: askalski at gmail dot com Summary: file i/o is not buffered Status: Bogus Type: Bug Package: Filesystem function related Operating System: linux PHP Version: 5CVS-2005-11-03 (snap) Block user comment: N New Comment: So we need to add a note on the documentation say that this function not supported with filesystem wrapper, right? Previous Comments: ------------------------------------------------------------------------ [2005-11-03 23:40:24] askalski at gmail dot com > instead it uses the system's file io buffering function > to set the buffer. Assuming you're talking about setvbuf() and not kernel level write-behind caching, this statement is false. The file is opened by _php_stream_fopen(): fd = open(realpath, open_flags, 0666); (It is never subsequently wrapped with fdopen()) At this point, the stream is not buffered at all. When I later call stream_set_write_buffer(), it hits php_stdiop_set_option(): case PHP_STREAM_OPTION_WRITE_BUFFER: if (data->file == NULL) { return -1; } /* setvbuf happens down here */ Because there is no FILE* handle (data->file), setvbuf() is never called for the stream. One of either the documentation (http://us3.php.net/stream_set_write_buffer) or the PHP source is wrong. ------------------------------------------------------------------------ [2005-11-03 21:34:16] il...@php.net Thank you for taking the time to write to us, but this is not a bug. Please double-check the documentation available at http://www.php.net/manual/ and the instructions on how to report a bug at http://bugs.php.net/how-to-report.php PHP does not do any buffering itself, instead it uses the system's file io buffering function to set the buffer. There is already a feature request open to enable in-php buffering. ------------------------------------------------------------------------ [2005-11-03 21:29:08] der...@php.net Can you please answer why this is not a bug Wez? I forgot the reason :) ------------------------------------------------------------------------ [2005-11-03 19:16:09] askalski at gmail dot com Description: ------------ The documentation for stream_set_write_buffer() says that fwrite()s are buffered at 8K by default. In reality, it does not buffer at all. Any attempt to call stream_set_write_buffer() on a regular file handle results in failure. Reproduce code: --------------- $fh = fopen("asdf", "w"); // write some data using the default buffering for ($i = 0; $i < 5; $i++) fwrite($fh, "test"); // demonstrate that stream_set_write_buffer fails $n = stream_set_write_buffer($fh, 8192); if ($n != 0) echo "stream_set_write_buffer failed\n"; // write some more data to demonstrate the failure for ($i = 0; $i < 5; $i++) fwrite($fh, "again"); fclose($fh); Expected result: ---------------- PHP should buffer its I/O, and strace should log a single write(). stream_set_write_buffer() should not fail on regular files. Actual result: -------------- Output: stream_set_write_buffer failed Abridged strace output: open("/tmp/php5-200511031730/asdf", O_WRONLY|O_CREAT|O_TRUNC, 0666) = 3 fstat64(3, {st_mode=S_IFREG|0600, st_size=0, ...}) = 0 lseek(3, 0, SEEK_CUR) = 0 write(3, "test", 4) = 4 write(3, "test", 4) = 4 write(3, "test", 4) = 4 write(3, "test", 4) = 4 write(3, "test", 4) = 4 write(1, "stream_set_write_buffer failed\n", 31) = 31 write(3, "again", 5) = 5 write(3, "again", 5) = 5 write(3, "again", 5) = 5 write(3, "again", 5) = 5 write(3, "again", 5) = 5 close(3) = 0 ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/bug.php?id=35090&edit=1