47 lines
1.6 KiB
Plaintext
47 lines
1.6 KiB
Plaintext
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Patrick O'Lone suggests the following idea which sounds interesting to
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add as an optional mode of Cache_Lite class.
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(still not tested in the Cache_Lite context)
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-------------------------------------------------------------------------
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If you use the flags:
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ignore_user_abort(true);
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$fd = dio_open($szFilename, O_CREATE | O_EXCL | O_TRUNC | O_WRONLY,
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0644);
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if (is_resource($fd)) {
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dio_fcntl($fd, F_SETLKW, array('type' => F_WRLCK));
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dio_write($fd, $szBuffer);
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dio_fcntl($fd, F_SETLK, array('type' => F_UNLCK));
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dio_close($fd);
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}
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ignore_user_abort(false);
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Only the first process will attempt to create a file. Additional
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processes will see that a file already exists (at the system level), and
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will fail. Another thing to note is that the file descriptor must be
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opened using dio_open(), and certain features, like fgets() won't work
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with it. If your just doing a raw write, dio_write() should be just
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fine. The dio_read() function should be used like:
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$fd = dio_open($szFilename, O_RDONLY|O_NONBLOCK, 0644);
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if (is_resource($fd)) {
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dio_fcntl($fd, F_SETLKW, array('type' => F_RDLCK));
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$szBuffer = dio_read($fd, filesize($szFilename));
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dio_fcntl($fd, F_SETLK, array('type' => F_UNLCK));
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dio_close($fd);
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}
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You still use locking to ensure that a write process can finish before
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another attempts to read the file. We also set non-blocking mode in read
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mode so that multiple readers can access the same resource at the same
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time. NOTE: Direct I/O support must be compiled into PHP for these
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features to work (--enable-dio).
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-------------------------------------------------------------------------
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