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Add prefetching support on macOS

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macOS doesn't have posix_fadvise(), but fcntl() with the F_RDADVISE
command does the same thing.

Some related documentation has been generalized to not mention
posix_advise() specifically anymore.

Reviewed-by: Thomas Munro <thomas.munro@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/0827edec-1317-4917-a186-035eb1e3241d%40eisentraut.org
This commit is contained in:
Peter Eisentraut
2024-08-28 07:26:48 +02:00
parent 2e6a8047f0
commit 6654bb9204
6 changed files with 54 additions and 35 deletions
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57
src/backend/storage/file/fd.c
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@ -2068,40 +2068,59 @@ FileClose(File file)
/*
* FilePrefetch - initiate asynchronous read of a given range of the file.
*
* Currently the only implementation of this function is using posix_fadvise
* which is the simplest standardized interface that accomplishes this.
* We could add an implementation using libaio in the future; but note that
* this API is inappropriate for libaio, which wants to have a buffer provided
* to read into.
* Returns 0 on success, otherwise an errno error code (like posix_fadvise()).
*
* posix_fadvise() is the simplest standardized interface that accomplishes
* this.
*/
int
FilePrefetch(File file, off_t offset, off_t amount, uint32 wait_event_info)
{
#if defined(USE_POSIX_FADVISE) && defined(POSIX_FADV_WILLNEED)
int returnCode;
Assert(FileIsValid(file));
DO_DB(elog(LOG, "FilePrefetch: %d (%s) " INT64_FORMAT " " INT64_FORMAT,
file, VfdCache[file].fileName,
(int64) offset, (int64) amount));
returnCode = FileAccess(file);
if (returnCode < 0)
return returnCode;
#if defined(USE_POSIX_FADVISE) && defined(POSIX_FADV_WILLNEED)
{
int returnCode;
returnCode = FileAccess(file);
if (returnCode < 0)
return returnCode;
retry:
pgstat_report_wait_start(wait_event_info);
returnCode = posix_fadvise(VfdCache[file].fd, offset, amount,
POSIX_FADV_WILLNEED);
pgstat_report_wait_end();
pgstat_report_wait_start(wait_event_info);
returnCode = posix_fadvise(VfdCache[file].fd, offset, amount,
POSIX_FADV_WILLNEED);
pgstat_report_wait_end();
if (returnCode == EINTR)
goto retry;
if (returnCode == EINTR)
goto retry;
return returnCode;
return returnCode;
}
#elif defined(__darwin__)
{
struct radvisory
{
off_t ra_offset; /* offset into the file */
int ra_count; /* size of the read */
} ra;
int returnCode;
ra.ra_offset = offset;
ra.ra_count = amount;
pgstat_report_wait_start(wait_event_info);
returnCode = fcntl(VfdCache[file].fd, F_RDADVISE, &ra);
pgstat_report_wait_end();
if (returnCode != -1)
return 0;
else
return errno;
}
#else
Assert(FileIsValid(file));
return 0;
#endif
}