Fix issues in pgarch's new directory-scanning logic.
The arch_filenames[] array elements were one byte too small, so that
a maximum-length filename would get corrupted if another entry
were made after it. (Noted by Thomas Munro, fix by Nathan Bossart.)
Move these arrays into a palloc'd struct, so that we aren't wasting
a few kilobytes of static data in each non-archiver process.
Add a binaryheap_reset() call to make it plain that we start the
directory scan with an empty heap. I don't think there's any live
bug of that sort, but it seems fragile, and this is very cheap
insurance.
Cleanup for commit beb4e9ba1, so no back-patch needed.
Discussion: https://postgr.es/m/CA+hUKGLHAjHuKuwtzsW7uMJF4BVPcQRL-UMZG_HM-g0y7yLkUg@mail.gmail.com
This commit is contained in:
Tom Lane
parent
113fa3945f
commit
1fb17b1903
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@ -111,11 +111,20 @@ static PgArchData *PgArch = NULL;
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* completes, the file names are stored in ascending order of priority in
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* arch_files. pgarch_readyXlog() returns files from arch_files until it
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* is empty, at which point another directory scan must be performed.
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*
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* We only need this data in the archiver process, so make it a palloc'd
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* struct rather than a bunch of static arrays.
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*/
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static binaryheap *arch_heap = NULL;
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static char arch_filenames[NUM_FILES_PER_DIRECTORY_SCAN][MAX_XFN_CHARS];
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static char *arch_files[NUM_FILES_PER_DIRECTORY_SCAN];
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static int arch_files_size = 0;
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struct arch_files_state
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{
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binaryheap *arch_heap;
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int arch_files_size; /* number of live entries in arch_files[] */
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char *arch_files[NUM_FILES_PER_DIRECTORY_SCAN];
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/* buffers underlying heap, and later arch_files[], entries: */
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char arch_filenames[NUM_FILES_PER_DIRECTORY_SCAN][MAX_XFN_CHARS + 1];
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};
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static struct arch_files_state *arch_files = NULL;
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/*
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* Flags set by interrupt handlers for later service in the main loop.
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@ -231,9 +240,13 @@ PgArchiverMain(void)
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*/
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PgArch->pgprocno = MyProc->pgprocno;
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/* Create workspace for pgarch_readyXlog() */
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arch_files = palloc(sizeof(struct arch_files_state));
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arch_files->arch_files_size = 0;
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/* Initialize our max-heap for prioritizing files to archive. */
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arch_heap = binaryheap_allocate(NUM_FILES_PER_DIRECTORY_SCAN,
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ready_file_comparator, NULL);
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arch_files->arch_heap = binaryheap_allocate(NUM_FILES_PER_DIRECTORY_SCAN,
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ready_file_comparator, NULL);
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pgarch_MainLoop();
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@ -363,7 +376,7 @@ pgarch_ArchiverCopyLoop(void)
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char xlog[MAX_XFN_CHARS + 1];
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/* force directory scan in the first call to pgarch_readyXlog() */
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arch_files_size = 0;
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arch_files->arch_files_size = 0;
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/*
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* loop through all xlogs with archive_status of .ready and archive
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@ -658,7 +671,7 @@ pgarch_readyXlog(char *xlog)
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SpinLockRelease(&PgArch->arch_lck);
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if (force_dir_scan)
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arch_files_size = 0;
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arch_files->arch_files_size = 0;
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/*
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* If we still have stored file names from the previous directory scan,
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@ -666,14 +679,14 @@ pgarch_readyXlog(char *xlog)
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* is still present, as the archive_command for a previous file may
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* have already marked it done.
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*/
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while (arch_files_size > 0)
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while (arch_files->arch_files_size > 0)
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{
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struct stat st;
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char status_file[MAXPGPATH];
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char *arch_file;
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arch_files_size--;
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arch_file = arch_files[arch_files_size];
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arch_files->arch_files_size--;
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arch_file = arch_files->arch_files[arch_files->arch_files_size];
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StatusFilePath(status_file, arch_file, ".ready");
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if (stat(status_file, &st) == 0)
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@ -687,6 +700,9 @@ pgarch_readyXlog(char *xlog)
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errmsg("could not stat file \"%s\": %m", status_file)));
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}
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/* arch_heap is probably empty, but let's make sure */
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binaryheap_reset(arch_files->arch_heap);
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/*
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* Open the archive status directory and read through the list of files
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* with the .ready suffix, looking for the earliest files.
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@ -720,53 +736,53 @@ pgarch_readyXlog(char *xlog)
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/*
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* Store the file in our max-heap if it has a high enough priority.
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*/
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if (arch_heap->bh_size < NUM_FILES_PER_DIRECTORY_SCAN)
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if (arch_files->arch_heap->bh_size < NUM_FILES_PER_DIRECTORY_SCAN)
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{
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/* If the heap isn't full yet, quickly add it. */
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arch_file = arch_filenames[arch_heap->bh_size];
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arch_file = arch_files->arch_filenames[arch_files->arch_heap->bh_size];
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strcpy(arch_file, basename);
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binaryheap_add_unordered(arch_heap, CStringGetDatum(arch_file));
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binaryheap_add_unordered(arch_files->arch_heap, CStringGetDatum(arch_file));
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/* If we just filled the heap, make it a valid one. */
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if (arch_heap->bh_size == NUM_FILES_PER_DIRECTORY_SCAN)
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binaryheap_build(arch_heap);
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if (arch_files->arch_heap->bh_size == NUM_FILES_PER_DIRECTORY_SCAN)
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binaryheap_build(arch_files->arch_heap);
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}
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else if (ready_file_comparator(binaryheap_first(arch_heap),
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else if (ready_file_comparator(binaryheap_first(arch_files->arch_heap),
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CStringGetDatum(basename), NULL) > 0)
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{
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/*
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* Remove the lowest priority file and add the current one to
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* the heap.
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*/
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arch_file = DatumGetCString(binaryheap_remove_first(arch_heap));
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arch_file = DatumGetCString(binaryheap_remove_first(arch_files->arch_heap));
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strcpy(arch_file, basename);
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binaryheap_add(arch_heap, CStringGetDatum(arch_file));
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binaryheap_add(arch_files->arch_heap, CStringGetDatum(arch_file));
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}
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}
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FreeDir(rldir);
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/* If no files were found, simply return. */
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if (arch_heap->bh_size == 0)
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if (arch_files->arch_heap->bh_size == 0)
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return false;
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/*
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* If we didn't fill the heap, we didn't make it a valid one. Do that
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* now.
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*/
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if (arch_heap->bh_size < NUM_FILES_PER_DIRECTORY_SCAN)
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binaryheap_build(arch_heap);
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if (arch_files->arch_heap->bh_size < NUM_FILES_PER_DIRECTORY_SCAN)
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binaryheap_build(arch_files->arch_heap);
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/*
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* Fill arch_files array with the files to archive in ascending order
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* of priority.
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*/
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arch_files_size = arch_heap->bh_size;
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for (int i = 0; i < arch_files_size; i++)
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arch_files[i] = DatumGetCString(binaryheap_remove_first(arch_heap));
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arch_files->arch_files_size = arch_files->arch_heap->bh_size;
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for (int i = 0; i < arch_files->arch_files_size; i++)
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arch_files->arch_files[i] = DatumGetCString(binaryheap_remove_first(arch_files->arch_heap));
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/* Return the highest priority file. */
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arch_files_size--;
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strcpy(xlog, arch_files[arch_files_size]);
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arch_files->arch_files_size--;
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strcpy(xlog, arch_files->arch_files[arch_files->arch_files_size]);
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return true;
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}
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