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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-04 12:15:05 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-04 12:15:05 +0000
commit46651ce6fe013220ed397add242004d764fc0153 (patch)
tree6e5299f990f88e60174a1d3ae6e48eedd2688b2b /src/bin/pg_rewind/datapagemap.c
parentInitial commit. (diff)
downloadpostgresql-14-46651ce6fe013220ed397add242004d764fc0153.tar.xz
postgresql-14-46651ce6fe013220ed397add242004d764fc0153.zip
Adding upstream version 14.5.upstream/14.5upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/bin/pg_rewind/datapagemap.c')
-rw-r--r--src/bin/pg_rewind/datapagemap.c127
1 files changed, 127 insertions, 0 deletions
diff --git a/src/bin/pg_rewind/datapagemap.c b/src/bin/pg_rewind/datapagemap.c
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+++ b/src/bin/pg_rewind/datapagemap.c
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+/*-------------------------------------------------------------------------
+ *
+ * datapagemap.c
+ * A data structure for keeping track of data pages that have changed.
+ *
+ * This is a fairly simple bitmap.
+ *
+ * Copyright (c) 2013-2021, PostgreSQL Global Development Group
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres_fe.h"
+
+#include "common/logging.h"
+#include "datapagemap.h"
+
+struct datapagemap_iterator
+{
+ datapagemap_t *map;
+ BlockNumber nextblkno;
+};
+
+/*****
+ * Public functions
+ */
+
+/*
+ * Add a block to the bitmap.
+ */
+void
+datapagemap_add(datapagemap_t *map, BlockNumber blkno)
+{
+ int offset;
+ int bitno;
+
+ offset = blkno / 8;
+ bitno = blkno % 8;
+
+ /* enlarge or create bitmap if needed */
+ if (map->bitmapsize <= offset)
+ {
+ int oldsize = map->bitmapsize;
+ int newsize;
+
+ /*
+ * The minimum to hold the new bit is offset + 1. But add some
+ * headroom, so that we don't need to repeatedly enlarge the bitmap in
+ * the common case that blocks are modified in order, from beginning
+ * of a relation to the end.
+ */
+ newsize = offset + 1;
+ newsize += 10;
+
+ map->bitmap = pg_realloc(map->bitmap, newsize);
+
+ /* zero out the newly allocated region */
+ memset(&map->bitmap[oldsize], 0, newsize - oldsize);
+
+ map->bitmapsize = newsize;
+ }
+
+ /* Set the bit */
+ map->bitmap[offset] |= (1 << bitno);
+}
+
+/*
+ * Start iterating through all entries in the page map.
+ *
+ * After datapagemap_iterate, call datapagemap_next to return the entries,
+ * until it returns false. After you're done, use pg_free() to destroy the
+ * iterator.
+ */
+datapagemap_iterator_t *
+datapagemap_iterate(datapagemap_t *map)
+{
+ datapagemap_iterator_t *iter;
+
+ iter = pg_malloc(sizeof(datapagemap_iterator_t));
+ iter->map = map;
+ iter->nextblkno = 0;
+
+ return iter;
+}
+
+bool
+datapagemap_next(datapagemap_iterator_t *iter, BlockNumber *blkno)
+{
+ datapagemap_t *map = iter->map;
+
+ for (;;)
+ {
+ BlockNumber blk = iter->nextblkno;
+ int nextoff = blk / 8;
+ int bitno = blk % 8;
+
+ if (nextoff >= map->bitmapsize)
+ break;
+
+ iter->nextblkno++;
+
+ if (map->bitmap[nextoff] & (1 << bitno))
+ {
+ *blkno = blk;
+ return true;
+ }
+ }
+
+ /* no more set bits in this bitmap. */
+ return false;
+}
+
+/*
+ * A debugging aid. Prints out the contents of the page map.
+ */
+void
+datapagemap_print(datapagemap_t *map)
+{
+ datapagemap_iterator_t *iter;
+ BlockNumber blocknum;
+
+ iter = datapagemap_iterate(map);
+ while (datapagemap_next(iter, &blocknum))
+ pg_log_debug("block %u", blocknum);
+
+ pg_free(iter);
+}