Add new pg_walsummary tool.

This can dump the contents of the WAL summary files found in
pg_wal/summaries. Normally, this shouldn't really be something anyone
needs to do, but it may be needed for debugging problems with
incremental backup, or could possibly be useful to external tools.

Discussion: http://postgr.es/m/CA+Tgmobvqqj-DW9F7uUzT-cQqs6wcVb-Xhs=w=hzJnXSE-kRGw@mail.gmail.com

1 files changed, 280 insertions, 0 deletions

diff --git a/src/bin/pg_walsummary/pg_walsummary.c b/src/bin/pg_walsummary/pg_walsummary.c
new file mode 100644
index 00000000000..0c0225eeb89
--- /dev/null
+++ b/src/bin/pg_walsummary/pg_walsummary.c
@@ -0,0 +1,280 @@
+/*-------------------------------------------------------------------------
+ *
+ * pg_walsummary.c
+ *		Prints the contents of WAL summary files.
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  src/bin/pg_walsummary/pg_walsummary.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres_fe.h"
+
+#include <fcntl.h>
+#include <limits.h>
+
+#include "common/blkreftable.h"
+#include "common/logging.h"
+#include "fe_utils/option_utils.h"
+#include "lib/stringinfo.h"
+#include "getopt_long.h"
+
+typedef struct ws_options
+{
+	bool		individual;
+	bool		quiet;
+} ws_options;
+
+typedef struct ws_file_info
+{
+	int			fd;
+	char	   *filename;
+} ws_file_info;
+
+static BlockNumber *block_buffer = NULL;
+static unsigned block_buffer_size = 512;	/* Initial size. */
+
+static void dump_one_relation(ws_options *opt, RelFileLocator *rlocator,
+							  ForkNumber forknum, BlockNumber limit_block,
+							  BlockRefTableReader *reader);
+static void help(const char *progname);
+static int	compare_block_numbers(const void *a, const void *b);
+static int	walsummary_read_callback(void *callback_arg, void *data,
+									 int length);
+static void walsummary_error_callback(void *callback_arg, char *fmt,...) pg_attribute_printf(2, 3);
+
+/*
+ * Main program.
+ */
+int
+main(int argc, char *argv[])
+{
+	static struct option long_options[] = {
+		{"individual", no_argument, NULL, 'i'},
+		{"quiet", no_argument, NULL, 'q'},
+		{NULL, 0, NULL, 0}
+	};
+
+	const char *progname;
+	int			optindex;
+	int			c;
+	ws_options	opt;
+
+	memset(&opt, 0, sizeof(ws_options));
+
+	pg_logging_init(argv[0]);
+	progname = get_progname(argv[0]);
+	handle_help_version_opts(argc, argv, progname, help);
+
+	/* process command-line options */
+	while ((c = getopt_long(argc, argv, "f:iqw:",
+							long_options, &optindex)) != -1)
+	{
+		switch (c)
+		{
+			case 'i':
+				opt.individual = true;
+				break;
+			case 'q':
+				opt.quiet = true;
+				break;
+			default:
+				/* getopt_long already emitted a complaint */
+				pg_log_error_hint("Try \"%s --help\" for more information.", progname);
+				exit(1);
+		}
+	}
+
+	if (optind >= argc)
+	{
+		pg_log_error("%s: no input files specified", progname);
+		pg_log_error_hint("Try \"%s --help\" for more information.", progname);
+		exit(1);
+	}
+
+	while (optind < argc)
+	{
+		ws_file_info ws;
+		BlockRefTableReader *reader;
+		RelFileLocator rlocator;
+		ForkNumber	forknum;
+		BlockNumber limit_block;
+
+		ws.filename = argv[optind++];
+		if ((ws.fd = open(ws.filename, O_RDONLY | PG_BINARY, 0)) < 0)
+			pg_fatal("could not open file \"%s\": %m", ws.filename);
+
+		reader = CreateBlockRefTableReader(walsummary_read_callback, &ws,
+										   ws.filename,
+										   walsummary_error_callback, NULL);
+		while (BlockRefTableReaderNextRelation(reader, &rlocator, &forknum,
+											   &limit_block))
+			dump_one_relation(&opt, &rlocator, forknum, limit_block, reader);
+
+		DestroyBlockRefTableReader(reader);
+		close(ws.fd);
+	}
+
+	exit(0);
+}
+
+/*
+ * Dump details for one relation.
+ */
+static void
+dump_one_relation(ws_options *opt, RelFileLocator *rlocator,
+				  ForkNumber forknum, BlockNumber limit_block,
+				  BlockRefTableReader *reader)
+{
+	unsigned	i = 0;
+	unsigned	nblocks;
+	BlockNumber startblock = InvalidBlockNumber;
+	BlockNumber endblock = InvalidBlockNumber;
+
+	/* Dump limit block, if any. */
+	if (limit_block != InvalidBlockNumber)
+		printf("TS %u, DB %u, REL %u, FORK %s: limit %u\n",
+			   rlocator->spcOid, rlocator->dbOid, rlocator->relNumber,
+			   forkNames[forknum], limit_block);
+
+	/* If we haven't allocated a block buffer yet, do that now. */
+	if (block_buffer == NULL)
+		block_buffer = palloc_array(BlockNumber, block_buffer_size);
+
+	/* Try to fill the block buffer. */
+	nblocks = BlockRefTableReaderGetBlocks(reader,
+										   block_buffer,
+										   block_buffer_size);
+
+	/* If we filled the block buffer completely, we must enlarge it. */
+	while (nblocks >= block_buffer_size)
+	{
+		unsigned	new_size;
+
+		/* Double the size, being careful about overflow. */
+		new_size = block_buffer_size * 2;
+		if (new_size < block_buffer_size)
+			new_size = PG_UINT32_MAX;
+		block_buffer = repalloc_array(block_buffer, BlockNumber, new_size);
+
+		/* Try to fill the newly-allocated space. */
+		nblocks +=
+			BlockRefTableReaderGetBlocks(reader,
+										 block_buffer + block_buffer_size,
+										 new_size - block_buffer_size);
+
+		/* Save the new size for later calls. */
+		block_buffer_size = new_size;
+	}
+
+	/* If we don't need to produce any output, skip the rest of this. */
+	if (opt->quiet)
+		return;
+
+	/*
+	 * Sort the returned block numbers. If the block reference table was using
+	 * the bitmap representation for a given chunk, the block numbers in that
+	 * chunk will already be sorted, but when the array-of-offsets
+	 * representation is used, we can receive block numbers here out of order.
+	 */
+	qsort(block_buffer, nblocks, sizeof(BlockNumber), compare_block_numbers);
+
+	/* Dump block references. */
+	while (i < nblocks)
+	{
+		/*
+		 * Find the next range of blocks to print, but if --individual was
+		 * specified, then consider each block a separate range.
+		 */
+		startblock = endblock = block_buffer[i++];
+		if (!opt->individual)
+		{
+			while (i < nblocks && block_buffer[i] == endblock + 1)
+			{
+				endblock++;
+				i++;
+			}
+		}
+
+		/* Format this range of block numbers as a string. */
+		if (startblock == endblock)
+			printf("TS %u, DB %u, REL %u, FORK %s: block %u\n",
+				   rlocator->spcOid, rlocator->dbOid, rlocator->relNumber,
+				   forkNames[forknum], startblock);
+		else
+			printf("TS %u, DB %u, REL %u, FORK %s: blocks %u..%u\n",
+				   rlocator->spcOid, rlocator->dbOid, rlocator->relNumber,
+				   forkNames[forknum], startblock, endblock);
+	}
+}
+
+/*
+ * Quicksort comparator for block numbers.
+ */
+static int
+compare_block_numbers(const void *a, const void *b)
+{
+	BlockNumber aa = *(BlockNumber *) a;
+	BlockNumber bb = *(BlockNumber *) b;
+
+	if (aa > bb)
+		return 1;
+	else if (aa == bb)
+		return 0;
+	else
+		return -1;
+}
+
+/*
+ * Error callback.
+ */
+void
+walsummary_error_callback(void *callback_arg, char *fmt,...)
+{
+	va_list		ap;
+
+	va_start(ap, fmt);
+	pg_log_generic_v(PG_LOG_ERROR, PG_LOG_PRIMARY, fmt, ap);
+	va_end(ap);
+
+	exit(1);
+}
+
+/*
+ * Read callback.
+ */
+int
+walsummary_read_callback(void *callback_arg, void *data, int length)
+{
+	ws_file_info *ws = callback_arg;
+	int			rc;
+
+	if ((rc = read(ws->fd, data, length)) < 0)
+		pg_fatal("could not read file \"%s\": %m", ws->filename);
+
+	return rc;
+}
+
+/*
+ * help
+ *
+ * Prints help page for the program
+ *
+ * progname: the name of the executed program, such as "pg_walsummary"
+ */
+static void
+help(const char *progname)
+{
+	printf(_("%s prints the contents of a WAL summary file.\n\n"), progname);
+	printf(_("Usage:\n"));
+	printf(_("  %s [OPTION]... FILE...\n"), progname);
+	printf(_("\nOptions:\n"));
+	printf(_("  -i, --individual          list block numbers individually, not as ranges\n"));
+	printf(_("  -q, --quiet               don't print anything, just parse the files\n"));
+	printf(_("  -?, --help                show this help, then exit\n"));
+
+	printf(_("\nReport bugs to <%s>.\n"), PACKAGE_BUGREPORT);
+	printf(_("%s home page: <%s>\n"), PACKAGE_NAME, PACKAGE_URL);
+}