postgres/src/bin/pg_basebackup/pg_receivexlog.c

/*-------------------------------------------------------------------------
 *
 * pg_receivexlog.c - receive streaming transaction log data and write it
 *					  to a local file.
 *
 * Author: Magnus Hagander <magnus@hagander.net>
 *
 * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *		  src/bin/pg_basebackup/pg_receivexlog.c
 *-------------------------------------------------------------------------
 */

/*
 * We have to use postgres.h not postgres_fe.h here, because there's so much
 * backend-only stuff in the XLOG include files we need.  But we need a
 * frontend-ish environment otherwise.	Hence this ugly hack.
 */
#define FRONTEND 1
#include "postgres.h"
#include "libpq-fe.h"
#include "libpq/pqsignal.h"
#include "access/xlog_internal.h"

#include "receivelog.h"
#include "streamutil.h"

#include <dirent.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>

#include "getopt_long.h"

/* Time to sleep between reconnection attempts */
#define RECONNECT_SLEEP_TIME 5

/* Global options */
char	   *basedir = NULL;
int			verbose = 0;
int			noloop = 0;
int			standby_message_timeout = 10 * 1000;		/* 10 sec = default */
volatile bool time_to_abort = false;


static void usage(void);
static XLogRecPtr FindStreamingStart(XLogRecPtr currentpos,
				   uint32 currenttimeline);
static void StreamLog();
static bool stop_streaming(XLogRecPtr segendpos, uint32 timeline,
			   bool segment_finished);

#define disconnect_and_exit(code)				\
	{											\
	if (conn != NULL) PQfinish(conn);			\
	exit(code);									\
	}


static void
usage(void)
{
	printf(_("%s receives PostgreSQL streaming transaction logs.\n\n"),
		   progname);
	printf(_("Usage:\n"));
	printf(_("  %s [OPTION]...\n"), progname);
	printf(_("\nOptions:\n"));
	printf(_("  -D, --directory=DIR    receive transaction log files into this directory\n"));
	printf(_("  -n, --no-loop          do not loop on connection lost\n"));
	printf(_("  -v, --verbose          output verbose messages\n"));
	printf(_("  -V, --version          output version information, then exit\n"));
	printf(_("  -?, --help             show this help, then exit\n"));
	printf(_("\nConnection options:\n"));
	printf(_("  -h, --host=HOSTNAME    database server host or socket directory\n"));
	printf(_("  -p, --port=PORT        database server port number\n"));
	printf(_("  -s, --status-interval=INTERVAL\n"
			 "                         time between status packets sent to server (in seconds)\n"));
	printf(_("  -U, --username=NAME    connect as specified database user\n"));
	printf(_("  -w, --no-password      never prompt for password\n"));
	printf(_("  -W, --password         force password prompt (should happen automatically)\n"));
	printf(_("\nReport bugs to <pgsql-bugs@postgresql.org>.\n"));
}

static bool
stop_streaming(XLogRecPtr segendpos, uint32 timeline, bool segment_finished)
{
	if (verbose && segment_finished)
		fprintf(stderr, _("%s: finished segment at %X/%X (timeline %u)\n"),
				progname, segendpos.xlogid, segendpos.xrecoff, timeline);

	if (time_to_abort)
	{
		fprintf(stderr, _("%s: received interrupt signal, exiting.\n"),
				progname);
		return true;
	}
	return false;
}

/*
 * Determine starting location for streaming, based on:
 * 1. If there are existing xlog segments, start at the end of the last one
 *	  that is complete (size matches XLogSegSize)
 * 2. If no valid xlog exists, start from the beginning of the current
 *	  WAL segment.
 */
static XLogRecPtr
FindStreamingStart(XLogRecPtr currentpos, uint32 currenttimeline)
{
	DIR		   *dir;
	struct dirent *dirent;
	int			i;
	bool		b;
	uint32		high_log = 0;
	uint32		high_seg = 0;

	dir = opendir(basedir);
	if (dir == NULL)
	{
		fprintf(stderr, _("%s: could not open directory \"%s\": %s\n"),
				progname, basedir, strerror(errno));
		disconnect_and_exit(1);
	}

	while (errno = 0, (dirent = readdir(dir)) != NULL)
	{
		char		fullpath[MAXPGPATH];
		struct stat statbuf;
		uint32		tli,
					log,
					seg;

		if (strcmp(dirent->d_name, ".") == 0 ||
			strcmp(dirent->d_name, "..") == 0)
			continue;

		/* xlog files are always 24 characters */
		if (strlen(dirent->d_name) != 24)
			continue;

		/* Filenames are always made out of 0-9 and A-F */
		b = false;
		for (i = 0; i < 24; i++)
		{
			if (!(dirent->d_name[i] >= '0' && dirent->d_name[i] <= '9') &&
				!(dirent->d_name[i] >= 'A' && dirent->d_name[i] <= 'F'))
			{
				b = true;
				break;
			}
		}
		if (b)
			continue;

		/*
		 * Looks like an xlog file. Parse its position.
		 */
		if (sscanf(dirent->d_name, "%08X%08X%08X", &tli, &log, &seg) != 3)
		{
			fprintf(stderr,
				 _("%s: could not parse transaction log file name \"%s\"\n"),
					progname, dirent->d_name);
			disconnect_and_exit(1);
		}

		/* Ignore any files that are for another timeline */
		if (tli != currenttimeline)
			continue;

		/* Check if this is a completed segment or not */
		snprintf(fullpath, sizeof(fullpath), "%s/%s", basedir, dirent->d_name);
		if (stat(fullpath, &statbuf) != 0)
		{
			fprintf(stderr, _("%s: could not stat file \"%s\": %s\n"),
					progname, fullpath, strerror(errno));
			disconnect_and_exit(1);
		}

		if (statbuf.st_size == XLOG_SEG_SIZE)
		{
			/* Completed segment */
			if (log > high_log ||
				(log == high_log && seg > high_seg))
			{
				high_log = log;
				high_seg = seg;
				continue;
			}
		}
		else
		{
			fprintf(stderr,
			  _("%s: segment file \"%s\" has incorrect size %d, skipping\n"),
					progname, dirent->d_name, (int) statbuf.st_size);
			continue;
		}
	}

#ifdef WIN32
	/* Bug in old Mingw dirent.c;  fixed in mingw-runtime-3.2, 2003-10-10 */
	if (GetLastError() == ERROR_NO_MORE_FILES)
		errno = 0;
#endif

	if (errno)
	{
		fprintf(stderr, _("%s: could not read directory \"%s\": %s\n"),
				progname, basedir, strerror(errno));
		disconnect_and_exit(1);
	}

	if (closedir(dir))
	{
		fprintf(stderr, _("%s: could not close directory \"%s\": %s\n"),
				progname, basedir, strerror(errno));
		disconnect_and_exit(1);
	}

	if (high_log > 0 || high_seg > 0)
	{
		XLogRecPtr	high_ptr;

		/*
		 * Move the starting pointer to the start of the next segment, since
		 * the highest one we've seen was completed.
		 */
		NextLogSeg(high_log, high_seg);

		high_ptr.xlogid = high_log;
		high_ptr.xrecoff = high_seg * XLOG_SEG_SIZE;

		return high_ptr;
	}
	else
		return currentpos;
}

/*
 * Start the log streaming
 */
static void
StreamLog(void)
{
	PGresult   *res;
	uint32		timeline;
	XLogRecPtr	startpos;
	int			minServerMajor,
				maxServerMajor;
	int			serverMajor;

	/*
	 * Connect in replication mode to the server
	 */
	conn = GetConnection();
	if (!conn)
		/* Error message already written in GetConnection() */
		return;

	/*
	 * Check server version. IDENTIFY_SYSTEM didn't return the current xlog
	 * position before 9.1, so we can't work with servers older than 9.1. And
	 * we don't support servers newer than the client.
	 */
	minServerMajor = 901;
	maxServerMajor = PG_VERSION_NUM / 100;
	serverMajor = PQserverVersion(conn) / 100;
	if (serverMajor < minServerMajor || serverMajor > maxServerMajor)
	{
		fprintf(stderr, _("%s: unsupported server version %s\n"),
				progname, PQparameterStatus(conn, "server_version"));
		disconnect_and_exit(1);
	}

	/*
	 * Run IDENTIFY_SYSTEM so we can get the timeline and current xlog
	 * position.
	 */
	res = PQexec(conn, "IDENTIFY_SYSTEM");
	if (PQresultStatus(res) != PGRES_TUPLES_OK)
	{
		fprintf(stderr, _("%s: could not send replication command \"%s\": %s"),
				progname, "IDENTIFY_SYSTEM", PQerrorMessage(conn));

		disconnect_and_exit(1);
	}
	if (PQntuples(res) != 1 || PQnfields(res) != 3)
	{
		fprintf(stderr,
				_("%s: could not identify system: got %d rows and %d fields, expected %d rows and %d fields\n"),
				progname, PQntuples(res), PQnfields(res), 1, 3);

		disconnect_and_exit(1);
	}
	timeline = atoi(PQgetvalue(res, 0, 1));
	if (sscanf(PQgetvalue(res, 0, 2), "%X/%X", &startpos.xlogid, &startpos.xrecoff) != 2)
	{
		fprintf(stderr,
				_("%s: could not parse transaction log location \"%s\"\n"),
				progname, PQgetvalue(res, 0, 2));
		disconnect_and_exit(1);
	}
	PQclear(res);

	/*
	 * Figure out where to start streaming.
	 */
	startpos = FindStreamingStart(startpos, timeline);

	/*
	 * Always start streaming at the beginning of a segment
	 */
	startpos.xrecoff -= startpos.xrecoff % XLOG_SEG_SIZE;

	/*
	 * Start the replication
	 */
	if (verbose)
		fprintf(stderr,
				_("%s: starting log streaming at %X/%X (timeline %u)\n"),
				progname, startpos.xlogid, startpos.xrecoff, timeline);

	ReceiveXlogStream(conn, startpos, timeline, NULL, basedir,
					  stop_streaming, standby_message_timeout, false);

	PQfinish(conn);
}

/*
 * When sigint is called, just tell the system to exit at the next possible
 * moment.
 */
#ifndef WIN32

static void
sigint_handler(int signum)
{
	time_to_abort = true;
}
#endif

int
main(int argc, char **argv)
{
	static struct option long_options[] = {
		{"help", no_argument, NULL, '?'},
		{"version", no_argument, NULL, 'V'},
		{"directory", required_argument, NULL, 'D'},
		{"host", required_argument, NULL, 'h'},
		{"port", required_argument, NULL, 'p'},
		{"username", required_argument, NULL, 'U'},
		{"no-loop", no_argument, NULL, 'n'},
		{"no-password", no_argument, NULL, 'w'},
		{"password", no_argument, NULL, 'W'},
		{"status-interval", required_argument, NULL, 's'},
		{"verbose", no_argument, NULL, 'v'},
		{NULL, 0, NULL, 0}
	};
	int			c;
	int			option_index;

	progname = get_progname(argv[0]);
	set_pglocale_pgservice(argv[0], PG_TEXTDOMAIN("pg_receivexlog"));

	if (argc > 1)
	{
		if (strcmp(argv[1], "--help") == 0 || strcmp(argv[1], "-?") == 0)
		{
			usage();
			exit(0);
		}
		else if (strcmp(argv[1], "-V") == 0 ||
				 strcmp(argv[1], "--version") == 0)
		{
			puts("pg_receivexlog (PostgreSQL) " PG_VERSION);
			exit(0);
		}
	}

	while ((c = getopt_long(argc, argv, "D:h:p:U:s:nwWv",
							long_options, &option_index)) != -1)
	{
		switch (c)
		{
			case 'D':
				basedir = xstrdup(optarg);
				break;
			case 'h':
				dbhost = xstrdup(optarg);
				break;
			case 'p':
				if (atoi(optarg) <= 0)
				{
					fprintf(stderr, _("%s: invalid port number \"%s\"\n"),
							progname, optarg);
					exit(1);
				}
				dbport = xstrdup(optarg);
				break;
			case 'U':
				dbuser = xstrdup(optarg);
				break;
			case 'w':
				dbgetpassword = -1;
				break;
			case 'W':
				dbgetpassword = 1;
				break;
			case 's':
				standby_message_timeout = atoi(optarg) * 1000;
				if (standby_message_timeout < 0)
				{
					fprintf(stderr, _("%s: invalid status interval \"%s\"\n"),
							progname, optarg);
					exit(1);
				}
				break;
			case 'n':
				noloop = 1;
				break;
			case 'v':
				verbose++;
				break;
			default:

				/*
				 * getopt_long already emitted a complaint
				 */
				fprintf(stderr, _("Try \"%s --help\" for more information.\n"),
						progname);
				exit(1);
		}
	}

	/*
	 * Any non-option arguments?
	 */
	if (optind < argc)
	{
		fprintf(stderr,
				_("%s: too many command-line arguments (first is \"%s\")\n"),
				progname, argv[optind]);
		fprintf(stderr, _("Try \"%s --help\" for more information.\n"),
				progname);
		exit(1);
	}

	/*
	 * Required arguments
	 */
	if (basedir == NULL)
	{
		fprintf(stderr, _("%s: no target directory specified\n"), progname);
		fprintf(stderr, _("Try \"%s --help\" for more information.\n"),
				progname);
		exit(1);
	}

#ifndef WIN32
	pqsignal(SIGINT, sigint_handler);
#endif

	while (true)
	{
		StreamLog();
		if (time_to_abort)
		{
			/*
			 * We've been Ctrl-C'ed. That's not an error, so exit without an
			 * errorcode.
			 */
			exit(0);
		}
		else if (noloop)
		{
			fprintf(stderr, _("%s: disconnected.\n"), progname);
			exit(1);
		}
		else
		{
			fprintf(stderr,
					/* translator: check source for value for %d */
					_("%s: disconnected. Waiting %d seconds to try again.\n"),
					progname, RECONNECT_SLEEP_TIME);
			pg_usleep(RECONNECT_SLEEP_TIME * 1000000);
		}
	}

	/* Never get here */
	exit(2);
}