mirror of https://github.com/postgres/postgres
walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.REL9_0_ALPHA4_BRANCH
Heikki Linnakangas
16 years ago
parent
eb210ce85a
commit
32bc08b1d4
@ -1,24 +1,22 @@ |
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#-------------------------------------------------------------------------
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#
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# Makefile--
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# Makefile for src/backend/replication/walreceiver
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# Makefile for src/backend/replication/libpqwalreceiver
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#
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# IDENTIFICATION
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# $PostgreSQL: pgsql/src/backend/replication/walreceiver/Makefile,v 1.4 2010/01/15 21:06:26 tgl Exp $
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# $PostgreSQL: pgsql/src/backend/replication/libpqwalreceiver/Makefile,v 1.1 2010/01/20 09:16:24 heikki Exp $
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#
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#-------------------------------------------------------------------------
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subdir = src/backend/replication/walreceiver
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subdir = src/backend/postmaster/libpqwalreceiver
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top_builddir = ../../../..
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include $(top_builddir)/src/Makefile.global |
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override CPPFLAGS := -I$(libpq_srcdir) $(CPPFLAGS) |
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OBJS = walreceiver.o
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override CPPFLAGS := -I$(srcdir) -I$(libpq_srcdir) $(CPPFLAGS) |
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OBJS = libpqwalreceiver.o
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SHLIB_LINK = $(libpq)
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NAME := walreceiver
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NAME = libpqwalreceiver
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all: submake-libpq all-shared-lib |
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@ -0,0 +1,317 @@ |
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/*-------------------------------------------------------------------------
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* |
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* libpqwalreceiver.c |
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* |
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* This file contains the libpq-specific parts of walreceiver. It's |
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* loaded as a dynamic module to avoid linking the main server binary with |
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* libpq. |
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* |
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* Portions Copyright (c) 2010-2010, PostgreSQL Global Development Group |
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* |
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* |
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* IDENTIFICATION |
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* $PostgreSQL: pgsql/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c,v 1.1 2010/01/20 09:16:24 heikki Exp $ |
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* |
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*------------------------------------------------------------------------- |
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*/ |
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#include "postgres.h" |
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#include <unistd.h> |
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#include <sys/time.h> |
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#include "libpq-fe.h" |
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#include "access/xlog.h" |
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#include "miscadmin.h" |
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#include "replication/walreceiver.h" |
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#include "utils/builtins.h" |
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#ifdef HAVE_POLL_H |
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#include <poll.h> |
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#endif |
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#ifdef HAVE_SYS_POLL_H |
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#include <sys/poll.h> |
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#endif |
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#ifdef HAVE_SYS_SELECT_H |
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#include <sys/select.h> |
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#endif |
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PG_MODULE_MAGIC; |
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void _PG_init(void); |
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/* Current connection to the primary, if any */ |
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static PGconn *streamConn = NULL; |
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static bool justconnected = false; |
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/* Buffer for currently read records */ |
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static char *recvBuf = NULL; |
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/* Prototypes for interface functions */ |
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static bool libpqrcv_connect(char *conninfo, XLogRecPtr startpoint); |
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static bool libpqrcv_receive(int timeout, XLogRecPtr *recptr, char **buffer, |
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int *len); |
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static void libpqrcv_disconnect(void); |
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/* Prototypes for private functions */ |
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static bool libpq_select(int timeout_ms); |
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/*
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* Module load callback |
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*/ |
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void |
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_PG_init(void) |
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{ |
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/* Tell walreceiver how to reach us */ |
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if (walrcv_connect != NULL || walrcv_receive != NULL || walrcv_disconnect) |
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elog(ERROR, "libpqwalreceiver already loaded"); |
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walrcv_connect = libpqrcv_connect; |
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walrcv_receive = libpqrcv_receive; |
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walrcv_disconnect = libpqrcv_disconnect; |
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} |
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/*
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* Establish the connection to the primary server for XLOG streaming |
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*/ |
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static bool |
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libpqrcv_connect(char *conninfo, XLogRecPtr startpoint) |
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{ |
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char conninfo_repl[MAXCONNINFO + 14]; |
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char *primary_sysid; |
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char standby_sysid[32]; |
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TimeLineID primary_tli; |
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TimeLineID standby_tli; |
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PGresult *res; |
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char cmd[64]; |
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Assert(startpoint.xlogid != 0 || startpoint.xrecoff != 0); |
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/* Connect */ |
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snprintf(conninfo_repl, sizeof(conninfo_repl), "%s replication=true", conninfo); |
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streamConn = PQconnectdb(conninfo_repl); |
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if (PQstatus(streamConn) != CONNECTION_OK) |
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ereport(ERROR, |
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(errmsg("could not connect to the primary server : %s", |
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PQerrorMessage(streamConn)))); |
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/*
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* Get the system identifier and timeline ID as a DataRow message |
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* from the primary server. |
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*/ |
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res = PQexec(streamConn, "IDENTIFY_SYSTEM"); |
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if (PQresultStatus(res) != PGRES_TUPLES_OK) |
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{ |
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PQclear(res); |
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ereport(ERROR, |
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(errmsg("could not receive the SYSID and timeline ID from " |
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"the primary server: %s", |
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PQerrorMessage(streamConn)))); |
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} |
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if (PQnfields(res) != 2 || PQntuples(res) != 1) |
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{ |
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int ntuples = PQntuples(res); |
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int nfields = PQnfields(res); |
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PQclear(res); |
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ereport(ERROR, |
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(errmsg("invalid response from primary server"), |
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errdetail("expected 1 tuple with 2 fields, got %d tuples with %d fields", |
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ntuples, nfields))); |
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} |
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primary_sysid = PQgetvalue(res, 0, 0); |
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primary_tli = pg_atoi(PQgetvalue(res, 0, 1), 4, 0); |
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/*
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* Confirm that the system identifier of the primary is the same |
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* as ours. |
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*/ |
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snprintf(standby_sysid, sizeof(standby_sysid), UINT64_FORMAT, |
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GetSystemIdentifier()); |
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if (strcmp(primary_sysid, standby_sysid) != 0) |
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{ |
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PQclear(res); |
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ereport(ERROR, |
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(errmsg("system differs between the primary and standby"), |
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errdetail("the primary SYSID is %s, standby SYSID is %s", |
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primary_sysid, standby_sysid))); |
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} |
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/*
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* Confirm that the current timeline of the primary is the same |
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* as the recovery target timeline. |
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*/ |
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standby_tli = GetRecoveryTargetTLI(); |
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PQclear(res); |
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if (primary_tli != standby_tli) |
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ereport(ERROR, |
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(errmsg("timeline %u of the primary does not match recovery target timeline %u", |
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primary_tli, standby_tli))); |
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ThisTimeLineID = primary_tli; |
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/* Start streaming from the point requested by startup process */ |
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snprintf(cmd, sizeof(cmd), "START_REPLICATION %X/%X", |
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startpoint.xlogid, startpoint.xrecoff); |
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res = PQexec(streamConn, cmd); |
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if (PQresultStatus(res) != PGRES_COPY_OUT) |
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ereport(ERROR, |
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(errmsg("could not start XLOG streaming: %s", |
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PQerrorMessage(streamConn)))); |
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PQclear(res); |
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justconnected = true; |
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return true; |
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} |
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/*
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* Wait until we can read WAL stream, or timeout. |
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* |
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* Returns true if data has become available for reading, false if timed out |
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* or interrupted by signal. |
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* |
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* This is based on pqSocketCheck. |
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*/ |
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static bool |
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libpq_select(int timeout_ms) |
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{ |
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int ret; |
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Assert(streamConn != NULL); |
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if (PQsocket(streamConn) < 0) |
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ereport(ERROR, |
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(errcode_for_socket_access(), |
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errmsg("socket not open"))); |
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/* We use poll(2) if available, otherwise select(2) */ |
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{ |
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#ifdef HAVE_POLL |
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struct pollfd input_fd; |
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input_fd.fd = PQsocket(streamConn); |
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input_fd.events = POLLIN | POLLERR; |
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input_fd.revents = 0; |
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ret = poll(&input_fd, 1, timeout_ms); |
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#else /* !HAVE_POLL */ |
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fd_set input_mask; |
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struct timeval timeout; |
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struct timeval *ptr_timeout; |
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FD_ZERO(&input_mask); |
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FD_SET(PQsocket(streamConn), &input_mask); |
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if (timeout_ms < 0) |
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ptr_timeout = NULL; |
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else |
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{ |
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timeout.tv_sec = timeout_ms / 1000; |
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timeout.tv_usec = (timeout_ms % 1000) * 1000; |
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ptr_timeout = &timeout; |
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} |
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ret = select(PQsocket(streamConn) + 1, &input_mask, |
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NULL, NULL, ptr_timeout); |
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#endif /* HAVE_POLL */ |
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} |
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if (ret == 0 || (ret < 0 && errno == EINTR)) |
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return false; |
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if (ret < 0) |
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ereport(ERROR, |
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(errcode_for_socket_access(), |
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errmsg("select() failed: %m"))); |
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return true; |
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} |
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/*
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* Disconnect connection to primary, if any. |
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*/ |
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static void |
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libpqrcv_disconnect(void) |
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{ |
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PQfinish(streamConn); |
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streamConn = NULL; |
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justconnected = false; |
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} |
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/*
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* Receive any WAL records available from XLOG stream, blocking for |
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* maximum of 'timeout' ms. |
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* |
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* Returns: |
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* |
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* True if data was received. *recptr, *buffer and *len are set to |
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* the WAL location of the received data, buffer holding it, and length, |
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* respectively. |
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* |
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* False if no data was available within timeout, or wait was interrupted |
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* by signal. |
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* |
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* The buffer returned is only valid until the next call of this function or |
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* libpq_connect/disconnect. |
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* |
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* ereports on error. |
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*/ |
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static bool |
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libpqrcv_receive(int timeout, XLogRecPtr *recptr, char **buffer, int *len) |
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{ |
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int rawlen; |
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if (recvBuf != NULL) |
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PQfreemem(recvBuf); |
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recvBuf = NULL; |
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/*
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* If the caller requested to block, wait for data to arrive. But if |
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* this is the first call after connecting, don't wait, because |
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* there might already be some data in libpq buffer that we haven't |
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* returned to caller. |
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*/ |
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if (timeout > 0 && !justconnected) |
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{ |
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if (!libpq_select(timeout)) |
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return false; |
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if (PQconsumeInput(streamConn) == 0) |
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ereport(ERROR, |
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(errmsg("could not read xlog records: %s", |
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PQerrorMessage(streamConn)))); |
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} |
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justconnected = false; |
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/* Receive CopyData message */ |
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rawlen = PQgetCopyData(streamConn, &recvBuf, 1); |
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if (rawlen == 0) /* no records available yet, then return */ |
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return false; |
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if (rawlen == -1) /* end-of-streaming or error */ |
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{ |
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PGresult *res; |
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res = PQgetResult(streamConn); |
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if (PQresultStatus(res) == PGRES_COMMAND_OK) |
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{ |
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PQclear(res); |
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ereport(ERROR, |
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(errmsg("replication terminated by primary server"))); |
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} |
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PQclear(res); |
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ereport(ERROR, |
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(errmsg("could not read xlog records: %s", |
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PQerrorMessage(streamConn)))); |
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} |
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if (rawlen < -1) |
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ereport(ERROR, |
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(errmsg("could not read xlog records: %s", |
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PQerrorMessage(streamConn)))); |
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if (rawlen < sizeof(XLogRecPtr)) |
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ereport(ERROR, |
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(errmsg("invalid WAL message received from primary"))); |
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/* Return received WAL records to caller */ |
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*recptr = *((XLogRecPtr *) recvBuf); |
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*buffer = recvBuf + sizeof(XLogRecPtr); |
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*len = rawlen - sizeof(XLogRecPtr); |
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return true; |
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} |
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Loading…
Reference in new issue