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Commitc657bc6

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Apply WaitLSN patch (PGPRO-90)
1 parent2de2911 commitc657bc6

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14 files changed

+395
-5
lines changed

14 files changed

+395
-5
lines changed

‎doc/src/sgml/ref/allfiles.sgml

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@@ -172,6 +172,7 @@ Complete list of usable sgml source files in this directory.
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<!ENTITY update SYSTEM "update.sgml">
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<!ENTITY vacuum SYSTEM "vacuum.sgml">
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<!ENTITY values SYSTEM "values.sgml">
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<!ENTITY waitlsn SYSTEM "waitlsn.sgml">
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<!-- applications and utilities -->
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<!ENTITY clusterdb SYSTEM "clusterdb.sgml">

‎doc/src/sgml/ref/waitlsn.sgml

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<!--
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doc/src/sgml/ref/waitlsn.sgml
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PostgreSQL documentation
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-->
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<refentry id="SQL-WAITLSN">
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<indexterm zone="sql-waitlsn">
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<primary>WAITLSN</primary>
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</indexterm>
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<refmeta>
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<refentrytitle>WAITLSN</refentrytitle>
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<manvolnum>7</manvolnum>
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<refmiscinfo>SQL - Language Statements</refmiscinfo>
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</refmeta>
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<refnamediv>
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<refname>WAITLSN</refname>
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<refpurpose>wait when target <acronym>LSN</> been replayed</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<synopsis>
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WAITLSN <replaceable class="PARAMETER">'LSN'</replaceable> [ , <replaceable class="PARAMETER">delay</replaceable> ]
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</synopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para>
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The <command>WAITLSN</command> wait till target <acronym>LSN</> will
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be replayed with an optional <quote>delay</> (milliseconds by default
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infinity) to be wait for LSN to replayed.
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</para>
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<para>
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<command>WAITLSN</command> provides a simple
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interprocess <acronym>LSN</> wait mechanism for a backends on slave
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in master-slave replication scheme on <productname>PostgreSQL</productname> database.
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</para>
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</refsect1>
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<refsect1>
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<title>Parameters</title>
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<variablelist>
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<varlistentry>
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<term><replaceable class="PARAMETER">LSN</replaceable></term>
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<listitem>
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<para>
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Target log sequence number to be wait for.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="PARAMETER">delay</replaceable></term>
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<listitem>
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<para>
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Time in miliseconds to waiting for LSN to be replayed.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>Notes</title>
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<para>
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Delay time to waiting for LSN to be replayed must be integer. For
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default it is infinity. Waiting can be interupped using Ctl+C, or
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by Postmaster death.
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</para>
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</refsect1>
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<refsect1>
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<title>Examples</title>
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<para>
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Configure and execute a waitlsn from
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<application>psql</application>:
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<programlisting>
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WAITLSN '0/3F07A6B1', 10000;
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NOTICE: LSN is not reached. Try to make bigger delay.
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WAITLSN
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WAITLSN '0/3F07A611';
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WAITLSN
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WAITLSN '0/3F0FF791', 500000;
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^CCancel request sent
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NOTICE: LSN is not reached. Try to make bigger delay.
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ERROR: canceling statement due to user request
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</programlisting>
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</para>
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</refsect1>
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<refsect1>
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<title>Compatibility</title>
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<para>
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There is no <command>WAITLSN</command> statement in the SQL
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standard.
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</para>
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</refsect1>
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</refentry>

‎doc/src/sgml/reference.sgml

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@@ -200,6 +200,7 @@
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&update;
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&vacuum;
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&values;
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&waitlsn;
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</reference>
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‎src/backend/access/transam/xlog.c

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@@ -39,6 +39,7 @@
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#include"catalog/pg_control.h"
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#include"catalog/pg_database.h"
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#include"commands/tablespace.h"
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#include"commands/waitlsn.h"
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#include"miscadmin.h"
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#include"pgstat.h"
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#include"postmaster/bgwriter.h"
@@ -6949,6 +6950,11 @@ StartupXLOG(void)
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break;
69506951
}
69516952

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/*
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* After update lastReplayedEndRecPtr set Latches in SHMEM array
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*/
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WaitLSNSetLatch();
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/* Else, try to fetch the next WAL record */
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record=ReadRecord(xlogreader,InvalidXLogRecPtr,LOG, false);
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}while (record!=NULL);

‎src/backend/commands/Makefile

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@@ -20,6 +20,6 @@ OBJS = amcmds.o aggregatecmds.o alter.o analyze.o async.o cluster.o comment.o \
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policy.o portalcmds.o prepare.o proclang.o\
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schemacmds.o seclabel.o sequence.o tablecmds.o tablespace.o trigger.o\
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tsearchcmds.o typecmds.o user.o vacuum.o vacuumlazy.o\
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variable.o view.o
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variable.o view.o waitlsn.o
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include$(top_srcdir)/src/backend/common.mk

‎src/backend/commands/async.c

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#include"utils/ps_status.h"
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#include"utils/timestamp.h"
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/*
144143
* Maximum size of a NOTIFY payload, including terminating NULL. This
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* must be kept small enough so that a notification message fits on one

‎src/backend/commands/waitlsn.c

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/*-------------------------------------------------------------------------
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*
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* waitlsn.c
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* WaitLSN statment: WAITLSN
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*
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* Portions Copyright (c) 1996-2015, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* IDENTIFICATION
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* src/backend/commands/waitlsn.c
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*
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*-------------------------------------------------------------------------
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*/
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/*-------------------------------------------------------------------------
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* Wait for LSN been replayed on slave as of 9.5:
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* README
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*-------------------------------------------------------------------------
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*/
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#include"postgres.h"
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#include"fmgr.h"
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#include"utils/pg_lsn.h"
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#include"storage/latch.h"
25+
#include"miscadmin.h"
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#include"storage/spin.h"
27+
#include"storage/backendid.h"
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#include"access/xact.h"
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#include"storage/shmem.h"
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#include"storage/ipc.h"
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#include"access/xlog_fn.h"
32+
#include"utils/timestamp.h"
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#include"storage/pmsignal.h"
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#include"access/xlog.h"
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#include"access/xlogdefs.h"
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#include"commands/waitlsn.h"
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/* Latches Own-DisownLatch and AbortCаllBack */
40+
staticuint32GetSHMEMSize(void);
41+
staticvoidWLDisownLatchAbort(XactEventevent,void*arg);
42+
staticvoidWLOwnLatch(void);
43+
staticvoidWLDisownLatch(void);
44+
45+
void_PG_init(void);
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/* Shared memory structures */
48+
typedefstruct
49+
{
50+
intpid;
51+
volatileslock_tslock;
52+
Latchlatch;
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}BIDLatch;
54+
55+
typedefstruct
56+
{
57+
chardummy;
58+
BIDLatchl_arr[FLEXIBLE_ARRAY_MEMBER];
59+
}GlobState;
60+
61+
staticvolatileGlobState*state;
62+
boolis_latch_owned= false;
63+
64+
staticvoid
65+
WLOwnLatch(void)
66+
{
67+
SpinLockAcquire(&state->l_arr[MyBackendId].slock);
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OwnLatch(&state->l_arr[MyBackendId].latch);
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is_latch_owned= true;
70+
state->l_arr[MyBackendId].pid=MyProcPid;
71+
SpinLockRelease(&state->l_arr[MyBackendId].slock);
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}
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staticvoid
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WLDisownLatch(void)
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{
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SpinLockAcquire(&state->l_arr[MyBackendId].slock);
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DisownLatch(&state->l_arr[MyBackendId].latch);
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is_latch_owned= false;
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state->l_arr[MyBackendId].pid=0;
81+
SpinLockRelease(&state->l_arr[MyBackendId].slock);
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}
83+
84+
/* CallBack function */
85+
staticvoid
86+
WLDisownLatchAbort(XactEventevent,void*arg)
87+
{
88+
if (is_latch_owned&& (event==XACT_EVENT_PARALLEL_ABORT||
89+
event==XACT_EVENT_ABORT))
90+
{
91+
WLDisownLatch();
92+
}
93+
}
94+
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/* Module load callback */
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void
97+
_PG_init(void)
98+
{
99+
if (!IsUnderPostmaster)
100+
RegisterXactCallback(WLDisownLatchAbort,NULL);
101+
}
102+
103+
staticuint32
104+
GetSHMEMSize(void)
105+
{
106+
return offsetof(GlobState,l_arr)+sizeof(BIDLatch)* (MaxConnections+1);
107+
}
108+
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void
110+
WaitLSNShmemInit(void)
111+
{
112+
boolfound;
113+
uinti;
114+
115+
state= (GlobState*)ShmemInitStruct("pg_wait_lsn",
116+
GetSHMEMSize(),
117+
&found);
118+
if (!found)
119+
{
120+
for (i=0;i< (MaxConnections+1);i++)
121+
{
122+
state->l_arr[i].pid=0;
123+
SpinLockInit(&state->l_arr[i].slock);
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InitSharedLatch(&state->l_arr[i].latch);
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}
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}
127+
}
128+
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void
130+
WaitLSNSetLatch(void)
131+
{
132+
uinti;
133+
for (i=0;i< (MaxConnections+1);i++)
134+
{
135+
SpinLockAcquire(&state->l_arr[i].slock);
136+
if (state->l_arr[i].pid!=0)
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SetLatch(&state->l_arr[i].latch);
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SpinLockRelease(&state->l_arr[i].slock);
139+
}
140+
}
141+
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void
143+
WaitLSNUtility(constchar*lsn,constint*delay)
144+
{
145+
XLogRecPtrtrg_lsn;
146+
XLogRecPtrcur_lsn;
147+
intlatch_events;
148+
inttdelay=delay;
149+
TimestampTztimer=GetCurrentTimestamp();
150+
trg_lsn=DatumGetLSN(DirectFunctionCall1(pg_lsn_in,CStringGetDatum(lsn)));
151+
152+
tdelay *=1000;
153+
154+
if (delay>0)
155+
latch_events=WL_LATCH_SET |WL_TIMEOUT |WL_POSTMASTER_DEATH;
156+
else
157+
latch_events=WL_LATCH_SET |WL_POSTMASTER_DEATH;
158+
159+
WLOwnLatch();
160+
161+
for (;;)
162+
{
163+
ResetLatch(&state->l_arr[MyBackendId].latch);
164+
cur_lsn=GetXLogReplayRecPtr(NULL);
165+
166+
/* If LSN had been Replayed */
167+
if (trg_lsn <=cur_lsn)
168+
break;
169+
170+
/* If the postmaster dies, finish immediately */
171+
if (!PostmasterIsAlive())
172+
break;
173+
174+
/* If Delay time is over */
175+
if (latch_events&WL_TIMEOUT)
176+
{
177+
tdelay-= (GetCurrentTimestamp()-timer);
178+
if (tdelay <=0)
179+
break;
180+
timer=GetCurrentTimestamp();
181+
}
182+
183+
/* Tom Lane insists on! Discussion: <1661(dot)1469996911(at)sss(dot)pgh(dot)pa(dot)us> */
184+
CHECK_FOR_INTERRUPTS();
185+
WaitLatch(&state->l_arr[MyBackendId].latch,latch_events,tdelay);
186+
}
187+
188+
WLDisownLatch();
189+
190+
if (trg_lsn>cur_lsn)
191+
elog(NOTICE,"LSN is not reached. Try to make bigger delay.");
192+
}

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