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Document the existence of the socket lock file under unix_socket_directory,

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which is perhaps not a terribly good spot for it but there doesn't seem to be
a better place.  Also add a source-code comment pointing out a couple reasons
for having a separate lock file.  Per suggestion from Greg Smith.
This commit is contained in:
Tom Lane 2010-08-26 22:00:19 +00:00
parent 4832291655
commit 73b3bd5574
2 changed files with 64 additions and 33 deletions
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90
doc/src/sgml/config.sgml
View File

@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.308 2010/08/24 13:32:25 momjian Exp $ --> <!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.309 2010/08/26 22:00:19 tgl Exp $ -->
<chapter Id="runtime-config"> <chapter Id="runtime-config">
<title>Server Configuration</title> <title>Server Configuration</title>
@ -426,6 +426,20 @@ SET ENABLE_SEQSCAN TO OFF;
<filename>/tmp</filename>, but can be changed at build time. <filename>/tmp</filename>, but can be changed at build time.
This parameter can only be set at server start. This parameter can only be set at server start.
</para> </para>
<para>
In addition to the socket file itself, which is named
<literal>.s.PGSQL.<replaceable>nnnn</></literal> where
<replaceable>nnnn</> is the server's port number, an ordinary file
named <literal>.s.PGSQL.<replaceable>nnnn</>.lock</literal> will be
created in the <varname>unix_socket_directory</> directory. Neither
file should ever be removed manually.
</para>
<para>
This parameter is irrelevant on Windows, which does not have
Unix-domain sockets.
</para>
</listitem> </listitem>
</varlistentry> </varlistentry>
@ -445,6 +459,11 @@ SET ENABLE_SEQSCAN TO OFF;
group of the server user. This parameter can only be set at group of the server user. This parameter can only be set at
server start. server start.
</para> </para>
<para>
This parameter is irrelevant on Windows, which does not have
Unix-domain sockets.
</para>
</listitem> </listitem>
</varlistentry> </varlistentry>
@ -482,6 +501,11 @@ SET ENABLE_SEQSCAN TO OFF;
<para> <para>
This parameter can only be set at server start. This parameter can only be set at server start.
</para> </para>
<para>
This parameter is irrelevant on Windows, which does not have
Unix-domain sockets.
</para>
</listitem> </listitem>
</varlistentry> </varlistentry>
@ -523,18 +547,19 @@ SET ENABLE_SEQSCAN TO OFF;
</indexterm> </indexterm>
<listitem> <listitem>
<para> <para>
Specifies the number of seconds before sending a keepalive packet on an otherwise idle Specifies the number of seconds before sending a keepalive packet on
connection. A value of 0 uses the system default. This parameter is supported an otherwise idle connection. A value of 0 uses the system default.
only on systems that support the <symbol>TCP_KEEPIDLE</> or <symbol>TCP_KEEPALIVE</> This parameter is supported only on systems that support the
symbols, and on Windows; on other systems, it must be zero. This parameter is <symbol>TCP_KEEPIDLE</> or <symbol>TCP_KEEPALIVE</> symbols, and on
ignored for connections made via a Unix-domain socket. Windows; on other systems, it must be zero. This parameter is ignored
<note> for connections made via a Unix-domain socket.
<para>
On Windows, a value of 0 will set this parameter to 2 hours,
since Windows does not provide a way to read the default value.
</para>
</note>
</para> </para>
<note>
<para>
On Windows, a value of 0 will set this parameter to 2 hours,
since Windows does not provide a way to read the system default value.
</para>
</note>
</listitem> </listitem>
</varlistentry> </varlistentry>
@ -545,18 +570,19 @@ SET ENABLE_SEQSCAN TO OFF;
</indexterm> </indexterm>
<listitem> <listitem>
<para> <para>
Specifies the number of seconds between sending keepalives on an otherwise idle Specifies the number of seconds between sending keepalives on an
connection. A value of 0 uses the system default. This parameter is supported otherwise idle connection. A value of 0 uses the system default.
only on systems that support the <symbol>TCP_KEEPINTVL</> This parameter is supported only on systems that support the
symbol, and on Windows; on other systems, it must be zero. This parameter is <symbol>TCP_KEEPINTVL</> symbol, and on Windows; on other systems, it
ignored for connections made via a Unix-domain socket. must be zero. This parameter is ignored for connections made via a
<note> Unix-domain socket.
<para>
On Windows, a value of 0 will set this parameter to 1 second,
since Windows does not provide a way to read the default value.
</para>
</note>
</para> </para>
<note>
<para>
On Windows, a value of 0 will set this parameter to 1 second,
since Windows does not provide a way to read the system default value.
</para>
</note>
</listitem> </listitem>
</varlistentry> </varlistentry>
@ -568,16 +594,16 @@ SET ENABLE_SEQSCAN TO OFF;
<listitem> <listitem>
<para> <para>
Specifies the number of keepalive packets to send on an otherwise idle Specifies the number of keepalive packets to send on an otherwise idle
connection. A value of 0 uses the system default. This parameter is supported connection. A value of 0 uses the system default. This parameter is
only on systems that support the <symbol>TCP_KEEPCNT</> supported only on systems that support the <symbol>TCP_KEEPCNT</>
symbol; on other systems, it must be zero. This parameter is symbol; on other systems, it must be zero. This parameter is ignored
ignored for connections made via a Unix-domain socket. for connections made via a Unix-domain socket.
<note>
<para>
This parameter is not supported on Windows, and must be zero.
</para>
</note>
</para> </para>
<note>
<para>
This parameter is not supported on Windows, and must be zero.
</para>
</note>
</listitem> </listitem>
</varlistentry> </varlistentry>

7
src/backend/libpq/pqcomm.c
View File

@ -30,7 +30,7 @@
* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California * Portions Copyright (c) 1994, Regents of the University of California
* *
* $PostgreSQL: pgsql/src/backend/libpq/pqcomm.c,v 1.212 2010/07/08 16:19:50 mha Exp $ * $PostgreSQL: pgsql/src/backend/libpq/pqcomm.c,v 1.213 2010/08/26 22:00:19 tgl Exp $
* *
*------------------------------------------------------------------------- *-------------------------------------------------------------------------
*/ */
@ -484,6 +484,11 @@ Lock_AF_UNIX(unsigned short portNumber, char *unixSocketName)
/* /*
* Grab an interlock file associated with the socket file. * Grab an interlock file associated with the socket file.
*
* Note: there are two reasons for using a socket lock file, rather than
* trying to interlock directly on the socket itself. First, it's a lot
* more portable, and second, it lets us remove any pre-existing socket
* file without race conditions.
*/ */
CreateSocketLockFile(sock_path, true); CreateSocketLockFile(sock_path, true);