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pg_on_connection_loss command for libpgtcl. Patch from

Browse Source 
Gerhard Hintermayer, revised and documented by Tom Lane.

This patch also fixes a 'must fix' bug: libpgtcl's LISTEN/NOTIFY
support was broken by the recent changes to the PGnotify structure.
Guess that change wasn't quite so safe as we thought.
This commit is contained in:
Tom Lane
2002-09-02 21:51:47 +00:00
parent b356b969ef
commit 8c8aa53953
6 changed files with 310 additions and 35 deletions
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105
doc/src/sgml/libpgtcl.sgml
View File

@ -72,6 +72,10 @@
<ENTRY><function>pg_listen</function></ENTRY>
<ENTRY>establish a callback for NOTIFY messages</ENTRY>
</ROW>
<ROW>
<ENTRY><function>pg_on_connection_loss</function></ENTRY>
<ENTRY>establish a callback for unexpected connection loss</ENTRY>
</ROW>
<ROW>
<ENTRY><function>pg_lo_creat</function></ENTRY>
@ -1245,7 +1249,7 @@ pg_listen <REPLACEABLE CLASS="PARAMETER">dbHandle</REPLACEABLE> <REPLACEABLE CLA
<REPLACEABLE CLASS="PARAMETER">callbackCommand</REPLACEABLE>
</TERM>
<LISTITEM>
<PARA>If present and not empty, provides the command string to execute
<PARA>If present, provides the command string to execute
when a matching notification arrives.
</PARA>
</LISTITEM>
@ -1312,6 +1316,105 @@ invoke the SQL NOTIFY statement using <FUNCTION>pg_exec</FUNCTION>.
<!-- ********************************************************** -->
<REFENTRY ID="PGTCL-PGON_CONNECTION_LOSS">
<REFMETA>
<REFENTRYTITLE>pg_on_connection_loss</REFENTRYTITLE>
<REFMISCINFO>PGTCL - Asynchronous Notify</REFMISCINFO>
</REFMETA>
<REFNAMEDIV>
<REFNAME>pg_on_connection_loss
</REFNAME>
<REFPURPOSE>set or change a callback for unexpected connection loss
</REFPURPOSE>
<INDEXTERM
ID="IX-PGTCL-PGON_CONNECTION_LOSS-1"><PRIMARY>pgtcl</PRIMARY><SECONDARY>connection loss</SECONDARY></INDEXTERM>
<INDEXTERM ID="IX-PGTCL-PGON_CONNECTION_LOSS-2"><PRIMARY>connection loss</PRIMARY></INDEXTERM>
</REFNAMEDIV>
<REFSYNOPSISDIV>
<REFSYNOPSISDIVINFO>
<DATE>2002-09-02</DATE>
</REFSYNOPSISDIVINFO>
<SYNOPSIS>
pg_on_connection_loss <REPLACEABLE CLASS="PARAMETER">dbHandle</REPLACEABLE> <REPLACEABLE CLASS="PARAMETER">callbackCommand</REPLACEABLE>
</SYNOPSIS>
<REFSECT2 ID="R2-PGTCL-PGON_CONNECTION_LOSS-1">
<REFSECT2INFO>
<DATE>2002-09-02</DATE>
</REFSECT2INFO>
<TITLE>Inputs
</TITLE>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<REPLACEABLE CLASS="PARAMETER">dbHandle</REPLACEABLE>
</TERM>
<LISTITEM>
<PARA>Specifies a valid database handle.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<REPLACEABLE CLASS="PARAMETER">callbackCommand</REPLACEABLE>
</TERM>
<LISTITEM>
<PARA>If present, provides the command string to execute
when connection loss is detected.
</PARA>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</REFSECT2>
<REFSECT2 ID="R2-PGTCL-PGON_CONNECTION_LOSS-2">
<REFSECT2INFO>
<DATE>2002-09-02</DATE>
</REFSECT2INFO>
<TITLE>Outputs
</TITLE>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
None
</TERM>
<LISTITEM>
<PARA>
</PARA>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</REFSECT2>
</REFSYNOPSISDIV>
<REFSECT1 ID="R1-PGTCL-PGON_CONNECTION_LOSS-1">
<REFSECT1INFO>
<DATE>2002-09-02</DATE>
</REFSECT1INFO>
<TITLE>Description
</TITLE>
<PARA><FUNCTION>pg_on_connection_loss</FUNCTION> creates, changes, or cancels
a request to execute a callback command if an unexpected loss of connection
to the database occurs.
With a <parameter>callbackCommand</>
parameter, the request is established, or the command string of an already
existing request is replaced. With no <parameter>callbackCommand</>
parameter, a prior request is canceled.
</PARA>
<para>
The callback command string is executed from the Tcl idle loop. That is the
normal idle state of an application written with Tk. In non-Tk Tcl shells,
you can
execute <FUNCTION>update</FUNCTION> or <FUNCTION>vwait</FUNCTION> to cause
the idle loop to be entered.
</Para>
</REFSECT1>
</REFENTRY>
<!-- ********************************************************** -->
<REFENTRY ID="PGTCL-PGLOCREAT">
<REFMETA>
<REFENTRYTITLE>pg_lo_creat</REFENTRYTITLE>