This patch brings up to date what I did last year (now unfortunately

bitrotted) to allow the logging of the end of a session, enabled by
the config setting "log_disconnections".

Andrew Dunstan

doc/src/sgml/runtime.sgml

 <!--
-$PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.237 2004/02/13 12:25:09 wieck Exp $
+$PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.238 2004/02/17 03:54:56 momjian Exp $
 -->
 
 <Chapter Id="runtime">
@@ -1909,6 +1909,20 @@ SET ENABLE_SEQSCAN TO OFF;
      </varlistentry>
 
 
+     <varlistentry>
+      <term><varname>log_disconnections</varname> (<type>boolean</type>)</term>
+      <listitem>
+       <para>
+       This outputs a line in the server logs similar to LOG_CONNECTIONS 
+       but at session termination, and includes the duration of the 
+       session.   This is off by default. This option can only be set at 
+       server start or in the <filename>postgresql.conf</filename> 
+       configuration file.
+       </para>
+      </listitem>
+     </varlistentry>
+
+
      <varlistentry>
       <term><varname>log_duration</varname> (<type>boolean</type>)</term>
       <listitem>

src/backend/postmaster/postmaster.c

@@ -37,7 +37,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.366 2004/02/11 22:25:02 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.367 2004/02/17 03:54:56 momjian Exp $
  *
  * NOTES
  *
@@ -2428,6 +2428,13 @@ BackendInit(Port *port)
 	 * Signal handlers setting is moved to tcop/postgres...
 	 */
 
+	/* save start time for end of session reporting */
+	gettimeofday(&(port->session_start),NULL);
+
+	/* set these to empty in case they are needed before we set them up */
+	port->remote_host = "";
+	port->remote_port = "";
+
 	/* Save port etc. for ps status */
 	MyProcPort = port;
 
@@ -2483,6 +2490,12 @@ BackendInit(Port *port)
 		StrNCpy(remote_host, tmphost, sizeof(remote_host));
 	}
 
+	/*
+	 * save remote_host and remote_port in port stucture
+	 */
+	port->remote_host = strdup(remote_host);
+	port->remote_port = strdup(remote_port);
+
 	/*
 	 * Ready to begin client interaction.  We will give up and exit(0)
 	 * after a time delay, so that a broken client can't hog a connection

src/backend/tcop/postgres.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/tcop/postgres.c,v 1.389 2004/02/06 19:36:18 wieck Exp $
+ *	  $PostgreSQL: pgsql/src/backend/tcop/postgres.c,v 1.390 2004/02/17 03:54:57 momjian Exp $
  *
  * NOTES
  *	  this is the "main" module of the postgres backend and
@@ -84,6 +84,9 @@ sigjmp_buf	Warn_restart;
 bool		Warn_restart_ready = false;
 bool		InError = false;
 
+/* flag for logging end of session */
+bool        Log_disconnections = false;
+
 /*
  * Flags for expensive function optimization -- JMH 3/9/92
  */
@@ -149,6 +152,7 @@ static void start_xact_command(void);
 static void finish_xact_command(void);
 static void SigHupHandler(SIGNAL_ARGS);
 static void FloatExceptionHandler(SIGNAL_ARGS);
+static void log_session_end(void);
 
 
 /* ----------------------------------------------------------------
@@ -2406,7 +2410,10 @@ PostgresMain(int argc, char *argv[], const char *username)
 	 * other output options.
 	 */
 	if (debug_flag >= 1)
+	{
 		SetConfigOption("log_connections", "true", debug_context, gucsource);
+		SetConfigOption("log_disconnections", "true", debug_context, gucsource);
+	}
 	if (debug_flag >= 2)
 		SetConfigOption("log_statement", "true", debug_context, gucsource);
 	if (debug_flag >= 3)
@@ -2435,6 +2442,12 @@ PostgresMain(int argc, char *argv[], const char *username)
 			gucopts = lnext(gucopts);
 			SetConfigOption(name, value, PGC_BACKEND, PGC_S_CLIENT);
 		}
+
+		/*
+		 * set up handler to log session end.
+		 */
+		if (IsUnderPostmaster && Log_disconnections)
+			on_proc_exit(log_session_end,0);
 	}
 
 	/*
@@ -3178,3 +3191,61 @@ ShowUsage(const char *title)
 
 	pfree(str.data);
 }
+
+/*
+ * on_proc_exit handler to log end of session
+ */
+static void 
+log_session_end(void)
+{
+	Port * port = MyProcPort;
+	struct timeval end;
+	int  hours, minutes, seconds;
+
+	char session_time[20];
+	char uname[6+NAMEDATALEN];
+	char dbname[10+NAMEDATALEN];
+	char remote_host[7 + NI_MAXHOST];
+	char remote_port[7 + NI_MAXSERV];
+      
+	snprintf(uname, sizeof(uname)," user=%s",port->user_name);
+	snprintf(dbname, sizeof(dbname)," database=%s",port->database_name);
+	snprintf(remote_host,sizeof(remote_host)," host=%s",
+			 port->remote_host);
+	/* prevent redundant or empty reporting of port */
+	if (!LogSourcePort && strlen(port->remote_port))
+		snprintf(remote_port,sizeof(remote_port)," port=%s",port->remote_port);
+	else
+		remote_port[0] = '\0';
+
+
+	gettimeofday(&end,NULL);
+
+	if (end.tv_usec < port->session_start.tv_usec)
+	{
+		end.tv_sec--;
+		end.tv_usec += 1000000;
+	}
+	end.tv_sec -= port->session_start.tv_sec;
+	end.tv_usec -= port->session_start.tv_usec;
+
+	hours = end.tv_sec / 3600;
+	end.tv_sec %= 3600;
+	minutes = end.tv_sec / 60;
+	seconds = end.tv_sec % 60;
+
+	/* if time has gone backwards for some reason say so, or print time */
+
+	if (end.tv_sec < 0)
+		snprintf(session_time,sizeof(session_time),"negative!");
+	else
+		/* for stricter accuracy here we could round - this is close enough */
+		snprintf(session_time, sizeof(session_time),"%d:%02d:%02d.%02ld",
+				 hours, minutes, seconds, end.tv_usec/10000);
+      
+	ereport(
+		LOG,
+		(errmsg("disconnection: session time: %s%s%s%s%s",
+				session_time,uname,dbname,remote_host,remote_port)));
+
+}

src/backend/utils/misc/guc.c

@@ -10,7 +10,7 @@
  * Written by Peter Eisentraut <peter_e@gmx.net>.
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.186 2004/02/06 19:36:18 wieck Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.187 2004/02/17 03:54:57 momjian Exp $
  *
  *--------------------------------------------------------------------
  */
@@ -65,6 +65,7 @@
 
 /* XXX these should appear in other modules' header files */
 extern bool Log_connections;
+extern bool Log_disconnections;
 extern bool check_function_bodies;
 extern int	PreAuthDelay;
 extern int	AuthenticationTimeout;
@@ -499,6 +500,14 @@ static struct config_bool ConfigureNamesBool[] =
 		&Log_connections,
 		false, NULL, NULL
 	},
+	{
+		{"log_disconnections", PGC_BACKEND, LOGGING_WHAT,
+		 gettext_noop("Logs end of a session, including duration"),
+		 NULL
+		},
+		&Log_disconnections,
+		false, NULL, NULL
+	},
 	{
 		{"log_timestamp", PGC_SIGHUP, LOGGING_WHAT,
 			gettext_noop("Prefixes server log messages with a time stamp."),

src/backend/utils/misc/postgresql.conf.sample

@@ -182,6 +182,7 @@
 #debug_print_plan = false
 #debug_pretty_print = false
 #log_connections = false
+#log_disconnections = false
 #log_duration = false
 #log_pid = false
 #log_statement = false

src/include/libpq/libpq-be.h

@@ -11,7 +11,7 @@
  * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/libpq/libpq-be.h,v 1.39 2003/12/20 17:31:21 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/libpq/libpq-be.h,v 1.40 2004/02/17 03:54:57 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -47,6 +47,9 @@ typedef struct Port
 	ProtocolVersion proto;		/* FE/BE protocol version */
 	SockAddr	laddr;			/* local addr (postmaster) */
 	SockAddr	raddr;			/* remote addr (client) */
+	char        *remote_host;   /* name (or ip addr) of remote host */
+	char        *remote_port;   /* text rep of remote port */
+	struct timeval  session_start;  /* for session duration logging */
 	CAC_state	canAcceptConnections;	/* postmaster connection status */
 
 	/*