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pg_on_connection_loss command for libpgtcl. Patch from
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
@ -10,7 +10,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/interfaces/libpgtcl/Attic/pgtcl.c,v 1.25 2002/06/20 20:29:53 momjian Exp $
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* $Header: /cvsroot/pgsql/src/interfaces/libpgtcl/Attic/pgtcl.c,v 1.26 2002/09/02 21:51:47 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -151,8 +151,13 @@ Pgtcl_Init(Tcl_Interp *interp)
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"pg_listen",
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Pg_listen,
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(ClientData) NULL, (Tcl_CmdDeleteProc *) NULL);
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Tcl_CreateCommand(interp,
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"pg_on_connection_loss",
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Pg_on_connection_loss,
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(ClientData) NULL, (Tcl_CmdDeleteProc *) NULL);
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Tcl_PkgProvide(interp, "Pgtcl", "1.3");
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Tcl_PkgProvide(interp, "Pgtcl", "1.4");
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return TCL_OK;
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}
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/interfaces/libpgtcl/Attic/pgtclCmds.c,v 1.65 2002/09/02 06:11:43 momjian Exp $
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* $Header: /cvsroot/pgsql/src/interfaces/libpgtcl/Attic/pgtclCmds.c,v 1.66 2002/09/02 21:51:47 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -1876,6 +1876,7 @@ Pg_listen(ClientData cData, Tcl_Interp *interp, int argc, char *argv[])
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notifies = (Pg_TclNotifies *) ckalloc(sizeof(Pg_TclNotifies));
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notifies->interp = interp;
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Tcl_InitHashTable(¬ifies->notify_hash, TCL_STRING_KEYS);
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notifies->conn_loss_cmd = NULL;
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notifies->next = connid->notify_list;
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connid->notify_list = notifies;
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Tcl_CallWhenDeleted(interp, PgNotifyInterpDelete,
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@ -1970,3 +1971,84 @@ Pg_listen(ClientData cData, Tcl_Interp *interp, int argc, char *argv[])
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ckfree(caserelname);
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return TCL_OK;
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}
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/***********************************
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Pg_on_connection_loss
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create or remove a callback request for unexpected connection loss
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syntax:
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pg_on_connection_loss conn ?callbackcommand?
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With a third arg, creates or changes the callback command for
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connection loss; without, cancels the callback request.
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Callbacks can occur whenever Tcl is executing its event loop.
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This is the normal idle loop in Tk; in plain tclsh applications,
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vwait or update can be used to enter the Tcl event loop.
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***********************************/
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int
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Pg_on_connection_loss(ClientData cData, Tcl_Interp *interp, int argc, char *argv[])
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{
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char *callback = NULL;
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Pg_TclNotifies *notifies;
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Pg_ConnectionId *connid;
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PGconn *conn;
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if (argc < 2 || argc > 3)
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{
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Tcl_AppendResult(interp, "wrong # args, should be \"",
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argv[0], " connection ?callback?\"", 0);
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return TCL_ERROR;
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}
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/*
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* Get the command arguments.
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*/
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conn = PgGetConnectionId(interp, argv[1], &connid);
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if (conn == (PGconn *) NULL)
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return TCL_ERROR;
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if ((argc > 2) && *argv[2])
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{
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callback = (char *) ckalloc((unsigned) (strlen(argv[2]) + 1));
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strcpy(callback, argv[2]);
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}
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/* Find or make a Pg_TclNotifies struct for this interp and connection */
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for (notifies = connid->notify_list; notifies; notifies = notifies->next)
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{
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if (notifies->interp == interp)
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break;
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}
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if (notifies == NULL)
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{
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notifies = (Pg_TclNotifies *) ckalloc(sizeof(Pg_TclNotifies));
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notifies->interp = interp;
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Tcl_InitHashTable(¬ifies->notify_hash, TCL_STRING_KEYS);
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notifies->conn_loss_cmd = NULL;
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notifies->next = connid->notify_list;
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connid->notify_list = notifies;
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Tcl_CallWhenDeleted(interp, PgNotifyInterpDelete,
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(ClientData) notifies);
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}
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/* Store new callback setting */
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if (notifies->conn_loss_cmd)
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ckfree((void *) notifies->conn_loss_cmd);
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notifies->conn_loss_cmd = callback;
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if (callback)
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{
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/*
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* Start the notify event source if it isn't already running.
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* The notify source will cause Tcl to watch read-ready on the
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* connection socket, so that we find out quickly if the connection
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* drops.
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*/
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PgStartNotifyEventSource(connid);
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}
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return TCL_OK;
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}
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@ -6,7 +6,7 @@
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* Portions Copyright (c) 1996-2002, 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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* $Id: pgtclCmds.h,v 1.26 2002/06/20 20:29:53 momjian Exp $
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* $Id: pgtclCmds.h,v 1.27 2002/09/02 21:51:47 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -21,7 +21,7 @@
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#define RES_START 16
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/*
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* From Tcl verion 8.0 on we can make large object access binary.
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* From Tcl version 8.0 on we can make large object access binary.
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*/
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#ifdef TCL_MAJOR_VERSION
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#if (TCL_MAJOR_VERSION >= 8)
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@ -36,6 +36,9 @@
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* deleted while the connection remains open. A free side benefit is that
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* multiple interpreters can be registered to listen for the same notify
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* name. (All their callbacks will be called, but in an unspecified order.)
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*
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* We use the same approach for pg_on_connection_loss callbacks, but they
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* are not kept in a hashtable since there's no name associated.
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*/
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typedef struct Pg_TclNotifies_s
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@ -48,6 +51,8 @@ typedef struct Pg_TclNotifies_s
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* got round to deleting the Pg_TclNotifies structure.
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*/
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Tcl_HashTable notify_hash; /* Active pg_listen requests */
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char *conn_loss_cmd; /* pg_on_connection_loss cmd, or NULL */
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} Pg_TclNotifies;
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typedef struct Pg_ConnectionId_s
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@ -128,5 +133,7 @@ extern int Pg_lo_export(
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ClientData cData, Tcl_Interp *interp, int argc, char *argv[]);
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extern int Pg_listen(
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ClientData cData, Tcl_Interp *interp, int argc, char *argv[]);
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extern int Pg_on_connection_loss(
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ClientData cData, Tcl_Interp *interp, int argc, char *argv[]);
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#endif /* PGTCLCMDS_H */
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@ -13,7 +13,7 @@
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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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* $Header: /cvsroot/pgsql/src/interfaces/libpgtcl/Attic/pgtclId.c,v 1.32 2002/08/18 01:39:43 momjian Exp $
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* $Header: /cvsroot/pgsql/src/interfaces/libpgtcl/Attic/pgtclId.c,v 1.33 2002/09/02 21:51:47 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -268,6 +268,8 @@ PgDelConnectionId(DRIVER_DEL_PROTO)
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entry = Tcl_NextHashEntry(&hsearch))
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ckfree((char *) Tcl_GetHashValue(entry));
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Tcl_DeleteHashTable(¬ifies->notify_hash);
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if (notifies->conn_loss_cmd)
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ckfree((void *) notifies->conn_loss_cmd);
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Tcl_DontCallWhenDeleted(notifies->interp, PgNotifyInterpDelete,
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(ClientData) notifies);
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ckfree((void *) notifies);
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@ -275,9 +277,9 @@ PgDelConnectionId(DRIVER_DEL_PROTO)
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/*
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* Turn off the Tcl event source for this connection, and delete any
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* pending notify events.
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* pending notify and connection-loss events.
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*/
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PgStopNotifyEventSource(connid);
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PgStopNotifyEventSource(connid, true);
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/* Close the libpq connection too */
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PQfinish(connid->conn);
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@ -495,7 +497,8 @@ error_out:
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typedef struct
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{
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Tcl_Event header; /* Standard Tcl event info */
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PGnotify info; /* Notify name from SQL server */
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PGnotify *notify; /* Notify event from libpq, or NULL */
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/* We use a NULL notify pointer to denote a connection-loss event */
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Pg_ConnectionId *connid; /* Connection for server */
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} NotifyEvent;
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@ -506,7 +509,6 @@ Pg_Notify_EventProc(Tcl_Event *evPtr, int flags)
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{
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NotifyEvent *event = (NotifyEvent *) evPtr;
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Pg_TclNotifies *notifies;
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Tcl_HashEntry *entry;
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char *callback;
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char *svcallback;
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@ -516,7 +518,11 @@ Pg_Notify_EventProc(Tcl_Event *evPtr, int flags)
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/* If connection's been closed, just forget the whole thing. */
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if (event->connid == NULL)
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{
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if (event->notify)
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PQfreeNotify(event->notify);
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return 1;
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}
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/*
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* Preserve/Release to ensure the connection struct doesn't disappear
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@ -541,17 +547,29 @@ Pg_Notify_EventProc(Tcl_Event *evPtr, int flags)
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/*
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* Find the callback to be executed for this interpreter, if any.
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*/
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entry = Tcl_FindHashEntry(¬ifies->notify_hash,
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event->info.relname);
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if (entry == NULL)
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continue; /* no pg_listen in this interpreter */
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callback = (char *) Tcl_GetHashValue(entry);
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if (event->notify)
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{
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/* Ordinary NOTIFY event */
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Tcl_HashEntry *entry;
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entry = Tcl_FindHashEntry(¬ifies->notify_hash,
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event->notify->relname);
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if (entry == NULL)
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continue; /* no pg_listen in this interpreter */
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callback = (char *) Tcl_GetHashValue(entry);
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}
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else
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{
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/* Connection-loss event */
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callback = notifies->conn_loss_cmd;
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}
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if (callback == NULL)
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continue; /* safety check -- shouldn't happen */
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continue; /* nothing to do for this interpreter */
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/*
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* We have to copy the callback string in case the user executes a
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* new pg_listen during the callback.
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* new pg_listen or pg_on_connection_loss during the callback.
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*/
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svcallback = (char *) ckalloc((unsigned) (strlen(callback) + 1));
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strcpy(svcallback, callback);
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@ -562,7 +580,10 @@ Pg_Notify_EventProc(Tcl_Event *evPtr, int flags)
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Tcl_Preserve((ClientData) interp);
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if (Tcl_GlobalEval(interp, svcallback) != TCL_OK)
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{
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Tcl_AddErrorInfo(interp, "\n (\"pg_listen\" script)");
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if (event->notify)
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Tcl_AddErrorInfo(interp, "\n (\"pg_listen\" script)");
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else
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Tcl_AddErrorInfo(interp, "\n (\"pg_on_connection_loss\" script)");
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Tcl_BackgroundError(interp);
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}
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Tcl_Release((ClientData) interp);
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@ -578,6 +599,9 @@ Pg_Notify_EventProc(Tcl_Event *evPtr, int flags)
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Tcl_Release((ClientData) event->connid);
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if (event->notify)
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PQfreeNotify(event->notify);
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return 1;
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}
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@ -598,20 +622,45 @@ PgNotifyTransferEvents(Pg_ConnectionId * connid)
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NotifyEvent *event = (NotifyEvent *) ckalloc(sizeof(NotifyEvent));
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event->header.proc = Pg_Notify_EventProc;
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event->info = *notify;
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event->notify = notify;
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event->connid = connid;
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Tcl_QueueEvent((Tcl_Event *) event, TCL_QUEUE_TAIL);
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PQfreeNotify(notify);
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}
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/*
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* This is also a good place to check for unexpected closure of the
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* connection (ie, backend crash), in which case we must shut down the
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* notify event source to keep Tcl from trying to select() on the now-
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* closed socket descriptor.
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* closed socket descriptor. But don't kill on-connection-loss events;
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* in fact, register one.
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*/
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if (PQsocket(connid->conn) < 0)
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PgStopNotifyEventSource(connid);
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PgConnLossTransferEvents(connid);
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}
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/*
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* Handle a connection-loss event
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*/
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void
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PgConnLossTransferEvents(Pg_ConnectionId * connid)
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{
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if (connid->notifier_running)
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{
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/* Put the on-connection-loss event in the Tcl queue */
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NotifyEvent *event = (NotifyEvent *) ckalloc(sizeof(NotifyEvent));
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event->header.proc = Pg_Notify_EventProc;
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event->notify = NULL;
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event->connid = connid;
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Tcl_QueueEvent((Tcl_Event *) event, TCL_QUEUE_TAIL);
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}
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/*
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* Shut down the notify event source to keep Tcl from trying to select()
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* on the now-closed socket descriptor. And zap any unprocessed notify
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* events ... but not, of course, the connection-loss event.
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*/
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PgStopNotifyEventSource(connid, false);
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}
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/*
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@ -633,7 +682,7 @@ PgNotifyInterpDelete(ClientData clientData, Tcl_Interp *interp)
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}
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/*
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* Comparison routine for detecting events to be removed by Tcl_DeleteEvents.
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* Comparison routines for detecting events to be removed by Tcl_DeleteEvents.
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* NB: In (at least) Tcl versions 7.6 through 8.0.3, there is a serious
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* bug in Tcl_DeleteEvents: if there are multiple events on the queue and
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* you tell it to delete the last one, the event list pointers get corrupted,
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@ -649,6 +698,22 @@ NotifyEventDeleteProc(Tcl_Event *evPtr, ClientData clientData)
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{
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Pg_ConnectionId *connid = (Pg_ConnectionId *) clientData;
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if (evPtr->proc == Pg_Notify_EventProc)
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{
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NotifyEvent *event = (NotifyEvent *) evPtr;
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if (event->connid == connid && event->notify != NULL)
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event->connid = NULL;
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}
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return 0;
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}
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/* This version deletes on-connection-loss events too */
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static int
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AllNotifyEventDeleteProc(Tcl_Event *evPtr, ClientData clientData)
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{
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Pg_ConnectionId *connid = (Pg_ConnectionId *) clientData;
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if (evPtr->proc == Pg_Notify_EventProc)
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{
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NotifyEvent *event = (NotifyEvent *) evPtr;
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@ -675,10 +740,19 @@ Pg_Notify_FileHandler(ClientData clientData, int mask)
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* it internally to libpq; but it will clear the read-ready
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* condition).
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*/
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PQconsumeInput(connid->conn);
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/* Transfer notify events from libpq to Tcl event queue. */
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PgNotifyTransferEvents(connid);
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if (PQconsumeInput(connid->conn))
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{
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/* Transfer notify events from libpq to Tcl event queue. */
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PgNotifyTransferEvents(connid);
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}
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else
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{
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/*
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* If there is no input but we have read-ready,
|
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* assume this means we lost the connection.
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*/
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PgConnLossTransferEvents(connid);
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}
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}
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||||
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@ -686,8 +760,8 @@ Pg_Notify_FileHandler(ClientData clientData, int mask)
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* Start and stop the notify event source for a connection.
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*
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* We do not bother to run the notifier unless at least one pg_listen
|
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* has been executed on the connection. Currently, once started the
|
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* notifier is run until the connection is closed.
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* or pg_on_connection_loss has been executed on the connection. Currently,
|
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* once started the notifier is run until the connection is closed.
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*
|
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* FIXME: if PQreset is executed on the underlying PGconn, the active
|
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* socket number could change. How and when should we test for this
|
||||
@ -724,7 +798,7 @@ PgStartNotifyEventSource(Pg_ConnectionId * connid)
|
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}
|
||||
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void
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PgStopNotifyEventSource(Pg_ConnectionId * connid)
|
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PgStopNotifyEventSource(Pg_ConnectionId * connid, bool allevents)
|
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{
|
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/* Remove the event source */
|
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if (connid->notifier_running)
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@ -742,6 +816,9 @@ PgStopNotifyEventSource(Pg_ConnectionId * connid)
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connid->notifier_running = 0;
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}
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/* Kill any queued Tcl events that reference this channel */
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Tcl_DeleteEvents(NotifyEventDeleteProc, (ClientData) connid);
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/* Kill queued Tcl events that reference this channel */
|
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if (allevents)
|
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Tcl_DeleteEvents(AllNotifyEventDeleteProc, (ClientData) connid);
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else
|
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Tcl_DeleteEvents(NotifyEventDeleteProc, (ClientData) connid);
|
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}
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@ -10,7 +10,7 @@
|
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* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
|
||||
* Portions Copyright (c) 1994, Regents of the University of California
|
||||
*
|
||||
* $Id: pgtclId.h,v 1.20 2002/08/18 01:39:43 momjian Exp $
|
||||
* $Id: pgtclId.h,v 1.21 2002/09/02 21:51:47 tgl Exp $
|
||||
*
|
||||
*-------------------------------------------------------------------------
|
||||
*/
|
||||
@ -44,8 +44,9 @@ extern PGresult *PgGetResultId(Tcl_Interp *interp, char *id);
|
||||
extern void PgDelResultId(Tcl_Interp *interp, char *id);
|
||||
extern int PgGetConnByResultId(Tcl_Interp *interp, char *resid);
|
||||
extern void PgStartNotifyEventSource(Pg_ConnectionId * connid);
|
||||
extern void PgStopNotifyEventSource(Pg_ConnectionId * connid);
|
||||
extern void PgStopNotifyEventSource(Pg_ConnectionId * connid, bool allevents);
|
||||
extern void PgNotifyTransferEvents(Pg_ConnectionId * connid);
|
||||
extern void PgConnLossTransferEvents(Pg_ConnectionId * connid);
|
||||
extern void PgNotifyInterpDelete(ClientData clientData, Tcl_Interp *interp);
|
||||
|
||||
/* GetFileProc is needed in Tcl 7.6 *only* ... it went away again in 8.0 */
|
||||
|
||||
Reference in New Issue
Block a user