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Add a PQfireResultCreateEvents function to allow applications to mimic the
sequence of operations that libpq goes through while creating a PGresult. Also, remove ill-considered "const" decoration on parameters passed to event procedures.
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4 files changed

+94
-17
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4 files changed

+94
-17
lines changed

‎doc/src/sgml/libpq.sgml

Lines changed: 50 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
<!-- $PostgreSQL: pgsql/doc/src/sgml/libpq.sgml,v 1.262 2008/09/19 16:40:40 tgl Exp $ -->
1+
<!-- $PostgreSQL: pgsql/doc/src/sgml/libpq.sgml,v 1.263 2008/09/19 20:06:13 tgl Exp $ -->
22

33
<chapter id="libpq">
44
<title><application>libpq</application> - C Library</title>
@@ -4592,17 +4592,58 @@ char *pg_encoding_to_char(int <replaceable>encoding_id</replaceable>);
45924592
<parameter>conn</parameter> is not null and <parameter>status</>
45934593
indicates an error, the current error message of the specified
45944594
connection is copied into the <structname>PGresult</structname>.
4595-
Also, if <parameter>conn</parameter> is not null, any event handlers
4595+
Also, if <parameter>conn</parameter> is not null, any event procedures
45964596
registered in the connection are copied into the
4597-
<structname>PGresult</structname> (but they don't get
4598-
<literal>PGEVT_RESULTCREATE</> calls).
4597+
<structname>PGresult</structname>. (They do not get
4598+
<literal>PGEVT_RESULTCREATE</> calls, but see
4599+
<function>PQfireResultCreateEvents</function>.)
45994600
Note that <function>PQclear</function> should eventually be called
46004601
on the object, just as with a <structname>PGresult</structname>
46014602
returned by <application>libpq</application> itself.
46024603
</para>
46034604
</listitem>
46044605
</varlistentry>
46054606

4607+
<varlistentry>
4608+
<term>
4609+
<function>PQfireResultCreateEvents</function>
4610+
<indexterm>
4611+
<primary>PQfireResultCreateEvents</primary>
4612+
</indexterm>
4613+
</term>
4614+
<listitem>
4615+
<para>
4616+
Fires a <literal>PGEVT_RESULTCREATE</literal> event (see <xref
4617+
linkend="libpq-events">) for each event procedure registered in the
4618+
<structname>PGresult</structname> object. Returns non-zero for success,
4619+
zero if any event procedure fails.
4620+
4621+
<synopsis>
4622+
int PQfireResultCreateEvents(PGconn *conn, PGresult *res);
4623+
</synopsis>
4624+
</para>
4625+
4626+
<para>
4627+
The <literal>conn</> argument is passed through to event procedures
4628+
but not used directly. It can be <literal>NULL</> if the event
4629+
procedures won't use it.
4630+
</para>
4631+
4632+
<para>
4633+
Event procedures that have already received a
4634+
<literal>PGEVT_RESULTCREATE</> or <literal>PGEVT_RESULTCOPY</> event
4635+
for this object are not fired again.
4636+
</para>
4637+
4638+
<para>
4639+
The main reason that this function is separate from
4640+
<function>PQmakeEmptyPGResult</function> is that it is often appropriate
4641+
to create a <structname>PGresult</structname> and fill it with data
4642+
before invoking the event procedures.
4643+
</para>
4644+
</listitem>
4645+
</varlistentry>
4646+
46064647
<varlistentry>
46074648
<term>
46084649
<function>PQcopyResult</function>
@@ -4904,7 +4945,7 @@ defaultNoticeProcessor(void *arg, const char *message)
49044945
<synopsis>
49054946
typedef struct
49064947
{
4907-
const PGconn *conn;
4948+
PGconn *conn;
49084949
} PGEventRegister;
49094950
</synopsis>
49104951

@@ -4937,7 +4978,7 @@ typedef struct
49374978
<synopsis>
49384979
typedef struct
49394980
{
4940-
const PGconn *conn;
4981+
PGconn *conn;
49414982
} PGEventConnReset;
49424983
</synopsis>
49434984

@@ -4967,7 +5008,7 @@ typedef struct
49675008
<synopsis>
49685009
typedef struct
49695010
{
4970-
const PGconn *conn;
5011+
PGconn *conn;
49715012
} PGEventConnDestroy;
49725013
</synopsis>
49735014

@@ -4995,7 +5036,7 @@ typedef struct
49955036
<synopsis>
49965037
typedef struct
49975038
{
4998-
const PGconn *conn;
5039+
PGconn *conn;
49995040
PGresult *result;
50005041
} PGEventResultCreate;
50015042
</synopsis>
@@ -5063,7 +5104,7 @@ typedef struct
50635104
<synopsis>
50645105
typedef struct
50655106
{
5066-
const PGresult *result;
5107+
PGresult *result;
50675108
} PGEventResultDestroy;
50685109
</synopsis>
50695110

‎src/interfaces/libpq/exports.txt

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
# $PostgreSQL: pgsql/src/interfaces/libpq/exports.txt,v 1.20 2008/09/17 04:31:08 tgl Exp $
1+
# $PostgreSQL: pgsql/src/interfaces/libpq/exports.txt,v 1.21 2008/09/19 20:06:13 tgl Exp $
22
# Functions to be exported by libpq DLLs
33
PQconnectdb 1
44
PQsetdbLogin 2
@@ -150,3 +150,4 @@ PQinstanceData 147
150150
PQsetInstanceData 148
151151
PQresultInstanceData 149
152152
PQresultSetInstanceData 150
153+
PQfireResultCreateEvents 151

‎src/interfaces/libpq/libpq-events.c

Lines changed: 33 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/interfaces/libpq/libpq-events.c,v 1.2 2008/09/19 16:40:40 tgl Exp $
11+
* $PostgreSQL: pgsql/src/interfaces/libpq/libpq-events.c,v 1.3 2008/09/19 20:06:13 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -175,3 +175,35 @@ PQresultInstanceData(const PGresult *result, PGEventProc proc)
175175

176176
return NULL;
177177
}
178+
179+
/*
180+
* Fire RESULTCREATE events for an application-created PGresult.
181+
*
182+
* The conn argument can be NULL if event procedures won't use it.
183+
*/
184+
int
185+
PQfireResultCreateEvents(PGconn *conn, PGresult *res)
186+
{
187+
int i;
188+
189+
if (!res)
190+
return FALSE;
191+
192+
for (i = 0; i < res->nEvents; i++)
193+
{
194+
if (!res->events[i].resultInitialized)
195+
{
196+
PGEventResultCreate evt;
197+
198+
evt.conn = conn;
199+
evt.result = res;
200+
if (!res->events[i].proc(PGEVT_RESULTCREATE, &evt,
201+
res->events[i].passThrough))
202+
return FALSE;
203+
204+
res->events[i].resultInitialized = TRUE;
205+
}
206+
}
207+
208+
return TRUE;
209+
}

‎src/interfaces/libpq/libpq-events.h

Lines changed: 9 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
99
* Portions Copyright (c) 1994, Regents of the University of California
1010
*
11-
* $PostgreSQL: pgsql/src/interfaces/libpq/libpq-events.h,v 1.1 2008/09/17 04:31:08 tgl Exp $
11+
* $PostgreSQL: pgsql/src/interfaces/libpq/libpq-events.h,v 1.2 2008/09/19 20:06:13 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -36,22 +36,22 @@ typedef enum
3636

3737
typedef struct
3838
{
39-
const PGconn *conn;
39+
PGconn *conn;
4040
} PGEventRegister;
4141

4242
typedef struct
4343
{
44-
const PGconn *conn;
44+
PGconn *conn;
4545
} PGEventConnReset;
4646

4747
typedef struct
4848
{
49-
const PGconn *conn;
49+
PGconn *conn;
5050
} PGEventConnDestroy;
5151

5252
typedef struct
5353
{
54-
const PGconn *conn;
54+
PGconn *conn;
5555
PGresult *result;
5656
} PGEventResultCreate;
5757

@@ -63,7 +63,7 @@ typedef struct
6363

6464
typedef struct
6565
{
66-
const PGresult *result;
66+
PGresult *result;
6767
} PGEventResultDestroy;
6868

6969
typedef int (*PGEventProc) (PGEventId evtId, void *evtInfo, void *passThrough);
@@ -84,6 +84,9 @@ extern int PQresultSetInstanceData(PGresult *result, PGEventProc proc, void *dat
8484
/* Gets the PGresult instance data for the provided proc. */
8585
extern void *PQresultInstanceData(const PGresult *result, PGEventProc proc);
8686

87+
/* Fires RESULTCREATE events for an application-created PGresult. */
88+
extern int PQfireResultCreateEvents(PGconn *conn, PGresult *res);
89+
8790
#ifdef __cplusplus
8891
}
8992
#endif

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