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robertmhaasrobertmhaas
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Support frontend-backend protocol communication using a shm_mq.
A background worker can use pq_redirect_to_shm_mq() to direct protocol that would normally be sent to the frontend to a shm_mq so that another process may read them. The receiving process may use pq_parse_errornotice() to parse an ErrorResponse or NoticeResponse from the background worker and, if it wishes, ThrowErrorData() to propagate the error (with or without further modification). Patch by me. Review by Andres Freund.
1 parent 252e652 commit 2bd9e41

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9 files changed

+428
-47
lines changed

9 files changed

+428
-47
lines changed

‎src/backend/libpq/Makefile

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -15,7 +15,7 @@ include $(top_builddir)/src/Makefile.global
1515
# be-fsstubs is here for historical reasons, probably belongs elsewhere
1616

1717
OBJS = be-fsstubs.o be-secure.o auth.o crypt.o hba.o ip.o md5.o pqcomm.o \
18-
pqformat.o pqsignal.o
18+
pqformat.o pqmq.o pqsignal.o
1919

2020
ifeq ($(with_openssl),yes)
2121
OBJS += be-secure-openssl.o

‎src/backend/libpq/pqcomm.c

Lines changed: 62 additions & 36 deletions
Original file line numberDiff line numberDiff line change
@@ -102,7 +102,6 @@
102102
int Unix_socket_permissions;
103103
char *Unix_socket_group;
104104

105-
106105
/* Where the Unix socket files are (list of palloc'd strings) */
107106
static List *sock_paths = NIL;
108107

@@ -134,16 +133,38 @@ static bool DoingCopyOut;
134133

135134

136135
/* Internal functions */
137-
static void pq_close(int code, Datum arg);
136+
static void socket_comm_reset(void);
137+
static void socket_close(int code, Datum arg);
138+
static void socket_set_nonblocking(bool nonblocking);
139+
static int socket_flush(void);
140+
static int socket_flush_if_writable(void);
141+
static bool socket_is_send_pending(void);
142+
static int socket_putmessage(char msgtype, const char *s, size_t len);
143+
static void socket_putmessage_noblock(char msgtype, const char *s, size_t len);
144+
static void socket_startcopyout(void);
145+
static void socket_endcopyout(bool errorAbort);
138146
static int internal_putbytes(const char *s, size_t len);
139147
static int internal_flush(void);
140-
static void pq_set_nonblocking(bool nonblocking);
148+
static void socket_set_nonblocking(bool nonblocking);
141149

142150
#ifdef HAVE_UNIX_SOCKETS
143151
static int Lock_AF_UNIX(char *unixSocketDir, char *unixSocketPath);
144152
static int Setup_AF_UNIX(char *sock_path);
145153
#endif /* HAVE_UNIX_SOCKETS */
146154

155+
PQcommMethods PQcommSocketMethods;
156+
157+
static PQcommMethods PqCommSocketMethods = {
158+
socket_comm_reset,
159+
socket_flush,
160+
socket_flush_if_writable,
161+
socket_is_send_pending,
162+
socket_putmessage,
163+
socket_putmessage_noblock,
164+
socket_startcopyout,
165+
socket_endcopyout
166+
};
167+
147168

148169
/* --------------------------------
149170
* pq_init - initialize libpq at backend startup
@@ -152,24 +173,25 @@ static int Setup_AF_UNIX(char *sock_path);
152173
void
153174
pq_init(void)
154175
{
176+
PqCommMethods = &PqCommSocketMethods;
155177
PqSendBufferSize = PQ_SEND_BUFFER_SIZE;
156178
PqSendBuffer = MemoryContextAlloc(TopMemoryContext, PqSendBufferSize);
157179
PqSendPointer = PqSendStart = PqRecvPointer = PqRecvLength = 0;
158180
PqCommBusy = false;
159181
DoingCopyOut = false;
160-
on_proc_exit(pq_close, 0);
182+
on_proc_exit(socket_close, 0);
161183
}
162184

163185
/* --------------------------------
164-
* pq_comm_reset - reset libpq during error recovery
186+
* socket_comm_reset - reset libpq during error recovery
165187
*
166188
* This is called from error recovery at the outer idle loop. It's
167189
* just to get us out of trouble if we somehow manage to elog() from
168190
* inside a pqcomm.c routine (which ideally will never happen, but...)
169191
* --------------------------------
170192
*/
171-
void
172-
pq_comm_reset(void)
193+
static void
194+
socket_comm_reset(void)
173195
{
174196
/* Do not throw away pending data, but do reset the busy flag */
175197
PqCommBusy = false;
@@ -178,14 +200,14 @@ pq_comm_reset(void)
178200
}
179201

180202
/* --------------------------------
181-
* pq_close - shutdown libpq at backend exit
203+
* socket_close - shutdown libpq at backend exit
182204
*
183205
* Note: in a standalone backend MyProcPort will be null,
184206
* don't crash during exit...
185207
* --------------------------------
186208
*/
187209
static void
188-
pq_close(int code, Datum arg)
210+
socket_close(int code, Datum arg)
189211
{
190212
if (MyProcPort != NULL)
191213
{
@@ -783,15 +805,20 @@ TouchSocketFiles(void)
783805
*/
784806

785807
/* --------------------------------
786-
* pq_set_nonblocking - set socket blocking/non-blocking
808+
* socket_set_nonblocking - set socket blocking/non-blocking
787809
*
788810
* Sets the socket non-blocking if nonblocking is TRUE, or sets it
789811
* blocking otherwise.
790812
* --------------------------------
791813
*/
792814
static void
793-
pq_set_nonblocking(bool nonblocking)
815+
socket_set_nonblocking(bool nonblocking)
794816
{
817+
if (MyProcPort == NULL)
818+
ereport(ERROR,
819+
(errcode(ERRCODE_CONNECTION_DOES_NOT_EXIST),
820+
errmsg("there is no client connection")));
821+
795822
if (MyProcPort->noblock == nonblocking)
796823
return;
797824

@@ -844,7 +871,7 @@ pq_recvbuf(void)
844871
}
845872

846873
/* Ensure that we're in blocking mode */
847-
pq_set_nonblocking(false);
874+
socket_set_nonblocking(false);
848875

849876
/* Can fill buffer from PqRecvLength and upwards */
850877
for (;;)
@@ -935,7 +962,7 @@ pq_getbyte_if_available(unsigned char *c)
935962
}
936963

937964
/* Put the socket into non-blocking mode */
938-
pq_set_nonblocking(true);
965+
socket_set_nonblocking(true);
939966

940967
r = secure_read(MyProcPort, c, 1);
941968
if (r < 0)
@@ -1194,7 +1221,7 @@ internal_putbytes(const char *s, size_t len)
11941221
/* If buffer is full, then flush it out */
11951222
if (PqSendPointer >= PqSendBufferSize)
11961223
{
1197-
pq_set_nonblocking(false);
1224+
socket_set_nonblocking(false);
11981225
if (internal_flush())
11991226
return EOF;
12001227
}
@@ -1210,21 +1237,21 @@ internal_putbytes(const char *s, size_t len)
12101237
}
12111238

12121239
/* --------------------------------
1213-
* pq_flush - flush pending output
1240+
* socket_flush - flush pending output
12141241
*
12151242
* returns 0 if OK, EOF if trouble
12161243
* --------------------------------
12171244
*/
1218-
int
1219-
pq_flush(void)
1245+
static int
1246+
socket_flush(void)
12201247
{
12211248
int res;
12221249

12231250
/* No-op if reentrant call */
12241251
if (PqCommBusy)
12251252
return 0;
12261253
PqCommBusy = true;
1227-
pq_set_nonblocking(false);
1254+
socket_set_nonblocking(false);
12281255
res = internal_flush();
12291256
PqCommBusy = false;
12301257
return res;
@@ -1310,8 +1337,8 @@ internal_flush(void)
13101337
* Returns 0 if OK, or EOF if trouble.
13111338
* --------------------------------
13121339
*/
1313-
int
1314-
pq_flush_if_writable(void)
1340+
static int
1341+
socket_flush_if_writable(void)
13151342
{
13161343
int res;
13171344

@@ -1324,7 +1351,7 @@ pq_flush_if_writable(void)
13241351
return 0;
13251352

13261353
/* Temporarily put the socket into non-blocking mode */
1327-
pq_set_nonblocking(true);
1354+
socket_set_nonblocking(true);
13281355

13291356
PqCommBusy = true;
13301357
res = internal_flush();
@@ -1333,11 +1360,11 @@ pq_flush_if_writable(void)
13331360
}
13341361

13351362
/* --------------------------------
1336-
* pq_is_send_pending - is there any pending data in the output buffer?
1363+
* socket_is_send_pending - is there any pending data in the output buffer?
13371364
* --------------------------------
13381365
*/
1339-
bool
1340-
pq_is_send_pending(void)
1366+
static bool
1367+
socket_is_send_pending(void)
13411368
{
13421369
return (PqSendStart < PqSendPointer);
13431370
}
@@ -1351,7 +1378,7 @@ pq_is_send_pending(void)
13511378

13521379

13531380
/* --------------------------------
1354-
* pq_putmessage - send a normal message (suppressed in COPY OUT mode)
1381+
* socket_putmessage - send a normal message (suppressed in COPY OUT mode)
13551382
*
13561383
* If msgtype is not '\0', it is a message type code to place before
13571384
* the message body. If msgtype is '\0', then the message has no type
@@ -1375,8 +1402,8 @@ pq_is_send_pending(void)
13751402
* returns 0 if OK, EOF if trouble
13761403
* --------------------------------
13771404
*/
1378-
int
1379-
pq_putmessage(char msgtype, const char *s, size_t len)
1405+
static int
1406+
socket_putmessage(char msgtype, const char *s, size_t len)
13801407
{
13811408
if (DoingCopyOut || PqCommBusy)
13821409
return 0;
@@ -1408,8 +1435,8 @@ pq_putmessage(char msgtype, const char *s, size_t len)
14081435
* If the output buffer is too small to hold the message, the buffer
14091436
* is enlarged.
14101437
*/
1411-
void
1412-
pq_putmessage_noblock(char msgtype, const char *s, size_t len)
1438+
static void
1439+
socket_putmessage_noblock(char msgtype, const char *s, size_t len)
14131440
{
14141441
int res PG_USED_FOR_ASSERTS_ONLY;
14151442
int required;
@@ -1431,18 +1458,18 @@ pq_putmessage_noblock(char msgtype, const char *s, size_t len)
14311458

14321459

14331460
/* --------------------------------
1434-
* pq_startcopyout - inform libpq that an old-style COPY OUT transfer
1461+
* socket_startcopyout - inform libpq that an old-style COPY OUT transfer
14351462
* is beginning
14361463
* --------------------------------
14371464
*/
1438-
void
1439-
pq_startcopyout(void)
1465+
static void
1466+
socket_startcopyout(void)
14401467
{
14411468
DoingCopyOut = true;
14421469
}
14431470

14441471
/* --------------------------------
1445-
* pq_endcopyout - end an old-style COPY OUT transfer
1472+
* socket_endcopyout - end an old-style COPY OUT transfer
14461473
*
14471474
* If errorAbort is indicated, we are aborting a COPY OUT due to an error,
14481475
* and must send a terminator line. Since a partial data line might have
@@ -1451,8 +1478,8 @@ pq_startcopyout(void)
14511478
* not allow binary transfers, so a textual terminator is always correct.
14521479
* --------------------------------
14531480
*/
1454-
void
1455-
pq_endcopyout(bool errorAbort)
1481+
static void
1482+
socket_endcopyout(bool errorAbort)
14561483
{
14571484
if (!DoingCopyOut)
14581485
return;
@@ -1462,7 +1489,6 @@ pq_endcopyout(bool errorAbort)
14621489
DoingCopyOut = false;
14631490
}
14641491

1465-
14661492
/*
14671493
* Support for TCP Keepalive parameters
14681494
*/

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