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Make struct ParallelSlot private within pg_dump/parallel.c.
The only field of this struct that other files have any need to touch is the pointer to the TocEntry a worker is working on. (Well, pg_backup_archiver.c is actually looking at workerStatus too, but that can be finessed by specifying that the TocEntry pointer is NULL for a non-busy worker.) Hence, move out the TocEntry pointers to a separate array within struct ParallelState, and then we can make struct ParallelSlot private. I noted the possibility of this previously, but hadn't got round to actually doing it. Discussion: <1188.1464544443@sss.pgh.pa.us>
1 parent fb03d08 commit 0109ab2

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3 files changed

+65
-54
lines changed

3 files changed

+65
-54
lines changed

‎src/bin/pg_dump/parallel.c

Lines changed: 54 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -45,6 +45,8 @@
4545
* WRKR_IDLE: it's waiting for a command
4646
* WRKR_WORKING: it's working on a command
4747
* WRKR_TERMINATED: process ended
48+
* The pstate->te[] entry for each worker is valid when it's in WRKR_WORKING
49+
* state, and must be NULL in other states.
4850
*/
4951

5052
#include "postgres_fe.h"
@@ -71,6 +73,45 @@
7173

7274
#define NO_SLOT (-1) /* Failure result for GetIdleWorker() */
7375

76+
/* Worker process statuses */
77+
typedef enum
78+
{
79+
WRKR_IDLE,
80+
WRKR_WORKING,
81+
WRKR_TERMINATED
82+
} T_WorkerStatus;
83+
84+
/*
85+
* Private per-parallel-worker state (typedef for this is in parallel.h).
86+
*
87+
* Much of this is valid only in the master process (or, on Windows, should
88+
* be touched only by the master thread). But the AH field should be touched
89+
* only by workers. The pipe descriptors are valid everywhere.
90+
*/
91+
struct ParallelSlot
92+
{
93+
T_WorkerStatus workerStatus; /* see enum above */
94+
95+
/* These fields are valid if workerStatus == WRKR_WORKING: */
96+
ParallelCompletionPtr callback; /* function to call on completion */
97+
void *callback_data; /* passthru data for it */
98+
99+
ArchiveHandle *AH; /* Archive data worker is using */
100+
101+
int pipeRead; /* master's end of the pipes */
102+
int pipeWrite;
103+
int pipeRevRead; /* child's end of the pipes */
104+
int pipeRevWrite;
105+
106+
/* Child process/thread identity info: */
107+
#ifdef WIN32
108+
uintptr_t hThread;
109+
unsigned int threadId;
110+
#else
111+
pid_t pid;
112+
#endif
113+
};
114+
74115
#ifdef WIN32
75116

76117
/*
@@ -475,9 +516,10 @@ WaitForTerminatingWorkers(ParallelState *pstate)
475516
}
476517
#endif /* WIN32 */
477518

478-
/* On all platforms, update workerStatus as well */
519+
/* On all platforms, update workerStatus and te[] as well */
479520
Assert(j < pstate->numWorkers);
480521
slot->workerStatus = WRKR_TERMINATED;
522+
pstate->te[j] = NULL;
481523
}
482524
}
483525

@@ -870,20 +912,22 @@ ParallelBackupStart(ArchiveHandle *AH)
870912
{
871913
ParallelState *pstate;
872914
int i;
873-
const size_t slotSize = AH->public.numWorkers * sizeof(ParallelSlot);
874915

875916
Assert(AH->public.numWorkers > 0);
876917

877918
pstate = (ParallelState *) pg_malloc(sizeof(ParallelState));
878919

879920
pstate->numWorkers = AH->public.numWorkers;
921+
pstate->te = NULL;
880922
pstate->parallelSlot = NULL;
881923

882924
if (AH->public.numWorkers == 1)
883925
return pstate;
884926

885-
pstate->parallelSlot = (ParallelSlot *) pg_malloc(slotSize);
886-
memset((void *) pstate->parallelSlot, 0, slotSize);
927+
pstate->te = (TocEntry **)
928+
pg_malloc0(pstate->numWorkers * sizeof(TocEntry *));
929+
pstate->parallelSlot = (ParallelSlot *)
930+
pg_malloc0(pstate->numWorkers * sizeof(ParallelSlot));
887931

888932
#ifdef WIN32
889933
/* Make fmtId() and fmtQualifiedId() use thread-local storage */
@@ -929,9 +973,10 @@ ParallelBackupStart(ArchiveHandle *AH)
929973
"could not create communication channels: %s\n",
930974
strerror(errno));
931975

976+
pstate->te[i] = NULL; /* just for safety */
977+
932978
slot->workerStatus = WRKR_IDLE;
933979
slot->AH = NULL;
934-
slot->te = NULL;
935980
slot->callback = NULL;
936981
slot->callback_data = NULL;
937982

@@ -1062,6 +1107,7 @@ ParallelBackupEnd(ArchiveHandle *AH, ParallelState *pstate)
10621107
set_cancel_pstate(NULL);
10631108

10641109
/* Release state (mere neatnik-ism, since we're about to terminate) */
1110+
free(pstate->te);
10651111
free(pstate->parallelSlot);
10661112
free(pstate);
10671113
}
@@ -1201,9 +1247,9 @@ DispatchJobForTocEntry(ArchiveHandle *AH,
12011247

12021248
/* Remember worker is busy, and which TocEntry it's working on */
12031249
pstate->parallelSlot[worker].workerStatus = WRKR_WORKING;
1204-
pstate->parallelSlot[worker].te = te;
12051250
pstate->parallelSlot[worker].callback = callback;
12061251
pstate->parallelSlot[worker].callback_data = callback_data;
1252+
pstate->te[worker] = te;
12071253
}
12081254

12091255
/*
@@ -1394,13 +1440,13 @@ ListenToWorkers(ArchiveHandle *AH, ParallelState *pstate, bool do_wait)
13941440
if (messageStartsWith(msg, "OK "))
13951441
{
13961442
ParallelSlot *slot = &pstate->parallelSlot[worker];
1397-
TocEntry *te = slot->te;
1443+
TocEntry *te = pstate->te[worker];
13981444
int status;
13991445

14001446
status = parseWorkerResponse(AH, te, msg);
14011447
slot->callback(AH, te, status, slot->callback_data);
14021448
slot->workerStatus = WRKR_IDLE;
1403-
slot->te = NULL;
1449+
pstate->te[worker] = NULL;
14041450
}
14051451
else
14061452
exit_horribly(modulename,

‎src/bin/pg_dump/parallel.h

Lines changed: 5 additions & 40 deletions
Original file line numberDiff line numberDiff line change
@@ -33,51 +33,16 @@ typedef enum
3333
WFW_ALL_IDLE
3434
} WFW_WaitOption;
3535

36-
/* Worker process statuses */
37-
typedef enum
38-
{
39-
WRKR_IDLE,
40-
WRKR_WORKING,
41-
WRKR_TERMINATED
42-
} T_WorkerStatus;
43-
44-
/*
45-
* Per-parallel-worker state of parallel.c.
46-
*
47-
* Much of this is valid only in the master process (or, on Windows, should
48-
* be touched only by the master thread). But the AH field should be touched
49-
* only by workers. The pipe descriptors are valid everywhere.
50-
*/
51-
typedef struct ParallelSlot
52-
{
53-
T_WorkerStatus workerStatus; /* see enum above */
54-
55-
/* These fields are valid if workerStatus == WRKR_WORKING: */
56-
TocEntry *te; /* item being worked on */
57-
ParallelCompletionPtr callback; /* function to call on completion */
58-
void *callback_data; /* passthru data for it */
59-
60-
ArchiveHandle *AH; /* Archive data worker is using */
61-
62-
int pipeRead; /* master's end of the pipes */
63-
int pipeWrite;
64-
int pipeRevRead; /* child's end of the pipes */
65-
int pipeRevWrite;
66-
67-
/* Child process/thread identity info: */
68-
#ifdef WIN32
69-
uintptr_t hThread;
70-
unsigned int threadId;
71-
#else
72-
pid_t pid;
73-
#endif
74-
} ParallelSlot;
36+
/* ParallelSlot is an opaque struct known only within parallel.c */
37+
typedef struct ParallelSlot ParallelSlot;
7538

7639
/* Overall state for parallel.c */
7740
typedef struct ParallelState
7841
{
7942
int numWorkers; /* allowed number of workers */
80-
ParallelSlot *parallelSlot; /* array of numWorkers slots */
43+
/* these arrays have numWorkers entries, one per worker: */
44+
TocEntry **te; /* item being worked on, or NULL */
45+
ParallelSlot *parallelSlot; /* private info about each worker */
8146
} ParallelState;
8247

8348
#ifdef WIN32

‎src/bin/pg_dump/pg_backup_archiver.c

Lines changed: 6 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -4027,8 +4027,10 @@ get_next_work_item(ArchiveHandle *AH, TocEntry *ready_list,
40274027

40284028
for (k = 0; k < pstate->numWorkers; k++)
40294029
{
4030-
if (pstate->parallelSlot[k].workerStatus == WRKR_WORKING &&
4031-
pstate->parallelSlot[k].te->section == SECTION_DATA)
4030+
TocEntry *running_te = pstate->te[k];
4031+
4032+
if (running_te != NULL &&
4033+
running_te->section == SECTION_DATA)
40324034
count++;
40334035
}
40344036
if (pstate->numWorkers == 0 || count * 4 < pstate->numWorkers)
@@ -4049,12 +4051,10 @@ get_next_work_item(ArchiveHandle *AH, TocEntry *ready_list,
40494051
*/
40504052
for (i = 0; i < pstate->numWorkers; i++)
40514053
{
4052-
TocEntry *running_te;
4054+
TocEntry *running_te = pstate->te[i];
40534055

4054-
if (pstate->parallelSlot[i].workerStatus != WRKR_WORKING)
4056+
if (running_te == NULL)
40554057
continue;
4056-
running_te = pstate->parallelSlot[i].te;
4057-
40584058
if (has_lock_conflicts(te, running_te) ||
40594059
has_lock_conflicts(running_te, te))
40604060
{

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