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| 1 | +diff --git a/src/backend/storage/ipc/procsignal.c b/src/backend/storage/ipc/procsignal.c |
| 2 | +index 7605b2c367..6a4327fe76 100644 |
| 3 | +--- a/src/backend/storage/ipc/procsignal.c |
| 4 | ++++ b/src/backend/storage/ipc/procsignal.c |
| 5 | +@@ -60,12 +60,20 @@ typedef struct |
| 6 | + */ |
| 7 | + #define NumProcSignalSlots (MaxBackends + NUM_AUXPROCTYPES) |
| 8 | + |
| 9 | ++#define IsCustomProcSignalReason(reason) \ |
| 10 | ++ ((reason) >= PROCSIG_CUSTOM_1 && (reason) <= PROCSIG_CUSTOM_N) |
| 11 | ++ |
| 12 | ++static bool CustomSignalPendings[NUM_CUSTOM_PROCSIGNALS]; |
| 13 | ++static ProcSignalHandler_type CustomInterruptHandlers[NUM_CUSTOM_PROCSIGNALS]; |
| 14 | ++ |
| 15 | + static ProcSignalSlot *ProcSignalSlots = NULL; |
| 16 | + static volatile ProcSignalSlot *MyProcSignalSlot = NULL; |
| 17 | + |
| 18 | + static bool CheckProcSignal(ProcSignalReason reason); |
| 19 | + static void CleanupProcSignalState(int status, Datum arg); |
| 20 | + |
| 21 | ++static void CheckAndSetCustomSignalInterrupts(void); |
| 22 | ++ |
| 23 | + /* |
| 24 | + * ProcSignalShmemSize |
| 25 | + * Compute space needed for procsignal's shared memory |
| 26 | +@@ -165,6 +173,36 @@ CleanupProcSignalState(int status, Datum arg) |
| 27 | + slot->pss_pid = 0; |
| 28 | + } |
| 29 | + |
| 30 | ++/* |
| 31 | ++ * RegisterCustomProcSignalHandler |
| 32 | ++ * Assign specific handler of custom process signal with new |
| 33 | ++ * ProcSignalReason key. |
| 34 | ++ * |
| 35 | ++ * This function has to be called in _PG_init function of extensions at the |
| 36 | ++ * stage of loading shared preloaded libraries. Otherwise it throws fatal error. |
| 37 | ++ * |
| 38 | ++ * Return INVALID_PROCSIGNAL if all slots for custom signals are occupied. |
| 39 | ++ */ |
| 40 | ++ProcSignalReason |
| 41 | ++RegisterCustomProcSignalHandler(ProcSignalHandler_type handler) |
| 42 | ++{ |
| 43 | ++ ProcSignalReason reason; |
| 44 | ++ |
| 45 | ++ if (!process_shared_preload_libraries_in_progress) |
| 46 | ++ ereport(FATAL, (errcode(ERRCODE_INTERNAL_ERROR), |
| 47 | ++ errmsg("cannot register custom signal after startup"))); |
| 48 | ++ |
| 49 | ++ /* Iterate through custom signal slots to find a free one */ |
| 50 | ++ for (reason = PROCSIG_CUSTOM_1; reason <= PROCSIG_CUSTOM_N; reason++) |
| 51 | ++ if (!CustomInterruptHandlers[reason - PROCSIG_CUSTOM_1]) |
| 52 | ++ { |
| 53 | ++ CustomInterruptHandlers[reason - PROCSIG_CUSTOM_1] = handler; |
| 54 | ++ return reason; |
| 55 | ++ } |
| 56 | ++ |
| 57 | ++ return INVALID_PROCSIGNAL; |
| 58 | ++} |
| 59 | ++ |
| 60 | + /* |
| 61 | + * SendProcSignal |
| 62 | + * Send a signal to a Postgres process |
| 63 | +@@ -292,9 +330,63 @@ procsignal_sigusr1_handler(SIGNAL_ARGS) |
| 64 | + if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN)) |
| 65 | + RecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN); |
| 66 | + |
| 67 | ++ CheckAndSetCustomSignalInterrupts(); |
| 68 | ++ |
| 69 | + SetLatch(MyLatch); |
| 70 | + |
| 71 | + latch_sigusr1_handler(); |
| 72 | + |
| 73 | + errno = save_errno; |
| 74 | + } |
| 75 | ++ |
| 76 | ++/* |
| 77 | ++ * Handle receipt of an interrupt indicating any of custom process signals. |
| 78 | ++ */ |
| 79 | ++static void |
| 80 | ++CheckAndSetCustomSignalInterrupts() |
| 81 | ++{ |
| 82 | ++ ProcSignalReason reason; |
| 83 | ++ |
| 84 | ++ for (reason = PROCSIG_CUSTOM_1; reason <= PROCSIG_CUSTOM_N; reason++) |
| 85 | ++ { |
| 86 | ++ if (CheckProcSignal(reason)) |
| 87 | ++ { |
| 88 | ++ |
| 89 | ++ /* set interrupt flags */ |
| 90 | ++ InterruptPending = true; |
| 91 | ++ CustomSignalPendings[reason - PROCSIG_CUSTOM_1] = true; |
| 92 | ++ } |
| 93 | ++ } |
| 94 | ++ |
| 95 | ++ SetLatch(MyLatch); |
| 96 | ++} |
| 97 | ++ |
| 98 | ++/* |
| 99 | ++ * CheckAndHandleCustomSignals |
| 100 | ++ * Check custom signal flags and call handler assigned to that signal |
| 101 | ++ * if it is not NULL |
| 102 | ++ * |
| 103 | ++ * This function is called within CHECK_FOR_INTERRUPTS if interrupt occurred. |
| 104 | ++ */ |
| 105 | ++void |
| 106 | ++CheckAndHandleCustomSignals(void) |
| 107 | ++{ |
| 108 | ++ int i; |
| 109 | ++ |
| 110 | ++ /* Disable interrupts to avoid recursive calls */ |
| 111 | ++ HOLD_INTERRUPTS(); |
| 112 | ++ |
| 113 | ++ /* Check on expiring of custom signals and call its handlers if exist */ |
| 114 | ++ for (i = 0; i < NUM_CUSTOM_PROCSIGNALS; i++) |
| 115 | ++ if (CustomSignalPendings[i]) |
| 116 | ++ { |
| 117 | ++ ProcSignalHandler_type handler; |
| 118 | ++ |
| 119 | ++ CustomSignalPendings[i] = false; |
| 120 | ++ handler = CustomInterruptHandlers[i]; |
| 121 | ++ if (handler != NULL) |
| 122 | ++ handler(); |
| 123 | ++ } |
| 124 | ++ |
| 125 | ++ RESUME_INTERRUPTS(); |
| 126 | ++} |
| 127 | +diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c |
| 128 | +index c28cc37012..f5a48b98e8 100644 |
| 129 | +--- a/src/backend/tcop/postgres.c |
| 130 | ++++ b/src/backend/tcop/postgres.c |
| 131 | +@@ -3139,6 +3139,8 @@ ProcessInterrupts(void) |
| 132 | + |
| 133 | + if (ParallelMessagePending) |
| 134 | + HandleParallelMessages(); |
| 135 | ++ |
| 136 | ++ CheckAndHandleCustomSignals(); |
| 137 | + } |
| 138 | + |
| 139 | + |
| 140 | +diff --git a/src/include/storage/procsignal.h b/src/include/storage/procsignal.h |
| 141 | +index 05b186a05c..d961790b7e 100644 |
| 142 | +--- a/src/include/storage/procsignal.h |
| 143 | ++++ b/src/include/storage/procsignal.h |
| 144 | +@@ -17,6 +17,8 @@ |
| 145 | + #include "storage/backendid.h" |
| 146 | + |
| 147 | + |
| 148 | ++#define NUM_CUSTOM_PROCSIGNALS 64 |
| 149 | ++ |
| 150 | + /* |
| 151 | + * Reasons for signalling a Postgres child process (a backend or an auxiliary |
| 152 | + * process, like checkpointer). We can cope with concurrent signals for different |
| 153 | +@@ -29,6 +31,8 @@ |
| 154 | + */ |
| 155 | + typedef enum |
| 156 | + { |
| 157 | ++ INVALID_PROCSIGNAL = -1, /* Must be first */ |
| 158 | ++ |
| 159 | + PROCSIG_CATCHUP_INTERRUPT, /* sinval catchup interrupt */ |
| 160 | + PROCSIG_NOTIFY_INTERRUPT, /* listen/notify interrupt */ |
| 161 | + PROCSIG_PARALLEL_MESSAGE, /* message from cooperating parallel backend */ |
| 162 | +@@ -42,9 +46,20 @@ typedef enum |
| 163 | + PROCSIG_RECOVERY_CONFLICT_BUFFERPIN, |
| 164 | + PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK, |
| 165 | + |
| 166 | ++ PROCSIG_CUSTOM_1, |
| 167 | ++ /* |
| 168 | ++ * PROCSIG_CUSTOM_2, |
| 169 | ++ * ..., |
| 170 | ++ * PROCSIG_CUSTOM_N-1, |
| 171 | ++ */ |
| 172 | ++ PROCSIG_CUSTOM_N = PROCSIG_CUSTOM_1 + NUM_CUSTOM_PROCSIGNALS - 1, |
| 173 | ++ |
| 174 | + NUM_PROCSIGNALS /* Must be last! */ |
| 175 | + } ProcSignalReason; |
| 176 | + |
| 177 | ++/* Handler of custom process signal */ |
| 178 | ++typedef void (*ProcSignalHandler_type) (void); |
| 179 | ++ |
| 180 | + /* |
| 181 | + * prototypes for functions in procsignal.c |
| 182 | + */ |
| 183 | +@@ -52,9 +67,13 @@ extern Size ProcSignalShmemSize(void); |
| 184 | + extern void ProcSignalShmemInit(void); |
| 185 | + |
| 186 | + extern void ProcSignalInit(int pss_idx); |
| 187 | ++extern ProcSignalReason |
| 188 | ++ RegisterCustomProcSignalHandler(ProcSignalHandler_type handler); |
| 189 | + extern int SendProcSignal(pid_t pid, ProcSignalReason reason, |
| 190 | + BackendId backendId); |
| 191 | + |
| 192 | ++extern void CheckAndHandleCustomSignals(void); |
| 193 | ++ |
| 194 | + extern void procsignal_sigusr1_handler(SIGNAL_ARGS); |
| 195 | + |
| 196 | + #endif /* PROCSIGNAL_H */ |
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