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Ekaterina Sokolovasokolcati
Ekaterina Sokolova
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sokolcati
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Add patches for PostgreSQL 18 core
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‎patches/custom_signals_18.0.patch‎

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diff --git a/src/backend/storage/ipc/procsignal.c b/src/backend/storage/ipc/procsignal.c
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index 087821311cc..f412ed57fbe 100644
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--- a/src/backend/storage/ipc/procsignal.c
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+++ b/src/backend/storage/ipc/procsignal.c
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@@ -6,6 +6,7 @@
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*
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* Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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+ * Portions Copyright (c) 2025, Postgres Professional
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*
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* IDENTIFICATION
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* src/backend/storage/ipc/procsignal.c
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@@ -102,6 +103,13 @@ struct ProcSignalHeader
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#define BARRIER_CLEAR_BIT(flags, type) \
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((flags) &= ~(((uint32) 1) << (uint32) (type)))
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+#define IsCustomProcSignalReason(reason) \
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+ ((reason) >= PROCSIG_CUSTOM_1 && (reason) <= PROCSIG_CUSTOM_N)
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+
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+static bool CustomSignalPendings[NUM_CUSTOM_PROCSIGNALS];
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+static bool CustomSignalProcessing[NUM_CUSTOM_PROCSIGNALS];
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+static ProcSignalHandler_type CustomInterruptHandlers[NUM_CUSTOM_PROCSIGNALS];
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+
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NON_EXEC_STATIC ProcSignalHeader *ProcSignal = NULL;
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static ProcSignalSlot *MyProcSignalSlot = NULL;
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@@ -109,6 +117,8 @@ static bool CheckProcSignal(ProcSignalReason reason);
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static void CleanupProcSignalState(int status, Datum arg);
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static void ResetProcSignalBarrierBits(uint32 flags);
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+static void CheckAndSetCustomSignalInterrupts(void);
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+
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/*
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* ProcSignalShmemSize
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* Compute space needed for ProcSignal's shared memory
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@@ -269,6 +279,36 @@ CleanupProcSignalState(int status, Datum arg)
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ConditionVariableBroadcast(&slot->pss_barrierCV);
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}
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+/*
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+ * RegisterCustomProcSignalHandler
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+ * Assign specific handler of custom process signal with new
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+ * ProcSignalReason key.
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+ *
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+ * This function has to be called in _PG_init function of extensions at the
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+ * stage of loading shared preloaded libraries. Otherwise it throws fatal error.
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+ *
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+ * Return INVALID_PROCSIGNAL if all slots for custom signals are occupied.
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+ */
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+ProcSignalReason
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+RegisterCustomProcSignalHandler(ProcSignalHandler_type handler)
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+{
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+ ProcSignalReason reason;
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+
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+ if (!process_shared_preload_libraries_in_progress)
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+ ereport(FATAL, (errcode(ERRCODE_INTERNAL_ERROR),
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+ errmsg("cannot register custom signal after startup")));
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+
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+ /* Iterate through custom signal slots to find a free one */
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+ for (reason = PROCSIG_CUSTOM_1; reason <= PROCSIG_CUSTOM_N; reason++)
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+ if (!CustomInterruptHandlers[reason - PROCSIG_CUSTOM_1])
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+ {
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+ CustomInterruptHandlers[reason - PROCSIG_CUSTOM_1] = handler;
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+ return reason;
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+ }
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+
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+ return INVALID_PROCSIGNAL;
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+}
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+
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/*
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* SendProcSignal
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* Send a signal to a Postgres process
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@@ -715,6 +755,8 @@ procsignal_sigusr1_handler(SIGNAL_ARGS)
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if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN))
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HandleRecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN);
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+ CheckAndSetCustomSignalInterrupts();
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+
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SetLatch(MyLatch);
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}
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@@ -797,3 +839,66 @@ SendCancelRequest(int backendPID, const uint8 *cancel_key, int cancel_key_len)
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(errmsg("PID %d in cancel request did not match any process",
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backendPID)));
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}
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+
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+/*
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+ * Handle receipt of an interrupt indicating any of custom process signals.
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+ */
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+static void
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+CheckAndSetCustomSignalInterrupts()
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+{
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+ ProcSignalReason reason;
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+
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+ for (reason = PROCSIG_CUSTOM_1; reason <= PROCSIG_CUSTOM_N; reason++)
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+ {
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+ if (CheckProcSignal(reason))
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+ {
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+
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+ /* set interrupt flags */
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+ InterruptPending = true;
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+ CustomSignalPendings[reason - PROCSIG_CUSTOM_1] = true;
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+ }
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+ }
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+
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+ SetLatch(MyLatch);
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+}
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+
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+/*
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+ * CheckAndHandleCustomSignals
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+ * Check custom signal flags and call handler assigned to that signal
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+ * if it is not NULL
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+ *
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+ * This function is called within CHECK_FOR_INTERRUPTS if interrupt occurred.
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+ */
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+void
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+CheckAndHandleCustomSignals(void)
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+{
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+ int i;
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+
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+ /*
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+ * This is invoked from ProcessInterrupts(), and since some of the
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+ * functions it calls contain CHECK_FOR_INTERRUPTS(), there is a potential
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+ * for recursive calls if more signals are received while this runs, so
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+ * let's block interrupts until done.
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+ */
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+ HOLD_INTERRUPTS();
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+
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+ /* Check on expiring of custom signals and call its handlers if exist */
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+ for (i = 0; i < NUM_CUSTOM_PROCSIGNALS; i++)
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+ {
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+ if (!CustomSignalProcessing[i] && CustomSignalPendings[i])
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+ {
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+ ProcSignalHandler_type handler;
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+
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+ CustomSignalPendings[i] = false;
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+ handler = CustomInterruptHandlers[i];
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+ if (handler != NULL)
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+ {
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+ CustomSignalProcessing[i] = true;
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+ handler();
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+ CustomSignalProcessing[i] = false;
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+ }
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+ }
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+ }
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+
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+ RESUME_INTERRUPTS();
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+}
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diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
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index 2f8c3d5f918..7baa3ebc98f 100644
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--- a/src/backend/tcop/postgres.c
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+++ b/src/backend/tcop/postgres.c
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@@ -3530,6 +3530,8 @@ ProcessInterrupts(void)
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if (ParallelMessagePending)
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ProcessParallelMessages();
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+ CheckAndHandleCustomSignals();
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+
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if (LogMemoryContextPending)
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ProcessLogMemoryContextInterrupt();
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diff --git a/src/include/storage/procsignal.h b/src/include/storage/procsignal.h
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index afeeb1ca019..814825fb839 100644
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--- a/src/include/storage/procsignal.h
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+++ b/src/include/storage/procsignal.h
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@@ -6,6 +6,7 @@
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*
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* Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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+ * Portions Copyright (c) 2025, Postgres Professional
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*
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* src/include/storage/procsignal.h
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*
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@@ -17,6 +18,8 @@
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#include "storage/procnumber.h"
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+#define NUM_CUSTOM_PROCSIGNALS 64
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+
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/*
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* Reasons for signaling a Postgres child process (a backend or an auxiliary
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* process, like checkpointer). We can cope with concurrent signals for different
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@@ -29,6 +32,8 @@
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*/
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typedef enum
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{
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+ INVALID_PROCSIGNAL = -1, /* Must be first */
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+
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PROCSIG_CATCHUP_INTERRUPT, /* sinval catchup interrupt */
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PROCSIG_NOTIFY_INTERRUPT, /* listen/notify interrupt */
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PROCSIG_PARALLEL_MESSAGE, /* message from cooperating parallel backend */
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@@ -37,6 +42,14 @@ typedef enum
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PROCSIG_LOG_MEMORY_CONTEXT, /* ask backend to log the memory contexts */
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PROCSIG_PARALLEL_APPLY_MESSAGE, /* Message from parallel apply workers */
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+ PROCSIG_CUSTOM_1,
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+ /*
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+ * PROCSIG_CUSTOM_2,
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+ * ...,
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+ * PROCSIG_CUSTOM_N-1,
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+ */
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+ PROCSIG_CUSTOM_N = PROCSIG_CUSTOM_1 + NUM_CUSTOM_PROCSIGNALS - 1,
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+
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/* Recovery conflict reasons */
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PROCSIG_RECOVERY_CONFLICT_FIRST,
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PROCSIG_RECOVERY_CONFLICT_DATABASE = PROCSIG_RECOVERY_CONFLICT_FIRST,
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@@ -56,6 +69,9 @@ typedef enum
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PROCSIGNAL_BARRIER_SMGRRELEASE, /* ask smgr to close files */
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} ProcSignalBarrierType;
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+/* Handler of custom process signal */
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+typedef void (*ProcSignalHandler_type) (void);
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+
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/*
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* Length of query cancel keys generated.
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*
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@@ -73,6 +89,8 @@ extern Size ProcSignalShmemSize(void);
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extern void ProcSignalShmemInit(void);
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extern void ProcSignalInit(const uint8 *cancel_key, int cancel_key_len);
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+extern ProcSignalReason
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+ RegisterCustomProcSignalHandler(ProcSignalHandler_type handler);
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extern int SendProcSignal(pid_t pid, ProcSignalReason reason,
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ProcNumber procNumber);
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extern void SendCancelRequest(int backendPID, const uint8 *cancel_key, int cancel_key_len);
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@@ -80,6 +98,7 @@ extern void SendCancelRequest(int backendPID, const uint8 *cancel_key, int cance
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extern uint64 EmitProcSignalBarrier(ProcSignalBarrierType type);
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extern void WaitForProcSignalBarrier(uint64 generation);
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extern void ProcessProcSignalBarrier(void);
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+extern void CheckAndHandleCustomSignals(void);
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extern void procsignal_sigusr1_handler(SIGNAL_ARGS);
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