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db_include/storage/procsignal.h

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+/*-------------------------------------------------------------------------
+ *
+ * procsignal.h
+ *	  Routines for interprocess signaling
+ *
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/storage/procsignal.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef PROCSIGNAL_H
+#define PROCSIGNAL_H
+
+#include "storage/backendid.h"
+
+
+/*
+ * Reasons for signaling a Postgres child process (a backend or an auxiliary
+ * process, like checkpointer).  We can cope with concurrent signals for different
+ * reasons.  However, if the same reason is signaled multiple times in quick
+ * succession, the process is likely to observe only one notification of it.
+ * This is okay for the present uses.
+ *
+ * Also, because of race conditions, it's important that all the signals be
+ * defined so that no harm is done if a process mistakenly receives one.
+ */
+typedef enum
+{
+	PROCSIG_CATCHUP_INTERRUPT,	/* sinval catchup interrupt */
+	PROCSIG_NOTIFY_INTERRUPT,	/* listen/notify interrupt */
+	PROCSIG_PARALLEL_MESSAGE,	/* message from cooperating parallel backend */
+	PROCSIG_WALSND_INIT_STOPPING,	/* ask walsenders to prepare for shutdown  */
+	PROCSIG_BARRIER,			/* global barrier interrupt  */
+	PROCSIG_LOG_MEMORY_CONTEXT, /* ask backend to log the memory contexts */
+
+	/* Recovery conflict reasons */
+	PROCSIG_RECOVERY_CONFLICT_DATABASE,
+	PROCSIG_RECOVERY_CONFLICT_TABLESPACE,
+	PROCSIG_RECOVERY_CONFLICT_LOCK,
+	PROCSIG_RECOVERY_CONFLICT_SNAPSHOT,
+	PROCSIG_RECOVERY_CONFLICT_BUFFERPIN,
+	PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK,
+
+	NUM_PROCSIGNALS				/* Must be last! */
+} ProcSignalReason;
+
+typedef enum
+{
+	/*
+	 * XXX. PROCSIGNAL_BARRIER_PLACEHOLDER should be replaced when the first
+	 * real user of the ProcSignalBarrier mechanism is added. It's just here
+	 * for now because we can't have an empty enum.
+	 */
+	PROCSIGNAL_BARRIER_PLACEHOLDER = 0
+} ProcSignalBarrierType;
+
+/*
+ * prototypes for functions in procsignal.c
+ */
+extern Size ProcSignalShmemSize(void);
+extern void ProcSignalShmemInit(void);
+
+extern void ProcSignalInit(int pss_idx);
+extern int	SendProcSignal(pid_t pid, ProcSignalReason reason,
+						   BackendId backendId);
+
+extern uint64 EmitProcSignalBarrier(ProcSignalBarrierType type);
+extern void WaitForProcSignalBarrier(uint64 generation);
+extern void ProcessProcSignalBarrier(void);
+
+extern void procsignal_sigusr1_handler(SIGNAL_ARGS);
+
+#endif							/* PROCSIGNAL_H */