bgworker_internals.h

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/*--------------------------------------------------------------------
 * bgworker_internals.h
 *      POSTGRES pluggable background workers internals
 *
 * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *      src/include/postmaster/bgworker_internals.h
 *--------------------------------------------------------------------
 */
#ifndef BGWORKER_INTERNALS_H
#define BGWORKER_INTERNALS_H
 
#include "datatype/timestamp.h"
#include "lib/ilist.h"
#include "postmaster/bgworker.h"
 
/* GUC options */
 
/*
 * Maximum possible value of parallel workers.
 */
#define MAX_PARALLEL_WORKER_LIMIT 1024
 
/*
 * List of background workers, private to postmaster.
 *
 * A worker that requests a database connection during registration will have
 * rw_backend set, and will be present in BackendList.  Note: do not rely on
 * rw_backend being non-NULL for shmem-connected workers!
 */
typedef struct RegisteredBgWorker
{
    BackgroundWorker rw_worker; /* its registry entry */
    struct bkend *rw_backend;   /* its BackendList entry, or NULL */
    pid_t       rw_pid;         /* 0 if not running */
    int         rw_child_slot;
    TimestampTz rw_crashed_at;  /* if not 0, time it last crashed */
    int         rw_shmem_slot;
    bool        rw_terminate;
    slist_node  rw_lnode;       /* list link */
} RegisteredBgWorker;
 
extern PGDLLIMPORT slist_head BackgroundWorkerList;
 
extern Size BackgroundWorkerShmemSize(void);
extern void BackgroundWorkerShmemInit(void);
extern void BackgroundWorkerStateChange(bool allow_new_workers);
extern void ForgetBackgroundWorker(slist_mutable_iter *cur);
extern void ReportBackgroundWorkerPID(RegisteredBgWorker *);
extern void ReportBackgroundWorkerExit(slist_mutable_iter *cur);
extern void BackgroundWorkerStopNotifications(pid_t pid);
extern void ForgetUnstartedBackgroundWorkers(void);
extern void ResetBackgroundWorkerCrashTimes(void);
 
/* Function to start a background worker, called from postmaster.c */
extern void StartBackgroundWorker(void) pg_attribute_noreturn();
 
#ifdef EXEC_BACKEND
extern BackgroundWorker *BackgroundWorkerEntry(int slotno);
#endif
 
#endif                          /* BGWORKER_INTERNALS_H */