postmaster.h

Go to the documentation of this file.

/*-------------------------------------------------------------------------
 *
 * postmaster.h
 *    Exports from postmaster/postmaster.c.
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * src/include/postmaster/postmaster.h
 *
 *-------------------------------------------------------------------------
 */
#ifndef _POSTMASTER_H
#define _POSTMASTER_H
 
#include "lib/ilist.h"
#include "miscadmin.h"
 
/*
 * A struct representing an active postmaster child process.  This is used
 * mainly to keep track of how many children we have and send them appropriate
 * signals when necessary.  All postmaster child processes are assigned a
 * PMChild entry.  That includes "normal" client sessions, but also autovacuum
 * workers, walsenders, background workers, and aux processes.  (Note that at
 * the time of launch, walsenders are labeled B_BACKEND; we relabel them to
 * B_WAL_SENDER upon noticing they've changed their PMChildFlags entry.  Hence
 * that check must be done before any operation that needs to distinguish
 * walsenders from normal backends.)
 *
 * "dead-end" children are also allocated a PMChild entry: these are children
 * launched just for the purpose of sending a friendly rejection message to a
 * would-be client.  We must track them because they are attached to shared
 * memory, but we know they will never become live backends.
 *
 * child_slot is an identifier that is unique across all running child
 * processes.  It is used as an index into the PMChildFlags array.  dead-end
 * children are not assigned a child_slot and have child_slot == 0 (valid
 * child_slot ids start from 1).
 */
typedef struct
{
    pid_t       pid;            /* process id of backend */
    int         child_slot;     /* PMChildSlot for this backend, if any */
    BackendType bkend_type;     /* child process flavor, see above */
    struct RegisteredBgWorker *rw;  /* bgworker info, if this is a bgworker */
    bool        bgworker_notify;    /* gets bgworker start/stop notifications */
    dlist_node  elem;           /* list link in ActiveChildList */
} PMChild;
 
#ifdef EXEC_BACKEND
extern PGDLLIMPORT int num_pmchild_slots;
#endif
 
/* GUC options */
extern PGDLLIMPORT bool EnableSSL;
extern PGDLLIMPORT int SuperuserReservedConnections;
extern PGDLLIMPORT int ReservedConnections;
extern PGDLLIMPORT int PostPortNumber;
extern PGDLLIMPORT int Unix_socket_permissions;
extern PGDLLIMPORT char *Unix_socket_group;
extern PGDLLIMPORT char *Unix_socket_directories;
extern PGDLLIMPORT char *ListenAddresses;
extern PGDLLIMPORT bool ClientAuthInProgress;
extern PGDLLIMPORT int PreAuthDelay;
extern PGDLLIMPORT int AuthenticationTimeout;
extern PGDLLIMPORT bool log_hostname;
extern PGDLLIMPORT bool enable_bonjour;
extern PGDLLIMPORT char *bonjour_name;
extern PGDLLIMPORT bool restart_after_crash;
extern PGDLLIMPORT bool remove_temp_files_after_crash;
extern PGDLLIMPORT bool send_abort_for_crash;
extern PGDLLIMPORT bool send_abort_for_kill;
 
#ifdef WIN32
extern PGDLLIMPORT HANDLE PostmasterHandle;
#else
extern PGDLLIMPORT int postmaster_alive_fds[2];
 
/*
 * Constants that represent which of postmaster_alive_fds is held by
 * postmaster, and which is used in children to check for postmaster death.
 */
#define POSTMASTER_FD_WATCH     0   /* used in children to check for
                                     * postmaster death */
#define POSTMASTER_FD_OWN       1   /* kept open by postmaster only */
#endif
 
extern PGDLLIMPORT const char *progname;
 
extern PGDLLIMPORT bool redirection_done;
extern PGDLLIMPORT bool LoadedSSL;
 
pg_noreturn extern void PostmasterMain(int argc, char *argv[]);
extern void ClosePostmasterPorts(bool am_syslogger);
extern void InitProcessGlobals(void);
 
extern int  MaxLivePostmasterChildren(void);
 
extern bool PostmasterMarkPIDForWorkerNotify(int);
 
#ifdef WIN32
extern void pgwin32_register_deadchild_callback(HANDLE procHandle, DWORD procId);
#endif
 
/* defined in globals.c */
extern PGDLLIMPORT struct ClientSocket *MyClientSocket;
 
/* prototypes for functions in launch_backend.c */
extern pid_t postmaster_child_launch(BackendType child_type,
                                     int child_slot,
                                     const void *startup_data,
                                     size_t startup_data_len,
                                     struct ClientSocket *client_sock);
const char *PostmasterChildName(BackendType child_type);
#ifdef EXEC_BACKEND
pg_noreturn extern void SubPostmasterMain(int argc, char *argv[]);
#endif
 
/* defined in pmchild.c */
extern PGDLLIMPORT dlist_head ActiveChildList;
 
extern void InitPostmasterChildSlots(void);
extern PMChild *AssignPostmasterChildSlot(BackendType btype);
extern PMChild *AllocDeadEndChild(void);
extern bool ReleasePostmasterChildSlot(PMChild *pmchild);
extern PMChild *FindPostmasterChildByPid(int pid);
 
/*
 * These values correspond to the special must-be-first options for dispatching
 * to various subprograms.  parse_dispatch_option() can be used to convert an
 * option name to one of these values.
 */
typedef enum DispatchOption
{
    DISPATCH_CHECK,
    DISPATCH_BOOT,
    DISPATCH_FORKCHILD,
    DISPATCH_DESCRIBE_CONFIG,
    DISPATCH_SINGLE,
    DISPATCH_POSTMASTER,        /* must be last */
} DispatchOption;
 
extern DispatchOption parse_dispatch_option(const char *name);
 
#endif                          /* _POSTMASTER_H */