Allow background workers to be started dynamically.
There is a new API, RegisterDynamicBackgroundWorker, which allows
an ordinary user backend to register a new background writer during
normal running. This means that it's no longer necessary for all
background workers to be registered during processing of
shared_preload_libraries, although the option of registering workers
at that time remains available.
When a background worker exits and will not be restarted, the
slot previously used by that background worker is automatically
released and becomes available for reuse. Slots used by background
workers that are configured for automatic restart can't (yet) be
released without shutting down the system.
This commit adds a new source file, bgworker.c, and moves some
of the existing control logic for background workers there.
Previously, there was little enough logic that it made sense to
keep everything in postmaster.c, but not any more.
This commit also makes the worker_spi contrib module into an
extension and adds a new function, worker_spi_launch, which can
be used to demonstrate the new facility.
2013-07-16 19:02:15 +02:00
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/*--------------------------------------------------------------------
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* bgworker_internals.h
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* POSTGRES pluggable background workers internals
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*
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* Portions Copyright (c) 1996-2013, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* IDENTIFICATION
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* src/include/postmaster/bgworker.h
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*--------------------------------------------------------------------
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*/
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#ifndef BGWORKER_INTERNALS_H
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#define BGWORKER_INTERNALS_H
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#include "datatype/timestamp.h"
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#include "lib/ilist.h"
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#include "postmaster/bgworker.h"
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/*
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* List of background workers, private to postmaster.
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*
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* A worker that requests a database connection during registration will have
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* rw_backend set, and will be present in BackendList. Note: do not rely on
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* rw_backend being non-NULL for shmem-connected workers!
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*/
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typedef struct RegisteredBgWorker
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{
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BackgroundWorker rw_worker; /* its registry entry */
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struct bkend *rw_backend; /* its BackendList entry, or NULL */
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pid_t rw_pid; /* 0 if not running */
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int rw_child_slot;
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TimestampTz rw_crashed_at; /* if not 0, time it last crashed */
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int rw_shmem_slot;
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slist_node rw_lnode; /* list link */
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} RegisteredBgWorker;
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extern slist_head BackgroundWorkerList;
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extern Size BackgroundWorkerShmemSize(void);
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extern void BackgroundWorkerShmemInit(void);
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extern void BackgroundWorkerStateChange(void);
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2013-07-24 23:41:55 +02:00
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extern void ForgetBackgroundWorker(slist_mutable_iter *cur);
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Allow background workers to be started dynamically.
There is a new API, RegisterDynamicBackgroundWorker, which allows
an ordinary user backend to register a new background writer during
normal running. This means that it's no longer necessary for all
background workers to be registered during processing of
shared_preload_libraries, although the option of registering workers
at that time remains available.
When a background worker exits and will not be restarted, the
slot previously used by that background worker is automatically
released and becomes available for reuse. Slots used by background
workers that are configured for automatic restart can't (yet) be
released without shutting down the system.
This commit adds a new source file, bgworker.c, and moves some
of the existing control logic for background workers there.
Previously, there was little enough logic that it made sense to
keep everything in postmaster.c, but not any more.
This commit also makes the worker_spi contrib module into an
extension and adds a new function, worker_spi_launch, which can
be used to demonstrate the new facility.
2013-07-16 19:02:15 +02:00
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#ifdef EXEC_BACKEND
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extern BackgroundWorker *BackgroundWorkerEntry(int slotno);
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#endif
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#endif /* BGWORKER_INTERNLS_H */
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