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cfeca62148
This first part of the background writer does no syncing at all. It's only purpose is to keep the LRU heads clean so that regular backends seldom to never have to call write(). Jan
124 lines
3.8 KiB
C
124 lines
3.8 KiB
C
/*-------------------------------------------------------------------------
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*
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* proc.h
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* per-process shared memory data structures
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*
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*
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* Portions Copyright (c) 1996-2003, 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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* $Id: proc.h,v 1.65 2003/11/19 15:55:08 wieck Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef _PROC_H_
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#define _PROC_H_
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#include "access/xlog.h"
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#include "storage/backendid.h"
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#include "storage/lock.h"
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#include "storage/pg_sema.h"
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/*
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* Each backend has a PGPROC struct in shared memory. There is also a list of
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* currently-unused PGPROC structs that will be reallocated to new backends.
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*
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* links: list link for any list the PGPROC is in. When waiting for a lock,
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* the PGPROC is linked into that lock's waitProcs queue. A recycled PGPROC
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* is linked into ProcGlobal's freeProcs list.
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*/
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struct PGPROC
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{
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/* proc->links MUST BE FIRST IN STRUCT (see ProcSleep,ProcWakeup,etc) */
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SHM_QUEUE links; /* list link if process is in a list */
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PGSemaphoreData sem; /* ONE semaphore to sleep on */
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int errType; /* STATUS_OK or STATUS_ERROR after wakeup */
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TransactionId xid; /* transaction currently being executed by
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* this proc */
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TransactionId xmin; /* minimal running XID as it was when we
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* were starting our xact: vacuum must not
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* remove tuples deleted by xid >= xmin ! */
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int pid; /* This backend's process id */
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Oid databaseId; /* OID of database this backend is using */
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/*
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* XLOG location of first XLOG record written by this backend's
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* current transaction. If backend is not in a transaction or hasn't
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* yet modified anything, logRec.xrecoff is zero.
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*/
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XLogRecPtr logRec;
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/* Info about LWLock the process is currently waiting for, if any. */
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bool lwWaiting; /* true if waiting for an LW lock */
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bool lwExclusive; /* true if waiting for exclusive access */
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struct PGPROC *lwWaitLink; /* next waiter for same LW lock */
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/* Info about lock the process is currently waiting for, if any. */
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/* waitLock and waitHolder are NULL if not currently waiting. */
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LOCK *waitLock; /* Lock object we're sleeping on ... */
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PROCLOCK *waitHolder; /* Per-holder info for awaited lock */
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LOCKMODE waitLockMode; /* type of lock we're waiting for */
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LOCKMASK heldLocks; /* bitmask for lock types already held on
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* this lock object by this backend */
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SHM_QUEUE procHolders; /* list of PROCLOCK objects for locks held
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* or awaited by this backend */
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};
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/* NOTE: "typedef struct PGPROC PGPROC" appears in storage/lock.h. */
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extern DLLIMPORT PGPROC *MyProc;
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/*
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* There is one ProcGlobal struct for the whole installation.
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*/
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typedef struct PROC_HDR
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{
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/* Head of list of free PGPROC structures */
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SHMEM_OFFSET freeProcs;
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} PROC_HDR;
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#define DUMMY_PROC_DEFAULT 0
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#define DUMMY_PROC_BGWRITER 1
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#define NUM_DUMMY_PROCS 2
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/* configurable options */
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extern int DeadlockTimeout;
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extern int StatementTimeout;
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/*
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* Function Prototypes
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*/
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extern int ProcGlobalSemas(int maxBackends);
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extern void InitProcGlobal(int maxBackends);
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extern void InitProcess(void);
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extern void InitDummyProcess(int proctype);
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extern void ProcReleaseLocks(bool isCommit);
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extern void ProcQueueInit(PROC_QUEUE *queue);
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extern int ProcSleep(LOCKMETHODTABLE *lockMethodTable, LOCKMODE lockmode,
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LOCK *lock, PROCLOCK *proclock);
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extern PGPROC *ProcWakeup(PGPROC *proc, int errType);
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extern void ProcLockWakeup(LOCKMETHODTABLE *lockMethodTable, LOCK *lock);
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extern bool LockWaitCancel(void);
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extern void ProcWaitForSignal(void);
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extern void ProcCancelWaitForSignal(void);
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extern void ProcSendSignal(BackendId procId);
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extern bool enable_sig_alarm(int delayms, bool is_statement_timeout);
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extern bool disable_sig_alarm(bool is_statement_timeout);
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extern void handle_sig_alarm(SIGNAL_ARGS);
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#endif /* PROC_H */
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