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/*-------------------------------------------------------------------------
*
* proc.h
* per-process shared memory data structures
*
*
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/storage/proc.h,v 1.109 2008/12/09 15:59:39 heikki Exp $
*
*-------------------------------------------------------------------------
*/
#ifndef _PROC_H_
#define _PROC_H_
#include "storage/lock.h"
#include "storage/pg_sema.h"
/*
* Each backend advertises up to PGPROC_MAX_CACHED_SUBXIDS TransactionIds
* for non-aborted subtransactions of its current top transaction. These
* have to be treated as running XIDs by other backends.
*
* We also keep track of whether the cache overflowed (ie, the transaction has
* generated at least one subtransaction that didn't fit in the cache).
* If none of the caches have overflowed, we can assume that an XID that's not
* listed anywhere in the PGPROC array is not a running transaction. Else we
* have to look at pg_subtrans.
*/
#define PGPROC_MAX_CACHED_SUBXIDS 64 /* XXX guessed-at value */
struct XidCache
{
bool overflowed;
int nxids;
TransactionId xids[PGPROC_MAX_CACHED_SUBXIDS];
};
/* Flags for PGPROC->vacuumFlags */
#define PROC_IS_AUTOVACUUM 0x01 /* is it an autovac worker? */
#define PROC_IN_VACUUM 0x02 /* currently running lazy vacuum */
#define PROC_IN_ANALYZE 0x04 /* currently running analyze */
#define PROC_VACUUM_FOR_WRAPAROUND 0x08 /* set by autovac only */
/* flags reset at EOXact */
#define PROC_VACUUM_STATE_MASK (0x0E)
/*
* Each backend has a PGPROC struct in shared memory. There is also a list of
* currently-unused PGPROC structs that will be reallocated to new backends.
*
* links: list link for any list the PGPROC is in. When waiting for a lock,
* the PGPROC is linked into that lock's waitProcs queue. A recycled PGPROC
* is linked into ProcGlobal's freeProcs list.
*
* Note: twophase.c also sets up a dummy PGPROC struct for each currently
* prepared transaction. These PGPROCs appear in the ProcArray data structure
* so that the prepared transactions appear to be still running and are
* correctly shown as holding locks. A prepared transaction PGPROC can be
* distinguished from a real one at need by the fact that it has pid == 0.
* The semaphore and lock-activity fields in a prepared-xact PGPROC are unused,
* but its myProcLocks[] lists are valid.
*/
struct PGPROC
{
/* proc->links MUST BE FIRST IN STRUCT (see ProcSleep,ProcWakeup,etc) */
SHM_QUEUE links; /* list link if process is in a list */
PGSemaphoreData sem; /* ONE semaphore to sleep on */
int waitStatus; /* STATUS_WAITING, STATUS_OK or STATUS_ERROR */
LocalTransactionId lxid; /* local id of top-level transaction currently
* being executed by this proc, if running;
* else InvalidLocalTransactionId */
TransactionId xid; /* id of top-level transaction currently being
* executed by this proc, if running and XID
* is assigned; else InvalidTransactionId */
TransactionId xmin; /* minimal running XID as it was when we were
* starting our xact, excluding LAZY VACUUM:
* vacuum must not remove tuples deleted by
* xid >= xmin ! */
int pid; /* This backend's process id, or 0 */
BackendId backendId; /* This backend's backend ID (if assigned) */
Oid databaseId; /* OID of database this backend is using */
Oid roleId; /* OID of role using this backend */
bool inCommit; /* true if within commit critical section */
uint8 vacuumFlags; /* vacuum-related flags, see above */
/* Info about LWLock the process is currently waiting for, if any. */
bool lwWaiting; /* true if waiting for an LW lock */
bool lwExclusive; /* true if waiting for exclusive access */
struct PGPROC *lwWaitLink; /* next waiter for same LW lock */
/* Info about lock the process is currently waiting for, if any. */
/* waitLock and waitProcLock are NULL if not currently waiting. */
LOCK *waitLock; /* Lock object we're sleeping on ... */
PROCLOCK *waitProcLock; /* Per-holder info for awaited lock */
LOCKMODE waitLockMode; /* type of lock we're waiting for */
LOCKMASK heldLocks; /* bitmask for lock types already held on this
* lock object by this backend */
/*
* All PROCLOCK objects for locks held or awaited by this backend are
* linked into one of these lists, according to the partition number of
* their lock.
*/
SHM_QUEUE myProcLocks[NUM_LOCK_PARTITIONS];
struct XidCache subxids; /* cache for subtransaction XIDs */
};
/* NOTE: "typedef struct PGPROC PGPROC" appears in storage/lock.h. */
extern PGDLLIMPORT PGPROC *MyProc;
/*
* There is one ProcGlobal struct for the whole database cluster.
*/
typedef struct PROC_HDR
{
/* Head of list of free PGPROC structures */
PGPROC *freeProcs;
/* Head of list of autovacuum's free PGPROC structures */
PGPROC *autovacFreeProcs;
/* Current shared estimate of appropriate spins_per_delay value */
int spins_per_delay;
} PROC_HDR;
/*
* We set aside some extra PGPROC structures for auxiliary processes,
* ie things that aren't full-fledged backends but need shmem access.
*/
#define NUM_AUXILIARY_PROCS 3
/* configurable options */
extern int DeadlockTimeout;
extern int StatementTimeout;
extern bool log_lock_waits;
extern volatile bool cancel_from_timeout;
/*
* Function Prototypes
*/
extern int ProcGlobalSemas(void);
extern Size ProcGlobalShmemSize(void);
extern void InitProcGlobal(void);
extern void InitProcess(void);
extern void InitProcessPhase2(void);
extern void InitAuxiliaryProcess(void);
extern bool HaveNFreeProcs(int n);
extern void ProcReleaseLocks(bool isCommit);
extern void ProcQueueInit(PROC_QUEUE *queue);
extern int ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable);
extern PGPROC *ProcWakeup(PGPROC *proc, int waitStatus);
extern void ProcLockWakeup(LockMethod lockMethodTable, LOCK *lock);
extern void LockWaitCancel(void);
extern void ProcWaitForSignal(void);
extern void ProcSendSignal(int pid);
extern bool enable_sig_alarm(int delayms, bool is_statement_timeout);
extern bool disable_sig_alarm(bool is_statement_timeout);
extern void handle_sig_alarm(SIGNAL_ARGS);
#endif /* PROC_H */
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