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/*-------------------------------------------------------------------------
*
* proc.h
* per-process shared memory data structures
*
*
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: proc.h,v 1.41 2001/03/22 04:01:08 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#ifndef _PROC_H_
#define _PROC_H_
#include "access/xlog.h"
#include "storage/lock.h"
/* configurable option */
extern int DeadlockTimeout;
typedef struct
{
IpcSemaphoreId semId; /* SysV semaphore set ID */
int semNum; /* semaphore number within set */
} SEMA;
/*
* Each backend has a PROC struct in shared memory. There is also a list of
* currently-unused PROC structs that will be reallocated to new backends.
*
* links: list link for any list the PROC is in. When waiting for a lock,
* the PROC is linked into that lock's waitProcs queue. A recycled PROC
* is linked into ProcGlobal's freeProcs list.
*/
struct proc
{
/* proc->links MUST BE FIRST IN STRUCT (see ProcSleep,ProcWakeup,etc) */
SHM_QUEUE links; /* list link if process is in a list */
SEMA sem; /* ONE semaphore to sleep on */
int errType; /* STATUS_OK or STATUS_ERROR after wakeup */
TransactionId xid; /* transaction currently being executed by
* this proc */
TransactionId xmin; /* minimal running XID as it was when we
* were starting our xact: vacuum must not
* remove tuples deleted by xid >= xmin ! */
/*
* XLOG location of first XLOG record written by this backend's
* current transaction. If backend is not in a transaction or hasn't
* yet modified anything, logRec.xrecoff is zero.
*/
XLogRecPtr logRec;
/* Info about lock the process is currently waiting for, if any. */
/* waitLock and waitHolder are NULL if not currently waiting. */
LOCK *waitLock; /* Lock object we're sleeping on ... */
HOLDER *waitHolder; /* 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 */
int pid; /* This backend's process id */
Oid databaseId; /* OID of database this backend is using */
short sLocks[MAX_SPINS]; /* Spin lock stats */
SHM_QUEUE procHolders; /* list of HOLDER objects for locks held
* or awaited by this backend */
};
/* NOTE: "typedef struct proc PROC" appears in storage/lock.h. */
extern PROC *MyProc;
extern SPINLOCK ProcStructLock;
#define PROC_INCR_SLOCK(lock) \
do { \
if (MyProc) (MyProc->sLocks[(lock)])++; \
} while (0)
#define PROC_DECR_SLOCK(lock) \
do { \
if (MyProc) (MyProc->sLocks[(lock)])--; \
} while (0)
/*
* There is one ProcGlobal struct for the whole installation.
*
* PROC_NSEMS_PER_SET is the number of semaphores in each sys-V semaphore set
* we allocate. It must be no more than 32 (or however many bits in an int
* on your machine), or our free-semaphores bitmap won't work. It also must
* be *less than* your kernel's SEMMSL (max semaphores per set) parameter,
* which is often around 25. (Less than, because we allocate one extra sema
* in each set for identification purposes.)
*
* PROC_SEM_MAP_ENTRIES is the number of semaphore sets we need to allocate
* to keep track of up to MAXBACKENDS backends.
*/
#define PROC_NSEMS_PER_SET 16
#define PROC_SEM_MAP_ENTRIES ((MAXBACKENDS-1)/PROC_NSEMS_PER_SET+1)
typedef struct procglobal
{
/* Head of list of free PROC structures */
SHMEM_OFFSET freeProcs;
/* Info about semaphore sets used for per-process semaphores */
IpcSemaphoreId procSemIds[PROC_SEM_MAP_ENTRIES];
int32 freeSemMap[PROC_SEM_MAP_ENTRIES];
/*
* In each freeSemMap entry, bit i is set if the i'th semaphore of the
* set is allocated to a process. (i counts from 0 at the LSB)
*/
} PROC_HDR;
/*
* Function Prototypes
*/
extern void InitProcGlobal(int maxBackends);
extern void InitProcess(void);
extern void ProcReleaseLocks(bool isCommit);
extern bool ProcRemove(int pid);
extern void ProcQueueInit(PROC_QUEUE *queue);
extern int ProcSleep(LOCKMETHODTABLE *lockMethodTable, LOCKMODE lockmode,
LOCK *lock, HOLDER *holder);
extern PROC *ProcWakeup(PROC *proc, int errType);
extern void ProcLockWakeup(LOCKMETHODTABLE *lockMethodTable, LOCK *lock);
extern void ProcReleaseSpins(PROC *proc);
extern bool LockWaitCancel(void);
extern void HandleDeadLock(SIGNAL_ARGS);
#endif /* PROC_H */
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