diff options
Diffstat (limited to 'src/include/storage/lock.h')
| -rw-r--r-- | src/include/storage/lock.h | 25 |
1 files changed, 17 insertions, 8 deletions
diff --git a/src/include/storage/lock.h b/src/include/storage/lock.h index 85e2f379786..6d84fea806a 100644 --- a/src/include/storage/lock.h +++ b/src/include/storage/lock.h @@ -7,7 +7,7 @@ * Portions Copyright (c) 1996-2000, PostgreSQL, Inc * Portions Copyright (c) 1994, Regents of the University of California * - * $Id: lock.h,v 1.41 2001/01/16 06:11:34 tgl Exp $ + * $Id: lock.h,v 1.42 2001/01/22 22:30:06 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -22,8 +22,8 @@ /* originally in procq.h */ typedef struct PROC_QUEUE { - SHM_QUEUE links; - int size; + SHM_QUEUE links; /* head of list of PROC objects */ + int size; /* number of entries in list */ } PROC_QUEUE; /* struct proc is declared in storage/proc.h, but must forward-reference it */ @@ -59,7 +59,7 @@ typedef int LOCKMASK; typedef int LOCKMODE; typedef int LOCKMETHOD; -/* MAX_LOCKMODES cannot be larger than the bits in LOCKMASK */ +/* MAX_LOCKMODES cannot be larger than the # of bits in LOCKMASK */ #define MAX_LOCKMODES 8 /* @@ -152,6 +152,7 @@ typedef struct LOCKTAG * tag -- uniquely identifies the object being locked * grantMask -- bitmask for all lock types currently granted on this object. * waitMask -- bitmask for all lock types currently awaited on this object. + * lockHolders -- list of HOLDER objects for this lock. * waitProcs -- queue of processes waiting for this lock. * requested -- count of each lock type currently requested on the lock * (includes requests already granted!!). @@ -167,6 +168,7 @@ typedef struct LOCK /* data */ int grantMask; /* bitmask for lock types already granted */ int waitMask; /* bitmask for lock types awaited */ + SHM_QUEUE lockHolders; /* list of HOLDER objects assoc. with lock */ PROC_QUEUE waitProcs; /* list of PROC objects waiting on lock */ int requested[MAX_LOCKMODES]; /* counts of requested locks */ int nRequested; /* total of requested[] array */ @@ -189,8 +191,8 @@ typedef struct LOCK * holder hashtable. A HOLDERTAG value uniquely identifies a lock holder. * * There are two possible kinds of holder tags: a transaction (identified - * both by the PID of the backend running it, and the xact's own ID) and - * a session (identified by backend PID, with xid = InvalidTransactionId). + * both by the PROC of the backend running it, and the xact's own ID) and + * a session (identified by backend PROC, with xid = InvalidTransactionId). * * Currently, session holders are used for user locks and for cross-xact * locks obtained for VACUUM. We assume that a session lock never conflicts @@ -201,11 +203,17 @@ typedef struct LOCK * zero holding[], for any lock that the process is currently waiting on. * Otherwise, holder objects whose counts have gone to zero are recycled * as soon as convenient. + * + * Each HOLDER object is linked into lists for both the associated LOCK object + * and the owning PROC object. Note that the HOLDER is entered into these + * lists as soon as it is created, even if no lock has yet been granted. + * A PROC that is waiting for a lock to be granted will also be linked into + * the lock's waitProcs queue. */ typedef struct HOLDERTAG { SHMEM_OFFSET lock; /* link to per-lockable-object information */ - int pid; /* PID of backend */ + SHMEM_OFFSET proc; /* link to PROC of owning backend */ TransactionId xid; /* xact ID, or InvalidTransactionId */ } HOLDERTAG; @@ -217,7 +225,8 @@ typedef struct HOLDER /* data */ int holding[MAX_LOCKMODES]; /* count of locks currently held */ int nHolding; /* total of holding[] array */ - SHM_QUEUE queue; /* list link for process' list of holders */ + SHM_QUEUE lockLink; /* list link for lock's list of holders */ + SHM_QUEUE procLink; /* list link for process's list of holders */ } HOLDER; #define SHMEM_HOLDERTAB_KEYSIZE sizeof(HOLDERTAG) |