diff options
Diffstat (limited to 'src/include/storage/proc.h')
| -rw-r--r-- | src/include/storage/proc.h | 23 |
1 files changed, 22 insertions, 1 deletions
diff --git a/src/include/storage/proc.h b/src/include/storage/proc.h index c2411bef073..4f7f39003ad 100644 --- a/src/include/storage/proc.h +++ b/src/include/storage/proc.h @@ -7,7 +7,7 @@ * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/include/storage/proc.h,v 1.71 2004/07/21 20:34:49 momjian Exp $ + * $PostgreSQL: pgsql/src/include/storage/proc.h,v 1.72 2004/08/01 17:32:21 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -21,6 +21,25 @@ /* + * 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]; +}; + +/* * 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. * @@ -68,6 +87,8 @@ struct PGPROC SHM_QUEUE procHolders; /* list of PROCLOCK objects for locks held * or awaited by this backend */ + + struct XidCache subxids; /* cache for subtransaction XIDs */ }; /* NOTE: "typedef struct PGPROC PGPROC" appears in storage/lock.h. */ |