diff options
Diffstat (limited to 'src/backend/access/transam/xact.c')
| -rw-r--r-- | src/backend/access/transam/xact.c | 46 |
1 files changed, 18 insertions, 28 deletions
diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 000c72f8de1..72a7cf40a63 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -10,7 +10,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/access/transam/xact.c,v 1.244 2007/05/30 21:01:39 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/access/transam/xact.c,v 1.245 2007/06/07 21:45:58 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -64,12 +64,12 @@ int CommitSiblings = 5; /* # concurrent xacts needed to sleep */ */ typedef enum TransState { - TRANS_DEFAULT, - TRANS_START, - TRANS_INPROGRESS, - TRANS_COMMIT, - TRANS_ABORT, - TRANS_PREPARE + TRANS_DEFAULT, /* idle */ + TRANS_START, /* transaction starting */ + TRANS_INPROGRESS, /* inside a valid transaction */ + TRANS_COMMIT, /* commit in progress */ + TRANS_ABORT, /* abort in progress */ + TRANS_PREPARE /* prepare in progress */ } TransState; /* @@ -255,34 +255,22 @@ static const char *TransStateAsString(TransState state); /* * IsTransactionState * - * This returns true if we are currently running a query - * within an executing transaction. + * This returns true if we are inside a valid transaction; that is, + * it is safe to initiate database access, take heavyweight locks, etc. */ bool IsTransactionState(void) { TransactionState s = CurrentTransactionState; - switch (s->state) - { - case TRANS_DEFAULT: - return false; - case TRANS_START: - return true; - case TRANS_INPROGRESS: - return true; - case TRANS_COMMIT: - return true; - case TRANS_ABORT: - return true; - case TRANS_PREPARE: - return true; - } - /* - * Shouldn't get here, but lint is not happy without this... + * TRANS_DEFAULT and TRANS_ABORT are obviously unsafe states. However, + * we also reject the startup/shutdown states TRANS_START, TRANS_COMMIT, + * TRANS_PREPARE since it might be too soon or too late within those + * transition states to do anything interesting. Hence, the only "valid" + * state is TRANS_INPROGRESS. */ - return false; + return (s->state == TRANS_INPROGRESS); } /* @@ -308,7 +296,9 @@ IsAbortedTransactionBlockState(void) * GetTopTransactionId * * Get the ID of the main transaction, even if we are currently inside - * a subtransaction. + * a subtransaction. If we are not in a transaction at all, or if we + * are in transaction startup and haven't yet assigned an XID, + * InvalidTransactionId is returned. */ TransactionId GetTopTransactionId(void) |