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Redefine IsTransactionState() to only return true for TRANS_INPROGRESS state,

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which is the only state in which it's safe to initiate database queries.
It turns out that all but two of the callers thought that's what it meant;
and the other two were using it as a proxy for "will GetTopTransactionId()
return a nonzero XID"?  Since it was in fact an unreliable guide to that,
make those two just invoke GetTopTransactionId() always, then deal with a
zero result if they get one.
This commit is contained in:
Tom Lane
2007-06-07 21:45:59 +00:00
parent 24ee8af573
commit 6d6d14b6d5
3 changed files with 23 additions and 39 deletions
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46
src/backend/access/transam/xact.c
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@ -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)