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Commit8abd424

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committed
More deadlock code to check for escallation locks.
offsetof() addition to local socket size.
1 parent54399bb commit8abd424

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4 files changed

+111
-30
lines changed

4 files changed

+111
-30
lines changed

‎src/backend/storage/lmgr/README

Lines changed: 9 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
$Header: /cvsroot/pgsql/src/backend/storage/lmgr/README,v 1.1.1.1 1996/07/09 06:21:55 scrappy Exp $
1+
$Header: /cvsroot/pgsql/src/backend/storage/lmgr/README,v 1.2 1998/01/28 02:29:26 momjian Exp $
22

33
This file is an attempt to save me (and future code maintainers) some
44
time and a lot of headaches. The existing lock manager code at the time
@@ -88,6 +88,12 @@ activeHolders -
8888
holders, summing the values of activeHolders should total to the value
8989
of nActive.
9090

91+
---------------------------------------------------------------------------
9192

92-
This is all I had the stomach for right now..... I will get back to this
93-
someday.-mer 17 June 1992 12:00 am
93+
Locks are accessed in two ways. Each PROC structure has a lockQueue,
94+
that is a circular linked list of LOCK pointers that this process holds
95+
or is waiting on.
96+
97+
Second, there is a hash table that can do a lookup by combined LOCK
98+
address and transaction id(xid) which allows a process to see what
99+
type of locks it holds on that table.

‎src/backend/storage/lmgr/lock.c

Lines changed: 93 additions & 21 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lock.c,v 1.23 1998/01/27 15:34:49 momjian Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lock.c,v 1.24 1998/01/28 02:29:27 momjian Exp $
1111
*
1212
* NOTES
1313
* Outside modules can create a lock table and acquire/release
@@ -755,7 +755,7 @@ LockResolveConflicts(LOCKTAB *ltable,
755755
tmpMask=2;
756756
for (i=1;i <=nLockTypes;i++,tmpMask <<=1)
757757
{
758-
if (lock->activeHolders[i]-myHolders[i])
758+
if (lock->activeHolders[i]!=myHolders[i])
759759
{
760760
bitmask |=tmpMask;
761761
}
@@ -1429,14 +1429,38 @@ DeadLockCheck(SHM_QUEUE *lockQueue, LOCK *findlock, bool skip_check)
14291429
XIDLookupEnt*tmp=NULL;
14301430
SHMEM_OFFSETend=MAKE_OFFSET(lockQueue);
14311431
LOCK*lock;
1432-
staticPROC*checked_procs[MaxBackendId];
1433-
staticintnprocs;
14341432

1433+
LOCKTAB*ltable;
1434+
XIDLookupEnt*result,
1435+
item;
1436+
HTAB*xidTable;
1437+
boolfound;
1438+
1439+
staticPROC*checked_procs[MaxBackendId];
1440+
staticintnprocs;
1441+
staticboolMyNHolding;
1442+
1443+
/* initialize at start of recursion */
14351444
if (skip_check)
14361445
{
1437-
/* initialize at start of recursion */
14381446
checked_procs[0]=MyProc;
14391447
nprocs=1;
1448+
1449+
ltable=AllTables[1];
1450+
xidTable=ltable->xidHash;
1451+
1452+
MemSet(&item,0,XID_TAGSIZE);
1453+
TransactionIdStore(MyProc->xid,&item.tag.xid);
1454+
item.tag.lock=MAKE_OFFSET(findlock);
1455+
#if0
1456+
item.tag.pid=pid;
1457+
#endif
1458+
1459+
if ((result= (XIDLookupEnt*)
1460+
hash_search(xidTable, (Pointer)&item,HASH_FIND,&found))&&found)
1461+
MyNHolding=result->nHolding;
1462+
else
1463+
MyNHolding=0;
14401464
}
14411465

14421466
if (SHMQueueEmpty(lockQueue))
@@ -1469,13 +1493,7 @@ DeadLockCheck(SHM_QUEUE *lockQueue, LOCK *findlock, bool skip_check)
14691493
if (lock==findlock&& !skip_check)
14701494
return true;
14711495

1472-
/*
1473-
*No sense in looking at the wait queue of the lock we are
1474-
*looking for as it is MyProc's lock entry.
1475-
* If lock == findlock, and I got here, skip_check must be true.
1476-
*/
1477-
if (lock!=findlock)
1478-
{
1496+
{
14791497
PROC_QUEUE*waitQueue=&(lock->waitProcs);
14801498
PROC*proc;
14811499
inti;
@@ -1484,16 +1502,70 @@ DeadLockCheck(SHM_QUEUE *lockQueue, LOCK *findlock, bool skip_check)
14841502
proc= (PROC*)MAKE_PTR(waitQueue->links.prev);
14851503
for (i=0;i<waitQueue->size;i++)
14861504
{
1487-
for (j=0;j<nprocs;j++)
1488-
if (checked_procs[j]==proc)
1489-
break;
1490-
if (j >=nprocs)
1505+
if (proc!=MyProc&&
1506+
lock==findlock&&/* skip_check also true */
1507+
MyNHolding)/* I already hold some lock on it */
1508+
{
1509+
/*
1510+
*For findlock's wait queue, we are interested in
1511+
*procs who are blocked waiting for a write-lock on the
1512+
*table we are waiting on, and already hold a lock on it.
1513+
*We first check to see if there is an escalation
1514+
*deadlock, where we hold a readlock and want a
1515+
*writelock, and someone else holds readlock on
1516+
*the same table, and wants a writelock.
1517+
*
1518+
*Basically, the test is, "Do we both hold some lock
1519+
*on findlock, and we are both waiting in the lock
1520+
*queue?"
1521+
*/
1522+
1523+
Assert(skip_check);
1524+
Assert(MyProc->prio==2);
1525+
1526+
ltable=AllTables[1];
1527+
xidTable=ltable->xidHash;
1528+
1529+
MemSet(&item,0,XID_TAGSIZE);
1530+
TransactionIdStore(proc->xid,&item.tag.xid);
1531+
item.tag.lock=MAKE_OFFSET(findlock);
1532+
#if0
1533+
item.tag.pid=pid;
1534+
#endif
1535+
1536+
if ((result= (XIDLookupEnt*)
1537+
hash_search(xidTable, (Pointer)&item,HASH_FIND,&found))&&found)
1538+
{
1539+
if (result->nHolding)
1540+
return true;
1541+
}
1542+
}
1543+
/*
1544+
*No sense in looking at the wait queue of the lock we are
1545+
*looking for.
1546+
* If lock == findlock, and I got here, skip_check must be
1547+
*true too.
1548+
*/
1549+
if (lock!=findlock)
14911550
{
1492-
checked_procs[nprocs++]=proc;
1493-
Assert(nprocs <=MaxBackendId);
1494-
/* If we found a deadlock, we can stop right now */
1495-
if (DeadLockCheck(&(proc->lockQueue),findlock, false))
1496-
return true;
1551+
for (j=0;j<nprocs;j++)
1552+
if (checked_procs[j]==proc)
1553+
break;
1554+
if (j >=nprocs&&lock!=findlock)
1555+
{
1556+
checked_procs[nprocs++]=proc;
1557+
Assert(nprocs <=MaxBackendId);
1558+
/*
1559+
*For non-MyProc entries, we are looking only waiters,
1560+
*not necessarily people who already hold locks and are
1561+
*waiting.
1562+
*Now we check for cases where we have two or more
1563+
*tables in a deadlock. We do this by continuing
1564+
*to search for someone holding a lock
1565+
*/
1566+
if (DeadLockCheck(&(proc->lockQueue),findlock, false))
1567+
return true;
1568+
}
14971569
}
14981570
proc= (PROC*)MAKE_PTR(proc->links.prev);
14991571
}

‎src/backend/storage/lmgr/proc.c

Lines changed: 5 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.29 1998/01/27 03:00:29 momjian Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.30 1998/01/28 02:29:29 momjian Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -46,7 +46,7 @@
4646
*This is so that we can support more backends. (system-wide semaphore
4747
*sets run out pretty fast.) -ay 4/95
4848
*
49-
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.29 1998/01/27 03:00:29 momjian Exp $
49+
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.30 1998/01/28 02:29:29 momjian Exp $
5050
*/
5151
#include<sys/time.h>
5252
#include<unistd.h>
@@ -249,7 +249,10 @@ InitProcess(IPCKey key)
249249
*/
250250
SpinRelease(ProcStructLock);
251251

252+
MyProc->pid=0;
253+
#if0
252254
MyProc->pid=MyProcPid;
255+
#endif
253256
MyProc->xid=InvalidTransactionId;
254257

255258
/* ----------------

‎src/include/libpq/pqcomm.h

Lines changed: 4 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,7 @@
66
*
77
* Copyright (c) 1994, Regents of the University of California
88
*
9-
* $Id: pqcomm.h,v 1.21 1998/01/27 15:35:22 momjian Exp $
9+
* $Id: pqcomm.h,v 1.22 1998/01/28 02:29:40 momjian Exp $
1010
*
1111
*-------------------------------------------------------------------------
1212
*/
@@ -35,10 +35,10 @@ typedef union SockAddr {
3535

3636
#defineUNIXSOCK_PATH(sun,port) \
3737
(sprintf((sun).sun_path, "/tmp/.s.PGSQL.%d", (port)) + \
38-
+ 1 + sizeof ((sun).sun_family))
38+
offsetof(struct sockaddr_un, sun_path))
3939
/*
40-
*+ 1isfor BSD-specific sizeof((sun).sun_len)
41-
*We never actually set sun_len, and I can't think of a
40+
*We do this because sun_lenisin BSD's struct, while others don't.
41+
*We never actually setBSD'ssun_len, and I can't think of a
4242
*platform-safe way of doing it, but the code still works. bjm
4343
*/
4444

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