Re: Revised Patch to allow multiple table locks in "Unison"

Patch applied. Thanks.

> Tom Lane wrote:
> >
> > Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > > Patch applied.
> >
> > Idly looking this over again, I noticed a big OOPS:
> >
> > >> ! freeList(lockstmt->rellist);
> >
> > >> ! pfree(relname);
> >
> > >> ! pfree(relname);
> >
> > It is most definitely NOT the executor's business to release pieces of
> > the querytree; this will certainly break plpgsql functions, for example,
> > where the same querytree is executed repeatedly.
>
> Thanks for having a look, Tom. I've taken you advice into account, and
> I've reworked the patch.
>
> A new patch is below.
>
> Neil
>
> --
> Neil Padgett
> Red Hat Canada Ltd. E-Mail: npadgett(at)redhat(dot)com
> 2323 Yonge Street, Suite #300,
> Toronto, ON M4P 2C9
>
> Index: doc/src/sgml/ref/lock.sgml
> ===================================================================
> RCS file:
> /home/projects/pgsql/cvsroot/pgsql/doc/src/sgml/ref/lock.sgml,v
> retrieving revision 1.26
> diff -c -p -r1.26 lock.sgml
> *** doc/src/sgml/ref/lock.sgml 2001/08/04 22:01:38 1.26
> --- doc/src/sgml/ref/lock.sgml 2001/08/07 18:34:23
> *************** Postgres documentation
> *** 15,21 ****
> LOCK
> </refname>
> <refpurpose>
> ! Explicitly lock a table inside a transaction
> </refpurpose>
> </refnamediv>
> <refsynopsisdiv>
> --- 15,21 ----
> LOCK
> </refname>
> <refpurpose>
> ! Explicitly lock a table / tables inside a transaction
> </refpurpose>
> </refnamediv>
> <refsynopsisdiv>
> *************** Postgres documentation
> *** 23,30 ****
> <date>2001-07-09</date>
> </refsynopsisdivinfo>
> <synopsis>
> ! LOCK [ TABLE ] <replaceable class="PARAMETER">name</replaceable>
> ! LOCK [ TABLE ] <replaceable class="PARAMETER">name</replaceable> IN
> <replaceable class="PARAMETER">lockmode</replaceable> MODE
>
> where <replaceable class="PARAMETER">lockmode</replaceable> is one of:
>
> --- 23,30 ----
> <date>2001-07-09</date>
> </refsynopsisdivinfo>
> <synopsis>
> ! LOCK [ TABLE ] <replaceable class="PARAMETER">name</replaceable> [,
> ...]
> ! LOCK [ TABLE ] <replaceable class="PARAMETER">name</replaceable> [,
> ...] IN <replaceable class="PARAMETER">lockmode</replaceable> MODE
>
> where <replaceable class="PARAMETER">lockmode</replaceable> is one of:
>
> *************** ERROR <replaceable class="PARAMETER">nam
> *** 373,378 ****
> --- 373,379 ----
> An example for this rule was given previously when discussing the
> use of SHARE ROW EXCLUSIVE mode rather than SHARE mode.
> </para>
> +
> </listitem>
> </itemizedlist>
>
> *************** ERROR <replaceable class="PARAMETER">nam
> *** 383,388 ****
> --- 384,395 ----
> </para>
> </note>
>
> + <para>
> + When locking multiple tables, the command LOCK a, b; is equivalent
> to LOCK
> + a; LOCK b;. The tables are locked one-by-one in the order specified
> in the
> + <command>LOCK</command> command.
> + </para>
> +
> <refsect2 id="R2-SQL-LOCK-3">
> <refsect2info>
> <date>1999-06-08</date>
> *************** ERROR <replaceable class="PARAMETER">nam
> *** 406,411 ****
> --- 413,419 ----
> <para>
> <command>LOCK</command> works only inside transactions.
> </para>
> +
> </refsect2>
> </refsect1>
>
> Index: src/backend/commands/command.c
> ===================================================================
> RCS file:
> /home/projects/pgsql/cvsroot/pgsql/src/backend/commands/command.c,v
> retrieving revision 1.138
> diff -c -p -r1.138 command.c
> *** src/backend/commands/command.c 2001/08/04 22:01:38 1.138
> --- src/backend/commands/command.c 2001/08/07 18:34:24
> *************** needs_toast_table(Relation rel)
> *** 1984,1991 ****
> MAXALIGN(data_length);
> return (tuple_length > TOAST_TUPLE_THRESHOLD);
> }
> !
> !
> /*
> *
> * LOCK TABLE
> --- 1984,1990 ----
> MAXALIGN(data_length);
> return (tuple_length > TOAST_TUPLE_THRESHOLD);
> }
> !
> /*
> *
> * LOCK TABLE
> *************** needs_toast_table(Relation rel)
> *** 1994,2019 ****
> void
> LockTableCommand(LockStmt *lockstmt)
> {
> ! Relation rel;
> ! int aclresult;
> !
> ! rel = heap_openr(lockstmt->relname, NoLock);
> !
> ! if (rel->rd_rel->relkind != RELKIND_RELATION)
> ! elog(ERROR, "LOCK TABLE: %s is not a table", lockstmt->relname);
> !
> ! if (lockstmt->mode == AccessShareLock)
> ! aclresult = pg_aclcheck(lockstmt->relname, GetUserId(), ACL_SELECT);
> ! else
> ! aclresult = pg_aclcheck(lockstmt->relname, GetUserId(),
> ! ACL_UPDATE | ACL_DELETE);
> !
> ! if (aclresult != ACLCHECK_OK)
> ! elog(ERROR, "LOCK TABLE: permission denied");
> !
> ! LockRelation(rel, lockstmt->mode);
> !
> ! heap_close(rel, NoLock); /* close rel, keep lock */
> }
>
>
> --- 1993,2030 ----
> void
> LockTableCommand(LockStmt *lockstmt)
> {
> ! List *p;
> ! Relation rel;
> !
> ! /* Iterate over the list and open, lock, and close the relations
> ! one at a time
> ! */
> !
> ! foreach(p, lockstmt->rellist)
> ! {
> ! char* relname = strVal(lfirst(p));
> ! int aclresult;
> !
> ! rel = heap_openr(relname, NoLock);
> !
> ! if (rel->rd_rel->relkind != RELKIND_RELATION)
> ! elog(ERROR, "LOCK TABLE: %s is not a table",
> ! relname);
> !
> ! if (lockstmt->mode == AccessShareLock)
> ! aclresult = pg_aclcheck(relname, GetUserId(),
> ! ACL_SELECT);
> ! else
> ! aclresult = pg_aclcheck(relname, GetUserId(),
> ! ACL_UPDATE | ACL_DELETE);
> !
> ! if (aclresult != ACLCHECK_OK)
> ! elog(ERROR, "LOCK TABLE: permission denied");
> !
> ! LockRelation(rel, lockstmt->mode);
> !
> ! heap_close(rel, NoLock); /* close rel, keep lock */
> ! }
> }
>
>
> Index: src/backend/nodes/copyfuncs.c
> ===================================================================
> RCS file:
> /home/projects/pgsql/cvsroot/pgsql/src/backend/nodes/copyfuncs.c,v
> retrieving revision 1.150
> diff -c -p -r1.150 copyfuncs.c
> *** src/backend/nodes/copyfuncs.c 2001/08/04 22:01:38 1.150
> --- src/backend/nodes/copyfuncs.c 2001/08/07 18:34:24
> *************** _copyLockStmt(LockStmt *from)
> *** 2425,2432 ****
> {
> LockStmt *newnode = makeNode(LockStmt);
>
> ! if (from->relname)
> ! newnode->relname = pstrdup(from->relname);
> newnode->mode = from->mode;
>
> return newnode;
> --- 2425,2432 ----
> {
> LockStmt *newnode = makeNode(LockStmt);
>
> ! Node_Copy(from, newnode, rellist);
> !
> newnode->mode = from->mode;
>
> return newnode;
> Index: src/backend/nodes/equalfuncs.c
> ===================================================================
> RCS file:
> /home/projects/pgsql/cvsroot/pgsql/src/backend/nodes/equalfuncs.c,v
> retrieving revision 1.98
> diff -c -p -r1.98 equalfuncs.c
> *** src/backend/nodes/equalfuncs.c 2001/08/04 22:01:38 1.98
> --- src/backend/nodes/equalfuncs.c 2001/08/07 18:34:24
> *************** _equalDropUserStmt(DropUserStmt *a, Drop
> *** 1283,1289 ****
> static bool
> _equalLockStmt(LockStmt *a, LockStmt *b)
> {
> ! if (!equalstr(a->relname, b->relname))
> return false;
> if (a->mode != b->mode)
> return false;
> --- 1283,1289 ----
> static bool
> _equalLockStmt(LockStmt *a, LockStmt *b)
> {
> ! if (!equal(a->rellist, b->rellist))
> return false;
> if (a->mode != b->mode)
> return false;
> Index: src/backend/parser/gram.y
> ===================================================================
> RCS file: /home/projects/pgsql/cvsroot/pgsql/src/backend/parser/gram.y,v
> retrieving revision 2.241
> diff -c -p -r2.241 gram.y
> *** src/backend/parser/gram.y 2001/08/06 05:42:48 2.241
> --- src/backend/parser/gram.y 2001/08/07 18:34:30
> *************** DeleteStmt: DELETE FROM relation_expr w
> *** 3281,3291 ****
> }
> ;
>
> ! LockStmt: LOCK_P opt_table relation_name opt_lock
> {
> LockStmt *n = makeNode(LockStmt);
>
> ! n->relname = $3;
> n->mode = $4;
> $$ = (Node *)n;
> }
> --- 3281,3291 ----
> }
> ;
>
> ! LockStmt: LOCK_P opt_table relation_name_list opt_lock
> {
> LockStmt *n = makeNode(LockStmt);
>
> ! n->rellist = $3;
> n->mode = $4;
> $$ = (Node *)n;
> }
> Index: src/include/nodes/parsenodes.h
> ===================================================================
> RCS file:
> /home/projects/pgsql/cvsroot/pgsql/src/include/nodes/parsenodes.h,v
> retrieving revision 1.138
> diff -c -p -r1.138 parsenodes.h
> *** src/include/nodes/parsenodes.h 2001/08/04 22:01:39 1.138
> --- src/include/nodes/parsenodes.h 2001/08/07 18:34:30
> *************** typedef struct VariableResetStmt
> *** 760,766 ****
> typedef struct LockStmt
> {
> NodeTag type;
> ! char *relname; /* relation to lock */
> int mode; /* lock mode */
> } LockStmt;
>
> --- 760,766 ----
> typedef struct LockStmt
> {
> NodeTag type;
> ! List *rellist; /* relations to lock */
> int mode; /* lock mode */
> } LockStmt;
>
> Index: src/interfaces/ecpg/preproc/preproc.y
> ===================================================================
> RCS file:
> /home/projects/pgsql/cvsroot/pgsql/src/interfaces/ecpg/preproc/preproc.y,v
> retrieving revision 1.148
> diff -c -p -r1.148 preproc.y
> *** src/interfaces/ecpg/preproc/preproc.y 2001/08/04 22:01:39 1.148
> --- src/interfaces/ecpg/preproc/preproc.y 2001/08/07 18:34:32
> *************** DeleteStmt: DELETE FROM relation_expr w
> *** 2421,2427 ****
> }
> ;
>
> ! LockStmt: LOCK_P opt_table relation_name opt_lock
> {
> $$ = cat_str(4, make_str("lock"), $2, $3, $4);
> }
> --- 2421,2427 ----
> }
> ;
>
> ! LockStmt: LOCK_P opt_table relation_name_list opt_lock
> {
> $$ = cat_str(4, make_str("lock"), $2, $3, $4);
> }
>
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--
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