A version without locks (still with inconsistency).

knizhnik · knizhnik · commit 9f63deab2e01 · 2015-09-14T18:05:35.000+03:00
diff --git a/contrib/pg_xtm/pg_dtm--1.0.sql b/contrib/pg_xtm/pg_dtm--1.0.sql
@@ -8,11 +8,3 @@ LANGUAGE C;
 CREATE FUNCTION dtm_get_snapshot() RETURNS void
 AS 'MODULE_PATHNAME','dtm_get_snapshot'
 LANGUAGE C;
-
-CREATE FUNCTION dtm_lock() RETURNS void
-AS 'MODULE_PATHNAME','dtm_lock'
-LANGUAGE C;
-
-CREATE FUNCTION dtm_unlock() RETURNS void
-AS 'MODULE_PATHNAME','dtm_unlock'
-LANGUAGE C;
diff --git a/contrib/pg_xtm/pg_dtm.c b/contrib/pg_xtm/pg_dtm.c
@@ -233,8 +233,6 @@ PG_MODULE_MAGIC;
 
 PG_FUNCTION_INFO_V1(dtm_begin_transaction);
 PG_FUNCTION_INFO_V1(dtm_get_snapshot);
-PG_FUNCTION_INFO_V1(dtm_lock);
-PG_FUNCTION_INFO_V1(dtm_unlock);
 
 Datum
 dtm_begin_transaction(PG_FUNCTION_ARGS)
@@ -254,9 +252,7 @@ Datum
 dtm_get_snapshot(PG_FUNCTION_ARGS)
 {
     DtmEnsureConnection();
-	LWLockAcquire(DtmLock, LW_EXCLUSIVE);
     DtmGlobalGetSnapshot(DtmConn, DtmNodeId, GetCurrentTransactionId(), &DtmSnapshot);
-	LWLockRelease(DtmLock);
 
     //    VacuumProcArray(&DtmSnapshot);
 
@@ -267,16 +263,3 @@ dtm_get_snapshot(PG_FUNCTION_ARGS)
 	PG_RETURN_VOID();
 }
 
-Datum
-dtm_lock(PG_FUNCTION_ARGS)
-{
-	LWLockAcquire(DtmLock, LW_EXCLUSIVE);
-	PG_RETURN_VOID();
-}
-
-Datum
-dtm_unlock(PG_FUNCTION_ARGS)
-{
-	LWLockRelease(DtmLock);
-	PG_RETURN_VOID();
-}
diff --git a/contrib/pg_xtm/tests/transfers.go b/contrib/pg_xtm/tests/transfers.go
@@ -65,8 +65,6 @@ func prepare_db() {
     exec(conn2, "create table t(u int primary key, v int)")
     
     // strt transaction
-    exec(conn1, "select dtm_lock()")
-    exec(conn2, "select dtm_lock()")
     exec(conn1, "begin")
     exec(conn2, "begin")
     
@@ -76,8 +74,6 @@ func prepare_db() {
     
     // register global transaction in DTMD
     exec(conn1, "select dtm_begin_transaction($1, $2)", nodes, xids)
-    exec(conn1, "select dtm_unlock()")
-    exec(conn2, "select dtm_unlock()")
     
     // first global statement 
     exec(conn1, "select dtm_get_snapshot()")
@@ -117,8 +113,6 @@ func transfer(id int, wg *sync.WaitGroup) {
         account2 := rand.Intn(N_ACCOUNTS)
 
         // strt transaction
-	exec(conn1, "select dtm_lock()")
-	exec(conn2, "select dtm_lock()")
         exec(conn1, "begin")
         exec(conn2, "begin")
         
@@ -128,8 +122,6 @@ func transfer(id int, wg *sync.WaitGroup) {
         
         // register global transaction in DTMD
         exec(conn1, "select dtm_begin_transaction($1, $2)", nodes, xids)
-	exec(conn1, "select dtm_unlock()")
-	exec(conn2, "select dtm_unlock()")
         
         // first global statement 
         exec(conn1, "select dtm_get_snapshot()")
@@ -160,8 +152,6 @@ func total() int32 {
     defer conn2.Close()
 
     for { 
-	exec(conn1, "select dtm_lock()")
-	exec(conn2, "select dtm_lock()")
         exec(conn1, "begin")
         exec(conn2, "begin")
  
@@ -171,8 +161,6 @@ func total() int32 {
         
         // register global transaction in DTMD
         exec(conn1, "select dtm_begin_transaction($1, $2)", nodes, xids)
-	exec(conn1, "select dtm_unlock()")
-	exec(conn2, "select dtm_unlock()")
 
         exec(conn1, "select dtm_get_snapshot()")
         exec(conn2, "select dtm_get_snapshot()")
diff --git a/src/include/storage/lwlock.h b/src/include/storage/lwlock.h
@@ -139,9 +139,8 @@ extern PGDLLIMPORT LWLockPadded *MainLWLockArray;
 #define CommitTsControlLock			(&MainLWLockArray[38].lock)
 #define CommitTsLock				(&MainLWLockArray[39].lock)
 #define ReplicationOriginLock		(&MainLWLockArray[40].lock)
-#define DtmLock				(&MainLWLockArray[41].lock)
 
-#define NUM_INDIVIDUAL_LWLOCKS		42
+#define NUM_INDIVIDUAL_LWLOCKS		41
 
 /*
  * It's a bit odd to declare NUM_BUFFER_PARTITIONS and NUM_LOCK_PARTITIONS
