Better integration of DTM in FDW

knizhnik · knizhnik · commit cae87f3fb464 · 2015-10-02T15:14:39.000+03:00
diff --git a/contrib/pg_xtm/dtmd/include/transaction.h b/contrib/pg_xtm/dtmd/include/transaction.h
@@ -15,7 +15,6 @@ typedef struct Transaction {
 	xid_t xid;
 
 	int size; // number of paritcipants
-	int max_size; // maximal number of participants
 
 	// for + against ≤ size
 	int votes_for;
diff --git a/contrib/pg_xtm/dtmd/src/main.c b/contrib/pg_xtm/dtmd/src/main.c
@@ -257,18 +257,11 @@ static char *onbegin(void *stream, void *clientdata, cmd_t *cmd) {
 	);
 
 	CHECK(
-		cmd->argc == 1,
+		cmd->argc == 0,
 		clientdata,
 		"BEGIN: wrong number of arguments"
 	);
 
-	int size = cmd->argv[0];
-	CHECK(
-		size <= MAX_NODES,
-		clientdata,
-		"BEGIN: 'size' > MAX_NODES"
-	);
-
 	CHECK(
 		CLIENT_XID(clientdata) == INVALID_XID,
 		clientdata,
@@ -280,7 +273,6 @@ static char *onbegin(void *stream, void *clientdata, cmd_t *cmd) {
 
 	prev_gxid = t->xid = next_gxid++;
 	t->snapshots_count = 0;
-	t->max_size = size;
     t->size = 1;
 
 	CLIENT_SNAPSENT(clientdata) = 0;
@@ -438,11 +430,6 @@ static char *onsnapshot(void *stream, void *clientdata, cmd_t *cmd) {
 		CLIENT_SNAPSENT(clientdata) = 0;
 		CLIENT_XID(clientdata) = t->xid;
         t->size += 1;
-        CHECK(
-            t->size <= t->max_size,
-            clientdata,
-            "SNAPSHOT: too many participants"
-            );
 	}
 
 	CHECK(
diff --git a/contrib/pg_xtm/dtmd/src/transaction.c b/contrib/pg_xtm/dtmd/src/transaction.c
@@ -28,7 +28,6 @@ void transaction_clear(Transaction *t) {
 
 	t->xid = INVALID_XID;
 	t->size = 0;
-	t->max_size = 0;
 	t->votes_for = 0;
 	t->votes_against = 0;
 	t->snapshots_count = 0;
diff --git a/contrib/pg_xtm/libdtm.c b/contrib/pg_xtm/libdtm.c
@@ -281,15 +281,15 @@ void DtmInitSnapshot(Snapshot snapshot)
 // transaction id, fills the 'snapshot' and 'gxmin' on success. 'gxmin' is the
 // smallest xmin among all snapshots known to DTM. Returns INVALID_XID
 // otherwise.
-TransactionId DtmGlobalStartTransaction(int nParticipants, Snapshot snapshot, TransactionId *gxmin)
+TransactionId DtmGlobalStartTransaction(Snapshot snapshot, TransactionId *gxmin)
 {
 	bool ok;
 	xid_t xid;
 	xid_t number;
 	DTMConn dtm = GetConnection();
 
 	// query
-	if (!dtm_query(dtm, 'b', 1, nParticipants)) goto failure;
+	if (!dtm_query(dtm, 'b', 0)) goto failure;
 
 	// response
 	if (!dtm_read_bool(dtm, &ok)) goto failure;
diff --git a/contrib/pg_xtm/libdtm.h b/contrib/pg_xtm/libdtm.h
@@ -10,11 +10,11 @@
 
 void DtmInitSnapshot(Snapshot snapshot);
 
-// Starts a new global transaction of nParticipants size. Returns the
+// Starts a new global transaction. Returns the
 // transaction id, fills the 'snapshot' and 'gxmin' on success. 'gxmin' is the
 // smallest xmin among all snapshots known to DTM. Returns INVALID_XID
 // otherwise.
-TransactionId DtmGlobalStartTransaction(int nParticipants, Snapshot snapshot, TransactionId *gxmin);
+TransactionId DtmGlobalStartTransaction(Snapshot snapshot, TransactionId *gxmin);
 
 // Asks the DTM for a fresh snapshot. Fills the 'snapshot' and 'gxmin' on
 // success. 'gxmin' is the smallest xmin among all snapshots known to DTM.
diff --git a/contrib/pg_xtm/pg_dtm--1.0.sql b/contrib/pg_xtm/pg_dtm--1.0.sql
@@ -1,7 +1,7 @@
 -- complain if script is sourced in psql, rather than via CREATE EXTENSION
 \echo Use "CREATE EXTENSION pg_dtm" to load this file. \quit
 
-CREATE FUNCTION dtm_begin_transaction(n_participants integer) RETURNS integer
+CREATE FUNCTION dtm_begin_transaction() RETURNS integer
 AS 'MODULE_PATHNAME','dtm_begin_transaction'
 LANGUAGE C;
 
diff --git a/contrib/pg_xtm/pg_dtm.c b/contrib/pg_xtm/pg_dtm.c
@@ -74,6 +74,7 @@ static bool DtmTransactionIdIsInProgress(TransactionId xid);
 static TransactionId DtmGetNextXid(void);
 static TransactionId DtmGetNewTransactionId(bool isSubXact);
 static TransactionId DtmGetOldestXmin(Relation rel, bool ignoreVacuum);
+static TransactionId DtmGetGlobalTransactionId(void);
 
 static bool TransactionIdIsInSnapshot(TransactionId xid, Snapshot snapshot);
 static bool TransactionIdIsInDoubt(TransactionId xid);
@@ -92,7 +93,7 @@ static bool DtmGlobalXidAssigned;
 static int DtmLocalXidReserve;
 static int DtmCurcid;
 static Snapshot DtmLastSnapshot;
-static TransactionManager DtmTM = { DtmGetTransactionStatus, DtmSetTransactionStatus, DtmGetSnapshot, DtmGetNewTransactionId, DtmGetOldestXmin, DtmTransactionIdIsInProgress };
+static TransactionManager DtmTM = { DtmGetTransactionStatus, DtmSetTransactionStatus, DtmGetSnapshot, DtmGetNewTransactionId, DtmGetOldestXmin, DtmTransactionIdIsInProgress, DtmGetGlobalTransactionId };
 
 
 #define XTM_TRACE(fmt, ...)
@@ -323,6 +324,12 @@ static TransactionId DtmGetNextXid()
 	return xid;
 }
 
+TransactionId
+DtmGetGlobalTransactionId()
+{
+    return DtmNextXid;
+}
+
 TransactionId
 DtmGetNewTransactionId(bool isSubXact)
 {
@@ -667,8 +674,8 @@ static void DtmInitialize()
 static void
 DtmXactCallback(XactEvent event, void *arg)
 {
+    XTM_INFO("%d: DtmXactCallbackevent=%d isGlobal=%d, nextxid=%d\n", getpid(), event, DtmGlobalXidAssigned, DtmNextXid);
 	if (event == XACT_EVENT_COMMIT || event == XACT_EVENT_ABORT) {
-		XTM_INFO("%d: DtmXactCallbackevent=%d isGlobal=%d, nextxid=%d\n", getpid(), event, DtmGlobalXidAssigned, DtmNextXid);
 		if (DtmGlobalXidAssigned) {
 			DtmGlobalXidAssigned = false;
 		} else if (TransactionIdIsValid(DtmNextXid)) {
@@ -780,10 +787,9 @@ dtm_get_current_snapshot_xmax(PG_FUNCTION_ARGS)
 Datum
 dtm_begin_transaction(PG_FUNCTION_ARGS)
 {
-	int nParticipants = PG_GETARG_INT32(0);
 	Assert(!TransactionIdIsValid(DtmNextXid));
 
-	DtmNextXid = DtmGlobalStartTransaction(nParticipants, &DtmSnapshot, &dtm->minXid);
+	DtmNextXid = DtmGlobalStartTransaction(&DtmSnapshot, &dtm->minXid);
 	Assert(TransactionIdIsValid(DtmNextXid));
 	XTM_INFO("%d: Start global transaction %d, dtm->minXid=%d\n", getpid(), DtmNextXid, dtm->minXid);
 
diff --git a/contrib/pg_xtm/tests/transfers-fdw.go b/contrib/pg_xtm/tests/transfers-fdw.go
@@ -3,7 +3,6 @@ package main
 import (
     "fmt"
     "sync"
-    "strconv"
     "math/rand"
     "time"
     "github.com/jackc/pgx"
@@ -91,7 +90,6 @@ func progress(total int, cCommits chan int, cAborts chan int) {
 
 func transfer(id int, cCommits chan int, cAborts chan int, wg *sync.WaitGroup) {
     var err error
-    var xid int32
     var nAborts = 0
     var nCommits = 0
     var myCommits = 0
@@ -106,10 +104,7 @@ func transfer(id int, cCommits chan int, cAborts chan int, wg *sync.WaitGroup) {
         account1 := rand.Intn(N_ACCOUNTS)
         account2 := ^rand.Intn(N_ACCOUNTS)
 
-        exec(conn, "begin")
-        xid = execQuery(conn, "select dtm_begin_transaction(2)")
-        exec(conn, "select postgres_fdw_exec('t_fdw'::regclass::oid, 'select public.dtm_join_transaction(" + strconv.Itoa(int(xid)) + ")')")
-        exec(conn, "commit")
+        exec(conn, "select dtm_begin_transaction()")
 
         exec(conn, "begin transaction isolation level " + ISOLATION_LEVEL)
 
@@ -141,25 +136,21 @@ func transfer(id int, cCommits chan int, cAborts chan int, wg *sync.WaitGroup) {
 func inspect(wg *sync.WaitGroup) {
     var sum int64
     var prevSum int64 = 0
-    var xid int32
 
     {
         conn, err := pgx.Connect(cfg1)
         checkErr(err)
 
         for running {
 
-            exec(conn, "begin")
-            xid = execQuery(conn, "select dtm_begin_transaction(2)")
-            exec(conn, "select postgres_fdw_exec('t_fdw'::regclass::oid, 'select public.dtm_join_transaction(" + strconv.Itoa(int(xid)) + ")')")
-            exec(conn, "commit")
+            exec(conn, "select dtm_begin_transaction()")
 
             exec(conn, "begin transaction isolation level " + ISOLATION_LEVEL)
 
             sum = execQuery64(conn, "select sum(v) from t")
 
             if (sum != prevSum) {
-                fmt.Printf("Total=%d xid=%d\n", sum, xid)
+                fmt.Printf("Total=%d\n", sum)
                 prevSum = sum
             }
 
diff --git a/contrib/pg_xtm/tests/transfers.go b/contrib/pg_xtm/tests/transfers.go
@@ -130,7 +130,7 @@ func transfer(id int, cCommits chan int, cAborts chan int, wg *sync.WaitGroup) {
         src := conn[0]
         dst := conn[1]
 
-        xid = execQuery(src, "select dtm_begin_transaction(2)")
+        xid = execQuery(src, "select dtm_begin_transaction()")
         exec(dst, "select dtm_join_transaction($1)", xid)
 
         // start transaction
@@ -176,7 +176,7 @@ func inspect(wg *sync.WaitGroup) {
         checkErr(err)
 
         for running {
-            xid = execQuery(conn1, "select dtm_begin_transaction(2)")
+            xid = execQuery(conn1, "select dtm_begin_transaction()")
             exec(conn2, "select dtm_join_transaction($1)", xid)
 
             exec(conn1, "begin transaction isolation level " + ISOLATION_LEVEL)
diff --git a/contrib/postgres_fdw/connection.c b/contrib/postgres_fdw/connection.c
@@ -15,6 +15,8 @@
 #include "postgres_fdw.h"
 
 #include "access/xact.h"
+#include "access/xtm.h"
+#include "access/transam.h"
 #include "mb/pg_wchar.h"
 #include "miscadmin.h"
 #include "utils/hsearch.h"
@@ -401,11 +403,21 @@ begin_remote_xact(ConnCacheEntry *entry)
 	/* Start main transaction if we haven't yet */
 	if (entry->xact_depth <= 0)
 	{
+        TransactionId gxid = GetTransactionManager()->GetGlobalTransactionId();
 		const char *sql;
 
 		elog(DEBUG3, "starting remote transaction on connection %p",
 			 entry->conn);
 
+        if (TransactionIdIsValid(gxid)) {
+            char stmt[64];
+            PGresult *res;
+
+            snprintf(stmt, sizeof(stmt), "select public.dtm_join_transaction(%d)", gxid);
+            res = PQexec(entry->conn, stmt);
+            PQclear(res);
+        }
+
 		if (IsolationIsSerializable())
 			sql = "START TRANSACTION ISOLATION LEVEL SERIALIZABLE";
 		else
diff --git a/src/backend/access/transam/clog.c b/src/backend/access/transam/clog.c
@@ -44,9 +44,21 @@
 #include "miscadmin.h"
 #include "pg_trace.h"
 
-TransactionManager DefaultTM = { CLOGTransactionIdGetStatus, CLOGTransactionIdSetTreeStatus, GetLocalSnapshotData, GetNewLocalTransactionId, GetOldestLocalXmin, TransactionIdIsRunning };
+static TransactionId GetGlobalTransactionId(void);
+
+TransactionId GetGlobalTransactionId(void)
+{
+    return InvalidTransactionId;
+}
+
+TransactionManager DefaultTM = { CLOGTransactionIdGetStatus, CLOGTransactionIdSetTreeStatus, GetLocalSnapshotData, GetNewLocalTransactionId, GetOldestLocalXmin, TransactionIdIsRunning, GetGlobalTransactionId };
 TransactionManager* TM = &DefaultTM;
 
+TransactionManager* GetTransactionManager(void)
+{
+    return TM;
+}
+
 /*
  * Defines for CLOG page sizes.  A page is the same BLCKSZ as is used
  * everywhere else in Postgres.
diff --git a/src/include/access/xtm.h b/src/include/access/xtm.h
@@ -17,14 +17,31 @@
 
 typedef struct
 {
+    /* Get current transaction status (encapsulation of TransactionIdGetStatus in clog.c) */
     XidStatus (*GetTransactionStatus)(TransactionId xid, XLogRecPtr *lsn);
+
+    /* Set current transaction status (encapsulation of TransactionIdGetStatus in clog.c) */
     void (*SetTransactionStatus)(TransactionId xid, int nsubxids, TransactionId *subxids, XidStatus status, XLogRecPtr lsn);
+
+    /* Get current transaction snaphot (encapsulation of GetSnapshotData in procarray.c) */
     Snapshot (*GetSnapshot)(Snapshot snapshot);
+
+    /* Assign new Xid to transaction (encapsulation of GetNewTransactionId in varsup.c) */
     TransactionId (*GetNewTransactionId)(bool isSubXact);
+
+    /* Get oldest transaction Xid that was running when any current transaction was started (encapsulation of GetOldestXmin in procarray.c) */
     TransactionId (*GetOldestXmin)(Relation rel, bool ignoreVacuum);
+
+    /* Check if current transaction is not yet completed (encapsulation of TransactionIdIsInProgress in procarray.c) */
     bool (*IsInProgress)(TransactionId xid);
+
+    /* Get global transaction XID: returns XID of current transaction if it is global, InvalidTransactionId otherwise */
+    TransactionId (*GetGlobalTransactionId)(void);
 } TransactionManager;
 
+
+TransactionManager* GetTransactionManager(void);
+
 extern TransactionManager* TM;
 extern TransactionManager DefaultTM;
 
