QPID-4327: HA TX transactions: basic replication.

On primary a PrimaryTxObserver observes a transaction's TxBuffer and generates
transaction events on a tx-replication-queue. On the backup a TxReplicator
receives the events and constructs a TxBuffer equivalent to the one in the
primary.

Unfinished:
- Primary does not wait for backups to prepare() before committing.
- All connected backups are assumed to be in the transaction, there are race
  conditions around brokers joining/leavinv where this assumption is invalid.
- Need more tests.

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk/qpid@1509423 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 104 insertions, 0 deletions

diff --git a/cpp/src/qpid/ha/PrimaryTxObserver.cpp b/cpp/src/qpid/ha/PrimaryTxObserver.cpp
new file mode 100644
index 0000000000..8a8364ac22
--- /dev/null
+++ b/cpp/src/qpid/ha/PrimaryTxObserver.cpp
@@ -0,0 +1,104 @@
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ *
+ */
+
+#include "Event.h"
+#include "HaBroker.h"
+#include "Primary.h"
+#include "PrimaryTxObserver.h"
+#include "QueueGuard.h"
+#include "RemoteBackup.h"
+#include "ReplicatingSubscription.h"
+
+#include "qpid/broker/Broker.h"
+#include "qpid/broker/Queue.h"
+#include <boost/lexical_cast.hpp>
+
+namespace qpid {
+namespace ha {
+
+using namespace std;
+using namespace boost;
+using namespace broker;
+
+PrimaryTxObserver::PrimaryTxObserver(HaBroker& hb) :
+    haBroker(hb), broker(hb.getBroker()),
+    id(true)          // FIXME aconway 2013-07-11: is UUID an appropriate TX ID?
+{
+    logPrefix = "Primary transaction "+id.str().substr(0,8)+": ";
+    QPID_LOG(trace, logPrefix << "started");
+    pair<shared_ptr<Queue>, bool> result =
+        broker.getQueues().declare(
+            TRANSACTION_REPLICATOR_PREFIX+id.str(),
+            QueueSettings(/*durable*/false, /*autodelete*/true));
+    assert(result.second);
+    txQueue = result.first;
+}
+
+void PrimaryTxObserver::enqueue(const QueuePtr& q, const broker::Message& m)
+{
+    QPID_LOG(trace, logPrefix << "enqueue: " << LogMessageId(*q, m));
+    enqueues[q] += m.getReplicationId();
+    txQueue->deliver(TxEnqueueEvent(q->getName(), m.getReplicationId()).message());
+    txQueue->deliver(m);
+}
+
+void PrimaryTxObserver::dequeue(
+    const QueuePtr& q, QueuePosition pos, ReplicationId id)
+{
+    QPID_LOG(trace, logPrefix << "dequeue: " << LogMessageId(*q, pos, id));
+    txQueue->deliver(TxDequeueEvent(q->getName(), id).message());
+}
+
+void PrimaryTxObserver::deduplicate() {
+    shared_ptr<Primary> primary(boost::dynamic_pointer_cast<Primary>(haBroker.getRole()));
+    assert(primary);
+    // FIXME aconway 2013-07-29: need to verify which backups are *in* the transaction.
+    // Use cluster membership for now
+    BrokerInfo::Set brokers = haBroker.getMembership().getBrokers();
+    types::Uuid selfId = haBroker.getMembership().getSelf();
+    // Tell replicating subscriptions to skip IDs in the transaction.
+    for (BrokerInfo::Set::iterator b = brokers.begin(); b != brokers.end(); ++b) {
+        if (b->getSystemId() == selfId) continue;
+        for (QueueIdsMap::iterator q = enqueues.begin(); q != enqueues.end(); ++q)
+            primary->skip(b->getSystemId(), q->first, q->second);
+    }
+}
+
+bool PrimaryTxObserver::prepare() {
+    // FIXME aconway 2013-07-23: need to delay completion of prepare till all
+    // backups have prepared.
+    QPID_LOG(trace, logPrefix << "prepare");
+    deduplicate();
+    txQueue->deliver(TxPrepareEvent().message());
+    return true;
+}
+
+void PrimaryTxObserver::commit() {
+    QPID_LOG(trace, logPrefix << "commit");
+    txQueue->deliver(TxCommitEvent().message());
+}
+
+void PrimaryTxObserver::rollback() {
+    QPID_LOG(trace, logPrefix << "rollback");
+    txQueue->deliver(TxRollbackEvent().message());
+}
+
+}} // namespace qpid::ha