cluster::InitialStatusMap and unit tests, support for improved cluster join protocol.

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@881420 13f79535-47bb-0310-9956-ffa450edef68

12 files changed, 365 insertions, 23 deletions

diff --git a/qpid/cpp/src/cluster.mk b/qpid/cpp/src/cluster.mk
index 1a8812d169..6e9bd27698 100644
--- a/qpid/cpp/src/cluster.mk
+++ b/qpid/cpp/src/cluster.mk
@@ -82,6 +82,8 @@ cluster_la_SOURCES =				\
   qpid/cluster/PollerDispatch.h			\
   qpid/cluster/ProxyInputHandler.h		\
   qpid/cluster/Quorum.h				\
+  qpid/cluster/InitialStatusMap.h		\
+  qpid/cluster/InitialStatusMap.cpp		\
   qpid/cluster/types.h
 
 cluster_la_LIBADD=  -lcpg $(libcman) libqpidbroker.la libqpidclient.la
diff --git a/qpid/cpp/src/qpid/cluster/Cluster.cpp b/qpid/cpp/src/qpid/cluster/Cluster.cpp
index 3ced6263df..d6312e7b93 100644
--- a/qpid/cpp/src/qpid/cluster/Cluster.cpp
+++ b/qpid/cpp/src/qpid/cluster/Cluster.cpp
@@ -153,7 +153,7 @@ namespace _qmf = ::qmf::org::apache::qpid::cluster;
  * Currently use SVN revision to avoid clashes with versions from
  * different branches.
  */
-const uint32_t Cluster::CLUSTER_VERSION = 834052;
+const uint32_t Cluster::CLUSTER_VERSION = 835547;
 
 struct ClusterDispatcher : public framing::AMQP_AllOperations::ClusterHandler {
     qpid::cluster::Cluster& cluster;
@@ -162,12 +162,19 @@ struct ClusterDispatcher : public framing::AMQP_AllOperations::ClusterHandler {
     ClusterDispatcher(Cluster& c, const MemberId& id, Cluster::Lock& l_) : cluster(c), member(id), l(l_) {}
 
     void updateRequest(const std::string& url) { cluster.updateRequest(member, url, l); }
+    void initialStatus(bool active, bool persistent, const framing::FieldTable& props) {
+        cluster.initialStatus(member, active, persistent, props);
+    }
     void ready(const std::string& url) { cluster.ready(member, url, l); }
     void configChange(const std::string& current) { cluster.configChange(member, current, l); }
-    void updateOffer(uint64_t updatee, const Uuid& id, uint32_t version) { cluster.updateOffer(member, updatee, id, version, l); }
+    void updateOffer(uint64_t updatee, const Uuid& id, uint32_t version) {
+        cluster.updateOffer(member, updatee, id, version, l);
+    }
     void retractOffer(uint64_t updatee) { cluster.retractOffer(member, updatee, l); }
     void messageExpired(uint64_t id) { cluster.messageExpired(member, id, l); }
-    void errorCheck(uint8_t type, const framing::SequenceNumber& frameSeq) { cluster.errorCheck(member, type, frameSeq, l); }
+    void errorCheck(uint8_t type, const framing::SequenceNumber& frameSeq) {
+        cluster.errorCheck(member, type, frameSeq, l);
+    }
 
     void shutdown() { cluster.shutdown(member, l); }
 
@@ -603,6 +610,10 @@ void Cluster::updateRequest(const MemberId& id, const std::string& url, Lock& l)
     makeOffer(id, l);
 }
 
+void Cluster::initialStatus(const MemberId&, bool /*active*/, bool /*persistent*/,
+                     const framing::FieldTable&) {
+    // FIXME aconway 2009-11-12: fill in.
+}
 void Cluster::ready(const MemberId& id, const std::string& url, Lock& l) {
     if (map.ready(id, Url(url))) 
         memberUpdate(l);
diff --git a/qpid/cpp/src/qpid/cluster/Cluster.h b/qpid/cpp/src/qpid/cluster/Cluster.h
index 286d7867c9..751a71867d 100644
--- a/qpid/cpp/src/qpid/cluster/Cluster.h
+++ b/qpid/cpp/src/qpid/cluster/Cluster.h
@@ -147,6 +147,7 @@ class Cluster : private Cpg::Handler, public management::Manageable {
     void updateOffer(const MemberId& updater, uint64_t updatee, const framing::Uuid&,
                      uint32_t version, Lock&);
     void retractOffer(const MemberId& updater, uint64_t updatee, Lock&);
+    void initialStatus(const MemberId&, bool active, bool persistent, const framing::FieldTable& props);
     void ready(const MemberId&, const std::string&, Lock&);
     void configChange(const MemberId&, const std::string& current, Lock& l);
     void messageExpired(const MemberId&, uint64_t, Lock& l);
diff --git a/qpid/cpp/src/qpid/cluster/ClusterMap.h b/qpid/cpp/src/qpid/cluster/ClusterMap.h
index 5735a6335d..2e682a6f4a 100644
--- a/qpid/cpp/src/qpid/cluster/ClusterMap.h
+++ b/qpid/cpp/src/qpid/cluster/ClusterMap.h
@@ -33,14 +33,11 @@
 #include <vector>
 #include <deque>
 #include <map>
-#include <set>
 #include <iosfwd>
 
 namespace qpid {
 namespace cluster {
 
-typedef std::set<MemberId> MemberSet;
-
 /**
  * Map of established cluster members and joiners waiting for an update,
  * along with other cluster state that must be updated.
diff --git a/qpid/cpp/src/qpid/cluster/Cpg.cpp b/qpid/cpp/src/qpid/cluster/Cpg.cpp
index 316b5386f1..49a814b848 100644
--- a/qpid/cpp/src/qpid/cluster/Cpg.cpp
+++ b/qpid/cpp/src/qpid/cluster/Cpg.cpp
@@ -217,12 +217,15 @@ MemberId Cpg::self() const {
 
 namespace { int byte(uint32_t value, int i) { return (value >> (i*8)) & 0xff; } }
 
-ostream& operator <<(ostream& out, const MemberId& id) {
-    out << byte(id.first, 0) << "."
-        << byte(id.first, 1) << "."
-        << byte(id.first, 2) << "."
-        << byte(id.first, 3);
-    return out << ":" << id.second;
+ostream& operator<<(ostream& out, const MemberId& id) {
+    if (id.first) {
+        out << byte(id.first, 0) << "."
+            << byte(id.first, 1) << "."
+            << byte(id.first, 2) << "."
+            << byte(id.first, 3)
+            << ":";
+    }
+    return out << id.second;
 }
 
 ostream& operator<<(ostream& o, const ConnectionId& c) {
diff --git a/qpid/cpp/src/qpid/cluster/InitialStatusMap.cpp b/qpid/cpp/src/qpid/cluster/InitialStatusMap.cpp
new file mode 100644
index 0000000000..8c55a66ed7
--- /dev/null
+++ b/qpid/cpp/src/qpid/cluster/InitialStatusMap.cpp
@@ -0,0 +1,110 @@
+/*
+ *
+ * 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 "InitialStatusMap.h"
+#include <algorithm>
+#include <boost/bind.hpp>
+
+using namespace std;
+using namespace boost;
+
+namespace qpid {
+namespace cluster {
+
+InitialStatusMap::InitialStatusMap(const MemberId& self_)
+    : self(self_), complete(), updateNeeded(), resendNeeded()
+{
+    map[self] = optional<Status>();
+}
+
+void InitialStatusMap::configChange(const MemberSet& members) {
+    resendNeeded = false;
+    if (firstConfig.empty()) firstConfig = members;
+    MemberSet::const_iterator i = members.begin();
+    Map::iterator j = map.begin();
+    while (i != members.end() || j != map.end()) {
+        if (i == members.end()) { // j not in members, member left
+            Map::iterator k = j++;
+            map.erase(k);
+        }
+        else if (j == map.end()) { // i not in map, member joined
+            resendNeeded = true;
+            map[*i] = optional<Status>();
+            ++i;
+        }
+        else if (*i < j->first) { // i not in map, member joined
+            resendNeeded = true;
+            map[*i] = optional<Status>();
+            ++i;
+        }
+        else if (*i > j->first) { // j not in members, member left
+            Map::iterator k = j++;
+            map.erase(k);
+        }
+        else {
+            i++; j++;
+        }
+    }
+    if (resendNeeded) {         // Clear all status
+        for (Map::iterator i = map.begin(); i != map.end(); ++i)
+            i->second = optional<Status>();
+    }
+}
+
+void InitialStatusMap::received(const MemberId& m, const Status& s){
+    map[m] = s;
+}
+
+bool InitialStatusMap::notInitialized(const Map::value_type& v) {
+    return !v.second;
+}
+
+bool InitialStatusMap::isActive(const Map::value_type& v) {
+    return v.second && v.second->getActive();
+}
+
+bool InitialStatusMap::isComplete() {
+    return find_if(map.begin(), map.end(), &notInitialized) == map.end();
+}
+
+bool InitialStatusMap::isResendNeeded() {
+    bool ret = resendNeeded;
+    resendNeeded = false;
+    return ret;
+}
+
+bool InitialStatusMap::isUpdateNeeded() {
+    assert(isComplete());
+    // If there are any active members we need an update.
+    return find_if(map.begin(), map.end(), &isActive) != map.end();
+}
+
+MemberSet InitialStatusMap::getElders() {
+    assert(isComplete());
+    MemberSet elders;
+    // Elders are from first config change, active or higher node-id.
+    for (MemberSet::iterator i = firstConfig.begin(); i != firstConfig.end(); ++i) {
+        if (map.find(*i) != map.end() && (map[*i]->getActive() || *i > self))
+            elders.insert(*i);
+    }
+    return elders;
+}
+
+}} // namespace qpid::cluster
diff --git a/qpid/cpp/src/qpid/cluster/InitialStatusMap.h b/qpid/cpp/src/qpid/cluster/InitialStatusMap.h
new file mode 100644
index 0000000000..d139722623
--- /dev/null
+++ b/qpid/cpp/src/qpid/cluster/InitialStatusMap.h
@@ -0,0 +1,68 @@
+#ifndef QPID_CLUSTER_INITIALSTATUSMAP_H
+#define QPID_CLUSTER_INITIALSTATUSMAP_H
+
+/*
+ *
+ * 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 "types.h"
+#include <qpid/framing/ClusterInitialStatusBody.h>
+#include <boost/optional.hpp>
+
+namespace qpid {
+namespace cluster {
+
+/**
+ * Track status of cluster members during initialization.
+ */
+class InitialStatusMap
+{
+  public:
+    typedef framing::ClusterInitialStatusBody Status;
+
+    InitialStatusMap(const MemberId& self);
+    /** Process a config change. @return true if we need to re-send our status */
+    void configChange(const MemberSet& newConfig);
+    /** @return true if we need to re-send status */
+    bool isResendNeeded();
+
+    /** Process received status */
+    void received(const MemberId&, const Status& is);
+
+    /**@return true if the map is complete. */
+    bool isComplete();
+    /**@pre isComplete. @return this node's elders */
+    MemberSet getElders();
+    /**@pre isComplete. @return True if we need an update. */
+    bool isUpdateNeeded();
+
+  private:
+    typedef std::map<MemberId, boost::optional<Status> > Map;
+    static bool notInitialized(const Map::value_type&);
+    static bool isActive(const Map::value_type&);
+    void check();
+    Map map;
+    MemberSet firstConfig;
+    MemberId self;
+    bool complete, updateNeeded, resendNeeded;
+};
+}} // namespace qpid::cluster
+
+#endif  /*!QPID_CLUSTER_INITIALSTATUSMAP_H*/
diff --git a/qpid/cpp/src/qpid/cluster/types.h b/qpid/cpp/src/qpid/cluster/types.h
index c19152e4d8..6777c9674c 100644
--- a/qpid/cpp/src/qpid/cluster/types.h
+++ b/qpid/cpp/src/qpid/cluster/types.h
@@ -29,6 +29,7 @@
 #include <utility>
 #include <iosfwd>
 #include <string>
+#include <set>
 
 
 extern "C" {
@@ -52,8 +53,8 @@ enum EventType { DATA, CONTROL };
 
 /** first=node-id, second=pid */
 struct MemberId : std::pair<uint32_t, uint32_t> {
-    explicit MemberId(uint64_t n) : std::pair<uint32_t,uint32_t>( n >> 32, n & 0xffffffff) {}
-    explicit MemberId(uint32_t node=0, uint32_t pid=0) : std::pair<uint32_t,uint32_t>(node, pid) {}
+    MemberId(uint64_t n=0) : std::pair<uint32_t,uint32_t>( n >> 32, n & 0xffffffff) {}
+    MemberId(uint32_t node, uint32_t pid) : std::pair<uint32_t,uint32_t>(node, pid) {}
     MemberId(const cpg_address& caddr) : std::pair<uint32_t,uint32_t>(caddr.nodeid, caddr.pid) {}
     MemberId(const std::string&); // Decode from string.
     uint32_t getNode() const { return first; }
@@ -75,6 +76,8 @@ struct ConnectionId : public std::pair<MemberId, uint64_t>  {
     uint64_t getNumber() const { return second; }
 };
 
+typedef std::set<MemberId> MemberSet;
+
 std::ostream& operator<<(std::ostream&, const ConnectionId&);
 
 std::ostream& operator<<(std::ostream&, EventType);
diff --git a/qpid/cpp/src/tests/InitialStatusMap.cpp b/qpid/cpp/src/tests/InitialStatusMap.cpp
new file mode 100644
index 0000000000..7709b1fbfc
--- /dev/null
+++ b/qpid/cpp/src/tests/InitialStatusMap.cpp
@@ -0,0 +1,141 @@
+/*
+ *
+ * Copyright (c) 2006 The Apache Software Foundation
+ *
+ * Licensed 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 "unit_test.h"
+#include "test_tools.h"
+#include "qpid/cluster/InitialStatusMap.h"
+#include <boost/assign.hpp>
+
+using namespace std;
+using namespace qpid::cluster;
+using namespace qpid::framing;
+using namespace boost::assign;
+
+namespace qpid {
+namespace tests {
+
+QPID_AUTO_TEST_SUITE(InitialStatusMapTestSuite)
+
+typedef InitialStatusMap::Status Status;
+
+Status activeStatus() { return Status(ProtocolVersion(), true, false, FieldTable()); }
+Status newcomerStatus() { return Status(ProtocolVersion(), false, false, FieldTable()); }
+
+QPID_AUTO_TEST_CASE(testFirstInCluster) {
+    // Single member is first in cluster.
+    InitialStatusMap map(MemberId(0));
+    BOOST_CHECK(!map.isComplete());
+    MemberSet members = list_of(MemberId(0));
+    map.configChange(members);
+    BOOST_CHECK(!map.isComplete());
+    map.received(MemberId(0), newcomerStatus());
+    BOOST_CHECK(map.isComplete());
+    BOOST_CHECK(map.getElders().empty());
+    BOOST_CHECK(!map.isUpdateNeeded());
+}
+
+QPID_AUTO_TEST_CASE(testJoinExistingCluster) {
+    // Single member 0 joins existing cluster 1,2
+    InitialStatusMap map(MemberId(0));
+    MemberSet members = list_of(MemberId(0))(MemberId(1))(MemberId(2));
+    map.configChange(members);
+    BOOST_CHECK(map.isResendNeeded());
+    BOOST_CHECK(!map.isComplete());
+    map.received(MemberId(0), newcomerStatus());
+    map.received(MemberId(1), activeStatus());
+    BOOST_CHECK(!map.isComplete());
+    map.received(MemberId(2), activeStatus());
+    BOOST_CHECK(map.isComplete());
+    BOOST_CHECK_EQUAL(map.getElders(), list_of<MemberId>(1)(2));
+    BOOST_CHECK(map.isUpdateNeeded());
+}
+
+QPID_AUTO_TEST_CASE(testMultipleFirstInCluster) {
+    // Multiple members 0,1,2 join at same time.
+    InitialStatusMap map(MemberId(1)); // self is 1
+    MemberSet members = list_of(MemberId(0))(MemberId(1))(MemberId(2));
+    map.configChange(members);
+    BOOST_CHECK(map.isResendNeeded());
+
+    // All new members
+    map.received(MemberId(0), newcomerStatus());
+    map.received(MemberId(1), newcomerStatus());
+    map.received(MemberId(2), newcomerStatus());
+    BOOST_CHECK(!map.isResendNeeded());
+    BOOST_CHECK(map.isComplete());
+    BOOST_CHECK_EQUAL(map.getElders(), list_of(MemberId(2)));
+    BOOST_CHECK(!map.isUpdateNeeded());
+}
+
+QPID_AUTO_TEST_CASE(testMultipleJoinExisting) {
+    // Multiple members 1,2,3 join existing cluster containing 0.
+    InitialStatusMap map(MemberId(2)); // self is 2
+    MemberSet members = list_of(MemberId(0))(MemberId(1))(MemberId(2))(MemberId(3));
+    map.configChange(members);
+    BOOST_CHECK(map.isResendNeeded());
+
+    map.received(MemberId(1), newcomerStatus());
+    map.received(MemberId(2), newcomerStatus());
+    map.received(MemberId(3), newcomerStatus());
+    map.received(MemberId(0), activeStatus());
+    BOOST_CHECK(!map.isResendNeeded());
+    BOOST_CHECK(map.isComplete());
+    BOOST_CHECK_EQUAL(map.getElders(), list_of(MemberId(0))(MemberId(3)));
+    BOOST_CHECK(map.isUpdateNeeded());
+}
+
+QPID_AUTO_TEST_CASE(testMembersLeave) {
+    // Test that map completes if members leave rather than send status.
+    InitialStatusMap map(MemberId(0));
+    map.configChange(list_of(MemberId(0))(MemberId(1))(MemberId(2)));
+    map.received(MemberId(0), newcomerStatus());
+    map.received(MemberId(1), activeStatus());
+    BOOST_CHECK(!map.isComplete());
+    map.configChange(list_of(MemberId(0))(MemberId(1))); // 2 left
+    BOOST_CHECK(map.isComplete());
+    BOOST_CHECK_EQUAL(map.getElders(), list_of(MemberId(1)));
+}
+
+QPID_AUTO_TEST_CASE(testInteveningConfig) {
+    // Multiple config changes arrives before we complete the map.
+    InitialStatusMap map(MemberId(0));
+
+    map.configChange(list_of<MemberId>(0)(1));
+    BOOST_CHECK(map.isResendNeeded());
+    map.received(MemberId(0), newcomerStatus());
+    BOOST_CHECK(!map.isComplete());
+    BOOST_CHECK(!map.isResendNeeded());
+    // New member 2 joins before we receive 1
+    map.configChange(list_of<MemberId>(0)(1)(2));
+    BOOST_CHECK(!map.isComplete());
+    BOOST_CHECK(map.isResendNeeded());
+    map.received(1, activeStatus());
+    map.received(2, newcomerStatus());
+    // We should not be complete as we haven't received 0 since new member joined
+    BOOST_CHECK(!map.isComplete());
+    BOOST_CHECK(!map.isResendNeeded());
+
+    map.received(0, newcomerStatus());
+    BOOST_CHECK(map.isComplete());
+    BOOST_CHECK_EQUAL(map.getElders(), list_of<MemberId>(1));
+}
+
+QPID_AUTO_TEST_SUITE_END()
+
+}} // namespace qpid::tests
diff --git a/qpid/cpp/src/tests/cluster.mk b/qpid/cpp/src/tests/cluster.mk
index 961d65f319..f33f87ee62 100644
--- a/qpid/cpp/src/tests/cluster.mk
+++ b/qpid/cpp/src/tests/cluster.mk
@@ -75,9 +75,10 @@ cluster_test_SOURCES =				\
 	ForkedBroker.h				\
 	ForkedBroker.cpp			\
 	PartialFailure.cpp			\
-	ClusterFailover.cpp
+	ClusterFailover.cpp			\
+	InitialStatusMap.cpp
 
-cluster_test_LDADD=$(lib_client) $(lib_broker) -lboost_unit_test_framework
+cluster_test_LDADD=$(lib_client) $(lib_broker) ../cluster.la -lboost_unit_test_framework
 
 qpidtest_SCRIPTS += run_cluster_tests cluster_tests.py run_long_cluster_tests long_cluster_tests.py testlib.py cluster_tests.fail
 
diff --git a/qpid/cpp/src/tests/cluster_test.cpp b/qpid/cpp/src/tests/cluster_test.cpp
index eb6d98eced..c2683727cf 100644
--- a/qpid/cpp/src/tests/cluster_test.cpp
+++ b/qpid/cpp/src/tests/cluster_test.cpp
@@ -54,11 +54,6 @@
 #include <algorithm>
 #include <iterator>
 
-namespace std {                 // ostream operators in std:: namespace
-template <class T>
-ostream& operator<<(ostream& o, const std::set<T>& s) { return seqPrint(o, s); }
-}
-
 using namespace std;
 using namespace qpid;
 using namespace qpid::cluster;
diff --git a/qpid/cpp/src/tests/test_tools.h b/qpid/cpp/src/tests/test_tools.h
index 832c04af04..4174751173 100644
--- a/qpid/cpp/src/tests/test_tools.h
+++ b/qpid/cpp/src/tests/test_tools.h
@@ -26,6 +26,7 @@
 #include <boost/regex.hpp>
 #include <boost/assign/list_of.hpp>
 #include <vector>
+#include <set>
 #include <ostream>
 
 // Print a sequence
@@ -43,14 +44,17 @@ bool seqEqual(const T& a, const U& b) {
     return (i == a.end()) && (j == b.end());
 }
 
-// ostream and == operators so we can compare vectors and boost::assign::list_of
-// with BOOST_CHECK_EQUALS
+// ostream and == operators so we can compare vectors and sets with
+// boost::assign::list_of with BOOST_CHECK_EQUALS
 namespace std {                 // In namespace std so boost can find them.
 
 template <class T>
 ostream& operator<<(ostream& o, const vector<T>& v) { return seqPrint(o, v); }
 
 template <class T>
+ostream& operator<<(ostream& o, const set<T>& v) { return seqPrint(o, v); }
+
+template <class T>
 ostream& operator<<(ostream& o, const boost::assign_detail::generic_list<T>& l) { return seqPrint(o, l); }
 
 template <class T>
@@ -58,6 +62,12 @@ bool operator == (const vector<T>& a, const boost::assign_detail::generic_list<T
 
 template <class T>
 bool operator == (const boost::assign_detail::generic_list<T>& b, const vector<T>& a) { return seqEqual(a, b); }
+
+template <class T>
+bool operator == (const set<T>& a, const boost::assign_detail::generic_list<T>& b) { return seqEqual(a, b); }
+
+template <class T>
+bool operator == (const boost::assign_detail::generic_list<T>& b, const set<T>& a) { return seqEqual(a, b); }
 }
 
 namespace qpid {