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@1509423 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 106 insertions, 0 deletions

diff --git a/qpid/cpp/include/qpid/framing/BufferTypes.h b/qpid/cpp/include/qpid/framing/BufferTypes.h
new file mode 100644
index 0000000000..4199755852
--- /dev/null
+++ b/qpid/cpp/include/qpid/framing/BufferTypes.h
@@ -0,0 +1,106 @@
+#ifndef QPID_FRAMING_BUFFERTYPES_H
+#define QPID_FRAMING_BUFFERTYPES_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.
+ *
+ */
+
+/**@file
+ * Using templates with framing::Buffer is difficultg becase of the many
+ * different put/get function names. Here we define a set of types
+ * corresponding the basic types of Buffer but presenting a uniform
+ * encode/decode/encodedSize interface.
+ *
+ * It also provides some convenience templates for the common case of
+ * encoding a single encodable value as a string, e.g.
+ *
+ * LongString ls("hello");
+ * std::string encoded = encodeStr(ls);
+ * LongString ls2 = decodeStr<LongString>(encoded);
+ * LongString ls3;
+ * decodeStr(encoded, ls3);
+ */
+
+namespace qpid {
+namespace framing {
+
+// Templates to help define types
+template <class ValueType> struct BufferTypeTraits {
+    typedef void (Buffer::*Put)(const ValueType&);
+    typedef void (Buffer::*Get)(ValueType&);
+};
+
+template <class ValueType,
+          typename BufferTypeTraits<ValueType>::Put PutFn,
+          typename BufferTypeTraits<ValueType>::Get GetFn>
+struct EncodeDecodeTemplate {
+    EncodeDecodeTemplate(const ValueType& s) : value(s) {}
+    operator ValueType() const { return value; }
+
+    ValueType value;
+    void encode(framing::Buffer& buf) const { (buf.*PutFn)(value); }
+    void decode(framing::Buffer& buf) { (buf.*GetFn)(value); }
+};
+
+template <size_t Size,
+          typename BufferTypeTraits<std::string>::Put PutFn,
+          typename BufferTypeTraits<std::string>::Get GetFn
+          >
+struct StringTypeTemplate : public EncodeDecodeTemplate<std::string, PutFn, GetFn> {
+    typedef EncodeDecodeTemplate<std::string, PutFn, GetFn> Base;
+    StringTypeTemplate(const std::string& s) : Base(s) {}
+    size_t encodedSize() const { return Size + Base::value.size(); }
+};
+
+
+// Convenience tempates for encoding/decoding values to/from a std::string.
+
+/** Encode value as a string. */
+template <class T> std::string encodeStr(const T& value) {
+    std::string encoded(value.encodedSize(), '\0');
+    framing::Buffer buffer(&encoded[0], encoded.size());
+    value.encode(buffer);
+    return encoded;
+}
+
+/** Decode value from a string. */
+template <class T> void decodeStr(const std::string& encoded, T& value) {
+    framing::Buffer b(const_cast<char*>(&encoded[0]), encoded.size());
+    value.decode(b);
+}
+
+/** Decode value from a string. */
+template <class T> T decodeStr(const std::string& encoded) {
+    T value;
+    decodeStr(encoded, value);
+    return value;
+}
+
+// The types
+
+typedef StringTypeTemplate<4, &Buffer::putLongString, &Buffer::getLongString> LongString;
+typedef StringTypeTemplate<2, &Buffer::putMediumString, &Buffer::getMediumString> MediumString;
+typedef StringTypeTemplate<1, &Buffer::putShortString, &Buffer::getShortString> ShortString;
+
+// TODO aconway 2013-07-26: Add integer types.
+
+}} // namespace qpid::framing
+
+#endif  /*!QPID_FRAMING_BUFFERTYPES_H*/