NO-JIRA: Refactor RefCountedBuffer to be simpler and more flexible.

RefCountedBuffer::pointer is replaced by a separate class BufferRef.

BufferRef is independent of RefCountedBuffer, it can be used to manage other
reference-counted buffer classes e.g. to implement buffer pools.
BufferRef also provides beginning and end of the buffer, not just beginning.

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk/qpid@1081631 13f79535-47bb-0310-9956-ffa450edef68

6 files changed, 98 insertions, 81 deletions

diff --git a/cpp/src/Makefile.am b/cpp/src/Makefile.am
index dfb2547613..0820a7a29a 100644
--- a/cpp/src/Makefile.am
+++ b/cpp/src/Makefile.am
@@ -176,7 +176,7 @@ nobase_include_HEADERS +=			\
   ../include/qpid/sys/posix/Time.h		\
   ../include/qpid/sys/posix/check.h
 
-if HAVE_EPOLL 
+if HAVE_EPOLL
   poller = qpid/sys/epoll/EpollPoller.cpp
 endif
 
@@ -195,7 +195,7 @@ libqpidcommon_la_SOURCES += $(poller) $(systeminfo)
 posix_broker_src = \
   qpid/broker/posix/BrokerDefaults.cpp
 
-lib_LTLIBRARIES = libqpidtypes.la libqpidcommon.la libqpidbroker.la libqpidclient.la libqpidmessaging.la 
+lib_LTLIBRARIES = libqpidtypes.la libqpidcommon.la libqpidbroker.la libqpidclient.la libqpidmessaging.la
 
 # Definitions for client and daemon plugins
 PLUGINLDFLAGS=-no-undefined -module -avoid-version
@@ -203,7 +203,7 @@ confdir=$(sysconfdir)/qpid
 dmoduledir=$(libdir)/qpid/daemon
 cmoduledir=$(libdir)/qpid/client
 dmodule_LTLIBRARIES =
-cmodule_LTLIBRARIES = 
+cmodule_LTLIBRARIES =
 
 include cluster.mk
 include acl.mk
@@ -341,6 +341,7 @@ libqpidcommon_la_SOURCES +=			\
   qpid/RefCounted.h				\
   qpid/RefCountedBuffer.cpp			\
   qpid/RefCountedBuffer.h			\
+  qpid/BufferRef.h				\
   qpid/Sasl.h                                   \
   qpid/SaslFactory.cpp                          \
   qpid/SaslFactory.h                            \
@@ -892,6 +893,6 @@ dist-hook: $(BUILT_SOURCES)
 install-data-local:
 	$(mkinstalldirs) $(DESTDIR)/$(localstatedir)/lib/qpidd
 
-# Support for pkg-config 
+# Support for pkg-config
 pkgconfigdir = $(libdir)/pkgconfig
 pkgconfig_DATA = qpid.pc
diff --git a/cpp/src/qpid/BufferRef.h b/cpp/src/qpid/BufferRef.h
new file mode 100644
index 0000000000..bfe1f9ebaa
--- /dev/null
+++ b/cpp/src/qpid/BufferRef.h
@@ -0,0 +1,70 @@
+#ifndef QPID_BUFFERREF_H
+#define QPID_BUFFERREF_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 "qpid/RefCounted.h"
+#include <boost/intrusive_ptr.hpp>
+
+namespace qpid {
+
+/** Template for mutable or const buffer references */
+template <class T> class BufferRefT {
+  public:
+    BufferRefT() : begin_(0), end_(0) {}
+
+    BufferRefT(boost::intrusive_ptr<RefCounted> c, T* begin, T* end) :
+        counter(c), begin_(begin), end_(end) {}
+
+    template <class U> BufferRefT(const BufferRefT<U>& other) :
+        counter(other.counter), begin_(other.begin_), end_(other.end_) {}
+
+    T* begin() const { return begin_; }
+    T* end() const { return end_; }
+
+    /** Return a sub-buffer of the current buffer */
+    BufferRefT sub_buffer(T* begin, T* end) {
+        assert(begin_ <= begin && begin <= end_);
+        assert(begin_ <= end && end <= end_);
+        assert(begin <= end);
+        return BufferRefT(counter, begin, end);
+    }
+
+  private:
+    boost::intrusive_ptr<RefCounted> counter;
+    T* begin_;
+    T* end_;
+};
+
+/**
+ * Reference to a mutable ref-counted buffer.
+ */
+typedef BufferRefT<char> BufferRef;
+
+/**
+ * Reference to a const ref-counted buffer.
+ */
+typedef BufferRefT<const char> ConstBufferRef;
+
+} // namespace qpid
+
+#endif  /*!QPID_BUFFERREF_H*/
diff --git a/cpp/src/qpid/RefCountedBuffer.cpp b/cpp/src/qpid/RefCountedBuffer.cpp
index 9b8f1ebd5e..40d620f7ad 100644
--- a/cpp/src/qpid/RefCountedBuffer.cpp
+++ b/cpp/src/qpid/RefCountedBuffer.cpp
@@ -24,30 +24,20 @@
 
 namespace qpid {
 
-RefCountedBuffer::RefCountedBuffer() : count(0) {}
-
-void RefCountedBuffer::destroy() const {
+void RefCountedBuffer::released() const {
     this->~RefCountedBuffer();
     ::delete[] reinterpret_cast<const char*>(this);
 }
 
-char* RefCountedBuffer::addr() const {
-    return const_cast<char*>(reinterpret_cast<const char*>(this)+sizeof(RefCountedBuffer));
-}
-
-RefCountedBuffer::pointer RefCountedBuffer::create(size_t n) {
+BufferRef RefCountedBuffer::create(size_t n) {
     char* store=::new char[n+sizeof(RefCountedBuffer)];
     new(store) RefCountedBuffer;
-    return pointer(reinterpret_cast<RefCountedBuffer*>(store));
+    char* start = store+sizeof(RefCountedBuffer);
+    return BufferRef(
+        boost::intrusive_ptr<RefCounted>(reinterpret_cast<RefCountedBuffer*>(store)),
+        start, start+n);
 }
 
-RefCountedBuffer::pointer::pointer() {}
-RefCountedBuffer::pointer::pointer(RefCountedBuffer* x) : p(x) {}
-RefCountedBuffer::pointer::pointer(const pointer& x) : p(x.p) {}
-RefCountedBuffer::pointer::~pointer() {}
-RefCountedBuffer::pointer& RefCountedBuffer::pointer::operator=(const RefCountedBuffer::pointer& x) { p = x.p; return *this; }
-
-char* RefCountedBuffer::pointer::cp() const { return p ? p->get() : 0; }
 } // namespace qpid
 
 
diff --git a/cpp/src/qpid/RefCountedBuffer.h b/cpp/src/qpid/RefCountedBuffer.h
index 75a23862be..f0ea86130b 100644
--- a/cpp/src/qpid/RefCountedBuffer.h
+++ b/cpp/src/qpid/RefCountedBuffer.h
@@ -22,68 +22,23 @@
  *
  */
 
-#include <boost/utility.hpp>
-#include <boost/detail/atomic_count.hpp>
-#include <boost/intrusive_ptr.hpp>
+#include <qpid/RefCounted.h>
+#include <qpid/BufferRef.h>
 
 namespace qpid {
 
 /**
- * Reference-counted byte buffer.
- * No alignment guarantees.
+ * Reference-counted byte buffer. No alignment guarantees.
  */
-class RefCountedBuffer : boost::noncopyable {
-    mutable boost::detail::atomic_count count;
-    RefCountedBuffer();
-    void destroy() const;
-    char* addr() const;
-
-public:
-    /** Smart char pointer to a reference counted buffer */
-    class pointer {
-        boost::intrusive_ptr<RefCountedBuffer> p;
-        char* cp() const;
-        pointer(RefCountedBuffer* x);
-      friend class RefCountedBuffer;
-
-      public:
-        pointer();
-        pointer(const pointer&);
-        ~pointer();
-        pointer& operator=(const pointer&);
-
-        char* get() { return cp(); }
-        operator char*() { return cp(); }
-        char& operator*() { return *cp(); }
-        char& operator[](size_t i) { return cp()[i]; }
-
-        const char* get() const { return cp(); }
-        operator const char*() const { return cp(); }
-        const char& operator*() const { return *cp(); }
-        const char& operator[](size_t i) const { return cp()[i]; }
-    };
-
+class RefCountedBuffer : public RefCounted {
+  public:
     /** Create a reference counted buffer of size n */
-    static pointer create(size_t n);
-
-    /** Get a pointer to the start of the buffer. */
-    char* get() { return addr(); }
-    const char* get() const { return addr(); }
-    char& operator[](size_t i) { return get()[i]; }
-    const char& operator[](size_t i) const { return get()[i]; }
+    static BufferRef create(size_t n);
 
-    void addRef() const { ++count; }
-    void release() const { if (--count==0) destroy(); }
-    long refCount() { return count; }
+  protected:
+    void released() const;
 };
 
 } // namespace qpid
 
-// intrusive_ptr support.
-namespace boost {
-inline void intrusive_ptr_add_ref(const qpid::RefCountedBuffer* p) { p->addRef(); }
-inline void intrusive_ptr_release(const qpid::RefCountedBuffer* p) { p->release(); }
-}
-
-
 #endif  /*!QPID_REFCOUNTEDBUFFER_H*/
diff --git a/cpp/src/qpid/cluster/Event.cpp b/cpp/src/qpid/cluster/Event.cpp
index cd775ce2f1..da2bc89d8c 100644
--- a/cpp/src/qpid/cluster/Event.cpp
+++ b/cpp/src/qpid/cluster/Event.cpp
@@ -7,9 +7,9 @@
  * 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
@@ -23,6 +23,7 @@
 #include "qpid/cluster/Cpg.h"
 #include "qpid/framing/Buffer.h"
 #include "qpid/framing/AMQFrame.h"
+#include "qpid/RefCountedBuffer.h"
 #include "qpid/assert.h"
 #include <ostream>
 #include <iterator>
diff --git a/cpp/src/qpid/cluster/Event.h b/cpp/src/qpid/cluster/Event.h
index c2dca073d1..13283edff7 100644
--- a/cpp/src/qpid/cluster/Event.h
+++ b/cpp/src/qpid/cluster/Event.h
@@ -23,7 +23,7 @@
  */
 
 #include "qpid/cluster/types.h"
-#include "qpid/RefCountedBuffer.h"
+#include "qpid/BufferRef.h"
 #include "qpid/framing/AMQFrame.h"
 #include <sys/uio.h>            // For iovec
 #include <iosfwd>
@@ -88,12 +88,12 @@ class Event : public EventHeader {
     static Event control(const framing::AMQFrame&, const ConnectionId&);
 
     // Data excluding header.
-    char* getData() { return store + HEADER_SIZE; }
-    const char* getData() const { return store + HEADER_SIZE; }
+    char* getData() { return store.begin() + HEADER_SIZE; }
+    const char* getData() const { return store.begin() + HEADER_SIZE; }
 
     // Store including header
-    char* getStore() { return store; }
-    const char* getStore() const { return store; }
+    char* getStore() { return store.begin(); }
+    const char* getStore() const { return store.begin(); }
 
     const framing::AMQFrame& getFrame() const;
 
@@ -104,7 +104,7 @@ class Event : public EventHeader {
   private:
     void encodeHeader() const;
 
-    RefCountedBuffer::pointer store;
+    BufferRef store;
     mutable framing::AMQFrame frame;
 };