Added a ByteStreamPool class for cases where we'd otherwise

have to do something complicated, or constantly create and dispose
of ByteStreams.

utils/messageqcpp/bytestreampool.cpp

@@ -0,0 +1,78 @@
+/* Copyright (C) 2019 MariaDB Corporaton
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License
+   as published by the Free Software Foundation; version 2 of
+   the License.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+   MA 02110-1301, USA. */
+   
+#include "bytestreampool.h"
+
+namespace messageqcpp
+{
+
+ByteStreamPool::ByteStreamPool()
+{
+    maxBufferSize = 1 << 20;  // 1MB
+    maxFreeBuffers = 10;
+}
+
+ByteStreamPool::ByteStreamPool(uint largeBufferSize)
+{
+    maxBufferSize = largeBufferSize;
+    maxFreeBuffers = 10;
+}
+
+ByteStreamPool::ByteStreamPool(uint largeBufferSize, uint freeBufferLimit)
+{
+    maxBufferSize = largeBufferSize;
+    maxFreeBuffers = freeBufferLimit;
+}
+
+ByteStreamPool::~ByteStreamPool()
+{
+    while (!freeByteStreams.empty()) 
+    {
+        ByteStream *next = freeByteStreams.front();
+        freeByteStreams.pop_front();
+        delete next;
+    }
+}
+
+ByteStream * ByteStreamPool::getByteStream()
+{
+    boost::mutex::scoped_lock s(mutex);
+    ByteStream *ret;
+    
+    if (!freeByteStreams.empty())
+    {
+        ret = freeByteStreams.front();
+        freeByteStreams.pop_front();
+    }
+    else
+        ret = new ByteStream();
+
+    return ret;
+}
+
+void ByteStreamPool::returnByteStream(ByteStream *bs)
+{
+    if (bs->getBufferSize() > maxBufferSize)
+        delete bs;
+    else 
+    {
+        boost::mutex::scoped_lock s(mutex);
+        freeByteStreams.push_back(bs);
+    }
+}
+
+}

utils/messageqcpp/bytestreampool.h

@@ -0,0 +1,53 @@
+/* Copyright (C) 2019 MariaDB Corporaton
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License
+   as published by the Free Software Foundation; version 2 of
+   the License.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+   MA 02110-1301, USA. */
+   
+#ifndef BYTESTREAMPOOL_H_
+#define BYTESTREAMPOOL_H_
+
+/* This class defines a pool of bytestreams to improve BS reuse, reducing
+the need to use the dynamic allocator.  It allocates as many BS's as needed,
+and automatically disposes of buffers that are 'large' to reduce mem usage. 
+Initially, 'large' is defined as 1MB.
+*/
+
+#include <deque>
+#include <boost/thread/mutex.hpp>
+
+namespace messageqcpp
+{
+
+class ByteStreamPool
+{
+    public:
+        ByteStreamPool();
+        ByteStreamPool(uint largeBufferSize);   // BS's above largeBufferSize get deallocated on return to the pool
+        ByteStreamPool(uint largeBufferSize, uint freeBufferLimit);   // freeBufferLimit is the max # of BSs to reserve
+        virtual ~ByteStreamPool();
+        
+        ByteStream * getByteStream();
+        void returnByteStream(ByteStream *);
+        
+    private:
+        std::deque<ByteStream *> freeByteStreams;
+        boost::mutex mutex;
+        uint maxBufferSize;
+        uint maxFreeBuffers;
+};
+
+}
+
+#endif