Replaced AtomicCount with AtomicValue template.

Uses gcc atomics for gcc on i686/x86_64, falls back to mutex otherwise.


git-svn-id: https://svn.apache.org/repos/asf/incubator/qpid/trunk/qpid@658816 13f79535-47bb-0310-9956-ffa450edef68

4 files changed, 183 insertions, 53 deletions

diff --git a/cpp/src/qpid/sys/AtomicCount.h b/cpp/src/qpid/sys/AtomicCount.h
deleted file mode 100644
index 54081092c8..0000000000
--- a/cpp/src/qpid/sys/AtomicCount.h
+++ /dev/null
@@ -1,53 +0,0 @@
-#ifndef _posix_AtomicCount_h
-#define _posix_AtomicCount_h
-
-/*
- *
- * 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 <boost/detail/atomic_count.hpp>
-#include "ScopedIncrement.h"
-
-namespace qpid {
-namespace sys {
-
-/**
- * Atomic counter.
- */
-class AtomicCount {
-  public:
-    typedef ::qpid::sys::ScopedDecrement<AtomicCount> ScopedDecrement;
-    typedef ::qpid::sys::ScopedIncrement<AtomicCount> ScopedIncrement;
-
-    AtomicCount(long value = 0) : count(value) {}
-    
-    void operator++() { ++count ; }
-    
-    long operator--() { return --count; }
-    
-    operator long() const { return count; }
-
-    
-  private:
-    boost::detail::atomic_count  count;
-};
-
-
-}}
-
-
-#endif // _posix_AtomicCount_h
diff --git a/cpp/src/qpid/sys/AtomicValue.h b/cpp/src/qpid/sys/AtomicValue.h
new file mode 100644
index 0000000000..426e6a8f49
--- /dev/null
+++ b/cpp/src/qpid/sys/AtomicValue.h
@@ -0,0 +1,34 @@
+#ifndef QPID_SYS_ATOMICVALUE_H
+#define QPID_SYS_ATOMICVALUE_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.
+ *
+ */
+
+#if defined( __GNUC__ ) && ( defined( __i686__ ) || defined( __x86_64__ ) )
+// Use the Gnu C built-in atomic operations if compiling with gcc on a suitable platform.
+#include "qpid/sys/AtomicValue_gcc.h"
+
+#else
+// Fall-back to mutex locked operations if we don't have atomic ops.
+#include "qpid/sys/AtomicValue_mutex.h"
+#endif
+
+#endif  /*!QPID_SYS_ATOMICVALUE_GCC_H*/
diff --git a/cpp/src/qpid/sys/AtomicValue_gcc.h b/cpp/src/qpid/sys/AtomicValue_gcc.h
new file mode 100644
index 0000000000..164c19d88e
--- /dev/null
+++ b/cpp/src/qpid/sys/AtomicValue_gcc.h
@@ -0,0 +1,68 @@
+#ifndef QPID_SYS_ATOMICVALUE_GCC_H
+#define QPID_SYS_ATOMICVALUE_GCC_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.
+ *
+ */
+
+#if !defined(QPID_SYS_ATOMICVALUE_H) || !defined(__GNUC__)
+#error "This file should only be included via AtomicValue.h."
+#endif
+
+namespace qpid {
+namespace sys {
+
+/**
+ * Atomic value of type T. T must be an integral type of size 1,2,4 or 8 bytes.
+ * All operations are atomic and preform a full memory barrier unless otherwise noted.
+ */
+template <class T>
+class AtomicValue
+{
+  public:
+    AtomicValue(T init=0) : value(init) {}
+
+    // Update and return new value.
+    inline T operator+=(T n) { return __sync_add_and_fetch(&value, n); }
+    inline T operator-=(T n) { return __sync_sub_and_fetch(&value, n); }
+    inline T operator++() { return *this += 1; }
+    inline T operator--() { return *this -= 1; }
+
+    // Update and return old value.
+    inline T fetchAndAdd(T n) { return __sync_fetch_and_add(&value, n); }
+    inline T fetchAndSub(T n) { return __sync_fetch_and_sub(&value, n); }
+    inline T operator++(int) { return fetchAndAdd(1); }
+    inline T operator--(int) { return fetchAndSub(1); }
+
+    /** If current value == testval then set to newval. Returns the old value. */
+    T valueCompareAndSwap(T testval, T newval) { return __sync_val_compare_and_swap(&value, testval, newval); }
+
+    /** If current value == testval then set to newval. Returns true if the swap was performed. */    
+    bool boolCompareAndSwap(T testval, T newval) { return __sync_bool_compare_and_swap(&value, testval, newval); }
+
+    T get() const { return const_cast<AtomicValue<T>*>(this)->fetchAndAdd(0); }
+        
+  private:
+    T value;
+};
+
+}} // namespace qpid::sys
+
+#endif  /*!QPID_SYS_ATOMICVALUE_GCC_H*/
diff --git a/cpp/src/qpid/sys/AtomicValue_mutex.h b/cpp/src/qpid/sys/AtomicValue_mutex.h
new file mode 100644
index 0000000000..8871addbda
--- /dev/null
+++ b/cpp/src/qpid/sys/AtomicValue_mutex.h
@@ -0,0 +1,81 @@
+#ifndef QPID_SYS_ATOMICVALUE_MUTEX_H
+#define QPID_SYS_ATOMICVALUE_MUTEX_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.
+ *
+ */
+
+#if !defined(QPID_SYS_ATOMICVALUE_H)
+#error "This file should only be included via AtomicValue.h."
+#endif
+
+#include "qpid/sys/Mutex.h"
+
+namespace qpid {
+namespace sys {
+
+/**
+ * Atomic value of type T. T must be an integral type of size 1,2,4 or 8 bytes.
+ * All operations are atomic and preform a full memory barrier unless otherwise noted.
+ */
+template <class T>
+class AtomicValue
+{
+  public:
+    AtomicValue(T init=0) : value(init) {}
+
+    // Update and return new value.
+    inline T operator+=(T n) { Lock l(lock); return value += n; }
+    inline T operator-=(T n) { Lock l(lock); return value -= n; }
+    inline T operator++() { return *this += 1; }
+    inline T operator--() { return *this -= 1; }
+
+    // Update and return old value.
+    inline T fetchAndAdd(T n) { Lock l(lock); T old=value; value += n; return old; }
+    inline T fetchAndSub(T n) { Lock l(lock); T old=value; value -= n; return old; }
+    inline T operator++(int) { return fetchAndAdd(1); }
+    inline T operator--(int) { return fetchAndSub(1); }
+
+    /** If current value == testval then set to newval. Returns the old value. */
+    T valueCompareAndSwap(T testval, T newval) {
+        Lock l(lock);
+        T old=value;
+        if (value == testval) value = newval;
+        return old;
+    }
+
+    /** If current value == testval then set to newval. Returns true if the swap was performed. */    
+    bool boolCompareAndSwap(T testval, T newval) {
+        Lock l(lock);
+        if (value == testval) { value = newval; return true; }
+        return false;
+    }
+
+    T get() const { Lock l(lock); return value; }
+        
+  private:
+    typedef Mutex::ScopedLock Lock;
+    T value;
+    mutable Mutex lock;
+};
+
+}} // namespace qpid::sys
+
+#endif  /*!QPID_SYS_ATOMICVALUE_MUTEX_H*/