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/*
*
* 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/sys/Serializer.h"
#include "qpid/log/Statement.h"
#include <boost/bind.hpp>
#include <assert.h>
namespace qpid {
namespace sys {
Serializer::Serializer(bool allowImmediate, Task notifyDispatchFn)
: state(IDLE), immediate(allowImmediate), notifyDispatch(notifyDispatchFn)
{
if (notifyDispatch.empty())
notifyDispatch = boost::bind(&Serializer::notifyWorker, this);
}
Serializer::~Serializer() {
{
Mutex::ScopedLock l(lock);
state = SHUTDOWN;
lock.notify();
}
if (worker.id() != 0)
worker.join();
}
void Serializer::dispatch(Task& task) {
Mutex::ScopedUnlock u(lock);
// Preconditions: lock is held, state is EXECUTING or DISPATCHING
assert(state != IDLE);
assert(state != SHUTDOWN);
assert(state == EXECUTING || state == DISPATCHING);
try {
task();
} catch (const std::exception& e) {
QPID_LOG(error, "Unexpected exception in Serializer::dispatch"
<< e.what());
assert(0); // Should not happen.
} catch (...) {
QPID_LOG(error, "Unexpected exception in Serializer::dispatch.");
assert(0); // Should not happen.
}
}
void Serializer::execute(Task& task) {
bool needNotify = false;
{
Mutex::ScopedLock l(lock);
assert(state != SHUTDOWN);
if (immediate && state == IDLE) {
state = EXECUTING;
dispatch(task);
if (state != SHUTDOWN) {
assert(state == EXECUTING);
state = IDLE;
}
}
else
queue.push_back(task);
if (!queue.empty() && state == IDLE) {
state = DISPATCHING;
needNotify = true;
}
}
if (needNotify)
notifyDispatch(); // Not my function, call outside lock.
}
void Serializer::dispatch() {
Mutex::ScopedLock l(lock);
// TODO aconway 2007-07-16: This loop could be unbounded
// if other threads add work while we're in dispatch(Task&).
// If we need to bound it we could dispatch just the elements
// that were enqueued when dispatch() was first called - save
// begin() iterator and pop only up to that.
while (!queue.empty() && state != SHUTDOWN) {
assert(state == DISPATCHING);
dispatch(queue.front());
queue.pop_front();
}
if (state != SHUTDOWN) {
assert(state == DISPATCHING);
state = IDLE;
}
}
void Serializer::notifyWorker() {
if (!worker.id())
worker = Thread(*this);
else
lock.notify();
}
void Serializer::run() {
Mutex::ScopedLock l(lock);
while (state != SHUTDOWN) {
dispatch();
lock.wait();
}
}
}} // namespace qpid::sys
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