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/*
*
* 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 <iostream>
#include <limits>
#include <boost/bind.hpp>
#include "qpid/sys/Runnable.h"
#include "EventChannelThreads.h"
namespace qpid {
namespace sys {
const size_t EventChannelThreads::unlimited =
std::numeric_limits<size_t>::max();
EventChannelThreads::shared_ptr EventChannelThreads::create(
EventChannel::shared_ptr ec, size_t min, size_t max
)
{
return EventChannelThreads::shared_ptr(
new EventChannelThreads(ec, min, max));
}
EventChannelThreads::EventChannelThreads(
EventChannel::shared_ptr ec, size_t min, size_t max) :
minThreads(std::max(size_t(1), min)),
maxThreads(std::min(min, max)),
channel(ec),
nWaiting(0),
state(RUNNING)
{
Monitor::ScopedLock l(monitor);
while (workers.size() < minThreads)
workers.push_back(Thread(*this));
}
EventChannelThreads::~EventChannelThreads() {
shutdown();
join();
}
void EventChannelThreads::shutdown()
{
Monitor::ScopedLock lock(monitor);
if (state != RUNNING) // Already shutting down.
return;
state = TERMINATING;
channel->shutdown();
monitor.notify(); // Wake up one join() thread.
}
void EventChannelThreads::join()
{
{
Monitor::ScopedLock lock(monitor);
while (state == RUNNING) // Wait for shutdown to start.
monitor.wait();
if (state == SHUTDOWN) // Shutdown is complete
return;
if (state == JOINING) {
// Someone else is doing the join.
while (state != SHUTDOWN)
monitor.wait();
return;
}
// I'm the joining thread
assert(state == TERMINATING);
state = JOINING;
} // Drop the lock.
for (size_t i = 0; i < workers.size(); ++i) {
assert(state == JOINING); // Only this thread can change JOINING.
workers[i].join();
}
state = SHUTDOWN;
monitor.notifyAll(); // Notify any other join() threads.
}
void EventChannelThreads::addThread() {
Monitor::ScopedLock l(monitor);
if (workers.size() < maxThreads)
workers.push_back(Thread(*this));
}
void EventChannelThreads::run()
{
// Start life waiting. Decrement on exit.
AtomicCount::ScopedIncrement inc(nWaiting);
try {
while (true) {
Event* e = channel->wait();
assert(e != 0);
AtomicCount::ScopedDecrement dec(nWaiting);
// Make sure there's at least one waiting thread.
if (dec == 0 && state == RUNNING)
addThread();
e->dispatch();
}
}
catch (const EventChannel::ShutdownException& e) {
return;
}
catch (const std::exception& e) {
Exception::log(e, "Exception in EventChannelThreads::run()");
}
}
}}
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