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#ifndef _sys_EventChannel_h
#define _sys_EventChannel_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 "SharedObject.h"
#include "Exception.h"
#include "sys/Monitor.h"
#include "sys/Time.h"
#include <boost/function.hpp>
#include <memory>
namespace qpid {
namespace sys {
class Event;
/**
* Channel to post and wait for events.
*/
class EventChannel : public qpid::SharedObject<EventChannel>
{
public:
static shared_ptr create();
/** Exception throw from wait() if channel is shut down. */
class ShutdownException : public qpid::Exception {};
~EventChannel();
/** Post an event to the channel. */
void post(Event& event);
/** Post an event to the channel. Must not be 0. */
void post(Event* event);
/**
* Wait for the next complete event, up to timeout.
*@return Pointer to event or 0 if timeout elapses.
*@exception ShutdownException if the channel is shut down.
*/
Event* wait(Time timeout = TIME_INFINITE);
/**
* Shut down the event channel.
* Blocks till all threads have exited wait()
*/
void shutdown();
// Internal classes.
class Impl;
class Queue;
class Descriptor;
private:
EventChannel();
Mutex lock;
boost::shared_ptr<Impl> impl;
};
/**
* Base class for all Events.
*
* Derived classes define events representing various async IO operations.
* When an event is complete, it is returned by the EventChannel to
* a thread calling wait. The thread will call Event::dispatch() to
* execute code associated with event completion.
*/
class Event
{
public:
/** Type for callback when event is dispatched */
typedef boost::function0<void> Callback;
virtual ~Event();
/** Call the callback provided to the constructor, if any. */
void dispatch();
/**
*If there was an exception processing this Event, return it.
*@return 0 if there was no exception.
*/
qpid::Exception::shared_ptr_const getException() const;
/** If getException() throw the corresponding exception. */
void throwIfException();
/** Set the dispatch callback. */
void setCallback(Callback cb) { callback = cb; }
/** Set the exception. */
void setException(const std::exception& e);
protected:
Event(Callback cb=0) : callback(cb) {}
virtual void prepare(EventChannel::Impl&) = 0;
virtual void complete(EventChannel::Descriptor&) = 0;
Callback callback;
Exception::shared_ptr_const exception;
friend class EventChannel;
friend class EventChannel::Queue;
};
/**
* An event that does not wait for anything, it is processed
* immediately by one of the channel threads.
*/
class DispatchEvent : public Event {
public:
DispatchEvent(Callback cb=0) : Event(cb) {}
protected:
void prepare(EventChannel::Impl&);
void complete(EventChannel::Descriptor&);
};
// Utility base class.
class FDEvent : public Event {
public:
int getDescriptor() const { return descriptor; }
protected:
FDEvent(Callback cb = 0, int fd = 0)
: Event(cb), descriptor(fd) {}
int descriptor;
};
// Utility base class
class IOEvent : public FDEvent {
public:
size_t getSize() const { return size; }
protected:
IOEvent(Callback cb, int fd, size_t sz, bool noWait_) :
FDEvent(cb, fd), size(sz), noWait(noWait_) {}
size_t size;
bool noWait;
};
/** Asynchronous read event */
class ReadEvent : public IOEvent
{
public:
explicit ReadEvent(
int fd=-1, void* buf=0, size_t sz=0,
Callback cb=0, bool noWait=false
) : IOEvent(cb, fd, sz, noWait), buffer(buf), bytesRead(0) {}
void* getBuffer() const { return buffer; }
size_t getBytesRead() const { return bytesRead; }
private:
void prepare(EventChannel::Impl&);
void complete(EventChannel::Descriptor&);
ssize_t doRead();
void* buffer;
size_t bytesRead;
};
/** Asynchronous write event */
class WriteEvent : public IOEvent
{
public:
explicit WriteEvent(int fd=-1, const void* buf=0, size_t sz=0,
Callback cb=0) :
IOEvent(cb, fd, sz, noWait), buffer(buf), bytesWritten(0) {}
const void* getBuffer() const { return buffer; }
size_t getBytesWritten() const { return bytesWritten; }
private:
void prepare(EventChannel::Impl&);
void complete(EventChannel::Descriptor&);
ssize_t doWrite();
const void* buffer;
size_t bytesWritten;
};
/** Asynchronous socket accept event */
class AcceptEvent : public FDEvent
{
public:
/** Accept a connection on fd. */
explicit AcceptEvent(int fd=-1, Callback cb=0) :
FDEvent(cb, fd), accepted(0) {}
/** Get descriptor for accepted server socket */
int getAcceptedDesscriptor() const { return accepted; }
private:
void prepare(EventChannel::Impl&);
void complete(EventChannel::Descriptor&);
int accepted;
};
}}
#endif /*!_sys_EventChannel_h*/
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