pcsx2/common/include/Utilities/PersistentThread.h

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/* PCSX2 - PS2 Emulator for PCs
* Copyright (C) 2002-2009 PCSX2 Dev Team
*
* PCSX2 is free software: you can redistribute it and/or modify it under the terms
* of the GNU Lesser General Public License as published by the Free Software Found-
* ation, either version 3 of the License, or (at your option) any later version.
*
* PCSX2 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 PCSX2.
* If not, see <http://www.gnu.org/licenses/>.
*/
#pragma once
#include "Threading.h"
#include "EventSource.h"
namespace Threading
{
// --------------------------------------------------------------------------------------
// IThread - Interface for the public access to PersistentThread.
// --------------------------------------------------------------------------------------
// Class usage: Can be used for allowing safe nullification of a thread handle. Rather
// than being NULL'd, the handle can be mapped to an IThread implementation which acts
// as a do-nothing placebo or an assertion generator.
//
class IThread
{
DeclareNoncopyableObject(IThread);
public:
IThread() {}
virtual ~IThread() throw() {}
virtual bool IsSelf() const { return false; }
virtual bool IsRunning() { return false; }
virtual void Start() {}
virtual void Cancel( bool isBlocking = true ) {}
virtual void Block() {}
virtual bool Detach() { return false; }
};
// --------------------------------------------------------------------------------------
// ThreadDeleteEvent
// --------------------------------------------------------------------------------------
class EventListener_Thread : public IEventDispatcher<int>
{
public:
typedef int EvtParams;
protected:
PersistentThread* m_thread;
public:
EventListener_Thread()
{
m_thread = NULL;
}
virtual ~EventListener_Thread() throw() {}
void SetThread( PersistentThread& thr ) { m_thread = &thr; }
void SetThread( PersistentThread* thr ) { m_thread = thr; }
void DispatchEvent( const int& params )
{
OnThreadCleanup();
}
protected:
// Invoked by the PersistentThread when the thread execution is ending. This is
// typically more useful than a delete listener since the extended thread information
// provided by virtualized functions/methods will be available.
// Important! This event is executed *by the thread*, so care must be taken to ensure
// thread sync when necessary (posting messages to the main thread, etc).
virtual void OnThreadCleanup()=0;
};
// --------------------------------------------------------------------------------------
// PersistentThread - Helper class for the basics of starting/managing persistent threads.
// --------------------------------------------------------------------------------------
// This class is meant to be a helper for the typical threading model of "start once and
// reuse many times." This class incorporates a lot of extra overhead in stopping and
// starting threads, but in turn provides most of the basic thread-safety and event-handling
// functionality needed for a threaded operation. In practice this model is usually an
// ideal one for efficiency since Operating Systems themselves typically subscribe to a
// design where sleeping, suspending, and resuming threads is very efficient, but starting
// new threads has quite a bit of overhead.
//
// To use this as a base class for your threaded procedure, overload the following virtual
// methods:
// void OnStart();
// void ExecuteTaskInThread();
// void OnCleanupInThread();
//
// Use the public methods Start() and Cancel() to start and shutdown the thread, and use
// m_sem_event internally to post/receive events for the thread (make a public accessor for
// it in your derived class if your thread utilizes the post).
//
// Notes:
// * Constructing threads as static global vars isn't recommended since it can potentially
// confuse w32pthreads, if the static initializers are executed out-of-order (C++ offers
// no dependency options for ensuring correct static var initializations). Use heap
// allocation to create thread objects instead.
//
class PersistentThread : public virtual IThread
{
DeclareNoncopyableObject(PersistentThread);
friend void pxYield( int ms );
protected:
wxString m_name; // diagnostic name for our thread.
pthread_t m_thread;
uptr m_native_id; // typically an id, but implementing platforms can do whatever.
uptr m_native_handle; // typically a pointer/handle, but implementing platforms can do whatever.
Semaphore m_sem_event; // general wait event that's needed by most threads
Semaphore m_sem_startup; // startup sync tool
Mutex m_lock_InThread; // used for canceling and closing threads in a deadlock-safe manner
MutexLockRecursive m_lock_start; // used to lock the Start() code from starting simultaneous threads accidentally.
volatile long m_detached; // a boolean value which indicates if the m_thread handle is valid
volatile long m_running; // set true by Start(), and set false by Cancel(), Block(), etc.
// exception handle, set non-NULL if the thread terminated with an exception
// Use RethrowException() to re-throw the exception using its original exception type.
ScopedPtr<Exception::BaseException> m_except;
EventSource<EventListener_Thread> m_evtsrc_OnDelete;
public:
virtual ~PersistentThread() throw();
PersistentThread();
PersistentThread( const char* name );
pthread_t GetId() const { return m_thread; }
u64 GetCpuTime() const;
virtual void Start();
virtual void Cancel( bool isBlocking = true );
virtual bool Cancel( const wxTimeSpan& timeout );
virtual bool Detach();
virtual void Block();
virtual void RethrowException() const;
void AddListener( EventListener_Thread& evt );
void AddListener( EventListener_Thread* evt )
{
if( evt == NULL ) return;
AddListener( *evt );
}
void WaitOnSelf( Semaphore& mutex ) const;
void WaitOnSelf( Mutex& mutex ) const;
bool WaitOnSelf( Semaphore& mutex, const wxTimeSpan& timeout ) const;
bool WaitOnSelf( Mutex& mutex, const wxTimeSpan& timeout ) const;
bool IsRunning() const;
bool IsSelf() const;
wxString GetName() const;
bool HasPendingException() const { return !!m_except; }
protected:
// Extending classes should always implement your own OnStart(), which is called by
// Start() once necessary locks have been obtained. Do not override Start() directly
// unless you're really sure that's what you need to do. ;)
virtual void OnStart();
virtual void OnStartInThread();
// This is called when the thread has been canceled or exits normally. The PersistentThread
// automatically binds it to the pthread cleanup routines as soon as the thread starts.
virtual void OnCleanupInThread();
// Implemented by derived class to perform actual threaded task!
virtual void ExecuteTaskInThread()=0;
void TestCancel() const;
// Yields this thread to other threads and checks for cancellation. A sleeping thread should
// always test for cancellation, however if you really don't want to, you can use Threading::Sleep()
// or better yet, disable cancellation of the thread completely with DisableCancellation().
//
// Parameters:
// ms - 'minimum' yield time in milliseconds (rough -- typically yields are longer by 1-5ms
// depending on operating system/platform). If ms is 0 or unspecified, then a single
// timeslice is yielded to other contending threads. If no threads are contending for
// time when ms==0, then no yield is done, but cancellation is still tested.
void Yield( int ms = 0 )
{
pxAssert( IsSelf() );
Threading::Sleep( ms );
TestCancel();
}
void FrankenMutex( Mutex& mutex );
bool AffinityAssert_AllowFromSelf( const DiagnosticOrigin& origin ) const;
bool AffinityAssert_DisallowFromSelf( const DiagnosticOrigin& origin ) const;
// ----------------------------------------------------------------------------
// Section of methods for internal use only.
void _platform_specific_OnStartInThread();
void _platform_specific_OnCleanupInThread();
bool _basecancel();
void _selfRunningTest( const wxChar* name ) const;
void _DoSetThreadName( const wxString& name );
void _DoSetThreadName( const char* name );
void _internal_execute();
void _try_virtual_invoke( void (PersistentThread::*method)() );
void _ThreadCleanup();
static void* _internal_callback( void* func );
static void _pt_callback_cleanup( void* handle );
};
// --------------------------------------------------------------------------------------
// BaseTaskThread
// --------------------------------------------------------------------------------------
// an abstract base class which provides simple parallel execution of single tasks.
//
// FIXME: This class is incomplete and untested! Don't use, unless you want to fix it
// while you're at it. :D
//
// Implementation:
// To use this class your derived class will need to implement its own Task() function
// and also a "StartTask( parameters )" function which suits the need of your task, along
// with any local variables your task needs to do its job. You may additionally want to
// implement a "GetResult()" function, which would be a combination of WaitForResult()
// and a return value of the computational result.
//
// Thread Safety:
// If operating on local variables, you must execute WaitForResult() before leaving the
// variable scope -- or alternatively have your StartTask() implementation make full
// copies of dependent data. Also, by default PostTask() always assumes the previous
// task has completed. If your system can post a new task before the previous one has
// completed, then it needs to explicitly call WaitForResult() or provide a mechanism
// to cancel the previous task (which is probably more work than it's worth).
//
// Performance notes:
// * Remember that thread creation is generally slow, so you should make your object
// instance once early and then feed it tasks repeatedly over the course of program
// execution.
//
// * For threading to be a successful speedup, the task being performed should be as lock
// free as possible. For example using STL containers in parallel usually fails to
// yield any speedup due to the gratuitous amount of locking that the STL performs
// internally.
//
// * The best application of tasking threads is to divide a large loop over a linear array
// into smaller sections. For example, if you have 20,000 items to process, the task
// can be divided into two threads of 10,000 items each.
//
class BaseTaskThread : public PersistentThread
{
protected:
volatile bool m_Done;
volatile bool m_TaskPending;
Semaphore m_post_TaskComplete;
Mutex m_lock_TaskComplete;
public:
virtual ~BaseTaskThread() throw() {}
BaseTaskThread() :
m_Done( false )
, m_TaskPending( false )
, m_post_TaskComplete()
{
}
void Block();
void PostTask();
void WaitForResult();
protected:
// Abstract method run when a task has been posted. Implementing classes should do
// all your necessary processing work here.
virtual void Task()=0;
virtual void ExecuteTaskInThread();
};
}