pcsx2/common/include/Utilities/Threading.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 <errno.h> // EBUSY
#include <pthread.h>
#include <semaphore.h>
#include "Pcsx2Defs.h"
#include "ScopedPtr.h"
namespace Exception
{
//////////////////////////////////////////////////////////////////////////////////////////
// Thread termination exception, used to quickly terminate threads from anywhere in the
// thread's call stack. This exception is handled by the PCSX2 PersistentThread class. Threads
// not derived from that class will not handle this exception.
//
class ThreadTermination
{
};
}
class wxTimeSpan;
namespace Threading
{
//////////////////////////////////////////////////////////////////////////////////////////
// Define some useful object handles - wait events, mutexes.
// pthread Cond is an evil api that is not suited for Pcsx2 needs.
// Let's not use it. Use mutexes and semaphores instead to create waits. (Air)
#if 0
struct WaitEvent
{
pthread_cond_t cond;
pthread_mutex_t mutex;
WaitEvent();
~WaitEvent();
void Set();
void Wait();
};
#endif
struct Semaphore
{
sem_t sema;
Semaphore();
~Semaphore();
void Reset();
void Post();
void Post( int multiple );
#if wxUSE_GUI
void WaitGui();
bool WaitGui( const wxTimeSpan& timeout );
#endif
void Wait();
bool Wait( const wxTimeSpan& timeout );
void WaitNoCancel();
int Count();
};
struct MutexLock
{
pthread_mutex_t mutex;
MutexLock();
MutexLock( bool isRecursive );
~MutexLock();
void Lock();
void Unlock();
bool TryLock();
};
// Returns the number of available logical CPUs (cores plus hyperthreaded cpus)
extern void CountLogicalCores( int LogicalCoresPerPhysicalCPU, int PhysicalCoresPerPhysicalCPU );
// Releases a timeslice to other threads.
extern void Timeslice();
// For use in spin/wait loops.
extern void SpinWait();
// sleeps the current thread for the given number of milliseconds.
extern void Sleep( int ms );
// --------------------------------------------------------------------------------------
// 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; }
};
// --------------------------------------------------------------------------------------
// 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 ExecuteTask();
// void OnThreadCleanup();
//
// 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);
protected:
typedef int (*PlainJoeFP)();
wxString m_name; // diagnostic name for our thread.
pthread_t m_thread;
Semaphore m_sem_event; // general wait event that's needed by most threads.
Semaphore m_sem_finished; // used for canceling and closing threads in a deadlock-safe manner
MutexLock m_lock_start; // used to lock the Start() code from starting simutaneous 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;
public:
virtual ~PersistentThread() throw();
PersistentThread();
PersistentThread( const char* name );
virtual void Start();
virtual void Cancel( bool isBlocking = true );
virtual bool Detach();
virtual void Block();
virtual void RethrowException() const;
bool IsRunning() const;
bool IsSelf() const;
wxString GetName() const;
void _ThreadCleanup();
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()=0;
virtual void OnThreadCleanup()=0;
void DoSetThreadName( const wxString& name );
void DoSetThreadName( __unused const char* name );
void _internal_execute();
// Used to dispatch the thread callback function.
// (handles some thread cleanup on Win32, and is basically a typecast
// on linux).
static void* _internal_callback( void* func );
// Implemented by derived class to handle threading actions!
virtual void ExecuteTask()=0;
};
//////////////////////////////////////////////////////////////////////////////////////////
// ScopedLock: Helper class for using Mutexes.
// Using this class provides an exception-safe (and generally clean) method of locking
// code inside a function or conditional block.
//
class ScopedLock
{
DeclareNoncopyableObject(ScopedLock);
protected:
MutexLock& m_lock;
bool m_IsLocked;
public:
virtual ~ScopedLock() throw()
{
if( m_IsLocked )
m_lock.Unlock();
}
ScopedLock( MutexLock& locker ) :
m_lock( locker )
, m_IsLocked( true )
{
m_lock.Lock();
}
// Provides manual unlocking of a scoped lock prior to object destruction.
void Unlock()
{
if( !m_IsLocked ) return;
m_IsLocked = false;
m_lock.Unlock();
}
// provides manual locking of a scoped lock, to re-lock after a manual unlocking.
void Lock()
{
if( m_IsLocked ) return;
m_lock.Lock();
m_IsLocked = true;
}
};
//////////////////////////////////////////////////////////////////////////////////////////
// BaseTaskThread - an abstract base class which provides simple parallel execution of
// single tasks.
//
// 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;
MutexLock 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 ExecuteTask();
};
//////////////////////////////////////////////////////////////////////////////////////////
// Our fundamental interlocking functions. All other useful interlocks can be derived
// from these little beasties!
extern void AtomicExchange( volatile u32& Target, u32 value );
extern void AtomicExchangeAdd( volatile u32& Target, u32 value );
extern void AtomicIncrement( volatile u32& Target );
extern void AtomicDecrement( volatile u32& Target );
extern void AtomicExchange( volatile s32& Target, s32 value );
extern void AtomicExchangeAdd( volatile s32& Target, u32 value );
extern void AtomicIncrement( volatile s32& Target );
extern void AtomicDecrement( volatile s32& Target );
extern void _AtomicExchangePointer( const void ** target, const void* value );
extern void _AtomicCompareExchangePointer( const void ** target, const void* value, const void* comparand );
#define AtomicExchangePointer( target, value ) \
_AtomicExchangePointer( (const void**)(&target), (const void*)(value) )
#define AtomicCompareExchangePointer( target, value, comparand ) \
_AtomicCompareExchangePointer( (const void**)(&target), (const void*)(value), (const void*)(comparand) )
}