Amebis/wxWidgets
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

wxMutex changes (explicitly specify the type), return values for all wxMutex/wxSemaphore/wxCondition methods and general cleanup

Browse Source 
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@15761 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
This commit is contained in:
Vadim Zeitlin
2002-06-06 18:31:59 +00:00
parent b0e5c03934
commit 9e84b84742
4 changed files with 957 additions and 985 deletions
Download Patch File Download Diff File Expand all files Collapse all files

736
src/msw/thread.cpp
View File

@@ -1,12 +1,12 @@
/////////////////////////////////////////////////////////////////////////////
// Name: thread.cpp
// Name: src/msw/thread.cpp
// Purpose: wxThread Implementation
// Author: Original from Wolfram Gloger/Guilhem Lavaux
// Modified by: Vadim Zeitlin to make it work :-)
// Created: 04/22/98
// RCS-ID: $Id$
// Copyright: (c) Wolfram Gloger (1996, 1997); Guilhem Lavaux (1998),
// Vadim Zeitlin (1999)
// Copyright: (c) Wolfram Gloger (1996, 1997), Guilhem Lavaux (1998);
// Vadim Zeitlin (1999-2002)
// Licence: wxWindows licence
/////////////////////////////////////////////////////////////////////////////
@@ -36,10 +36,6 @@
#include "wx/module.h"
#include "wx/thread.h"
#ifdef Yield
# undef Yield
#endif
// must have this symbol defined to get _beginthread/_endthread declarations
#ifndef _MT
#define _MT
@@ -127,409 +123,17 @@ static size_t gs_nWaitingForGui = 0;
static bool gs_waitingForThread = FALSE;
// ============================================================================
// Windows implementation of thread classes
// Windows implementation of thread and related classes
// ============================================================================
// ----------------------------------------------------------------------------
// wxMutex implementation
// ----------------------------------------------------------------------------
class wxMutexInternal
{
public:
wxMutexInternal()
{
m_mutex = ::CreateMutex(NULL, FALSE, NULL);
if ( !m_mutex )
{
wxLogSysError(_("Can not create mutex"));
}
}
~wxMutexInternal() { if ( m_mutex ) ::CloseHandle(m_mutex); }
public:
HANDLE m_mutex;
};
wxMutex::wxMutex()
{
m_internal = new wxMutexInternal;
m_locked = 0;
}
wxMutex::~wxMutex()
{
if ( m_locked > 0 )
{
wxLogDebug(_T("Warning: freeing a locked mutex (%d locks)."), m_locked);
}
delete m_internal;
}
wxMutexError wxMutex::Lock()
{
DWORD ret;
ret = WaitForSingleObject(m_internal->m_mutex, INFINITE);
switch ( ret )
{
case WAIT_ABANDONED:
return wxMUTEX_BUSY;
case WAIT_OBJECT_0:
// ok
break;
case WAIT_FAILED:
wxLogSysError(_("Couldn't acquire a mutex lock"));
return wxMUTEX_MISC_ERROR;
case WAIT_TIMEOUT:
default:
wxFAIL_MSG(wxT("impossible return value in wxMutex::Lock"));
}
m_locked++;
return wxMUTEX_NO_ERROR;
}
wxMutexError wxMutex::TryLock()
{
DWORD ret;
ret = WaitForSingleObject(m_internal->m_mutex, 0);
if (ret == WAIT_TIMEOUT || ret == WAIT_ABANDONED)
return wxMUTEX_BUSY;
m_locked++;
return wxMUTEX_NO_ERROR;
}
wxMutexError wxMutex::Unlock()
{
if (m_locked > 0)
m_locked--;
BOOL ret = ReleaseMutex(m_internal->m_mutex);
if ( ret == 0 )
{
wxLogSysError(_("Couldn't release a mutex"));
return wxMUTEX_MISC_ERROR;
}
return wxMUTEX_NO_ERROR;
}
// ==========================================================================
// wxSemaphore
// ==========================================================================
// --------------------------------------------------------------------------
// wxSemaphoreInternal
// --------------------------------------------------------------------------
class wxSemaphoreInternal
{
public:
wxSemaphoreInternal( int initialcount = 0, int maxcount = 0 );
~wxSemaphoreInternal();
void Wait();
bool TryWait();
bool Wait( unsigned long timeout_millis );
void Post();
private:
HANDLE m_semaphore;
};
wxSemaphoreInternal::wxSemaphoreInternal( int initialcount, int maxcount )
{
if ( maxcount == 0 )
{
// make it practically infinite
maxcount = INT_MAX;
}
m_semaphore = ::CreateSemaphore( NULL, initialcount, maxcount, NULL );
if ( !m_semaphore )
{
wxLogLastError(_T("CreateSemaphore()"));
}
}
wxSemaphoreInternal::~wxSemaphoreInternal()
{
CloseHandle( m_semaphore );
}
void wxSemaphoreInternal::Wait()
{
if ( ::WaitForSingleObject( m_semaphore, INFINITE ) != WAIT_OBJECT_0 )
{
wxLogLastError(_T("WaitForSingleObject"));
}
}
bool wxSemaphoreInternal::TryWait()
{
return Wait(0);
}
bool wxSemaphoreInternal::Wait( unsigned long timeout_millis )
{
DWORD result = ::WaitForSingleObject( m_semaphore, timeout_millis );
switch ( result )
{
case WAIT_OBJECT_0:
return TRUE;
case WAIT_TIMEOUT:
break;
default:
wxLogLastError(_T("WaitForSingleObject()"));
}
return FALSE;
}
void wxSemaphoreInternal::Post()
{
if ( !::ReleaseSemaphore( m_semaphore, 1, NULL ) )
{
wxLogLastError(_T("ReleaseSemaphore"));
}
}
// --------------------------------------------------------------------------
// wxSemaphore
// --------------------------------------------------------------------------
wxSemaphore::wxSemaphore( int initialcount, int maxcount )
{
m_internal = new wxSemaphoreInternal( initialcount, maxcount );
}
wxSemaphore::~wxSemaphore()
{
delete m_internal;
}
void wxSemaphore::Wait()
{
m_internal->Wait();
}
bool wxSemaphore::TryWait()
{
return m_internal->TryWait();
}
bool wxSemaphore::Wait( unsigned long timeout_millis )
{
return m_internal->Wait( timeout_millis );
}
void wxSemaphore::Post()
{
m_internal->Post();
}
// ==========================================================================
// wxCondition
// ==========================================================================
// --------------------------------------------------------------------------
// wxConditionInternal
// --------------------------------------------------------------------------
class wxConditionInternal
{
public:
wxConditionInternal(wxMutex& mutex);
void Wait();
bool Wait( unsigned long timeout_millis );
void Signal();
void Broadcast();
private:
int m_numWaiters;
wxMutex m_mutexNumWaiters;
wxMutex& m_mutex;
wxSemaphore m_semaphore;
DECLARE_NO_COPY_CLASS(wxConditionInternal)
};
wxConditionInternal::wxConditionInternal(wxMutex& mutex)
: m_mutex(mutex)
{
m_numWaiters = 0;
}
void wxConditionInternal::Wait()
{
// increment the number of waiters
m_mutexNumWaiters.Lock();
m_numWaiters++;
m_mutexNumWaiters.Unlock();
m_mutex.Unlock();
// a potential race condition can occur here
//
// after a thread increments nwaiters, and unlocks the mutex and before the
// semaphore.Wait() is called, if another thread can cause a signal to be
// generated
//
// this race condition is handled by using a semaphore and incrementing the
// semaphore only if 'nwaiters' is greater that zero since the semaphore,
// can 'remember' signals the race condition will not occur
// wait ( if necessary ) and decrement semaphore
m_semaphore.Wait();
m_mutex.Lock();
}
bool wxConditionInternal::Wait( unsigned long timeout_millis )
{
m_mutexNumWaiters.Lock();
m_numWaiters++;
m_mutexNumWaiters.Unlock();
m_mutex.Unlock();
// a race condition can occur at this point in the code
//
// please see the comments in Wait(), for details
bool success = TRUE;
bool result = m_semaphore.Wait( timeout_millis );
if ( !result )
{
// another potential race condition exists here it is caused when a
// 'waiting' thread timesout, and returns from WaitForSingleObject, but
// has not yet decremented 'nwaiters'.
//
// at this point if another thread calls signal() then the semaphore
// will be incremented, but the waiting thread will miss it.
//
// to handle this particular case, the waiting thread calls
// WaitForSingleObject again with a timeout of 0, after locking
// 'nwaiters_mutex'. this call does not block because of the zero
// timeout, but will allow the waiting thread to catch the missed
// signals.
m_mutexNumWaiters.Lock();
result = m_semaphore.Wait( 0 );
if ( !result )
{
m_numWaiters--;
success = FALSE;
}
m_mutexNumWaiters.Unlock();
}
m_mutex.Lock();
return success;
}
void wxConditionInternal::Signal()
{
m_mutexNumWaiters.Lock();
if ( m_numWaiters > 0 )
{
// increment the semaphore by 1
m_semaphore.Post();
m_numWaiters--;
}
m_mutexNumWaiters.Unlock();
}
void wxConditionInternal::Broadcast()
{
m_mutexNumWaiters.Lock();
while ( m_numWaiters > 0 )
{
m_semaphore.Post();
m_numWaiters--;
}
m_mutexNumWaiters.Unlock();
}
// ----------------------------------------------------------------------------
// wxCondition implementation
// ----------------------------------------------------------------------------
wxCondition::wxCondition(wxMutex& mutex)
{
m_internal = new wxConditionInternal( mutex );
}
wxCondition::~wxCondition()
{
delete m_internal;
}
void wxCondition::Wait()
{
m_internal->Wait();
}
bool wxCondition::Wait( unsigned long timeout_millis )
{
return m_internal->Wait(timeout_millis);
}
void wxCondition::Signal()
{
m_internal->Signal();
}
void wxCondition::Broadcast()
{
m_internal->Broadcast();
}
// ----------------------------------------------------------------------------
// wxCriticalSection implementation
// wxCriticalSection
// ----------------------------------------------------------------------------
wxCriticalSection::wxCriticalSection()
{
#ifdef __WXDEBUG__
// Done this way to stop warnings during compilation about statement
// always being FALSE
int csSize = sizeof(CRITICAL_SECTION);
int bSize = sizeof(m_buffer);
wxASSERT_MSG( csSize <= bSize,
_T("must increase buffer size in wx/thread.h") );
#endif
wxCOMPILE_TIME_ASSERT( sizeof(CRITICAL_SECTION) <= sizeof(m_buffer),
wxCriticalSectionBufferTooSmall );
::InitializeCriticalSection((CRITICAL_SECTION *)m_buffer);
}
@@ -549,6 +153,325 @@ void wxCriticalSection::Leave()
::LeaveCriticalSection((CRITICAL_SECTION *)m_buffer);
}
// ----------------------------------------------------------------------------
// wxMutex
// ----------------------------------------------------------------------------
class wxMutexInternal
{
public:
wxMutexInternal(wxMutexType mutexType);
~wxMutexInternal();
bool IsOk() const { return m_mutex != NULL; }
wxMutexError Lock() { return LockTimeout(INFINITE); }
wxMutexError TryLock() { return LockTimeout(0); }
wxMutexError Unlock();
private:
wxMutexError LockTimeout(DWORD milliseconds);
HANDLE m_mutex;
};
// all mutexes are recursive under Win32 so we don't use mutexType
wxMutexInternal::wxMutexInternal(wxMutexType WXUNUSED(mutexType))
{
// create a nameless (hence intra process and always private) mutex
m_mutex = ::CreateMutex
(
NULL, // default secutiry attributes
FALSE, // not initially locked
NULL // no name
);
if ( !m_mutex )
{
wxLogLastError(_T("CreateMutex()"));
}
}
wxMutexInternal::~wxMutexInternal()
{
if ( m_mutex )
{
if ( !::CloseHandle(m_mutex) )
{
wxLogLastError(_T("CloseHandle(mutex)"));
}
}
}
wxMutexError wxMutexInternal::LockTimeout(DWORD milliseconds)
{
DWORD rc = ::WaitForSingleObject(m_mutex, milliseconds);
if ( rc == WAIT_ABANDONED )
{
// the previous caller died without releasing the mutex, but now we can
// really lock it
wxLogDebug(_T("WaitForSingleObject() returned WAIT_ABANDONED"));
// use 0 timeout, normally we should always get it
rc = ::WaitForSingleObject(m_mutex, 0);
}
switch ( rc )
{
case WAIT_OBJECT_0:
// ok
break;
case WAIT_TIMEOUT:
return wxMUTEX_BUSY;
case WAIT_ABANDONED: // checked for above
default:
wxFAIL_MSG(wxT("impossible return value in wxMutex::Lock"));
// fall through
case WAIT_FAILED:
wxLogLastError(_T("WaitForSingleObject(mutex)"));
return wxMUTEX_MISC_ERROR;
}
return wxMUTEX_NO_ERROR;
}
wxMutexError wxMutexInternal::Unlock()
{
if ( !::ReleaseMutex(m_mutex) )
{
wxLogLastError(_("ReleaseMutex()"));
return wxMUTEX_MISC_ERROR;
}
return wxMUTEX_NO_ERROR;
}
// --------------------------------------------------------------------------
// wxSemaphore
// --------------------------------------------------------------------------
// a trivial wrapper around Win32 semaphore
class wxSemaphoreInternal
{
public:
wxSemaphoreInternal(int initialcount, int maxcount);
~wxSemaphoreInternal();
bool IsOk() const { return m_semaphore != NULL; }
wxSemaError Wait() { return WaitTimeout(INFINITE); }
wxSemaError TryWait() { return WaitTimeout(0); }
wxSemaError WaitTimeout(unsigned long milliseconds);
wxSemaError Post();
private:
HANDLE m_semaphore;
};
wxSemaphoreInternal::wxSemaphoreInternal(int initialcount, int maxcount)
{
if ( maxcount == 0 )
{
// make it practically infinite
maxcount = INT_MAX;
}
m_semaphore = ::CreateSemaphore
(
NULL, // default security attributes
initialcount,
maxcount,
NULL // no name
);
if ( !m_semaphore )
{
wxLogLastError(_T("CreateSemaphore()"));
}
}
wxSemaphoreInternal::~wxSemaphoreInternal()
{
if ( m_semaphore )
{
if ( !::CloseHandle(m_semaphore) )
{
wxLogLastError(_T("CloseHandle(semaphore)"));
}
}
}
wxSemaError wxSemaphoreInternal::WaitTimeout(unsigned long milliseconds)
{
DWORD rc = ::WaitForSingleObject( m_semaphore, milliseconds );
switch ( rc )
{
case WAIT_OBJECT_0:
return wxSEMA_NO_ERROR;
case WAIT_TIMEOUT:
return wxSEMA_BUSY;
default:
wxLogLastError(_T("WaitForSingleObject(semaphore)"));
}
return wxSEMA_MISC_ERROR;
}
wxSemaError wxSemaphoreInternal::Post()
{
if ( !::ReleaseSemaphore(m_semaphore, 1, NULL /* ptr to previous count */) )
{
wxLogLastError(_T("ReleaseSemaphore"));
return wxSEMA_MISC_ERROR;
}
return wxSEMA_NO_ERROR;
}
// --------------------------------------------------------------------------
// wxCondition
// --------------------------------------------------------------------------
// Win32 doesn't have explicit support for the POSIX condition variables and
// the Win32 events have quite different semantics, so we reimplement the
// conditions from scratch using the mutexes and semaphores
class wxConditionInternal
{
public:
wxConditionInternal(wxMutex& mutex);
bool IsOk() const { return m_mutex.IsOk() && m_semaphore.IsOk(); }
wxCondError Wait();
wxCondError WaitTimeout(unsigned long milliseconds);
wxCondError Signal();
wxCondError Broadcast();
private:
// the number of threads currently waiting for this condition
LONG m_numWaiters;
// the critical section protecting m_numWaiters
wxCriticalSection m_csWaiters;
wxMutex& m_mutex;
wxSemaphore m_semaphore;
};
wxConditionInternal::wxConditionInternal(wxMutex& mutex)
: m_mutex(mutex)
{
// another thread can't access it until we return from ctor, so no need to
// protect access to m_numWaiters here
m_numWaiters = 0;
}
wxCondError wxConditionInternal::Wait()
{
// increment the number of waiters
::InterlockedIncrement(&m_numWaiters);
m_mutex.Unlock();
// a potential race condition can occur here
//
// after a thread increments nwaiters, and unlocks the mutex and before the
// semaphore.Wait() is called, if another thread can cause a signal to be
// generated
//
// this race condition is handled by using a semaphore and incrementing the
// semaphore only if 'nwaiters' is greater that zero since the semaphore,
// can 'remember' signals the race condition will not occur
// wait ( if necessary ) and decrement semaphore
wxSemaError err = m_semaphore.Wait();
m_mutex.Lock();
return err == wxSEMA_NO_ERROR ? wxCOND_NO_ERROR : wxCOND_MISC_ERROR;
}
wxCondError wxConditionInternal::WaitTimeout(unsigned long milliseconds)
{
::InterlockedIncrement(&m_numWaiters);
m_mutex.Unlock();
// a race condition can occur at this point in the code
//
// please see the comments in Wait(), for details
wxSemaError err = m_semaphore.WaitTimeout(milliseconds);
if ( err == wxSEMA_BUSY )
{
// another potential race condition exists here it is caused when a
// 'waiting' thread timesout, and returns from WaitForSingleObject, but
// has not yet decremented 'nwaiters'.
//
// at this point if another thread calls signal() then the semaphore
// will be incremented, but the waiting thread will miss it.
//
// to handle this particular case, the waiting thread calls
// WaitForSingleObject again with a timeout of 0, after locking
// 'nwaiters_mutex'. this call does not block because of the zero
// timeout, but will allow the waiting thread to catch the missed
// signals.
wxCriticalSectionLocker lock(m_csWaiters);
err = m_semaphore.WaitTimeout(0);
if ( err != wxSEMA_NO_ERROR )
{
m_numWaiters--;
}
}
m_mutex.Lock();
return err == wxSEMA_NO_ERROR ? wxCOND_NO_ERROR : wxCOND_MISC_ERROR;
}
wxCondError wxConditionInternal::Signal()
{
wxCriticalSectionLocker lock(m_csWaiters);
if ( m_numWaiters > 0 )
{
// increment the semaphore by 1
if ( m_semaphore.Post() != wxSEMA_NO_ERROR )
return wxCOND_MISC_ERROR;
m_numWaiters--;
}
return wxCOND_NO_ERROR;
}
wxCondError wxConditionInternal::Broadcast()
{
wxCriticalSectionLocker lock(m_csWaiters);
while ( m_numWaiters > 0 )
{
if ( m_semaphore.Post() != wxSEMA_NO_ERROR )
return wxCOND_MISC_ERROR;
m_numWaiters--;
}
return wxCOND_NO_ERROR;
}
// ----------------------------------------------------------------------------
// wxThread implementation
// ----------------------------------------------------------------------------
@@ -1429,6 +1352,11 @@ bool WXDLLEXPORT wxIsWaitingForThread()
return gs_waitingForThread;
}
// ----------------------------------------------------------------------------
// include common implementation code
// ----------------------------------------------------------------------------
#include "wx/thrimpl.cpp"
#endif // wxUSE_THREADS
// vi:sts=4:sw=4:et