semevent-posix.cpp revision 9e5c26690d45216629b5f588aced8fcfb68c23b6
/* $Id$ */
/** @file
* innotek Portable Runtime - Event Semaphore, POSIX.
*/
/*
* Copyright (C) 2006-2007 innotek GmbH
*
* This file is part of VirtualBox Open Source Edition (OSE), as
* available from http://www.virtualbox.org. This file is free software;
* you can redistribute it and/or modify it under the terms of the GNU
* General Public License (GPL) as published by the Free Software
* Foundation, in version 2 as it comes in the "COPYING" file of the
* VirtualBox OSE distribution. VirtualBox OSE is distributed in the
* hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
*
* The contents of this file may alternatively be used under the terms
* of the Common Development and Distribution License Version 1.0
* (CDDL) only, as it comes in the "COPYING.CDDL" file of the
* VirtualBox OSE distribution, in which case the provisions of the
* CDDL are applicable instead of those of the GPL.
*
* You may elect to license modified versions of this file under the
* terms and conditions of either the GPL or the CDDL or both.
*/
/*******************************************************************************
* Header Files *
*******************************************************************************/
#include <iprt/semaphore.h>
#include <iprt/assert.h>
#include <iprt/alloc.h>
#include <iprt/asm.h>
#include <iprt/err.h>
#include <errno.h>
#include <pthread.h>
#include <unistd.h>
#include <sys/time.h>
#ifdef RT_OS_DARWIN
# define pthread_yield() pthread_yield_np()
#endif
#ifdef RT_OS_SOLARIS
# include <sched.h>
# define pthread_yield() sched_yield()
#endif
/*******************************************************************************
* Structures and Typedefs *
*******************************************************************************/
/** Internal representation of the POSIX implementation of an Event semaphore.
* The POSIX implementation uses a mutex and a condition variable to implement
* the automatic reset event semaphore semantics.
*/
struct RTSEMEVENTINTERNAL
{
/** pthread condition. */
pthread_cond_t Cond;
/** pthread mutex which protects the condition and the event state. */
pthread_mutex_t Mutex;
/** The state of the semaphore.
* This is operated while owning mutex and using atomic updating. */
volatile uint32_t u32State;
/** Number of waiters. */
volatile uint32_t cWaiters;
};
/** The valus of the u32State variable in a RTSEMEVENTINTERNAL.
* @{ */
/** The object isn't initialized. */
#define EVENT_STATE_UNINITIALIZED 0
/** The semaphore is is signaled. */
#define EVENT_STATE_SIGNALED 0xff00ff00
/** The semaphore is not signaled. */
#define EVENT_STATE_NOT_SIGNALED 0x00ff00ff
/** @} */
/**
* Validate an Event semaphore handle passed to one of the interface.
*
* @returns true if valid.
* @returns false if invalid.
* @param pIntEventSem Pointer to the event semaphore to validate.
*/
inline bool rtsemEventValid(struct RTSEMEVENTINTERNAL *pIntEventSem)
{
if ((uintptr_t)pIntEventSem < 0x10000)
return false;
uint32_t u32 = pIntEventSem->u32State; /* this is volatile, so a explicit read like this is needed. */
if ( u32 != EVENT_STATE_NOT_SIGNALED
&& u32 != EVENT_STATE_SIGNALED)
return false;
return true;
}
RTDECL(int) RTSemEventCreate(PRTSEMEVENT pEventSem)
{
int rc;
/*
* Allocate semaphore handle.
*/
struct RTSEMEVENTINTERNAL *pIntEventSem = (struct RTSEMEVENTINTERNAL *)RTMemAlloc(sizeof(struct RTSEMEVENTINTERNAL));
if (pIntEventSem)
{
/*
* Create the condition variable.
*/
pthread_condattr_t CondAttr;
rc = pthread_condattr_init(&CondAttr);
if (!rc)
{
rc = pthread_cond_init(&pIntEventSem->Cond, &CondAttr);
if (!rc)
{
/*
* Create the semaphore.
*/
pthread_mutexattr_t MutexAttr;
rc = pthread_mutexattr_init(&MutexAttr);
if (!rc)
{
rc = pthread_mutex_init(&pIntEventSem->Mutex, &MutexAttr);
if (!rc)
{
pthread_mutexattr_destroy(&MutexAttr);
pthread_condattr_destroy(&CondAttr);
ASMAtomicXchgU32(&pIntEventSem->u32State, EVENT_STATE_NOT_SIGNALED);
ASMAtomicXchgU32(&pIntEventSem->cWaiters, 0);
*pEventSem = pIntEventSem;
return VINF_SUCCESS;
}
pthread_mutexattr_destroy(&MutexAttr);
}
pthread_cond_destroy(&pIntEventSem->Cond);
}
pthread_condattr_destroy(&CondAttr);
}
rc = RTErrConvertFromErrno(rc);
RTMemFree(pIntEventSem);
}
else
rc = VERR_NO_MEMORY;
return rc;
}
RTDECL(int) RTSemEventDestroy(RTSEMEVENT EventSem)
{
/*
* Validate handle.
*/
if (!rtsemEventValid(EventSem))
{
AssertMsgFailed(("Invalid handle %p!\n", EventSem));
return VERR_INVALID_HANDLE;
}
/*
* Abort all waiters forcing them to return failure.
*
*/
struct RTSEMEVENTINTERNAL *pIntEventSem = EventSem;
int rc;
for (int i = 30; i > 0; i--)
{
ASMAtomicXchgU32(&pIntEventSem->u32State, EVENT_STATE_UNINITIALIZED);
rc = pthread_cond_destroy(&pIntEventSem->Cond);
if (rc != EBUSY)
break;
pthread_cond_broadcast(&pIntEventSem->Cond);
usleep(1000);
} while (rc == EBUSY);
if (rc)
{
AssertMsgFailed(("Failed to destroy event sem %p, rc=%d.\n", EventSem, rc));
return RTErrConvertFromErrno(rc);
}
/*
* Destroy the semaphore
* If it's busy we'll wait a bit to give the threads a chance to be scheduled.
*/
for (int i = 30; i > 0; i--)
{
rc = pthread_mutex_destroy(&pIntEventSem->Mutex);
if (rc != EBUSY)
break;
usleep(1000);
}
if (rc)
{
AssertMsgFailed(("Failed to destroy event sem %p, rc=%d. (mutex)\n", EventSem, rc));
return RTErrConvertFromErrno(rc);
}
/*
* Free the semaphore memory and be gone.
*/
RTMemFree(pIntEventSem);
return VINF_SUCCESS;
}
RTDECL(int) RTSemEventSignal(RTSEMEVENT EventSem)
{
/*
* Validate input.
*/
if (!rtsemEventValid(EventSem))
{
AssertMsgFailed(("Invalid handle %p!\n", EventSem));
return VERR_INVALID_HANDLE;
}
/*
* Lock the mutex semaphore.
*/
struct RTSEMEVENTINTERNAL *pIntEventSem = EventSem;
int rc = pthread_mutex_lock(&pIntEventSem->Mutex);
if (rc)
{
AssertMsgFailed(("Failed to lock event sem %p, rc=%d.\n", EventSem, rc));
return RTErrConvertFromErrno(rc);
}
/*
* Check the state.
*/
if (pIntEventSem->u32State == EVENT_STATE_NOT_SIGNALED)
{
ASMAtomicXchgU32(&pIntEventSem->u32State, EVENT_STATE_SIGNALED);
rc = pthread_cond_signal(&pIntEventSem->Cond);
AssertMsg(!rc, ("Failed to signal event sem %p, rc=%d.\n", EventSem, rc));
}
else if (pIntEventSem->u32State == EVENT_STATE_SIGNALED)
{
rc = pthread_cond_signal(&pIntEventSem->Cond); /* give'm another kick... */
AssertMsg(!rc, ("Failed to signal event sem %p, rc=%d. (2)\n", EventSem, rc));
}
else
rc = VERR_SEM_DESTROYED;
/*
* Release the mutex and return.
*/
int rc2 = pthread_mutex_unlock(&pIntEventSem->Mutex);
AssertMsg(!rc2, ("Failed to unlock event sem %p, rc=%d.\n", EventSem, rc));
if (rc)
return RTErrConvertFromErrno(rc);
if (rc2)
return RTErrConvertFromErrno(rc2);
return VINF_SUCCESS;
}
static int rtSemEventWait(RTSEMEVENT EventSem, unsigned cMillies, bool fAutoResume)
{
/*
* Validate input.
*/
if (!rtsemEventValid(EventSem))
{
AssertMsgFailed(("Invalid handle %p!\n", EventSem));
return VERR_INVALID_HANDLE;
}
/*
* Timed or indefinite wait?
*/
struct RTSEMEVENTINTERNAL *pIntEventSem = EventSem;
if (cMillies == RT_INDEFINITE_WAIT)
{
/* for fairness, yield before going to sleep. */
if ( ASMAtomicIncU32(&pIntEventSem->cWaiters) > 1
&& pIntEventSem->u32State == EVENT_STATE_SIGNALED)
pthread_yield();
/* take mutex */
int rc = pthread_mutex_lock(&pIntEventSem->Mutex);
if (rc)
{
ASMAtomicDecU32(&pIntEventSem->cWaiters);
AssertMsgFailed(("Failed to lock event sem %p, rc=%d.\n", EventSem, rc));
return RTErrConvertFromErrno(rc);
}
for (;;)
{
/* check state. */
if (pIntEventSem->u32State == EVENT_STATE_SIGNALED)
{
ASMAtomicXchgU32(&pIntEventSem->u32State, EVENT_STATE_NOT_SIGNALED);
ASMAtomicDecU32(&pIntEventSem->cWaiters);
rc = pthread_mutex_unlock(&pIntEventSem->Mutex);
AssertMsg(!rc, ("Failed to unlock event sem %p, rc=%d.\n", EventSem, rc)); NOREF(rc);
return VINF_SUCCESS;
}
if (pIntEventSem->u32State == EVENT_STATE_UNINITIALIZED)
{
rc = pthread_mutex_unlock(&pIntEventSem->Mutex);
AssertMsg(!rc, ("Failed to unlock event sem %p, rc=%d.\n", EventSem, rc)); NOREF(rc);
return VERR_SEM_DESTROYED;
}
/* wait */
rc = pthread_cond_wait(&pIntEventSem->Cond, &pIntEventSem->Mutex);
if (rc)
{
AssertMsgFailed(("Failed to wait on event sem %p, rc=%d.\n", EventSem, rc));
ASMAtomicDecU32(&pIntEventSem->cWaiters);
int rc2 = pthread_mutex_unlock(&pIntEventSem->Mutex);
AssertMsg(!rc2, ("Failed to unlock event sem %p, rc=%d.\n", EventSem, rc2)); NOREF(rc2);
return RTErrConvertFromErrno(rc);
}
}
}
else
{
/*
* Get current time and calc end of wait time.
*/
struct timespec ts = {0,0};
#ifdef RT_OS_DARWIN
struct timeval tv = {0,0};
gettimeofday(&tv, NULL);
ts.tv_sec = tv.tv_sec;
ts.tv_nsec = tv.tv_usec * 1000;
#else
clock_gettime(CLOCK_REALTIME, &ts);
#endif
if (cMillies != 0)
{
ts.tv_nsec += (cMillies % 1000) * 1000000;
ts.tv_sec += cMillies / 1000;
if (ts.tv_nsec >= 1000000000)
{
ts.tv_nsec -= 1000000000;
ts.tv_sec++;
}
}
/* for fairness, yield before going to sleep. */
if (ASMAtomicIncU32(&pIntEventSem->cWaiters) > 1)
pthread_yield();
/* take mutex */
#ifdef RT_OS_DARWIN
int rc = pthread_mutex_lock(&pIntEventSem->Mutex);
#else
int rc = pthread_mutex_timedlock(&pIntEventSem->Mutex, &ts);
#endif
if (rc)
{
ASMAtomicDecU32(&pIntEventSem->cWaiters);
AssertMsg(rc == ETIMEDOUT, ("Failed to lock event sem %p, rc=%d.\n", EventSem, rc));
return RTErrConvertFromErrno(rc);
}
for (;;)
{
/* check state. */
if (pIntEventSem->u32State == EVENT_STATE_SIGNALED)
{
ASMAtomicXchgU32(&pIntEventSem->u32State, EVENT_STATE_NOT_SIGNALED);
ASMAtomicDecU32(&pIntEventSem->cWaiters);
rc = pthread_mutex_unlock(&pIntEventSem->Mutex);
AssertMsg(!rc, ("Failed to unlock event sem %p, rc=%d.\n", EventSem, rc)); NOREF(rc);
return VINF_SUCCESS;
}
if (pIntEventSem->u32State == EVENT_STATE_UNINITIALIZED)
{
rc = pthread_mutex_unlock(&pIntEventSem->Mutex);
AssertMsg(!rc, ("Failed to unlock event sem %p, rc=%d.\n", EventSem, rc)); NOREF(rc);
return VERR_SEM_DESTROYED;
}
/* wait */
rc = pthread_cond_timedwait(&pIntEventSem->Cond, &pIntEventSem->Mutex, &ts);
if (rc && (rc != EINTR || !fAutoResume)) /* according to SuS this function shall not return EINTR, but linux man page says differently. */
{
AssertMsg(rc == ETIMEDOUT, ("Failed to wait on event sem %p, rc=%d.\n", EventSem, rc));
ASMAtomicDecU32(&pIntEventSem->cWaiters);
int rc2 = pthread_mutex_unlock(&pIntEventSem->Mutex);
AssertMsg(!rc2, ("Failed to unlock event sem %p, rc2=%d.\n", EventSem, rc2)); NOREF(rc2);
return RTErrConvertFromErrno(rc);
}
} /* for (;;) */
}
}
RTDECL(int) RTSemEventWait(RTSEMEVENT EventSem, unsigned cMillies)
{
int rc = rtSemEventWait(EventSem, cMillies, true);
Assert(rc != VERR_INTERRUPTED);
return rc;
}
RTDECL(int) RTSemEventWaitNoResume(RTSEMEVENT EventSem, unsigned cMillies)
{
return rtSemEventWait(EventSem, cMillies, false);
}