path: root/unix/tclUnixThrd.c

/* 
 * tclUnixThrd.c --
 *
 *	This file implements the UNIX-specific thread support.
 *
 * Copyright (c) 1991-1994 The Regents of the University of California.
 * Copyright (c) 1994-1997 Sun Microsystems, Inc.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * SCCS:  @(#) tclUnixThrd.c 1.18 98/02/19 14:24:12
 */

#include "tclInt.h"

#ifdef TCL_THREADS

#include "tclPort.h"
#include "pthread.h"

/*
 * masterLock is used to serialize creation of mutexes, condition
 * variables, and thread local storage.
 * This is the only place that can count on the ability to statically
 * initialize the mutex.
 */

static pthread_mutex_t masterLock = PTHREAD_MUTEX_INITIALIZER;

/*
 * initLock is used to serialize initialization and finalization
 * of Tcl.  It cannot use any dyamically allocated storage.
 */

static pthread_mutex_t initLock = PTHREAD_MUTEX_INITIALIZER;

/*
 * allocLock is used by Tcl's version of malloc for synchronization.
 * For obvious reasons, cannot use any dyamically allocated storage.
 */

static pthread_mutex_t allocLock = PTHREAD_MUTEX_INITIALIZER;

/*
 * These are for the critical sections inside this file.
 */

#define MASTER_LOCK	pthread_mutex_lock(&masterLock)
#define MASTER_UNLOCK	pthread_mutex_unlock(&masterLock)

#endif /* TCL_THREADS */



#ifdef TCL_THREADS

/*
 *----------------------------------------------------------------------
 *
 * TclpThreadCreate --
 *
 *	This procedure creates a new thread.
 *
 * Results:
 *	TCL_OK if the thread could be created.  The thread ID is
 *	returned in a parameter.
 *
 * Side effects:
 *	A new thread is created.
 *
 *----------------------------------------------------------------------
 */

int
TclpThreadCreate(idPtr, proc, clientData)
    Tcl_ThreadId *idPtr;		/* Return, the ID of the thread */
    Tcl_ThreadCreateProc proc;		/* Main() function of the thread */
    ClientData clientData;		/* The one argument to Main() */
{
    pthread_attr_t attr;
    int result;

    pthread_attr_init(&attr);
    pthread_attr_setscope(&attr, PTHREAD_SCOPE_SYSTEM);
    if (pthread_create((pthread_t *)idPtr, &attr,
	    (void * (*)())proc, (void *)clientData) &&
	    pthread_create((pthread_t *)idPtr, NULL,
		    (void * (*)())proc, (void *)clientData)) {
	result = TCL_ERROR;
    } else {
	result = TCL_OK;
    }
    pthread_attr_destroy(&attr);
    return result;
}

/*
 *----------------------------------------------------------------------
 *
 * TclpThreadExit --
 *
 *	This procedure terminates the current thread.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	This procedure terminates the current thread.
 *
 *----------------------------------------------------------------------
 */

void
TclpThreadExit(status)
    int status;
{
    pthread_exit((VOID *)status);
}
#endif /* TCL_THREADS */

/*
 *----------------------------------------------------------------------
 *
 * Tcl_GetCurrentThread --
 *
 *	This procedure returns the ID of the currently running thread.
 *
 * Results:
 *	A thread ID.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

Tcl_ThreadId
Tcl_GetCurrentThread()
{
#ifdef TCL_THREADS
    return (Tcl_ThreadId) pthread_self();
#else
    return (Tcl_ThreadId) 0;
#endif
}


/*
 *----------------------------------------------------------------------
 *
 * TclpInitLock
 *
 *	This procedure is used to grab a lock that serializes initialization
 *	and finalization of Tcl.  On some platforms this may also initialize
 *	the mutex used to serialize creation of more mutexes and thread
 *	local storage keys.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Acquire the initialization mutex.
 *
 *----------------------------------------------------------------------
 */

void
TclpInitLock()
{
#ifdef TCL_THREADS
    pthread_mutex_lock(&initLock);
#endif
}


/*
 *----------------------------------------------------------------------
 *
 * TclpInitUnlock
 *
 *	This procedure is used to release a lock that serializes initialization
 *	and finalization of Tcl.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Release the initialization mutex.
 *
 *----------------------------------------------------------------------
 */

void
TclpInitUnlock()
{
#ifdef TCL_THREADS
    pthread_mutex_unlock(&initLock);
#endif
}

/*
 *----------------------------------------------------------------------
 *
 * TclpMasterLock
 *
 *	This procedure is used to grab a lock that serializes creation
 *	and finalization of serialization objects.  This interface is
 *	only needed in finalization; it is hidden during
 *	creation of the objects.
 *
 *	This lock must be different than the initLock because the
 *	initLock is held during creation of syncronization objects.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Acquire the master mutex.
 *
 *----------------------------------------------------------------------
 */

void
TclpMasterLock()
{
#ifdef TCL_THREADS
    pthread_mutex_lock(&masterLock);
#endif
}


/*
 *----------------------------------------------------------------------
 *
 * TclpMasterUnlock
 *
 *	This procedure is used to release a lock that serializes creation
 *	and finalization of synchronization objects.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Release the master mutex.
 *
 *----------------------------------------------------------------------
 */

void
TclpMasterUnlock()
{
#ifdef TCL_THREADS
    pthread_mutex_unlock(&masterLock);
#endif
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_GetAllocMutex
 *
 *	This procedure returns a pointer to a statically initialized
 *	mutex for use by the memory allocator.  The alloctor must
 *	use this lock, because all other locks are allocated...
 *
 * Results:
 *	A pointer to a mutex that is suitable for passing to
 *	Tcl_MutexLock and Tcl_MutexUnlock.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

Tcl_Mutex *
Tcl_GetAllocMutex()
{
#ifdef TCL_THREADS
    return (Tcl_Mutex *)&allocLock;
#else
    return NULL;
#endif
}

#ifdef TCL_THREADS

/*
 *----------------------------------------------------------------------
 *
 * Tcl_MutexLock --
 *
 *	This procedure is invoked to lock a mutex.  This procedure
 *	handles initializing the mutex, if necessary.  The caller
 *	can rely on the fact that Tcl_Mutex is an opaque pointer.
 *	This routine will change that pointer from NULL after first use.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	May block the current thread.  The mutex is aquired when
 *	this returns.  Will allocate memory for a pthread_mutex_t
 *	and initialize this the first time this Tcl_Mutex is used.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_MutexLock(mutexPtr)
    Tcl_Mutex *mutexPtr;	/* Really (pthread_mutex_t **) */
{
    pthread_mutex_t *pmutexPtr;
    if (*mutexPtr == NULL) {
	MASTER_LOCK;
	if (*mutexPtr == NULL) {
	    /* 
	     * Double inside master lock check to avoid a race.
	     */
    
	    pmutexPtr = (pthread_mutex_t *)ckalloc(sizeof(pthread_mutex_t));
	    pthread_mutex_init(pmutexPtr, NULL);
	    *mutexPtr = (Tcl_Mutex)pmutexPtr;
	    TclRememberMutex(mutexPtr);
	}
	MASTER_UNLOCK;
    }
    pmutexPtr = *((pthread_mutex_t **)mutexPtr);
    pthread_mutex_lock(pmutexPtr);
}


/*
 *----------------------------------------------------------------------
 *
 * TclpMutexUnlock --
 *
 *	This procedure is invoked to unlock a mutex.  The mutex must
 *	have been locked by Tcl_MutexLock.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The mutex is released when this returns.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_MutexUnlock(mutexPtr)
    Tcl_Mutex *mutexPtr;	/* Really (pthread_mutex_t **) */
{
    pthread_mutex_t *pmutexPtr = *(pthread_mutex_t **)mutexPtr;
    pthread_mutex_unlock(pmutexPtr);
}


/*
 *----------------------------------------------------------------------
 *
 * TclpFinalizeMutex --
 *
 *	This procedure is invoked to clean up one mutex.  This is only
 *	safe to call at the end of time.
 *
 *	This assumes the Master Lock is held.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The mutex list is deallocated.
 *
 *----------------------------------------------------------------------
 */

void
TclpFinalizeMutex(mutexPtr)
    Tcl_Mutex *mutexPtr;
{
    pthread_mutex_t *pmutexPtr = *(pthread_mutex_t **)mutexPtr;
    if (pmutexPtr != NULL) {
	ckfree((char *)pmutexPtr);
	*mutexPtr = NULL;
    }
}


/*
 *----------------------------------------------------------------------
 *
 * TclpThreadDataKeyInit --
 *
 *	This procedure initializes a thread specific data block key.
 *	Each thread has table of pointers to thread specific data.
 *	all threads agree on which table entry is used by each module.
 *	this is remembered in a "data key", that is just an index into
 *	this table.  To allow self initialization, the interface
 *	passes a pointer to this key and the first thread to use
 *	the key fills in the pointer to the key.  The key should be
 *	a process-wide static.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Will allocate memory the first time this process calls for
 *	this key.  In this case it modifies its argument
 *	to hold the pointer to information about the key.
 *
 *----------------------------------------------------------------------
 */

void
TclpThreadDataKeyInit(keyPtr)
    Tcl_ThreadDataKey *keyPtr;	/* Identifier for the data chunk,
				 * really (pthread_key_t **) */
{
    pthread_key_t *pkeyPtr;

    MASTER_LOCK;
    if (*keyPtr == NULL) {
	pkeyPtr = (pthread_key_t *)ckalloc(sizeof(pthread_key_t));
	pthread_key_create(pkeyPtr, NULL);
	*keyPtr = (Tcl_ThreadDataKey)pkeyPtr;
	TclRememberDataKey(keyPtr);
    }
    MASTER_UNLOCK;
}

/*
 *----------------------------------------------------------------------
 *
 * TclpThreadDataKeyGet --
 *
 *	This procedure returns a pointer to a block of thread local storage.
 *
 * Results:
 *	A thread-specific pointer to the data structure, or NULL
 *	if the memory has not been assigned to this key for this thread.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

VOID *
TclpThreadDataKeyGet(keyPtr)
    Tcl_ThreadDataKey *keyPtr;	/* Identifier for the data chunk,
				 * really (pthread_key_t **) */
{
    pthread_key_t *pkeyPtr = *(pthread_key_t **)keyPtr;
    if (pkeyPtr == NULL) {
	return NULL;
    } else {
	return (VOID *)pthread_getspecific(*pkeyPtr);
    }
}


/*
 *----------------------------------------------------------------------
 *
 * TclpThreadDataKeySet --
 *
 *	This procedure sets the pointer to a block of thread local storage.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Sets up the thread so future calls to TclpThreadDataKeyGet with
 *	this key will return the data pointer.
 *
 *----------------------------------------------------------------------
 */

void
TclpThreadDataKeySet(keyPtr, data)
    Tcl_ThreadDataKey *keyPtr;	/* Identifier for the data chunk,
				 * really (pthread_key_t **) */
    VOID *data;			/* Thread local storage */
{
    pthread_key_t *pkeyPtr = *(pthread_key_t **)keyPtr;
    pthread_setspecific(*pkeyPtr, data);
}

/*
 *----------------------------------------------------------------------
 *
 * TclpFinalizeThreadData --
 *
 *	This procedure cleans up the thread-local storage.  This is
 *	called once for each thread.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Frees up all thread local storage.
 *
 *----------------------------------------------------------------------
 */

void
TclpFinalizeThreadData(keyPtr)
    Tcl_ThreadDataKey *keyPtr;
{
    VOID *result;
    pthread_key_t *pkeyPtr;

    if (*keyPtr != NULL) {
	pkeyPtr = *(pthread_key_t **)keyPtr;
	result = (VOID *)pthread_getspecific(*pkeyPtr);
	if (result != NULL) {
	    ckfree((char *)result);
	    pthread_setspecific(*pkeyPtr, (void *)NULL);
	}
    }
}

/*
 *----------------------------------------------------------------------
 *
 * TclpFinalizeThreadDataKey --
 *
 *	This procedure is invoked to clean up one key.  This is a
 *	process-wide storage identifier.  The thread finalization code
 *	cleans up the thread local storage itself.
 *
 *	This assumes the master lock is held.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The key is deallocated.
 *
 *----------------------------------------------------------------------
 */

void
TclpFinalizeThreadDataKey(keyPtr)
    Tcl_ThreadDataKey *keyPtr;
{
    pthread_key_t *pkeyPtr;
    if (*keyPtr != NULL) {
	pkeyPtr = *(pthread_key_t **)keyPtr;
	pthread_key_delete(*pkeyPtr);
	ckfree((char *)pkeyPtr);
	*keyPtr = NULL;
    }
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_ConditionWait --
 *
 *	This procedure is invoked to wait on a condition variable.
 *	The mutex is automically released as part of the wait, and
 *	automatically grabbed when the condition is signaled.
 *
 *	The mutex must be held when this procedure is called.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	May block the current thread.  The mutex is aquired when
 *	this returns.  Will allocate memory for a pthread_mutex_t
 *	and initialize this the first time this Tcl_Mutex is used.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_ConditionWait(condPtr, mutexPtr, timePtr)
    Tcl_Condition *condPtr;	/* Really (pthread_cond_t **) */
    Tcl_Mutex *mutexPtr;	/* Really (pthread_mutex_t **) */
    Tcl_Time *timePtr;		/* Timeout on waiting period */
{
    pthread_cond_t *pcondPtr;
    pthread_mutex_t *pmutexPtr;
    struct timespec ptime;

    if (*condPtr == NULL) {
	MASTER_LOCK;

	/* 
	 * Double check inside mutex to avoid race,
	 * then initialize condition variable if necessary.
	 */

	if (*condPtr == NULL) {
	    pcondPtr = (pthread_cond_t *)ckalloc(sizeof(pthread_cond_t));
	    pthread_cond_init(pcondPtr, NULL);
	    *condPtr = (Tcl_Condition)pcondPtr;
	    TclRememberCondition(condPtr);
	}
	MASTER_UNLOCK;
    }
    pmutexPtr = *((pthread_mutex_t **)mutexPtr);
    pcondPtr = *((pthread_cond_t **)condPtr);
    if (timePtr == NULL) {
	pthread_cond_wait(pcondPtr, pmutexPtr);
    } else {
	ptime.tv_sec = timePtr->sec + TclpGetSeconds();
	ptime.tv_nsec = 1000 * timePtr->usec;
	pthread_cond_timedwait(pcondPtr, pmutexPtr, &ptime);
    }
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_ConditionNotify --
 *
 *	This procedure is invoked to signal a condition variable.
 *
 *	The mutex must be held during this call to avoid races,
 *	but this interface does not enforce that.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	May unblock another thread.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_ConditionNotify(condPtr)
    Tcl_Condition *condPtr;
{
    pthread_cond_t *pcondPtr = *((pthread_cond_t **)condPtr);
    if (pcondPtr != NULL) {
	pthread_cond_broadcast(pcondPtr);
    } else {
	/*
	 * Noone has used the condition variable, so there are no waiters.
	 */
    }
}


/*
 *----------------------------------------------------------------------
 *
 * TclpFinalizeCondition --
 *
 *	This procedure is invoked to clean up a condition variable.
 *	This is only safe to call at the end of time.
 *
 *	This assumes the Master Lock is held.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The condition variable is deallocated.
 *
 *----------------------------------------------------------------------
 */

void
TclpFinalizeCondition(condPtr)
    Tcl_Condition *condPtr;
{
    pthread_cond_t *pcondPtr = *(pthread_cond_t **)condPtr;
    if (pcondPtr != NULL) {
	pthread_cond_destroy(pcondPtr);
	ckfree((char *)pcondPtr);
	*condPtr = NULL;
    }
}



#endif /* TCL_THREADS */