path: root/src/H5TS.c

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * Copyright by The HDF Group.                                               *
 * Copyright by the Board of Trustees of the University of Illinois.         *
 * All rights reserved.                                                      *
 *                                                                           *
 * This file is part of HDF5.  The full HDF5 copyright notice, including     *
 * terms governing use, modification, and redistribution, is contained in    *
 * the COPYING file, which can be found at the root of the source code       *
 * distribution tree, or in https://support.hdfgroup.org/ftp/HDF5/releases.  *
 * If you do not have access to either file, you may request a copy from     *
 * help@hdfgroup.org.                                                        *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/* private headers */
#include "H5private.h"    /*library                     */
#include "H5Eprivate.h"    /*error handling              */
#include "H5MMprivate.h"  /*memory management functions    */

#ifdef H5_HAVE_THREADSAFE

/* Module specific data structures */

/* cancelability structure */
typedef struct H5TS_cancel_struct {
    int previous_state;
    unsigned int cancel_count;
} H5TS_cancel_t;

/* Global variable definitions */
#ifdef H5_HAVE_WIN_THREADS
H5TS_once_t H5TS_first_init_g;
#else /* H5_HAVE_WIN_THREADS */
H5TS_once_t H5TS_first_init_g = PTHREAD_ONCE_INIT;
#endif /* H5_HAVE_WIN_THREADS */
H5TS_key_t H5TS_errstk_key_g;
H5TS_key_t H5TS_funcstk_key_g;
H5TS_key_t H5TS_apictx_key_g;
H5TS_key_t H5TS_cancel_key_g;

#ifndef H5_HAVE_WIN_THREADS

/* An h5_tid_t is a record of a thread identifier that is
 * available for reuse.
 */
struct _tid;
typedef struct _tid h5_tid_t;

struct _tid {
    h5_tid_t *next;
    unsigned long id;
};

/* Pointer to first free thread ID record or NULL. */
static h5_tid_t *tid_next_free = NULL;
static unsigned long tid_next_id = 0;

/* Mutual exclusion for access to tid_next_free and tid_next_id. */
static pthread_mutex_t tid_mtx;

/* Key for thread-local storage of the thread ID. */
static H5TS_key_t tid_key;

#endif /* H5_HAVE_WIN_THREADS */


/*--------------------------------------------------------------------------
 * NAME
 *    H5TS_key_destructor
 *
 * USAGE
 *    H5TS_key_destructor()
 *
 * RETURNS
 *
 * DESCRIPTION
 *   Frees the memory for a key.  Called by each thread as it exits.
 *   Currently all the thread-specific information for all keys are simple
 *   structures allocated with malloc, so we can free them all uniformly.
 *
 * PROGRAMMER: Quincey Koziol
 *             February 7, 2003
 *
 *--------------------------------------------------------------------------
 */
static void
H5TS_key_destructor(void *key_val)
{
    /* Use HDfree here instead of H5MM_xfree(), to avoid calling the H5CS routines */
    if(key_val != NULL)
        HDfree(key_val);
}


#ifndef H5_HAVE_WIN_THREADS

/* When a thread shuts down, put its ID record on the free list. */
static void
tid_destructor(void *_v)
{
    h5_tid_t *tid = _v;

    if (tid == NULL)
        return;

    /* XXX I can use mutexes in destructors, right? */
    /* TBD use an atomic CAS */
    pthread_mutex_lock(&tid_mtx);
    tid->next = tid_next_free;
    tid_next_free = tid;
    pthread_mutex_unlock(&tid_mtx);
}

/* Initialize for integer thread identifiers. */
static void
tid_init(void)
{
    pthread_mutex_init(&tid_mtx, NULL);
    pthread_key_create(&tid_key, tid_destructor);
}

/* Return an integer identifier, ID, for the current thread satisfies the
 * following properties:
 *
 * 1 1 <= ID <= ULONG_MAX
 * 2 The ID is constant over the thread's lifetime.
 * 3 No two threads share an ID during their lifetimes.
 * 4 A thread's ID is available for reuse as soon as it is joined.
 *
 * ID 0 is reserved.  H5TS_thread_id() returns 0 if the library was not built
 * with thread safety or if an error prevents it from assigning an ID.
 */
unsigned long
H5TS_thread_id(void)
{
    h5_tid_t *tid = pthread_getspecific(tid_key);
    h5_tid_t proto_tid;

    /* An ID is already assigned. */
    if (tid != NULL)
        return tid->id;

    /* An ID is *not* already assigned: reuse an ID that's on the
     * free list, or else generate a new ID.
     * 
     * Allocating memory while holding a mutex is bad form, so
     * point `tid` at `proto_tid` if we need to allocate some
     * memory.
     */
    pthread_mutex_lock(&tid_mtx);
    if ((tid = tid_next_free) != NULL)
        tid_next_free = tid->next;
    else if (tid_next_id != ULONG_MAX) {
        tid = &proto_tid;
        tid->id = ++tid_next_id;
    }
    pthread_mutex_unlock(&tid_mtx);

    /* If a prototype ID record was established, copy it to the heap. */
    if (tid == &proto_tid) {
        if ((tid = HDmalloc(sizeof(*tid))) != NULL)
            *tid = proto_tid;
    }

    if (tid == NULL)
        return 0;

    /* Finish initializing the ID record and set a thread-local pointer
     * to it.
     */
    tid->next = NULL;
    if (pthread_setspecific(tid_key, tid) != 0) {
        tid_destructor(tid);
        return 0;
    }

    return tid->id;
}

/*--------------------------------------------------------------------------
 * NAME
 *    H5TS_pthread_first_thread_init
 *
 * USAGE
 *    H5TS_pthread_first_thread_init()
 *
 * RETURNS
 *
 * DESCRIPTION
 *   Initialization of global API lock, keys for per-thread error stacks and
 *   cancallability information. Called by the first thread that enters the
 *   library.
 *
 * PROGRAMMER: Chee Wai LEE
 *             May 2, 2000
 *
 *--------------------------------------------------------------------------
 */
void
H5TS_pthread_first_thread_init(void)
{
    H5_g.H5_libinit_g = FALSE;  /* Library hasn't been initialized */
    H5_g.H5_libterm_g = FALSE;  /* Library isn't being shutdown */

#ifdef H5_HAVE_WIN32_API
# ifdef PTW32_STATIC_LIB
    pthread_win32_process_attach_np();
# endif
#endif

    /* initialize global API mutex lock */
    pthread_mutex_init(&H5_g.init_lock.atomic_lock, NULL);
    pthread_cond_init(&H5_g.init_lock.cond_var, NULL);
    H5_g.init_lock.lock_count = 0;

    /* Initialize integer thread identifiers. */
    tid_init();

    /* initialize key for thread-specific error stacks */
    pthread_key_create(&H5TS_errstk_key_g, H5TS_key_destructor);

    /* initialize key for thread-specific function stacks */
    pthread_key_create(&H5TS_funcstk_key_g, H5TS_key_destructor);

    /* initialize key for thread-specific API contexts */
    pthread_key_create(&H5TS_apictx_key_g, H5TS_key_destructor);

    /* initialize key for thread cancellability mechanism */
    pthread_key_create(&H5TS_cancel_key_g, H5TS_key_destructor);
}
#endif /* H5_HAVE_WIN_THREADS */


/*--------------------------------------------------------------------------
 * NAME
 *    H5TS_mutex_lock
 *
 * USAGE
 *    H5TS_mutex_lock(&mutex_var)
 *
 * RETURNS
 *    0 on success and non-zero on error.
 *
 * DESCRIPTION
 *    Recursive lock semantics for HDF5 (locking) -
 *    Multiple acquisition of a lock by a thread is permitted with a
 *    corresponding unlock operation required.
 *
 * PROGRAMMER: Chee Wai LEE
 *             May 2, 2000
 *
 *--------------------------------------------------------------------------
 */
herr_t
H5TS_mutex_lock(H5TS_mutex_t *mutex)
{
#ifdef  H5_HAVE_WIN_THREADS
    EnterCriticalSection( &mutex->CriticalSection); 
    return 0;
#else /* H5_HAVE_WIN_THREADS */
    herr_t ret_value = pthread_mutex_lock(&mutex->atomic_lock);

    if (ret_value)
        return ret_value;

    if(mutex->lock_count && pthread_equal(HDpthread_self(), mutex->owner_thread)) {
        /* already owned by self - increment count */
        mutex->lock_count++;
    } else {
        /* if owned by other thread, wait for condition signal */
        while(mutex->lock_count)
            pthread_cond_wait(&mutex->cond_var, &mutex->atomic_lock);

        /* After we've received the signal, take ownership of the mutex */
        mutex->owner_thread = HDpthread_self();
        mutex->lock_count = 1;
    }

    return pthread_mutex_unlock(&mutex->atomic_lock); 
#endif /* H5_HAVE_WIN_THREADS */
}


/*--------------------------------------------------------------------------
 * NAME
 *    H5TS_mutex_unlock
 *
 * USAGE
 *    H5TS_mutex_unlock(&mutex_var)
 *
 * RETURNS
 *    0 on success and non-zero on error.
 *
 * DESCRIPTION
 *    Recursive lock semantics for HDF5 (unlocking) -
 *    Multiple acquisition of a lock by a thread is permitted with a
 *    corresponding unlock operation required.
 *
 * PROGRAMMER: Chee Wai LEE
 *             May 2, 2000
 *
 *--------------------------------------------------------------------------
 */
herr_t
H5TS_mutex_unlock(H5TS_mutex_t *mutex)
{
#ifdef  H5_HAVE_WIN_THREADS
    /* Releases ownership of the specified critical section object. */
    LeaveCriticalSection(&mutex->CriticalSection);
    return 0; 
#else  /* H5_HAVE_WIN_THREADS */
    herr_t ret_value = pthread_mutex_lock(&mutex->atomic_lock);

    if(ret_value)
        return ret_value;

    mutex->lock_count--;

    ret_value = pthread_mutex_unlock(&mutex->atomic_lock);

    if(mutex->lock_count == 0) {
        int err;

        err = pthread_cond_signal(&mutex->cond_var);
        if(err != 0)
            ret_value = err;
    } /* end if */

    return ret_value; 
#endif /* H5_HAVE_WIN_THREADS */
} /* H5TS_mutex_unlock */


/*--------------------------------------------------------------------------
 * NAME
 *    H5TS_cancel_count_inc
 *
 * USAGE
 *    H5TS_cancel_count_inc()
 *
 * RETURNS
 *    0 on success non-zero error code on error.
 *
 * DESCRIPTION
 *    Creates a cancelation counter for a thread if it is the first time
 *    the thread is entering the library.
 *
 *    if counter value is zero, then set cancelability type of the thread
 *    to PTHREAD_CANCEL_DISABLE as thread is entering the library and store
 *    the previous cancelability type into cancelation counter.
 *    Increase the counter value by 1.
 *
 * PROGRAMMER: Chee Wai LEE
 *            May 2, 2000
 *
 *--------------------------------------------------------------------------
 */
herr_t
H5TS_cancel_count_inc(void)
{
#ifdef  H5_HAVE_WIN_THREADS
    /* unsupported; just return 0 */
    return SUCCEED;
#else /* H5_HAVE_WIN_THREADS */
    H5TS_cancel_t *cancel_counter;
    herr_t ret_value = SUCCEED; 

    cancel_counter = (H5TS_cancel_t *)H5TS_get_thread_local_value(H5TS_cancel_key_g); 

    if (!cancel_counter) {
        /*
         * First time thread calls library - create new counter and associate
         * with key.
         * 
         * Don't use H5MM calls here since the destructor has to use HDfree in
         * order to avoid codestack calls.
         */
        cancel_counter = (H5TS_cancel_t *)HDcalloc(1, sizeof(H5TS_cancel_t));

        if (!cancel_counter) {
            HERROR(H5E_RESOURCE, H5E_NOSPACE, "memory allocation failed");
            return FAIL;
        }

        ret_value = pthread_setspecific(H5TS_cancel_key_g, (void *)cancel_counter);
    }

    if (cancel_counter->cancel_count == 0)
        /* thread entering library */
        ret_value = pthread_setcancelstate(PTHREAD_CANCEL_DISABLE,
             &cancel_counter->previous_state);

    ++cancel_counter->cancel_count;

    return ret_value; 
#endif /* H5_HAVE_WIN_THREADS */
}


/*--------------------------------------------------------------------------
 * NAME
 *    H5TS_cancel_count_dec
 *
 * USAGE
 *    H5TS_cancel_count_dec()
 *
 * RETURNS
 *    0 on success and a non-zero error code on error.
 *
 * DESCRIPTION
 *    If counter value is one, then set cancelability type of the thread
 *    to the previous cancelability type stored in the cancelation counter.
 *    (the thread is leaving the library).
 *
 *    Decrement the counter value by 1.
 *
 * PROGRAMMER: Chee Wai LEE
 *             May 2, 2000
 *
 *--------------------------------------------------------------------------
 */
herr_t
H5TS_cancel_count_dec(void)
{
#ifdef  H5_HAVE_WIN_THREADS 
    /* unsupported; will just return 0 */
    return SUCCEED;
#else /* H5_HAVE_WIN_THREADS */
    register H5TS_cancel_t *cancel_counter; 
    herr_t ret_value = SUCCEED;

    cancel_counter = (H5TS_cancel_t *)H5TS_get_thread_local_value(H5TS_cancel_key_g); 

    if (cancel_counter->cancel_count == 1)
        ret_value = pthread_setcancelstate(cancel_counter->previous_state, NULL);

    --cancel_counter->cancel_count; 

    return ret_value;
#endif /* H5_HAVE_WIN_THREADS */
}


#ifdef H5_HAVE_WIN_THREADS
/*--------------------------------------------------------------------------
 * NAME
 *    H5TS_win32_process_enter
 *
 * RETURNS
 *    SUCCEED/FAIL
 *
 * DESCRIPTION
 *    Per-process setup on Windows when using Win32 threads.
 *
 *--------------------------------------------------------------------------
 */
H5_DLL BOOL CALLBACK 
H5TS_win32_process_enter(PINIT_ONCE InitOnce, PVOID Parameter, PVOID *lpContex)
{
    BOOL ret_value = TRUE;

    /* Initialize the critical section (can't fail) */
    InitializeCriticalSection(&H5_g.init_lock.CriticalSection);

    /* Set up thread local storage */
    if(TLS_OUT_OF_INDEXES == (H5TS_errstk_key_g = TlsAlloc()))
        ret_value = FALSE;

#ifdef H5_HAVE_CODESTACK
    if(TLS_OUT_OF_INDEXES == (H5TS_funcstk_key_g = TlsAlloc()))
        ret_value = FALSE;
#endif /* H5_HAVE_CODESTACK */

    if(TLS_OUT_OF_INDEXES == (H5TS_apictx_key_g = TlsAlloc()))
        ret_value = FALSE;

    return ret_value;
} /* H5TS_win32_process_enter() */
#endif /* H5_HAVE_WIN_THREADS */


#ifdef H5_HAVE_WIN_THREADS
/*--------------------------------------------------------------------------
 * NAME
 *    H5TS_win32_thread_enter
 *
 * RETURNS
 *    SUCCEED/FAIL
 *
 * DESCRIPTION
 *    Per-thread setup on Windows when using Win32 threads.
 *
 *--------------------------------------------------------------------------
 */
herr_t
H5TS_win32_thread_enter(void)
{
    herr_t ret_value = SUCCEED;

    /* Currently a placeholder function.  TLS setup is performed
     * elsewhere in the library.
     *
     * WARNING: Do NOT use C standard library functions here.
     * CRT functions are not allowed in DllMain, which is where this code
     * is used.
     */

    return ret_value;
} /* H5TS_win32_thread_enter() */
#endif /* H5_HAVE_WIN_THREADS */


#ifdef H5_HAVE_WIN_THREADS
/*--------------------------------------------------------------------------
 * NAME
 *    H5TS_win32_process_exit
 *
 * RETURNS
 *    SUCCEED/FAIL
 *
 * DESCRIPTION
 *    Per-process cleanup on Windows when using Win32 threads.
 *
 *--------------------------------------------------------------------------
 */
void
H5TS_win32_process_exit(void)
{

    /* Windows uses a different thread local storage mechanism which does
     * not support auto-freeing like pthreads' keys.
     *
     * This function is currently registered via atexit() and is called
     * AFTER H5_term_library().
     */

    /* Clean up critical section resources (can't fail) */
    DeleteCriticalSection(&H5_g.init_lock.CriticalSection);

    /* Clean up per-process thread local storage */
    TlsFree(H5TS_errstk_key_g);
#ifdef H5_HAVE_CODESTACK
    TlsFree(H5TS_funcstk_key_g);
#endif /* H5_HAVE_CODESTACK */
    TlsFree(H5TS_apictx_key_g);

    return;
} /* H5TS_win32_process_exit() */
#endif /* H5_HAVE_WIN_THREADS */


#ifdef H5_HAVE_WIN_THREADS
/*--------------------------------------------------------------------------
 * NAME
 *    H5TS_win32_thread_exit
 *
 * RETURNS
 *    SUCCEED/FAIL
 *
 * DESCRIPTION
 *    Per-thread cleanup on Windows when using Win32 threads.
 *
 *--------------------------------------------------------------------------
 */
herr_t
H5TS_win32_thread_exit(void)
{
    LPVOID lpvData;
    herr_t ret_value = SUCCEED;

    /* Windows uses a different thread local storage mechanism which does
     * not support auto-freeing like pthreads' keys.
     *
     * WARNING: Do NOT use C standard library functions here.
     * CRT functions are not allowed in DllMain, which is where this code
     * is used.
     */

    /* Clean up per-thread thread local storage */
    lpvData = TlsGetValue(H5TS_errstk_key_g);
    if(lpvData)
        LocalFree((HLOCAL)lpvData);

#ifdef H5_HAVE_CODESTACK
    lpvData = TlsGetValue(H5TS_funcstk_key_g);
    if(lpvData)
        LocalFree((HLOCAL)lpvData);
#endif /* H5_HAVE_CODESTACK */

    lpvData = TlsGetValue(H5TS_apictx_key_g);
    if(lpvData)
        LocalFree((HLOCAL)lpvData);

    return ret_value;
} /* H5TS_win32_thread_exit() */
#endif /* H5_HAVE_WIN_THREADS */


/*--------------------------------------------------------------------------
 * NAME
 *    H5TS_create_thread
 *
 * RETURNS
 *    Thread identifier.
 *
 * DESCRIPTION
 *    Spawn off a new thread calling function 'func' with input 'udata'.
 *
 * PROGRAMMER: Mike McGreevy
 *             August 31, 2010
 *
 *--------------------------------------------------------------------------
 */
H5TS_thread_t
H5TS_create_thread(void *(*func)(void *), H5TS_attr_t *attr, void *udata)
{
    H5TS_thread_t ret_value;

#ifdef  H5_HAVE_WIN_THREADS 

    /* When calling C runtime functions, you should use _beginthread or
     * _beginthreadex instead of CreateThread.  Threads created with
     * CreateThread risk being killed in low-memory situations. Since we
     * only create threads in our test code, this is unlikely to be an issue
     * and we'll use the easier-to-deal-with CreateThread for now.
     *
     * NOTE: _beginthread() auto-recycles its handle when execution completes
     *       so you can't wait on it, making it unsuitable for the existing
     *       test code.
     */
    ret_value = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)func, udata, 0, NULL);

#else /* H5_HAVE_WIN_THREADS */

    pthread_create(&ret_value, attr, (void * (*)(void *))func, udata);

#endif /* H5_HAVE_WIN_THREADS */

    return ret_value;

} /* H5TS_create_thread */

#else  /* H5_HAVE_THREADSAFE */

unsigned long
H5TS_thread_id(void)
{
    return 0;
}

#endif  /* H5_HAVE_THREADSAFE */