/*
 * Copyright (c) 2008, Likewise Software, Inc.
 * All rights reserved.
 */

/*
 * Copyright (c) 2007, Novell, Inc.
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the Novell, Inc. nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "dcethread-private.h"
#include "dcethread-debug.h"
#include "dcethread-exception.h"

#include <stdlib.h>
#include <signal.h>
#include <string.h>
#include <time.h>
#include <sys/time.h>

static pthread_once_t dcethread_init_once = DCETHREAD_ONCE_INIT;
static pthread_key_t dcethread_self_key;
static pthread_attr_t dcethread_attr_default;
static pthread_mutexattr_t dcethread_mutexattr_default;
static pthread_condattr_t dcethread_condattr_default;

#ifdef SIGRTMIN
#    define INTERRUPT_SIGNAL (SIGRTMIN + 5)
#else
#    define INTERRUPT_SIGNAL (SIGXCPU)
#endif

static void
interrupt_signal_handler(int sig)
{
    dcethread* thread = dcethread__self();

    /* In asynchronous interrupt mode all bets
       are off anyway, so don't bother to lock */
    if (thread->flag.async)
    {
	dcethread__dispatchinterrupt(thread);
    }
}

static void
self_destructor(void* data)
{
    if (data)
    {
        dcethread* self = (dcethread*) data;
        dcethread__lock(self);
        dcethread__change_state(self, DCETHREAD_STATE_DEAD);
        dcethread__release(self);
        dcethread__unlock(self);
    }
}

static void
init()
{
    int cancelstate, oldstate;
    struct sigaction act;

    pthread_key_create(&dcethread_self_key, self_destructor);

    pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cancelstate);
    pthread_attr_init(&dcethread_attr_default);
    pthread_mutexattr_init(&dcethread_mutexattr_default);

#if defined(RPC_MUTEX_DEBUG) && defined(__USE_UNIX98)
    pthread_mutexattr_settype(&dcethread_mutexattr_default, PTHREAD_MUTEX_ERRORCHECK);
#endif
    pthread_condattr_init(&dcethread_condattr_default);
    dcethread__init_exceptions();
    pthread_setcancelstate(cancelstate, &oldstate);

    sigemptyset(&act.sa_mask);
    act.sa_handler = interrupt_signal_handler;
    act.sa_flags = 0;
    sigaction(INTERRUPT_SIGNAL, &act, NULL);
    if (getenv("DCETHREAD_DEBUG"))
	dcethread__debug_set_callback(dcethread__default_log_callback, NULL);
}

#ifdef __SUNPRO_C
#pragma init dcethread__init
#else
void dcethread__init(void) __attribute__ ((constructor));
#endif

void dcethread__init(void)
{
    pthread_once(&dcethread_init_once, init);
}

int
dcethread__interrupt_syscall(dcethread* thread, void* data)
{
    pthread_kill(thread->pthread, INTERRUPT_SIGNAL);
    return 0;
}

static int
my_clock_gettime(struct timespec* tp)
{
#ifdef CLOCK_REALTIME
  return clock_gettime(CLOCK_REALTIME, tp);
#else
  int result;
  struct timeval tv;
       
  if ((result = gettimeofday(&tv, NULL)))
    return result;

  tp->tv_sec = tv.tv_sec;
  tp->tv_nsec = tv.tv_usec * 1000;

  return 0;
#endif
}

int
dcethread__interrupt_condwait(dcethread* thread, void* data)
{
    condwait_info* info = (condwait_info*) data;

    if (pthread_equal(info->mutex->owner, pthread_self()))
    {
        DCETHREAD_TRACE("Thread %p: already owned mutex used for interrupt", thread);
        if (pthread_cond_broadcast(info->cond))
        {
            DCETHREAD_ERROR("Thread %p: broadcast failed", thread);
            return 0;
        }
        else
        {
            DCETHREAD_TRACE("Thread %p: broadcast to interrupt condwait", thread);
            return 1;
        }
    }
    else if (!pthread_mutex_trylock((pthread_mutex_t*) &info->mutex->mutex))
    {
        info->mutex->owner = pthread_self();
        if (pthread_cond_broadcast(info->cond))
        {
            DCETHREAD_ERROR("Thread %p: broadcast failed", thread);
            info->mutex->owner = (pthread_t) -1;
            pthread_mutex_unlock((pthread_mutex_t*) &info->mutex->mutex);
            return 0;
        }
        else
        {
            DCETHREAD_TRACE("Thread %p: broadcast to interrupt condwait", thread);
            info->mutex->owner = (pthread_t) -1;
            pthread_mutex_unlock((pthread_mutex_t*) &info->mutex->mutex);
            return 1;
        }
    }
    else
    {
        DCETHREAD_VERBOSE("Thread %p: could not acquire lock to interrupt condwait", thread);
        return 0;
    }
}

dcethread*
dcethread__new (void)
{
    dcethread* thread;

    thread = calloc(1, sizeof(dcethread));

    thread->refs = 1;
    thread->flag.interruptible = 1;
    thread->flag.joinable = 0;
    thread->flag.async = 0;
    thread->state = DCETHREAD_STATE_CREATED;

    pthread_mutex_init((pthread_mutex_t*) &thread->lock, NULL);
    pthread_cond_init((pthread_cond_t*) &thread->state_change, NULL);

    /* Set default interrupt handler that throws an interrupt exception */
    thread->handle_interrupt = dcethread__exc_handle_interrupt;
    thread->handle_interrupt_data = (void*) &dcethread_interrupt_e;

    /* Set default interrupt method that pokes the thread with a signal */
    thread->interrupt = dcethread__interrupt_syscall;
    thread->interrupt_data = NULL;

    return thread;
}

dcethread*
dcethread__self(void)
{
    dcethread* thread;

    /* Ensure thread system is initialized */
    dcethread__init();

    /* Get self pointer from TLS */
    thread = (dcethread*) pthread_getspecific(dcethread_self_key);
    if (!thread)
    {
	/* Lazily create it if it didn't already exist */
	thread = dcethread__new();
	thread->pthread = pthread_self();
	pthread_setspecific(dcethread_self_key, (void*) thread);
	thread->state = DCETHREAD_STATE_ACTIVE;
    }

    return thread;
}

void
dcethread__init_self(dcethread* thread)
{
    /* Ensure thread system is initialized */
    dcethread__init();

    pthread_setspecific(dcethread_self_key, (void*) thread);
    dcethread__lock(thread);
    dcethread__change_state(thread, DCETHREAD_STATE_ACTIVE);
    dcethread__unlock(thread);
}

static void
dcethread__sanity(dcethread* thread)
{
    if (!thread)
        DCETHREAD_ERROR("NULL thread encountered");
    if (thread->refs < 0)
        DCETHREAD_ERROR("Thread %p: ref count < 0", thread);
    if (!thread->flag.locked)
        DCETHREAD_ERROR("Thread %p: not locked when expected", thread);
    switch (thread->state)
    {
    case DCETHREAD_STATE_CREATED:
    case DCETHREAD_STATE_ACTIVE:
    case DCETHREAD_STATE_BLOCKED:
    case DCETHREAD_STATE_INTERRUPT:
        if (thread->refs == 0)
            DCETHREAD_ERROR("Thread %p: ref count = 0 in living thread");
        break;
    case DCETHREAD_STATE_DEAD:
        break;
    }
}

void
dcethread__delete(dcethread* thread)
{
    DCETHREAD_TRACE("Thread %p: deleted", thread);
    pthread_mutex_destroy((pthread_mutex_t*) &thread->lock);
    pthread_cond_destroy((pthread_cond_t*) &thread->state_change);    
    if (thread->flag.joinable)
        pthread_detach(thread->pthread);
    free((void*) thread);
}

void
dcethread__retain(dcethread* thread)
{
    dcethread__sanity(thread);
    if (thread->refs == 0)
    {
	DCETHREAD_ERROR("Attempted to retain freed thread %p", thread);
    }
    else
    {
	thread->refs++;
	DCETHREAD_TRACE("Thread %p: ref count increased to %i", thread, thread->refs);
    }
}

void
dcethread__release(dcethread* thread)
{
    dcethread__sanity(thread);
    if (thread->refs <= 0)
    {
	DCETHREAD_ERROR("Thread %p: attempted to release freed thread", thread);
    }
    else
    {
	thread->refs--;
	DCETHREAD_TRACE("Thread %p: ref count decreased to %i", thread, thread->refs);
    }
}

void
dcethread__lock(dcethread* thread)
{
    if (pthread_mutex_lock((pthread_mutex_t*) &thread->lock))
        DCETHREAD_ERROR("Thread %p: failed to lock mutex", thread);
    thread->flag.locked = 1;
    dcethread__sanity(thread);
    DCETHREAD_TRACE("Thread %p: locked", thread);
}

void
dcethread__unlock(dcethread* thread)
{
    unsigned int refs;

    dcethread__sanity(thread);

    /* Access reference count while thread is still locked
       in order to avoid race conditions */
    refs = thread->refs;

    thread->flag.locked = 0;
    if (pthread_mutex_unlock((pthread_mutex_t*) &thread->lock))
        DCETHREAD_ERROR("Thread %p: failed to unlock mutex", thread);
    DCETHREAD_TRACE("Thread %p: unlocked", thread);

    if (refs == 0)
    {
	dcethread__delete(thread);
    }
}

void
dcethread__wait(dcethread* thread)
{
    dcethread__sanity(thread);
    thread->flag.locked = 0;
    pthread_cond_wait((pthread_cond_t*) &thread->state_change, 
                      (pthread_mutex_t*) &thread->lock);
    thread->flag.locked = 1;
}

void
dcethread__timedwait(dcethread* thread, struct timespec* ts)
{
    dcethread__sanity(thread);
    thread->flag.locked = 0;
    pthread_cond_timedwait((pthread_cond_t*) &thread->state_change, 
                           (pthread_mutex_t*) &thread->lock, ts);
    thread->flag.locked = 1;
}

static const char*
state_name(int state)
{
#define CASE(token) case token: return #token
    switch (state)
    {
	CASE(DCETHREAD_STATE_CREATED);
	CASE(DCETHREAD_STATE_ACTIVE);
	CASE(DCETHREAD_STATE_BLOCKED);
	CASE(DCETHREAD_STATE_INTERRUPT);
	CASE(DCETHREAD_STATE_DEAD);
    }
    return "UNKNOWN";
#undef CASE
}

void
dcethread__change_state(dcethread* thread, int state)
{
    DCETHREAD_TRACE("Thread %p: state transition %s -> %s",
		thread,
		state_name(thread->state),
		state_name(state));
    thread->state = state;
    pthread_cond_broadcast((pthread_cond_t*) &thread->state_change);
}

#ifndef HAVE_PTHREAD_LOCK_GLOBAL_NP
static pthread_mutex_t dcethread_g_global_lock = PTHREAD_MUTEX_INITIALIZER;
#endif /* HAVE_PTHREAD_LOCK_GLOBAL_NP */

void dcethread__lock_global(void)
{
#ifdef HAVE_PTHREAD_LOCK_GLOBAL_NP
    pthread_lock_global_np();
#else
    pthread_mutex_lock(&dcethread_g_global_lock);
#endif /* HAVE_PTHREAD_LOCK_GLOBAL_NP */
}

void dcethread__unlock_global(void)
{
#ifdef HAVE_PTHREAD_UNLOCK_GLOBAL_NP
    pthread_unlock_global_np();
#else
    pthread_mutex_unlock(&dcethread_g_global_lock);
#endif /* HAVE_PTHREAD_UNLOCK_GLOBAL_NP */
}

void
dcethread__dispatchinterrupt(dcethread* thread)
{
    DCETHREAD_TRACE("Thread %p: interrupt acknowledged", thread);
    thread->handle_interrupt(thread, thread->handle_interrupt_data);
}

void
dcethread__interrupt(dcethread* thread)
{
    int count = 0;
    int old_state = thread->state;
    
    if (old_state == DCETHREAD_STATE_INTERRUPT ||
        old_state == DCETHREAD_STATE_DEAD)
    {
        /* Don't bother */
        return;
    }

    DCETHREAD_TRACE("Thread %p: interrupt posted", thread);
    dcethread__change_state(thread, DCETHREAD_STATE_INTERRUPT);
    
    /* We need to poke the thread and wait for an acknowledgement of the interrupt if: */
    if (thread != dcethread__self() &&         /* The interrupted thread is not us, and */
        thread->flag.interruptible &&          /* The thread can be interrupted, and */
        old_state == DCETHREAD_STATE_BLOCKED)  /* The thread was blocked */
    {
        /* FIXME: potential livelock here if another thread
           re-interrupts when the lock is released */
        while (thread->state == DCETHREAD_STATE_INTERRUPT)
        {
            struct timespec waittime;

            if (count > 2)
                DCETHREAD_WARNING("Thread %p: still not interrupted after %i ms", thread, count * 100);
            
            if (thread->interrupt(thread, thread->interrupt_data))
            {
                /* Interrupt is guaranteed to have succeeded, so
                   leave state change wait loop */
                break;
            }

            count++;
            
            my_clock_gettime(&waittime);
            waittime.tv_nsec += 100000000;
            
            if (waittime.tv_nsec > 1000000000)
            {
	       waittime.tv_nsec -= 1000000000;
	       waittime.tv_sec += 1;
	    }
            
            /* Wait for state change */
            dcethread__timedwait(thread, &waittime);
        }
    }
}

void
dcethread__set_interrupt_handler(dcethread* thread, void (*handle_interrupt)(dcethread*, void*), void* data)
{
    thread->handle_interrupt = handle_interrupt;
    thread->handle_interrupt_data = data;
}

int
dcethread__begin_block(dcethread* thread, int (*interrupt)(dcethread*, void*), void* data,
                       int (**old_interrupt)(dcethread*, void*), void** old_data)
{
    int state;
    int interruptible;

    dcethread__lock(thread);
    state = thread->state;
    interruptible = thread->flag.interruptible;
    /* If thread is currently active */
    if (state == DCETHREAD_STATE_ACTIVE)
    {
	/* Set up interruption callbacks */
	if (old_interrupt)
	    *old_interrupt = thread->interrupt;
	if (old_data)
	    *old_data = thread->interrupt_data;
	if (interrupt)
	    thread->interrupt = interrupt;
	if (data)
	    thread->interrupt_data = data;
	
	/* Change to blocked state */
	dcethread__change_state(thread, DCETHREAD_STATE_BLOCKED);
    }
    /* If an interrupt request has been posted (and we can be interrupted) */
    else if (state == DCETHREAD_STATE_INTERRUPT && interruptible)
    {
	/* Clear request */
	dcethread__change_state(thread, DCETHREAD_STATE_ACTIVE);
    }
    dcethread__unlock(thread);

    return state == DCETHREAD_STATE_INTERRUPT && interruptible;
}

int
dcethread__poll_end_block(dcethread* thread, int (*interrupt)(dcethread*, void*), void* data)
{
    int state;
    int interruptible;

    dcethread__lock(thread);
    state = thread->state;
    interruptible = thread->flag.interruptible;
    
    if (state == DCETHREAD_STATE_INTERRUPT)
    {
        if (interrupt)
            thread->interrupt = interrupt;
        if (data)
            thread->interrupt_data = data;
        if ((interruptible && state == DCETHREAD_STATE_INTERRUPT) ||
            (state == DCETHREAD_STATE_BLOCKED))
            dcethread__change_state(thread, DCETHREAD_STATE_ACTIVE);
    }

    dcethread__unlock(thread);

    return state == DCETHREAD_STATE_INTERRUPT && interruptible;
}

int
dcethread__end_block(dcethread* thread, int (*interrupt)(dcethread*, void*), void* data)
{
    int state;
    int interruptible;

    dcethread__lock(thread);
    state = thread->state;
    interruptible = thread->flag.interruptible;

    /* Switch state back to active if:
       - We were not interrupted during the block
       - We were interrupted and the thread is interruptible

       If we were interrupted but are not currently interruptible,
       we want to leave the state alone so that is is caught when
       interruptiblility is enabled again.
    */
    if ((interruptible && state == DCETHREAD_STATE_INTERRUPT) ||
        (state == DCETHREAD_STATE_BLOCKED))
    {
        if (interrupt)
            thread->interrupt = interrupt;
        if (data)
            thread->interrupt_data = data;
        dcethread__change_state(thread, DCETHREAD_STATE_ACTIVE);
    }

    dcethread__unlock(thread);

    return state == DCETHREAD_STATE_INTERRUPT && interruptible;
}

void
dcethread__cleanup_self(dcethread* self)
{
    dcethread__change_state(self, DCETHREAD_STATE_DEAD);
    dcethread__release(self);
    pthread_setspecific(dcethread_self_key, NULL);
}