lp_fence.c

/**************************************************************************
 *
 * Copyright 2009 VMware, Inc.
 * All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
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 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial portions
 * of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
 * IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
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#include "pipe/p_screen.h"
#include "util/u_memory.h"
#include "lp_debug.h"
#include "lp_fence.h"


/**
 * Create a new fence object.
 *
 * The rank will be the number of bins in the scene.  Whenever a rendering
 * thread hits a fence command, it'll increment the fence counter.  When
 * the counter == the rank, the fence is finished.
 *
 * \param rank  the expected finished value of the fence counter.
 */
struct lp_fence *
lp_fence_create(unsigned rank)
{
   static int fence_id;
   struct lp_fence *fence = CALLOC_STRUCT(lp_fence);

   if (!fence)
      return NULL;

   pipe_reference_init(&fence->reference, 1);

   (void) mtx_init(&fence->mutex, mtx_plain);
   cnd_init(&fence->signalled);

   fence->id = fence_id++;
   fence->rank = rank;

   if (LP_DEBUG & DEBUG_FENCE)
      debug_printf("%s %d\n", __FUNCTION__, fence->id);

   return fence;
}


/** Destroy a fence.  Called when refcount hits zero. */
void
lp_fence_destroy(struct lp_fence *fence)
{
   if (LP_DEBUG & DEBUG_FENCE)
      debug_printf("%s %d\n", __FUNCTION__, fence->id);

   mtx_destroy(&fence->mutex);
   cnd_destroy(&fence->signalled);
   FREE(fence);
}


/**
 * Called by the rendering threads to increment the fence counter.
 * When the counter == the rank, the fence is finished.
 */
void
lp_fence_signal(struct lp_fence *fence)
{
   if (LP_DEBUG & DEBUG_FENCE)
      debug_printf("%s %d\n", __FUNCTION__, fence->id);

   mtx_lock(&fence->mutex);

   fence->count++;
   assert(fence->count <= fence->rank);

   if (LP_DEBUG & DEBUG_FENCE)
      debug_printf("%s count=%u rank=%u\n", __FUNCTION__,
                   fence->count, fence->rank);

   /* Wakeup all threads waiting on the mutex:
    */
   cnd_broadcast(&fence->signalled);

   mtx_unlock(&fence->mutex);
}

boolean
lp_fence_signalled(struct lp_fence *f)
{
   return f->count == f->rank;
}

void
lp_fence_wait(struct lp_fence *f)
{
   if (LP_DEBUG & DEBUG_FENCE)
      debug_printf("%s %d\n", __FUNCTION__, f->id);

   mtx_lock(&f->mutex);
   assert(f->issued);
   while (f->count < f->rank) {
      cnd_wait(&f->signalled, &f->mutex);
   }
   mtx_unlock(&f->mutex);
}


boolean
lp_fence_timedwait(struct lp_fence *f, uint64_t timeout)
{
   struct timespec ts;
   int ret;

   timespec_get(&ts, TIME_UTC);

   ts.tv_nsec += timeout % 1000000000L;
   ts.tv_sec += timeout / 1000000000L;
   if (ts.tv_nsec >= 1000000000L) {
      ts.tv_sec++;
      ts.tv_nsec -= 1000000000L;
   }

   if (LP_DEBUG & DEBUG_FENCE)
      debug_printf("%s %d\n", __FUNCTION__, f->id);

   mtx_lock(&f->mutex);
   assert(f->issued);
   while (f->count < f->rank) {
      ret = cnd_timedwait(&f->signalled, &f->mutex, &ts);
      if (ret != thrd_success)
         break;
   }
   const boolean result = (f->count >= f->rank);
   mtx_unlock(&f->mutex);
   return result;
}