gcc/libobjc/sarray.c

/* Sparse Arrays for Objective C dispatch tables
   Copyright (C) 1993, 1995, 1996, 2002, 2004, 2009 Free Software Foundation, Inc.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.

GCC is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.

You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
<http://www.gnu.org/licenses/>.  */


#include "objc/sarray.h"
#include "objc/runtime.h"
#include <stdio.h>
#include "assert.h"

int nbuckets = 0;					/* !T:MUTEX */
int nindices = 0;					/* !T:MUTEX */
int narrays = 0;					/* !T:MUTEX */
int idxsize = 0;					/* !T:MUTEX */

static void *first_free_data = NULL;			/* !T:MUTEX */

#ifdef OBJC_SPARSE2
const char *__objc_sparse2_id = "2 level sparse indices";
#endif

#ifdef OBJC_SPARSE3
const char *__objc_sparse3_id = "3 level sparse indices";
#endif

/* This function removes any structures left over from free operations
   that were not safe in a multi-threaded environment. */
void
sarray_remove_garbage (void)
{
  void **vp;
  void *np;
  
  objc_mutex_lock (__objc_runtime_mutex);

  vp = first_free_data;
  first_free_data = NULL;

  while (vp) {
    np = *vp;
    objc_free (vp);
    vp = np;
  }
  
  objc_mutex_unlock (__objc_runtime_mutex);
}

/* Free a block of dynamically allocated memory.  If we are in multi-threaded
   mode, it is ok to free it.  If not, we add it to the garbage heap to be
   freed later. */

static void
sarray_free_garbage (void *vp)
{
  objc_mutex_lock (__objc_runtime_mutex);
  
  if (__objc_runtime_threads_alive == 1) {
    objc_free (vp);
    if (first_free_data)
      sarray_remove_garbage ();
  }
  else {
    *(void **)vp = first_free_data;
    first_free_data = vp;
  }
      
  objc_mutex_unlock (__objc_runtime_mutex);
}

/* sarray_at_put : copies data in such a way as to be thread reader safe. */
void
sarray_at_put (struct sarray *array, sidx index, void *element)
{
#ifdef OBJC_SPARSE3
  struct sindex **the_index;
  struct sindex *new_index;
#endif
  struct sbucket **the_bucket;
  struct sbucket *new_bucket;
#ifdef OBJC_SPARSE3
  size_t ioffset;
#endif
  size_t boffset;
  size_t eoffset;
#ifdef PRECOMPUTE_SELECTORS
  union sofftype xx; 
  xx.idx = index;
#ifdef OBJC_SPARSE3
  ioffset = xx.off.ioffset;
#endif
  boffset = xx.off.boffset;
  eoffset = xx.off.eoffset;
#else /* not PRECOMPUTE_SELECTORS */
#ifdef OBJC_SPARSE3
  ioffset = index/INDEX_CAPACITY;
  boffset = (index/BUCKET_SIZE)%INDEX_SIZE;
  eoffset = index%BUCKET_SIZE;
#else
  boffset = index/BUCKET_SIZE;
  eoffset = index%BUCKET_SIZE;
#endif
#endif /* not PRECOMPUTE_SELECTORS */

  assert (soffset_decode (index) < array->capacity); /* Range check */

#ifdef OBJC_SPARSE3
  the_index = &(array->indices[ioffset]);
  the_bucket = &((*the_index)->buckets[boffset]);
#else
  the_bucket = &(array->buckets[boffset]);
#endif
  
  if ((*the_bucket)->elems[eoffset] == element)
    return;		/* great! we just avoided a lazy copy */

#ifdef OBJC_SPARSE3

  /* First, perform lazy copy/allocation of index if needed */

  if ((*the_index) == array->empty_index) {

    /* The index was previously empty, allocate a new */
    new_index = (struct sindex *) objc_malloc (sizeof (struct sindex));
    memcpy (new_index, array->empty_index, sizeof (struct sindex));
    new_index->version.version = array->version.version;
    *the_index = new_index;                     /* Prepared for install. */
    the_bucket = &((*the_index)->buckets[boffset]);
    
    nindices += 1;
  } else if ((*the_index)->version.version != array->version.version) {

    /* This index must be lazy copied */
    struct sindex *old_index = *the_index;
    new_index = (struct sindex *) objc_malloc (sizeof (struct sindex));
    memcpy (new_index, old_index, sizeof (struct sindex));
    new_index->version.version = array->version.version;
    *the_index = new_index;                     /* Prepared for install. */
    the_bucket = &((*the_index)->buckets[boffset]);
    
    nindices += 1;
  }

#endif /* OBJC_SPARSE3 */

  /* next, perform lazy allocation/copy of the bucket if needed */

  if ((*the_bucket) == array->empty_bucket) {

    /* The bucket was previously empty (or something like that), */
    /* allocate a new.  This is the effect of `lazy' allocation */  
    new_bucket = (struct sbucket *) objc_malloc (sizeof (struct sbucket));
    memcpy ((void *) new_bucket, (const void *) array->empty_bucket, 
	    sizeof (struct sbucket));
    new_bucket->version.version = array->version.version;
    *the_bucket = new_bucket;                   /* Prepared for install. */
    
    nbuckets += 1;

  } else if ((*the_bucket)->version.version != array->version.version) {

    /* Perform lazy copy. */
    struct sbucket *old_bucket = *the_bucket;
    new_bucket = (struct sbucket *) objc_malloc (sizeof (struct sbucket));
    memcpy (new_bucket, old_bucket, sizeof (struct sbucket));
    new_bucket->version.version = array->version.version;
    *the_bucket = new_bucket;                   /* Prepared for install. */
    
    nbuckets += 1;

  }
  (*the_bucket)->elems[eoffset] = element;
}

void
sarray_at_put_safe (struct sarray *array, sidx index, void *element)
{
  if (soffset_decode (index) >= array->capacity)
    sarray_realloc (array, soffset_decode (index) + 1);
  sarray_at_put (array, index, element);
}

struct sarray *
sarray_new (int size, void *default_element)
{
  struct sarray *arr;
#ifdef OBJC_SPARSE3
  size_t num_indices = ((size - 1)/(INDEX_CAPACITY)) + 1;
  struct sindex **new_indices;
#else /* OBJC_SPARSE2 */
  size_t num_indices = ((size - 1)/BUCKET_SIZE) + 1;
  struct sbucket **new_buckets;
#endif
  size_t counter;

  assert (size > 0);

  /* Allocate core array */
  arr = (struct sarray *) objc_malloc (sizeof (struct sarray));
  arr->version.version = 0;
  
  /* Initialize members */
#ifdef OBJC_SPARSE3
  arr->capacity = num_indices*INDEX_CAPACITY;
  new_indices = (struct sindex **) 
    objc_malloc (sizeof (struct sindex *) * num_indices);

  arr->empty_index = (struct sindex *) objc_malloc (sizeof (struct sindex));
  arr->empty_index->version.version = 0;
  
  narrays  += 1;
  idxsize  += num_indices;
  nindices += 1;

#else /* OBJC_SPARSE2 */
  arr->capacity = num_indices*BUCKET_SIZE;
  new_buckets = (struct sbucket **) 
    objc_malloc (sizeof (struct sbucket *) * num_indices);
  
  narrays  += 1;
  idxsize  += num_indices;

#endif

  arr->empty_bucket = (struct sbucket *) objc_malloc (sizeof (struct sbucket));
  arr->empty_bucket->version.version = 0;
  
  nbuckets += 1;

  arr->ref_count = 1;
  arr->is_copy_of = (struct sarray *) 0;
  
  for (counter = 0; counter < BUCKET_SIZE; counter++)
    arr->empty_bucket->elems[counter] = default_element;

#ifdef OBJC_SPARSE3
  for (counter = 0; counter < INDEX_SIZE; counter++)
    arr->empty_index->buckets[counter] = arr->empty_bucket;

  for (counter = 0; counter < num_indices; counter++)
    new_indices[counter] = arr->empty_index;

#else /* OBJC_SPARSE2 */

  for (counter = 0; counter < num_indices; counter++)
    new_buckets[counter] = arr->empty_bucket;

#endif
  
#ifdef OBJC_SPARSE3
  arr->indices = new_indices;
#else /* OBJC_SPARSE2 */
  arr->buckets = new_buckets;
#endif
  
  return arr;
}


/* Reallocate the sparse array to hold `newsize' entries
   Note: We really allocate and then free.  We have to do this to ensure that
   any concurrent readers notice the update. */

void 
sarray_realloc (struct sarray *array, int newsize)
{
#ifdef OBJC_SPARSE3
  size_t old_max_index = (array->capacity - 1)/INDEX_CAPACITY;
  size_t new_max_index = ((newsize - 1)/INDEX_CAPACITY);
  size_t rounded_size = (new_max_index + 1) * INDEX_CAPACITY;

  struct sindex **new_indices;
  struct sindex **old_indices;
  
#else /* OBJC_SPARSE2 */
  size_t old_max_index = (array->capacity - 1)/BUCKET_SIZE;
  size_t new_max_index = ((newsize - 1)/BUCKET_SIZE);
  size_t rounded_size = (new_max_index + 1) * BUCKET_SIZE;

  struct sbucket **new_buckets;
  struct sbucket **old_buckets;
  
#endif

  size_t counter;

  assert (newsize > 0);

  /* The size is the same, just ignore the request */
  if (rounded_size <= array->capacity)
    return;

  assert (array->ref_count == 1);	/* stop if lazy copied... */

  /* We are asked to extend the array -- allocate new bucket table, */
  /* and insert empty_bucket in newly allocated places. */
  if (rounded_size > array->capacity) 
    {

#ifdef OBJC_SPARSE3
      new_max_index += 4;
      rounded_size = (new_max_index + 1) * INDEX_CAPACITY;
      
#else /* OBJC_SPARSE2 */
      new_max_index += 4;
      rounded_size = (new_max_index + 1) * BUCKET_SIZE;
#endif
      
      /* update capacity */
      array->capacity = rounded_size;

#ifdef OBJC_SPARSE3
      /* alloc to force re-read by any concurrent readers. */
      old_indices = array->indices;
      new_indices = (struct sindex **)
	objc_malloc ((new_max_index + 1) * sizeof (struct sindex *));
#else /* OBJC_SPARSE2 */
      old_buckets = array->buckets;
      new_buckets = (struct sbucket **)
	objc_malloc ((new_max_index + 1) * sizeof (struct sbucket *));
#endif

      /* copy buckets below old_max_index (they are still valid) */
      for (counter = 0; counter <= old_max_index; counter++ ) {
#ifdef OBJC_SPARSE3
	new_indices[counter] = old_indices[counter];
#else /* OBJC_SPARSE2 */
	new_buckets[counter] = old_buckets[counter];
#endif
      }

#ifdef OBJC_SPARSE3
      /* reset entries above old_max_index to empty_bucket */
      for (counter = old_max_index + 1; counter <= new_max_index; counter++)
	new_indices[counter] = array->empty_index;
#else /* OBJC_SPARSE2 */
      /* reset entries above old_max_index to empty_bucket */
      for (counter = old_max_index + 1; counter <= new_max_index; counter++)
	new_buckets[counter] = array->empty_bucket;
#endif
      
#ifdef OBJC_SPARSE3
      /* install the new indices */
      array->indices = new_indices;
#else /* OBJC_SPARSE2 */
      array->buckets = new_buckets;
#endif

#ifdef OBJC_SPARSE3
      /* free the old indices */
      sarray_free_garbage (old_indices);
#else /* OBJC_SPARSE2 */
      sarray_free_garbage (old_buckets);
#endif
      
      idxsize += (new_max_index-old_max_index);
      return;
    }
}


/* Free a sparse array allocated with sarray_new */

void 
sarray_free (struct sarray *array) {
#ifdef OBJC_SPARSE3
  size_t old_max_index = (array->capacity - 1)/INDEX_CAPACITY;
  struct sindex **old_indices;
#else
  size_t old_max_index = (array->capacity - 1)/BUCKET_SIZE;
  struct sbucket **old_buckets;
#endif
  size_t counter = 0;

  assert (array->ref_count != 0);	/* Freed multiple times!!! */

  if (--(array->ref_count) != 0)	/* There exists copies of me */
    return;

#ifdef OBJC_SPARSE3
  old_indices = array->indices;
#else
  old_buckets = array->buckets;
#endif

  /* Free all entries that do not point to empty_bucket */
  for (counter = 0; counter <= old_max_index; counter++ ) {
#ifdef OBJC_SPARSE3
    struct sindex *idx = old_indices[counter];
    if ((idx != array->empty_index) &&
       (idx->version.version == array->version.version)) {
      int c2; 
      for (c2 = 0; c2 < INDEX_SIZE; c2++) {
	struct sbucket *bkt = idx->buckets[c2];
	if ((bkt != array->empty_bucket) &&
	   (bkt->version.version == array->version.version))
	  {
	    sarray_free_garbage (bkt);
	    nbuckets -= 1;
	  }
      }
      sarray_free_garbage (idx);
      nindices -= 1;
    }
#else /* OBJC_SPARSE2 */
    struct sbucket *bkt = old_buckets[counter];
    if ((bkt != array->empty_bucket) &&
	(bkt->version.version == array->version.version))
      {
	sarray_free_garbage (bkt);
	nbuckets -= 1;
      }
#endif
  }
	
#ifdef OBJC_SPARSE3  
  /* free empty_index */
  if (array->empty_index->version.version == array->version.version) {
    sarray_free_garbage (array->empty_index);
    nindices -= 1;
  }
#endif

  /* free empty_bucket */
  if (array->empty_bucket->version.version == array->version.version) {
    sarray_free_garbage (array->empty_bucket);
    nbuckets -= 1;
  }
  idxsize -= (old_max_index + 1);
  narrays -= 1;

#ifdef OBJC_SPARSE3
  /* free bucket table */
  sarray_free_garbage (array->indices);

#else
  /* free bucket table */
  sarray_free_garbage (array->buckets);

#endif
  
  /* If this is a copy of another array, we free it (which might just
   * decrement its reference count so it will be freed when no longer in use).
   */
  if (array->is_copy_of)
    sarray_free (array->is_copy_of);

  /* free array */
  sarray_free_garbage (array);
}

/* This is a lazy copy.  Only the core of the structure is actually */
/* copied.   */

struct sarray *
sarray_lazy_copy (struct sarray *oarr)
{
  struct sarray *arr;

#ifdef OBJC_SPARSE3
  size_t num_indices = ((oarr->capacity - 1)/INDEX_CAPACITY) + 1;
  struct sindex **new_indices;
#else /* OBJC_SPARSE2 */
  size_t num_indices = ((oarr->capacity - 1)/BUCKET_SIZE) + 1;
  struct sbucket **new_buckets;
#endif

  /* Allocate core array */
  arr = (struct sarray *) objc_malloc (sizeof (struct sarray)); /* !!! */
  arr->version.version = oarr->version.version + 1;
#ifdef OBJC_SPARSE3
  arr->empty_index = oarr->empty_index;
#endif
  arr->empty_bucket = oarr->empty_bucket;
  arr->ref_count = 1;
  oarr->ref_count += 1;
  arr->is_copy_of = oarr;
  arr->capacity = oarr->capacity;
  
#ifdef OBJC_SPARSE3
  /* Copy bucket table */
  new_indices = (struct sindex **) 
    objc_malloc (sizeof (struct sindex *) * num_indices);
  memcpy (new_indices, oarr->indices, sizeof (struct sindex *) * num_indices);
  arr->indices = new_indices;
#else 
  /* Copy bucket table */
  new_buckets = (struct sbucket **) 
    objc_malloc (sizeof (struct sbucket *) * num_indices);
  memcpy (new_buckets, oarr->buckets, sizeof (struct sbucket *) * num_indices);
  arr->buckets = new_buckets;
#endif

  idxsize += num_indices;
  narrays += 1;
  
  return arr;
}