(sarray_{remove,free}_garbage): New functions.

(sarray_at_put, sarray_new, sarray_lazy_copy):
Modify/copy sarray structure/data in a thread-safe manner
(sarray_{realloc,free}): Reallocate/free sarray structure/data in a
thread-safe manner.

From-SVN: r11445

1 files changed, 202 insertions, 121 deletions

diff --git a/gcc/objc/sarray.c b/gcc/objc/sarray.c
index 9ed2196..fc7323a 100644
--- a/gcc/objc/sarray.c
+++ b/gcc/objc/sarray.c
@@ -1,5 +1,5 @@
 /* Sparse Arrays for Objective C dispatch tables
-   Copyright (C) 1993, 1995 Free Software Foundation, Inc.
+   Copyright (C) 1993, 1995, 1996 Free Software Foundation, Inc.
 
 This file is part of GNU CC.
 
@@ -25,13 +25,16 @@ Boston, MA 02111-1307, USA.  */
    the executable file might be covered by the GNU General Public License.  */
 
 #include "objc/sarray.h"
+#include "objc/runtime.h"
 #include <stdio.h>
 #include "assert.h"
 
-int nbuckets = 0;
-int nindices = 0;
-int narrays = 0;
-int idxsize = 0;
+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";
@@ -46,13 +49,60 @@ const void *memcpy (void*, const void*, size_t);
 void free (const void*);
 #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;
+    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) {
+    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
@@ -96,22 +146,24 @@ sarray_at_put(struct sarray* array, sidx index, void* element)
   if ((*the_index) == array->empty_index) {
 
     /* The index was previously empty, allocate a new */
-    *the_index = (struct sindex*)__objc_xmalloc(sizeof(struct sindex));
-    memcpy(*the_index, array->empty_index, sizeof(struct sindex));
-    (*the_index)->version = array->version;
+    new_index = (struct sindex*)__objc_xmalloc(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 != array->version) {
+    nindices += 1;
+  } else if ((*the_index)->version.version != array->version.version) {
 
     /* This index must be lazy copied */
     struct sindex* old_index = *the_index;
-    *the_index = (struct sindex*)__objc_xmalloc(sizeof(struct sindex));
-    memcpy( *the_index,old_index, sizeof(struct sindex));
-    (*the_index)->version = array->version;
+    new_index = (struct sindex*)__objc_xmalloc(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;
     
+    nindices += 1;
   }
 
 #endif /* OBJC_SPARSE3 */
@@ -122,18 +174,22 @@ sarray_at_put(struct sarray* array, sidx index, void* element)
 
     /* The bucket was previously empty (or something like that), */
     /* allocate a new.  This is the effect of `lazy' allocation */  
-    *the_bucket = (struct sbucket*)__objc_xmalloc(sizeof(struct sbucket));
-    memcpy((void *) *the_bucket, (const void*)array->empty_bucket, sizeof(struct sbucket));
-    (*the_bucket)->version = array->version;
+    new_bucket = (struct sbucket*)__objc_xmalloc(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 != array->version) {
+  } else if ((*the_bucket)->version.version != array->version.version) {
 
     /* Perform lazy copy. */
     struct sbucket* old_bucket = *the_bucket;
-    *the_bucket = (struct sbucket*)__objc_xmalloc(sizeof(struct sbucket));
-    memcpy( *the_bucket,old_bucket, sizeof(struct sbucket));
-    (*the_bucket)->version = array->version;
+    new_bucket = (struct sbucket*)__objc_xmalloc(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;
 
   }
@@ -151,42 +207,48 @@ sarray_at_put_safe(struct sarray* array, sidx index, void* 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
   int counter;
-  struct sarray* arr;
 
   assert(size > 0);
 
   /* Allocate core array */
   arr = (struct sarray*) __objc_xmalloc(sizeof(struct sarray));
-  arr->version = 0;
-  narrays  += 1;
+  arr->version.version = 0;
   
   /* Initialize members */
 #ifdef OBJC_SPARSE3
   arr->capacity = num_indices*INDEX_CAPACITY;
-  arr->indices = (struct sindex**) 
+  new_indices = (struct sindex**) 
     __objc_xmalloc(sizeof(struct sindex*)*num_indices);
-  idxsize  += num_indices;
 
   arr->empty_index = (struct sindex*) __objc_xmalloc(sizeof(struct sindex));
-  arr->empty_index->version = 0;
+  arr->empty_index->version.version = 0;
+  
+  narrays  += 1;
+  idxsize  += num_indices;
   nindices += 1;
 
 #else /* OBJC_SPARSE2 */
   arr->capacity = num_indices*BUCKET_SIZE;
-  arr->buckets = (struct sbucket**) 
+  new_buckets = (struct sbucket**) 
     __objc_xmalloc(sizeof(struct sbucket*)*num_indices);
+  
+  narrays  += 1;
   idxsize  += num_indices;
 
 #endif
 
   arr->empty_bucket = (struct sbucket*) __objc_xmalloc(sizeof(struct sbucket));
-  arr->empty_bucket->version = 0;
+  arr->empty_bucket->version.version = 0;
+  
   nbuckets += 1;
 
   arr->ref_count = 1;
@@ -200,20 +262,28 @@ sarray_new (int size, void* default_element)
     arr->empty_index->buckets[counter] = arr->empty_bucket;
 
   for (counter=0; counter<num_indices; counter++)
-    arr->indices[counter] = arr->empty_index;
+    new_indices[counter] = arr->empty_index;
 
 #else /* OBJC_SPARSE2 */
 
   for (counter=0; counter<num_indices; counter++)
-    arr->buckets[counter] = arr->empty_bucket;
+    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 */
+/* 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)
@@ -223,11 +293,17 @@ sarray_realloc(struct sarray* array, int newsize)
   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
 
   int counter;
@@ -235,87 +311,72 @@ sarray_realloc(struct sarray* array, int newsize)
   assert(newsize > 0);
 
   /* The size is the same, just ignore the request */
-  if(rounded_size == array->capacity)
+  if(rounded_size <= array->capacity)
     return;
 
   assert(array->ref_count == 1);	/* stop if lazy copied... */
 
-  if(rounded_size < array->capacity) 
+  /* 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;
 
-      /* free buckets above new_max_index */
-      for(counter = old_max_index; counter > new_max_index; counter-- ) {
 #ifdef OBJC_SPARSE3
-	struct sindex* idx = array->indices[counter];
-	if((idx != array->empty_index) && (idx->version == array->version)) {
-	  int c2; 
-	  for(c2=0; c2<INDEX_SIZE; c2++) {
-	    struct sbucket* bkt = idx->buckets[c2];
-	    if((bkt != array->empty_bucket) && (bkt->version == array->version))
-	      {
-		free(bkt);
-		nbuckets -= 1;
-	      }
-	  }
-	  free(idx);
-	  nindices -= 1;
-	}
+      /* alloc to force re-read by any concurrent readers. */
+      old_indices = array->indices;
+      new_indices = (struct sindex**)
+	__objc_xmalloc((new_max_index+1)*sizeof(struct sindex*));
 #else /* OBJC_SPARSE2 */
-	struct sbucket* bkt = array->buckets[counter];
-	if ((bkt != array->empty_bucket) && (bkt->version == array->version))
-	  {
-	    free(bkt);
-	    nbuckets -= 1;
-	  }
+      old_buckets = array->buckets;
+      new_buckets = (struct sbucket**)
+	__objc_xmalloc((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
-      /* realloc to free the space above new_max_index */
-      array->indices = (struct sindex**)
-	__objc_xrealloc(array->indices, 
-			(new_max_index+1)*sizeof(struct sindex*));
+	new_indices[counter] = old_indices[counter];
 #else /* OBJC_SPARSE2 */
-      array->buckets = (struct sbucket**)
-	__objc_xrealloc(array->buckets, 
-			(new_max_index+1)*sizeof(struct sbucket*));
-#endif      
-      idxsize -= (old_max_index-new_max_index);
-
-      return;
-    }
-
-  /* We are asked to extend the array -- reallocate the bucket table, */
-  /* and insert empty_bucket in newly allocated places. */
-  if(rounded_size > array->capacity) 
-    {
-      /* update capacity */
-      array->capacity = rounded_size;
+	new_buckets[counter] = old_buckets[counter];
+#endif
+      }
 
 #ifdef OBJC_SPARSE3
-      /* realloc to make room in table above old_max_index */
-      array->indices = (struct sindex**)
-	__objc_xrealloc(array->indices, 
-			(new_max_index+1)*sizeof(struct sindex*));
-
       /* reset entries above old_max_index to empty_bucket */
       for(counter = old_max_index+1; counter <= new_max_index; counter++)
-	array->indices[counter] = array->empty_index;
-
+	new_indices[counter] = array->empty_index;
 #else /* OBJC_SPARSE2 */
-
-      /* realloc to make room in table above old_max_index */
-      array->buckets = (struct sbucket**)
-	__objc_xrealloc(array->buckets, 
-			(new_max_index+1)*sizeof(struct sbucket*));
-
       /* reset entries above old_max_index to empty_bucket */
       for(counter = old_max_index+1; counter <= new_max_index; counter++)
-	array->buckets[counter] = array->empty_bucket;
+	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;
     }
@@ -326,10 +387,13 @@ sarray_realloc(struct sarray* array, int newsize)
 
 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
   int counter = 0;
 
@@ -338,31 +402,40 @@ sarray_free(struct sarray* array) {
   if(--(array->ref_count) != 0)	/* There exists copies of me */
     return;
 
+#ifdef OBJC_SPARSE3
+  old_indices = array->indices;
+#else
+  old_buckets = array->buckets;
+#endif
+  
   if((array->is_copy_of) && ((array->is_copy_of->ref_count - 1) == 0))
     sarray_free(array->is_copy_of);
 
   /* Free all entries that do not point to empty_bucket */
   for(counter = 0; counter <= old_max_index; counter++ ) {
 #ifdef OBJC_SPARSE3
-    struct sindex* idx = array->indices[counter];
-    if((idx != array->empty_index) && (idx->version == array->version)) {
+    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 == array->version))
+	if((bkt != array->empty_bucket) &&
+	   (bkt->version.version == array->version.version))
 	  {
-	    free(bkt);
+	    sarray_free_garbage(bkt);
 	    nbuckets -= 1;
 	  }
       }
-      free(idx);
+      sarray_free_garbage(idx);
       nindices -= 1;
     }
 #else /* OBJC_SPARSE2 */
     struct sbucket* bkt = array->buckets[counter];
-    if ((bkt != array->empty_bucket) && (bkt->version == array->version))
+    if ((bkt != array->empty_bucket) &&
+	(bkt->version.version == array->version.version))
       {
-	free(bkt);
+	sarray_free_garbage(bkt);
 	nbuckets -= 1;
       }
 #endif
@@ -370,33 +443,32 @@ sarray_free(struct sarray* array) {
 	
 #ifdef OBJC_SPARSE3  
   /* free empty_index */
-  if(array->empty_index->version == array->version) {
-    free(array->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 == array->version) {
-    free(array->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 */
-  free(array->indices);
-  idxsize -= (old_max_index+1);
+  sarray_free_garbage(array->indices);
 
 #else
   /* free bucket table */
-  free(array->buckets);
-  idxsize -= (old_max_index+1);
+  sarray_free_garbage(array->buckets);
 
 #endif
-
+  
   /* free array */
-  free(array);
-  narrays -= 1;
+  sarray_free_garbage(array);
 }
 
 /* This is a lazy copy.  Only the core of the structure is actually */
@@ -405,37 +477,46 @@ sarray_free(struct sarray* array) {
 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
-  struct sarray* arr;
 
   /* Allocate core array */
-  arr = (struct sarray*) __objc_xmalloc(sizeof(struct sarray));
-  memcpy( arr,oarr, sizeof(struct sarray));
-  arr->version = oarr->version + 1;
-  arr->is_copy_of = oarr;
-  oarr->ref_count += 1;
+  arr = (struct sarray*) __objc_xmalloc(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 */
-  arr->indices = (struct sindex**) 
+  new_indices = (struct sindex**) 
     __objc_xmalloc(sizeof(struct sindex*)*num_indices);
-  memcpy( arr->indices,oarr->indices, 
+  memcpy( new_indices,oarr->indices, 
 	sizeof(struct sindex*)*num_indices);
+  arr->indices = new_indices;
 #else 
   /* Copy bucket table */
-  arr->buckets = (struct sbucket**) 
+  new_buckets = (struct sbucket**) 
     __objc_xmalloc(sizeof(struct sbucket*)*num_indices);
-  memcpy( arr->buckets,oarr->buckets, 
+  memcpy( new_buckets,oarr->buckets, 
 	sizeof(struct sbucket*)*num_indices);
+  arr->buckets = new_buckets;
 #endif
 
   idxsize += num_indices;
   narrays += 1;
-
+  
   return arr;
 }