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authorVolker Lendecke <vl@samba.org>2008-01-05 18:26:54 +0100
committerJeremy Allison <jra@samba.org>2008-01-09 17:05:19 -0800
commit1ed4fcb271b7885c274bd88bafed8116779d8eb6 (patch)
tree11a2bf2be3acbd22e866abdf3001746bf69ba80d
parent6a1022288217304ebf4f3a3e59a1efa472ff2c5b (diff)
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Implement talloc_pool()
A talloc pool is a chunk of memory that can be used as a context for further talloc calls. Allocations with the pool as the parent just chew from that memory by incrementing a pointer. If the talloc pool is full, then we fall back to the normal system-level malloc(3) to get memory. The use case for talloc pools is the transient memory that is used for handling a single SMB request. Incrementing a pointer will be way faster than any malloc implementation. There is a downside of this: If you use talloc_steal() to move something out of the pool, the whole pool memory is kept around until the last object inside the pool is freed. So if you talloc_free() the pool, it might happen that the memory is freed later. So don't hang anything off a talloc pool that should live long. Volker (This used to be commit 287e29d988813007eeebc0c2bef3b46ab8bedee9)
-rw-r--r--source3/lib/talloc/talloc.c176
-rw-r--r--source3/lib/talloc/talloc.h1
-rw-r--r--source3/lib/talloc/testsuite.c37
3 files changed, 207 insertions, 7 deletions
diff --git a/source3/lib/talloc/talloc.c b/source3/lib/talloc/talloc.c
index 3e976bc0fc..178bbb97e4 100644
--- a/source3/lib/talloc/talloc.c
+++ b/source3/lib/talloc/talloc.c
@@ -60,6 +60,8 @@
#define TALLOC_MAGIC 0xe814ec70
#define TALLOC_FLAG_FREE 0x01
#define TALLOC_FLAG_LOOP 0x02
+#define TALLOC_FLAG_POOL 0x04 /* This is a talloc pool */
+#define TALLOC_FLAG_POOLMEM 0x08 /* This is allocated in a pool */
#define TALLOC_MAGIC_REFERENCE ((const char *)1)
/* by default we abort when given a bad pointer (such as when talloc_free() is called
@@ -109,6 +111,19 @@ struct talloc_chunk {
const char *name;
size_t size;
unsigned flags;
+
+ /*
+ * "pool" has dual use:
+ *
+ * For the talloc pool itself (i.e. TALLOC_FLAG_POOL is set), "pool"
+ * marks the end of the currently allocated area.
+ *
+ * For members of the pool (i.e. TALLOC_FLAG_POOLMEM is set), "pool"
+ * is a pointer to the struct talloc_chunk of the pool that it was
+ * allocated from. This way children can quickly find the pool to chew
+ * from.
+ */
+ void *pool;
};
/* 16 byte alignment seems to keep everyone happy */
@@ -200,12 +215,82 @@ const char *talloc_parent_name(const void *ptr)
return tc? tc->name : NULL;
}
+/*
+ A pool carries an in-pool object count count in the first 16 bytes.
+ bytes. This is done to support talloc_steal() to a parent outside of the
+ pool. The count includes the pool itself, so a talloc_free() on a pool will
+ only destroy the pool if the count has dropped to zero. A talloc_free() of a
+ pool member will reduce the count, and eventually also call free(3) on the
+ pool memory.
+
+ The object count is not put into "struct talloc_chunk" because it is only
+ relevant for talloc pools and the alignment to 16 bytes would increase the
+ memory footprint of each talloc chunk by those 16 bytes.
+*/
+
+#define TALLOC_POOL_HDR_SIZE 16
+
+static unsigned int *talloc_pool_objectcount(struct talloc_chunk *tc)
+{
+ return (unsigned int *)((char *)tc + sizeof(struct talloc_chunk));
+}
+
+/*
+ Allocate from a pool
+*/
+
+static struct talloc_chunk *talloc_alloc_pool(struct talloc_chunk *parent,
+ size_t size)
+{
+ struct talloc_chunk *pool_ctx = NULL;
+ size_t space_left;
+ struct talloc_chunk *result;
+
+ if (parent == NULL) {
+ return NULL;
+ }
+
+ if (parent->flags & TALLOC_FLAG_POOL) {
+ pool_ctx = parent;
+ }
+ else if (parent->flags & TALLOC_FLAG_POOLMEM) {
+ pool_ctx = (struct talloc_chunk *)parent->pool;
+ }
+
+ if (pool_ctx == NULL) {
+ return NULL;
+ }
+
+ space_left = ((char *)pool_ctx + TC_HDR_SIZE + pool_ctx->size)
+ - ((char *)pool_ctx->pool);
+
+ /*
+ * Align size to 16 bytes
+ */
+ size = ((size + 15) & ~15);
+
+ if (space_left < size) {
+ return NULL;
+ }
+
+ result = (struct talloc_chunk *)pool_ctx->pool;
+
+ pool_ctx->pool = (void *)((char *)result + size);
+
+ result->flags = TALLOC_MAGIC | TALLOC_FLAG_POOLMEM;
+ result->pool = pool_ctx;
+
+ *talloc_pool_objectcount(pool_ctx) += 1;
+
+ return result;
+}
+
/*
Allocate a bit of memory as a child of an existing pointer
*/
static inline void *__talloc(const void *context, size_t size)
{
- struct talloc_chunk *tc;
+ struct talloc_chunk *tc = NULL;
if (unlikely(context == NULL)) {
context = null_context;
@@ -215,11 +300,19 @@ static inline void *__talloc(const void *context, size_t size)
return NULL;
}
- tc = (struct talloc_chunk *)malloc(TC_HDR_SIZE+size);
- if (unlikely(tc == NULL)) return NULL;
+ if (context != NULL) {
+ tc = talloc_alloc_pool(talloc_chunk_from_ptr(context),
+ TC_HDR_SIZE+size);
+ }
+
+ if (tc == NULL) {
+ tc = (struct talloc_chunk *)malloc(TC_HDR_SIZE+size);
+ if (unlikely(tc == NULL)) return NULL;
+ tc->flags = TALLOC_MAGIC;
+ tc->pool = NULL;
+ }
tc->size = size;
- tc->flags = TALLOC_MAGIC;
tc->destructor = NULL;
tc->child = NULL;
tc->name = NULL;
@@ -246,6 +339,29 @@ static inline void *__talloc(const void *context, size_t size)
}
/*
+ * Create a talloc pool
+ */
+
+void *talloc_pool(const void *context, size_t size)
+{
+ void *result = __talloc(context, size + TALLOC_POOL_HDR_SIZE);
+ struct talloc_chunk *tc;
+
+ if (unlikely(result == NULL)) {
+ return NULL;
+ }
+
+ tc = talloc_chunk_from_ptr(result);
+
+ tc->flags |= TALLOC_FLAG_POOL;
+ tc->pool = (char *)result + TALLOC_POOL_HDR_SIZE;
+
+ *talloc_pool_objectcount(tc) = 1;
+
+ return result;
+}
+
+/*
setup a destructor to be called on free of a pointer
the destructor should return 0 on success, or -1 on failure.
if the destructor fails then the free is failed, and the memory can
@@ -420,7 +536,29 @@ static inline int _talloc_free(void *ptr)
}
tc->flags |= TALLOC_FLAG_FREE;
- free(tc);
+
+ if (tc->flags & (TALLOC_FLAG_POOL|TALLOC_FLAG_POOLMEM)) {
+ struct talloc_chunk *pool;
+ unsigned int *pool_object_count;
+
+ pool = (tc->flags & TALLOC_FLAG_POOL)
+ ? tc : (struct talloc_chunk *)tc->pool;
+
+ pool_object_count = talloc_pool_objectcount(pool);
+
+ if (*pool_object_count == 0) {
+ TALLOC_ABORT("Pool object count zero!");
+ }
+
+ *pool_object_count -= 1;
+
+ if (*pool_object_count == 0) {
+ free(pool);
+ }
+ }
+ else {
+ free(tc);
+ }
return 0;
}
@@ -718,6 +856,10 @@ void talloc_free_children(void *ptr)
talloc_steal(new_parent, child);
}
}
+
+ if (tc->flags & TALLOC_FLAG_POOL) {
+ tc->pool = ((char *)tc + TC_HDR_SIZE + TALLOC_POOL_HDR_SIZE);
+ }
}
/*
@@ -769,6 +911,7 @@ void *_talloc_realloc(const void *context, void *ptr, size_t size, const char *n
{
struct talloc_chunk *tc;
void *new_ptr;
+ bool malloced = false;
/* size zero is equivalent to free() */
if (unlikely(size == 0)) {
@@ -808,7 +951,23 @@ void *_talloc_realloc(const void *context, void *ptr, size_t size, const char *n
free(tc);
}
#else
- new_ptr = realloc(tc, size + TC_HDR_SIZE);
+ if (tc->flags & TALLOC_FLAG_POOLMEM) {
+
+ new_ptr = talloc_alloc_pool(tc, size + TC_HDR_SIZE);
+ *talloc_pool_objectcount(tc->pool) -= 1;
+
+ if (new_ptr == NULL) {
+ new_ptr = malloc(TC_HDR_SIZE+size);
+ malloced = true;
+ }
+
+ if (new_ptr) {
+ memcpy(new_ptr, tc, MIN(tc->size,size) + TC_HDR_SIZE);
+ }
+ }
+ else {
+ new_ptr = realloc(tc, size + TC_HDR_SIZE);
+ }
#endif
if (unlikely(!new_ptr)) {
tc->flags &= ~TALLOC_FLAG_FREE;
@@ -816,7 +975,10 @@ void *_talloc_realloc(const void *context, void *ptr, size_t size, const char *n
}
tc = (struct talloc_chunk *)new_ptr;
- tc->flags &= ~TALLOC_FLAG_FREE;
+ tc->flags &= ~TALLOC_FLAG_FREE;
+ if (malloced) {
+ tc->flags &= ~TALLOC_FLAG_POOLMEM;
+ }
if (tc->parent) {
tc->parent->child = tc;
}
diff --git a/source3/lib/talloc/talloc.h b/source3/lib/talloc/talloc.h
index e103391681..5431971655 100644
--- a/source3/lib/talloc/talloc.h
+++ b/source3/lib/talloc/talloc.h
@@ -116,6 +116,7 @@ typedef void TALLOC_CTX;
/* The following definitions come from talloc.c */
void *_talloc(const void *context, size_t size);
+void *talloc_pool(const void *context, size_t size);
void _talloc_set_destructor(const void *ptr, int (*destructor)(void *));
int talloc_increase_ref_count(const void *ptr);
size_t talloc_reference_count(const void *ptr);
diff --git a/source3/lib/talloc/testsuite.c b/source3/lib/talloc/testsuite.c
index e16c91f8b9..fedbda95aa 100644
--- a/source3/lib/talloc/testsuite.c
+++ b/source3/lib/talloc/testsuite.c
@@ -813,6 +813,25 @@ static bool test_speed(void)
talloc_free(ctx);
+ ctx = talloc_pool(NULL, 1024);
+
+ tv = timeval_current();
+ count = 0;
+ do {
+ void *p1, *p2, *p3;
+ for (i=0;i<loop;i++) {
+ p1 = talloc_size(ctx, loop % 100);
+ p2 = talloc_strdup(p1, "foo bar");
+ p3 = talloc_size(p1, 300);
+ talloc_free_children(ctx);
+ }
+ count += 3 * loop;
+ } while (timeval_elapsed(&tv) < 5.0);
+
+ talloc_free(ctx);
+
+ fprintf(stderr, "talloc_pool: %.0f ops/sec\n", count/timeval_elapsed(&tv));
+
tv = timeval_current();
count = 0;
do {
@@ -1066,6 +1085,23 @@ static bool test_autofree(void)
return true;
}
+static bool test_pool(void)
+{
+ void *pool;
+ void *p1, *p2, *p3, *p4;
+
+ pool = talloc_pool(NULL, 1024);
+
+ p1 = talloc_size(pool, 80);
+ p2 = talloc_size(pool, 20);
+ p3 = talloc_size(p1, 50);
+ p4 = talloc_size(p3, 1000);
+
+ talloc_free(pool);
+
+ return true;
+}
+
struct torture_context;
bool torture_local_talloc(struct torture_context *tctx)
{
@@ -1094,6 +1130,7 @@ bool torture_local_talloc(struct torture_context *tctx)
ret &= test_free_parent_deny_child();
ret &= test_talloc_ptrtype();
ret &= test_talloc_free_in_destructor();
+ ret &= test_pool();
if (ret) {
ret &= test_speed();