lib: data-stack - Don't keep largest unused block in memory

It's not that expensive to allocate it again, but it might be expensive to
keep allocated a block that became huge due to a bug. The huge block could
be just wasting memory without ever being used again.

diff --git a/src/lib/data-stack.c b/src/lib/data-stack.c
index 96cd64ad44f3c1ff464af4547353256960950765..4ce0e4cc132d8de28d5b4dc92b3d824a781609ba 100644 (file)
--- a/src/lib/data-stack.c
+++ b/src/lib/data-stack.c
@@ -83,7 +83,6 @@ static struct stack_frame_block *current_frame_block;
 static struct stack_frame_block *unused_frame_blocks;
 
 static struct stack_block *current_block; /* block now used for allocation */
-static struct stack_block *unused_block; /* largest unused block is kept here */
 
 static struct stack_block *last_buffer_block;
 static size_t last_buffer_size;
@@ -222,8 +221,7 @@ static void free_blocks(struct stack_block *block)
 {
        struct stack_block *next;
 
-       /* free all the blocks, except if any of them is bigger than
-          unused_block, replace it */
+       /* free all the blocks */
        while (block != NULL) {
                block_canary_check(block);
                next = block->next;
@@ -231,13 +229,8 @@ static void free_blocks(struct stack_block *block)
                if (clean_after_pop)
                        memset(STACK_BLOCK_DATA(block), CLEAR_CHR, block->size);
 
-               if (unused_block == NULL || block->size > unused_block->size) {
-                       free(unused_block);
-                       unused_block = block;
-               } else {
-                       if (block != &outofmem_area.block)
-                               free(block);
-               }
+               if (block != &outofmem_area.block)
+                       free(block);
 
                block = next;
        }
@@ -416,16 +409,11 @@ static void *t_malloc_real(size_t size, bool permanent)
        if (current_block->left < alloc_size) {
                struct stack_block *block;
 
-               /* current block is full, see if we can use the unused_block */
-               if (unused_block != NULL && unused_block->size >= alloc_size) {
-                       block = unused_block;
-                       unused_block = NULL;
-               } else {
-                       block = mem_block_alloc(alloc_size);
+               /* current block is full, allocate a new one */
+               block = mem_block_alloc(alloc_size);
 #ifdef DEBUG
-                       warn = TRUE;
+               warn = TRUE;
 #endif
-               }
 
                block->left = block->size;
                block->next = NULL;
@@ -648,8 +636,6 @@ void data_stack_deinit(void)
        }
 
        free(current_block);
-       free(unused_block);
        unused_frame_blocks = NULL;
        current_block = NULL;
-       unused_block = NULL;
 }