Subject: [PATCH v2 5/5] Expand implementation of mem-pool type

From: Jameson Miller <[email-masked]>
Date: Fri, 23 Mar 2018 10:44:08 -0400

This commit adds functionality to the mem-pool type that can be
generally useful. This functionality will be used in a future commit.

Signed-off-by: Jameson Miller <[email-masked]>
---
 mem-pool.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 mem-pool.h | 24 ++++++++++++++++++++++++
 2 files changed, 82 insertions(+)

diff --git a/mem-pool.c b/mem-pool.c
index 992e354e12..7d21a7e035 100644
--- a/mem-pool.c
+++ b/mem-pool.c
@@ -5,6 +5,8 @@
 #include "cache.h"
 #include "mem-pool.h"
 
+#define MIN_ALLOC_GROWTH_SIZE 1024 * 1024
+
 static struct mp_block *mem_pool_alloc_block(struct mem_pool *mem_pool)
 {
 	struct mp_block *p;
@@ -59,6 +61,36 @@ static struct mp_block *mem_pool_alloc_block_with_size(struct mem_pool *mem_pool
 	return p;
 }
 
+void mem_pool_init(struct mem_pool **mem_pool, size_t block_alloc, size_t initial_size)
+{
+	if (!(*mem_pool))
+	{
+		if (block_alloc < (MIN_ALLOC_GROWTH_SIZE - sizeof(struct mp_block)))
+			block_alloc = (MIN_ALLOC_GROWTH_SIZE - sizeof(struct mp_block));
+
+		*mem_pool = xmalloc(sizeof(struct mem_pool));
+		(*mem_pool)->pool_alloc = 0;
+		(*mem_pool)->mp_block = 0;
+		(*mem_pool)->block_alloc = block_alloc;
+
+		if (initial_size > 0)
+			mem_pool_alloc_block_with_size(*mem_pool, initial_size);
+	}
+}
+
+void mem_pool_discard(struct mem_pool *mem_pool)
+{
+	struct mp_block *block, *block_to_free;
+	for (block = mem_pool->mp_block; block;)
+	{
+		block_to_free = block;
+		block = block->next_block;
+		free(block_to_free);
+	}
+
+	free(mem_pool);
+}
+
 void *mem_pool_alloc(struct mem_pool *mem_pool, size_t len)
 {
 	struct mp_block *p;
@@ -101,3 +133,29 @@ void *mem_pool_calloc(struct mem_pool *mem_pool, size_t count, size_t size)
 	memset(r, 0, len);
 	return r;
 }
+
+int mem_pool_contains(struct mem_pool *mem_pool, void *mem)
+{
+	struct mp_block *p;
+	for (p = mem_pool->mp_block; p; p = p->next_block)
+		if ((mem >= ((void *)p->space)) &&
+		    (mem < ((void *)p->end)))
+			return 1;
+
+	return 0;
+}
+
+void mem_pool_combine(struct mem_pool *dst, struct mem_pool *src)
+{
+	struct mp_block **tail = &dst->mp_block;
+	/* find pointer of dst's last block (if any) */
+	while (*tail)
+		tail = &(*tail)->next_block;
+
+	/* append the blocks from src to dst */
+	*tail = src->mp_block;
+
+	dst->pool_alloc += src->pool_alloc;
+	src->pool_alloc = 0;
+	src->mp_block = NULL;
+}
diff --git a/mem-pool.h b/mem-pool.h
index 829ad58ecf..d9e7f21541 100644
--- a/mem-pool.h
+++ b/mem-pool.h
@@ -21,6 +21,17 @@ struct mem_pool {
 	size_t pool_alloc;
 };
 
+/*
+ * Initialize mem_pool with specified parameters for initial size and
+ * how much to grow when a larger memory block is required.
+ */
+void mem_pool_init(struct mem_pool **mem_pool, size_t alloc_growth_size, size_t initial_size);
+
+/*
+ * Discard a memory pool and free all the memory it is responsible for.
+ */
+void mem_pool_discard(struct mem_pool *mem_pool);
+
 /*
  * Alloc memory from the mem_pool.
  */
@@ -31,4 +42,17 @@ void *mem_pool_alloc(struct mem_pool *pool, size_t len);
  */
 void *mem_pool_calloc(struct mem_pool *pool, size_t count, size_t size);
 
+/*
+ * Move the memory associated with the 'src' pool to the 'dst' pool. The 'src'
+ * pool will be empty and not contain any memory. It still needs to be free'd
+ * with a call to `mem_pool_discard`.
+ */
+void mem_pool_combine(struct mem_pool *dst, struct mem_pool *src);
+
+/*
+ * Check if a memory pointed at by 'mem' is part of the range of
+ * memory managed by the specified mem_pool.
+ */
+int mem_pool_contains(struct mem_pool *mem_pool, void *mem);
+
 #endif
-- 
2.14.3