Subject: [PATCH v4 3/3] Move reusable parts of memory pool into its own file

From: Jameson Miller <[email-masked]>
Date: Wed, 11 Apr 2018 18:37:55 +0000

This moves the reusable parts of the memory pool logic used by
fast-import.c into its own file for use by other components.

Signed-off-by: Jameson Miller <[email-masked]>
---
 Makefile      |  1 +
 fast-import.c | 70 +----------------------------------------------------------
 mem-pool.c    | 55 ++++++++++++++++++++++++++++++++++++++++++++++
 mem-pool.h    | 34 +++++++++++++++++++++++++++++
 4 files changed, 91 insertions(+), 69 deletions(-)
 create mode 100644 mem-pool.c
 create mode 100644 mem-pool.h

diff --git a/Makefile b/Makefile
index f181687250..5aa4f8064f 100644
--- a/Makefile
+++ b/Makefile
@@ -844,6 +844,7 @@ LIB_OBJS += log-tree.o
 LIB_OBJS += mailinfo.o
 LIB_OBJS += mailmap.o
 LIB_OBJS += match-trees.o
+LIB_OBJS += mem-pool.o
 LIB_OBJS += merge.o
 LIB_OBJS += merge-blobs.o
 LIB_OBJS += merge-recursive.o
diff --git a/fast-import.c b/fast-import.c
index 48d4797ab5..05d1079d23 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -170,6 +170,7 @@ Format of STDIN stream:
 #include "run-command.h"
 #include "packfile.h"
 #include "object-store.h"
+#include "mem-pool.h"
 
 #define PACK_ID_BITS 16
 #define MAX_PACK_ID ((1<<PACK_ID_BITS)-1)
@@ -211,26 +212,6 @@ struct last_object {
 	unsigned no_swap : 1;
 };
 
-struct mp_block {
-	struct mp_block *next_block;
-	char *next_free;
-	char *end;
-	uintmax_t space[FLEX_ARRAY]; /* more */
-};
-
-struct mem_pool {
-	struct mp_block *mp_block;
-
-	/*
-	 * The amount of available memory to grow the pool by.
-	 * This size does not include the overhead for the mp_block.
-	 */
-	size_t block_alloc;
-
-	/* The total amount of memory allocated by the pool. */
-	size_t pool_alloc;
-};
-
 struct atom_str {
 	struct atom_str *next_atom;
 	unsigned short str_len;
@@ -649,55 +630,6 @@ static unsigned int hc_str(const char *s, size_t len)
 	return r;
 }
 
-static struct mp_block *mem_pool_alloc_block(struct mem_pool *mem_pool, size_t block_alloc)
-{
-	struct mp_block *p;
-
-	mem_pool->pool_alloc += sizeof(struct mp_block) + block_alloc;
-	p = xmalloc(st_add(sizeof(struct mp_block), block_alloc));
-	p->next_block = mem_pool->mp_block;
-	p->next_free = (char *)p->space;
-	p->end = p->next_free + block_alloc;
-	mem_pool->mp_block = p;
-
-	return p;
-}
-
-static void *mem_pool_alloc(struct mem_pool *mem_pool, size_t len)
-{
-	struct mp_block *p;
-	void *r;
-
-	/* round up to a 'uintmax_t' alignment */
-	if (len & (sizeof(uintmax_t) - 1))
-		len += sizeof(uintmax_t) - (len & (sizeof(uintmax_t) - 1));
-
-	for (p = mem_pool->mp_block; p; p = p->next_block)
-		if (p->end - p->next_free >= len)
-			break;
-
-	if (!p) {
-		if (len >= (mem_pool->block_alloc / 2)) {
-			mem_pool->pool_alloc += len;
-			return xmalloc(len);
-		}
-
-		p = mem_pool_alloc_block(mem_pool, mem_pool->block_alloc);
-	}
-
-	r = p->next_free;
-	p->next_free += len;
-	return r;
-}
-
-static void *mem_pool_calloc(struct mem_pool *mem_pool, size_t count, size_t size)
-{
-	size_t len = st_mult(count, size);
-	void *r = mem_pool_alloc(mem_pool, len);
-	memset(r, 0, len);
-	return r;
-}
-
 static char *pool_strdup(const char *s)
 {
 	size_t len = strlen(s) + 1;
diff --git a/mem-pool.c b/mem-pool.c
new file mode 100644
index 0000000000..389d7af447
--- /dev/null
+++ b/mem-pool.c
@@ -0,0 +1,55 @@
+/*
+ * Memory Pool implementation logic.
+ */
+
+#include "cache.h"
+#include "mem-pool.h"
+
+static struct mp_block *mem_pool_alloc_block(struct mem_pool *mem_pool, size_t block_alloc)
+{
+	struct mp_block *p;
+
+	mem_pool->pool_alloc += sizeof(struct mp_block) + block_alloc;
+	p = xmalloc(st_add(sizeof(struct mp_block), block_alloc));
+	p->next_block = mem_pool->mp_block;
+	p->next_free = (char *)p->space;
+	p->end = p->next_free + block_alloc;
+	mem_pool->mp_block = p;
+
+	return p;
+}
+
+void *mem_pool_alloc(struct mem_pool *mem_pool, size_t len)
+{
+	struct mp_block *p;
+	void *r;
+
+	/* round up to a 'uintmax_t' alignment */
+	if (len & (sizeof(uintmax_t) - 1))
+		len += sizeof(uintmax_t) - (len & (sizeof(uintmax_t) - 1));
+
+	for (p = mem_pool->mp_block; p; p = p->next_block)
+		if (p->end - p->next_free >= len)
+			break;
+
+	if (!p) {
+		if (len >= (mem_pool->block_alloc / 2)) {
+			mem_pool->pool_alloc += len;
+			return xmalloc(len);
+		}
+
+		p = mem_pool_alloc_block(mem_pool, mem_pool->block_alloc);
+	}
+
+	r = p->next_free;
+	p->next_free += len;
+	return r;
+}
+
+void *mem_pool_calloc(struct mem_pool *mem_pool, size_t count, size_t size)
+{
+	size_t len = st_mult(count, size);
+	void *r = mem_pool_alloc(mem_pool, len);
+	memset(r, 0, len);
+	return r;
+}
diff --git a/mem-pool.h b/mem-pool.h
new file mode 100644
index 0000000000..829ad58ecf
--- /dev/null
+++ b/mem-pool.h
@@ -0,0 +1,34 @@
+#ifndef MEM_POOL_H
+#define MEM_POOL_H
+
+struct mp_block {
+	struct mp_block *next_block;
+	char *next_free;
+	char *end;
+	uintmax_t space[FLEX_ARRAY]; /* more */
+};
+
+struct mem_pool {
+	struct mp_block *mp_block;
+
+	/*
+	 * The amount of available memory to grow the pool by.
+	 * This size does not include the overhead for the mp_block.
+	 */
+	size_t block_alloc;
+
+	/* The total amount of memory allocated by the pool. */
+	size_t pool_alloc;
+};
+
+/*
+ * Alloc memory from the mem_pool.
+ */
+void *mem_pool_alloc(struct mem_pool *pool, size_t len);
+
+/*
+ * Allocate and zero memory from the memory pool.
+ */
+void *mem_pool_calloc(struct mem_pool *pool, size_t count, size_t size);
+
+#endif
-- 
2.14.3