On Fri, May 11, 2018 at 03:11:46PM +0200, Duy Nguyen wrote:
> Back to fast-export, can we just allocate a new int on heap and point
> it there? Allocating small pieces becomes quite cheap and fast with
> mem-pool.h and we can avoid this storing integer in pointer business.
Something like this seems to work, but we use 4-ish more bytes per
object, or 100MB overhead on a repo with 25M objects. I think it's a
reasonable trade off.
-- 8< --
diff --git a/builtin/fast-export.c b/builtin/fast-export.c
index 530df12f05..de593035b1 100644
--- a/builtin/fast-export.c
+++ b/builtin/fast-export.c
@@ -21,6 +21,7 @@
#include "quote.h"
#include "remote.h"
#include "blob.h"
+#include "mem-pool.h"
static const char *fast_export_usage[] = {
N_("git fast-export [rev-list-opts]"),
@@ -38,6 +39,7 @@ static struct string_list extra_refs = STRING_LIST_INIT_NODUP;
static struct refspec *refspecs;
static int refspecs_nr;
static int anonymize;
+static struct mem_pool int_pool = MEM_POOL_INIT(2 * 1024 * 1024);
static int parse_opt_signed_tag_mode(const struct option *opt,
const char *arg, int unset)
@@ -156,20 +158,22 @@ static void anonymize_path(struct strbuf *out, const char *path,
}
}
-/* Since intptr_t is C99, we do not use it here */
-static inline uint32_t *mark_to_ptr(uint32_t mark)
+static inline uint32_t ptr_to_mark(void *mark)
{
- return ((uint32_t *)NULL) + mark;
-}
-
-static inline uint32_t ptr_to_mark(void * mark)
-{
- return (uint32_t *)mark - (uint32_t *)NULL;
+ if (!mark)
+ BUG("not marked!");
+ return *(uint32_t *)mark;
}
static inline void mark_object(struct object *object, uint32_t mark)
{
- add_decoration(&idnums, object, mark_to_ptr(mark));
+ uint32_t *ptr = lookup_decoration(&idnums, object);
+
+ if (!ptr)
+ ptr = mem_pool_alloc(&int_pool, sizeof(uint32_t));
+
+ *ptr = mark;
+ add_decoration(&idnums, object, ptr);
}
static inline void mark_next_object(struct object *object)
diff --git a/fast-import.c b/fast-import.c
index 34edf3fb8f..ce5ce2081f 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -300,8 +300,7 @@ static int global_argc;
static const char **global_argv;
/* Memory pools */
-static struct mem_pool fi_mem_pool = {NULL, 2*1024*1024 -
- sizeof(struct mp_block), 0 };
+static struct mem_pool fi_mem_pool = MEM_POOL_INIT(2*1024*1024);
/* Atom management */
static unsigned int atom_table_sz = 4451;
diff --git a/mem-pool.h b/mem-pool.h
index 829ad58ecf..bccbd3f224 100644
--- a/mem-pool.h
+++ b/mem-pool.h
@@ -21,6 +21,8 @@ struct mem_pool {
size_t pool_alloc;
};
+#define MEM_POOL_INIT(block_size) { NULL, (block_size) - sizeof(struct mp_block), 0 }
+
/*
* Alloc memory from the mem_pool.
*/
-- 8< --
