[PATCH v3] alloc.h|c: migrate alloc_states to mem-pool

From: ZheNing Hu <adlternative@gmail.com>

In "object.h",I use `mem_pool` to replace the five "alloc_state *" which used to allocate memory for different types of object nodes.Now that one `mem_pool` unified management of the allocation and release of the memory of multiple nodes. The advantage of changing to a `mem_pool` is: 1.we can allocate more memory at a time than the original `alloc_state`,thus reducing the number of system calls to malloc. 2.the user interface is take memory in a memory pool,We no longer need to take from multiple pools as before.

At the same time, mem_pool may have its disadvantages:
1. There is memory fragmentation
2. It is not conducive to counting or traversing
different types of nodes.
This may require some refinement or disregard.

Signed-off-by: ZheNing Hu <adlternative@gmail.com>
---
    object.h: migrate alloc_states to mem-pool
    
    Notice that "mem-pool" api may have similar effort with alloc_state,
    "parsed_object_pool" have five member with alloc_state type, and "TODO"
    usage in "object.h":"migrate alloc_states to mem-pool?", so let us
    change it to mem-pool version.
    
    After I learned the role of the memory pool,I think in the future git
    may be more inclined to use the memory pool instead of the old interface
    "alloc_state".
    
    Thanks.
    
    cc: Junio C Hamano gitster@pobox.com cc: Stefan Beller
    sbeller@google.com

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-857%2Fadlternative%2Falloc_states_to_mem_pool-v3
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-857/adlternative/alloc_states_to_mem_pool-v3
Pull-Request: https://github.com/gitgitgadget/git/pull/857

Range-diff vs v2:

 1:  e9c1f9eef428 ! 1:  4b292c037ed2 alloc.h|c: migrate alloc_states to mem-pool
     @@ Metadata
       ## Commit message ##
          alloc.h|c: migrate alloc_states to mem-pool
      
     -    "alloc_state" may have similar effects with "mem_pool".
     -    Using the new memory pool API may be more beneficial
     -    to our memory management in the future.
     -
     -    So I change them in the "struct parsed_object_pool",and
     -    The corresponding interface has also been changed.
     -    functions "alloc_*_node" now change to "mem_pool_alloc_*_node".
     -
     -    At the same time ,I add the member `alloc_count` of
     -    struct mem_pool ,so that we can effective track
     -    node alloc count,and adapt to the original interface `alloc_report`.
     +    In "object.h",I use `mem_pool` to replace the five
     +    "alloc_state *" which used to allocate memory for
     +    different types of object nodes.Now that one `mem_pool`
     +    unified management of the allocation and release of
     +    the memory of multiple nodes.
     +    The advantage of changing to a `mem_pool` is:
     +    1.we can allocate more memory at a time than the original
     +    `alloc_state`,thus reducing the number of system calls to malloc.
     +    2.the user interface is take memory in a memory pool,We no longer
     +    need to take from multiple pools as before.
     +
     +    At the same time, mem_pool may have its disadvantages:
     +    1. There is memory fragmentation
     +    2. It is not conducive to counting or traversing
     +    different types of nodes.
     +    This may require some refinement or disregard.
      
          Signed-off-by: ZheNing Hu <adlternative@gmail.com>
      
       ## alloc.c ##
     -@@ alloc.c: static inline void *alloc_node(struct alloc_state *s, size_t node_size)
     - 	return ret;
     - }
     +@@ alloc.c: struct alloc_state {
     + 	int slab_nr, slab_alloc;
     + };
       
     --void *alloc_blob_node(struct repository *r)
     -+void *mem_pool_alloc_blob_node(struct repository *r)
     +-struct alloc_state *allocate_alloc_state(void)
     +-{
     +-	return xcalloc(1, sizeof(struct alloc_state));
     +-}
     +-
     +-void clear_alloc_state(struct alloc_state *s)
     +-{
     +-	while (s->slab_nr > 0) {
     +-		s->slab_nr--;
     +-		free(s->slabs[s->slab_nr]);
     +-	}
     +-
     +-	FREE_AND_NULL(s->slabs);
     +-}
     +-
     +-static inline void *alloc_node(struct alloc_state *s, size_t node_size)
     +-{
     +-	void *ret;
     +-
     +-	if (!s->nr) {
     +-		s->nr = BLOCKING;
     +-		s->p = xmalloc(BLOCKING * node_size);
     +-
     +-		ALLOC_GROW(s->slabs, s->slab_nr + 1, s->slab_alloc);
     +-		s->slabs[s->slab_nr++] = s->p;
     +-	}
     +-	s->nr--;
     +-	s->count++;
     +-	ret = s->p;
     +-	s->p = (char *)s->p + node_size;
     +-	memset(ret, 0, node_size);
     +-
     +-	return ret;
     +-}
     +-
     + void *alloc_blob_node(struct repository *r)
       {
      -	struct blob *b = alloc_node(r->parsed_objects->blob_state, sizeof(struct blob));
     -+	struct blob *b = mem_pool_calloc(r->parsed_objects->blob_pool, 1, sizeof(struct blob));
     ++	struct blob *b = mem_pool_calloc(&r->parsed_objects->objects_pool, 1, sizeof(struct blob));
       	b->object.type = OBJ_BLOB;
       	return b;
       }
       
     --void *alloc_tree_node(struct repository *r)
     -+void *mem_pool_alloc_tree_node(struct repository *r)
     + void *alloc_tree_node(struct repository *r)
       {
      -	struct tree *t = alloc_node(r->parsed_objects->tree_state, sizeof(struct tree));
     -+	struct tree *t = mem_pool_calloc(r->parsed_objects->tree_pool, 1, sizeof(struct tree));
     ++	struct tree *t = mem_pool_calloc(&r->parsed_objects->objects_pool, 1, sizeof(struct tree));
       	t->object.type = OBJ_TREE;
       	return t;
       }
       
     --void *alloc_tag_node(struct repository *r)
     -+void *mem_pool_alloc_tag_node(struct repository *r)
     + void *alloc_tag_node(struct repository *r)
       {
      -	struct tag *t = alloc_node(r->parsed_objects->tag_state, sizeof(struct tag));
     -+	struct tag *t = mem_pool_calloc(r->parsed_objects->tag_pool, 1, sizeof(struct tag));
     ++	struct tag *t = mem_pool_calloc(&r->parsed_objects->objects_pool, 1, sizeof(struct tag));
       	t->object.type = OBJ_TAG;
       	return t;
       }
       
     --void *alloc_object_node(struct repository *r)
     -+void *mem_pool_alloc_object_node(struct repository *r)
     + void *alloc_object_node(struct repository *r)
       {
      -	struct object *obj = alloc_node(r->parsed_objects->object_state, sizeof(union any_object));
     -+	struct object *obj = mem_pool_calloc(r->parsed_objects->object_pool, 1, sizeof(union any_object));
     ++	struct object *obj = mem_pool_calloc(&r->parsed_objects->objects_pool, 1, sizeof(union any_object));
       	obj->type = OBJ_NONE;
       	return obj;
       }
      @@ alloc.c: void init_commit_node(struct commit *c)
     - 	c->index = alloc_commit_index();
     - }
       
     --void *alloc_commit_node(struct repository *r)
     -+void *mem_pool_alloc_commit_node(struct repository *r)
     + void *alloc_commit_node(struct repository *r)
       {
      -	struct commit *c = alloc_node(r->parsed_objects->commit_state, sizeof(struct commit));
     -+	struct commit *c = mem_pool_calloc(r->parsed_objects->commit_pool, 1, sizeof(struct commit));
     ++	struct commit *c = mem_pool_calloc(&r->parsed_objects->objects_pool, 1, sizeof(struct commit));
       	init_commit_node(c);
       	return c;
       }
     -@@ alloc.c: static void report(const char *name, unsigned int count, size_t size)
     - }
     - 
     - #define REPORT(name, type)	\
     +-
     +-static void report(const char *name, unsigned int count, size_t size)
     +-{
     +-	fprintf(stderr, "%10s: %8u (%"PRIuMAX" kB)\n",
     +-			name, count, (uintmax_t) size);
     +-}
     +-
     +-#define REPORT(name, type)	\
      -    report(#name, r->parsed_objects->name##_state->count, \
      -		  r->parsed_objects->name##_state->count * sizeof(type) >> 10)
     -+    report(#name, r->parsed_objects->name##_pool->alloc_count, \
     -+		  r->parsed_objects->name##_pool->alloc_count * sizeof(type) >> 10)
     - 
     - void alloc_report(struct repository *r)
     - {
     +-
     +-void alloc_report(struct repository *r)
     +-{
     +-	REPORT(blob, struct blob);
     +-	REPORT(tree, struct tree);
     +-	REPORT(commit, struct commit);
     +-	REPORT(tag, struct tag);
     +-	REPORT(object, union any_object);
     +-}
      
       ## alloc.h ##
     -@@ alloc.h: struct commit;
     - struct tag;
     - struct repository;
     - 
     --void *alloc_blob_node(struct repository *r);
     --void *alloc_tree_node(struct repository *r);
     -+void *mem_pool_alloc_blob_node(struct repository *r);
     -+void *mem_pool_alloc_tree_node(struct repository *r);
     - void init_commit_node(struct commit *c);
     --void *alloc_commit_node(struct repository *r);
     --void *alloc_tag_node(struct repository *r);
     --void *alloc_object_node(struct repository *r);
     -+void *mem_pool_alloc_commit_node(struct repository *r);
     -+void *mem_pool_alloc_tag_node(struct repository *r);
     -+void *mem_pool_alloc_object_node(struct repository *r);
     +@@ alloc.h: void *alloc_tag_node(struct repository *r);
     + void *alloc_object_node(struct repository *r);
       void alloc_report(struct repository *r);
       
     - struct alloc_state *allocate_alloc_state(void);
     -
     - ## blame.c ##
     -@@ blame.c: static struct commit *fake_working_tree_commit(struct repository *r,
     - 
     - 	repo_read_index(r);
     - 	time(&now);
     --	commit = alloc_commit_node(r);
     -+	commit = mem_pool_alloc_commit_node(r);
     - 	commit->object.parsed = 1;
     - 	commit->date = now;
     - 	parent_tail = &commit->parents;
     -
     - ## blob.c ##
     -@@ blob.c: struct blob *lookup_blob(struct repository *r, const struct object_id *oid)
     - {
     - 	struct object *obj = lookup_object(r, oid);
     - 	if (!obj)
     --		return create_object(r, oid, alloc_blob_node(r));
     -+		return create_object(r, oid, mem_pool_alloc_blob_node(r));
     - 	return object_as_type(obj, OBJ_BLOB, 0);
     - }
     - 
     -
     - ## commit-graph.c ##
     -@@ commit-graph.c: int verify_commit_graph(struct repository *r, struct commit_graph *g, int flags)
     - 		hashcpy(cur_oid.hash, g->chunk_oid_lookup + g->hash_len * i);
     - 
     - 		graph_commit = lookup_commit(r, &cur_oid);
     --		odb_commit = (struct commit *)create_object(r, &cur_oid, alloc_commit_node(r));
     -+		odb_commit = (struct commit *)create_object(r, &cur_oid, mem_pool_alloc_commit_node(r));
     - 		if (parse_commit_internal(odb_commit, 0, 0)) {
     - 			graph_report(_("failed to parse commit %s from object database for commit-graph"),
     - 				     oid_to_hex(&cur_oid));
     -
     - ## commit.c ##
     -@@ commit.c: struct commit *lookup_commit(struct repository *r, const struct object_id *oid)
     - {
     - 	struct object *obj = lookup_object(r, oid);
     - 	if (!obj)
     --		return create_object(r, oid, alloc_commit_node(r));
     -+		return create_object(r, oid, mem_pool_alloc_commit_node(r));
     - 	return object_as_type(obj, OBJ_COMMIT, 0);
     - }
     - 
     +-struct alloc_state *allocate_alloc_state(void);
     +-void clear_alloc_state(struct alloc_state *s);
     +-
     + #endif
      
       ## mem-pool.c ##
     -@@ mem-pool.c: static struct mp_block *mem_pool_alloc_block(struct mem_pool *pool,
     - 	return p;
     - }
     +@@
     + #include "cache.h"
     + #include "mem-pool.h"
       
     -+struct mem_pool *mem_pool_new(void)
     -+{
     -+	return xmalloc(sizeof(struct mem_pool));
     -+}
     -+
     - void mem_pool_init(struct mem_pool *pool, size_t initial_size)
     - {
     - 	memset(pool, 0, sizeof(*pool));
     +-#define BLOCK_GROWTH_SIZE 1024*1024 - sizeof(struct mp_block);
     + 
     + /*
     +  * Allocate a new mp_block and insert it after the block specified in
      @@ mem-pool.c: void *mem_pool_alloc(struct mem_pool *pool, size_t len)
       	struct mp_block *p = NULL;
       	void *r;
     @@ mem-pool.h: struct mem_pool {
      +	size_t alloc_count;
       };
       
     -+/*
     -+ * Create a new mem_pool.
     -+ */
     -+struct mem_pool *mem_pool_new(void);
     ++#define BLOCK_GROWTH_SIZE 1024*1024 - sizeof(struct mp_block)
      +
       /*
        * Initialize mem_pool with specified initial size.
        */
      
     - ## merge-ort.c ##
     -@@ merge-ort.c: static struct commit *make_virtual_commit(struct repository *repo,
     - 					  struct tree *tree,
     - 					  const char *comment)
     - {
     --	struct commit *commit = alloc_commit_node(repo);
     -+	struct commit *commit = mem_pool_alloc_commit_node(repo);
     - 
     - 	set_merge_remote_desc(commit, comment, (struct object *)commit);
     - 	set_commit_tree(commit, tree);
     -
     - ## merge-recursive.c ##
     -@@ merge-recursive.c: static struct commit *make_virtual_commit(struct repository *repo,
     - 					  struct tree *tree,
     - 					  const char *comment)
     - {
     --	struct commit *commit = alloc_commit_node(repo);
     -+	struct commit *commit = mem_pool_alloc_commit_node(repo);
     - 
     - 	set_merge_remote_desc(commit, comment, (struct object *)commit);
     - 	set_commit_tree(commit, tree);
     -
       ## object.c ##
      @@ object.c: struct object *lookup_unknown_object(const struct object_id *oid)
       	struct object *obj = lookup_object(the_repository, oid);
       	if (!obj)
       		obj = create_object(the_repository, oid,
      -				    alloc_object_node(the_repository));
     -+				mem_pool_alloc_object_node(the_repository));
     ++				alloc_object_node(the_repository));
       	return obj;
       }
       
      @@ object.c: struct parsed_object_pool *parsed_object_pool_new(void)
     + {
       	struct parsed_object_pool *o = xmalloc(sizeof(*o));
       	memset(o, 0, sizeof(*o));
     - 
     +-
      -	o->blob_state = allocate_alloc_state();
      -	o->tree_state = allocate_alloc_state();
      -	o->commit_state = allocate_alloc_state();
      -	o->tag_state = allocate_alloc_state();
      -	o->object_state = allocate_alloc_state();
     -+	o->blob_pool = mem_pool_new();
     -+	o->tree_pool = mem_pool_new();
     -+	o->commit_pool = mem_pool_new();
     -+	o->tag_pool = mem_pool_new();
     -+	o->object_pool = mem_pool_new();
     -+	mem_pool_init(o->blob_pool,0);
     -+	mem_pool_init(o->tree_pool,0);
     -+	mem_pool_init(o->commit_pool,0);
     -+	mem_pool_init(o->tag_pool,0);
     -+	mem_pool_init(o->object_pool,0);
     - 
     +-
     ++	mem_pool_init(&o->objects_pool, BLOCK_GROWTH_SIZE);
       	o->is_shallow = -1;
       	o->shallow_stat = xcalloc(1, sizeof(*o->shallow_stat));
     + 
      @@ object.c: void parsed_object_pool_clear(struct parsed_object_pool *o)
       	free_commit_buffer_slab(o->buffer_slab);
       	o->buffer_slab = NULL;
     @@ object.c: void parsed_object_pool_clear(struct parsed_object_pool *o)
      -	clear_alloc_state(o->commit_state);
      -	clear_alloc_state(o->tag_state);
      -	clear_alloc_state(o->object_state);
     -+	mem_pool_discard(o->blob_pool,1);
     -+	mem_pool_discard(o->tree_pool,1);
     -+	mem_pool_discard(o->tag_pool,1);
     -+	mem_pool_discard(o->object_pool,1);
     -+	mem_pool_discard(o->commit_pool,1);
     ++	mem_pool_discard(&o->objects_pool,0);
       	stat_validity_clear(o->shallow_stat);
      -	FREE_AND_NULL(o->blob_state);
      -	FREE_AND_NULL(o->tree_state);
      -	FREE_AND_NULL(o->commit_state);
      -	FREE_AND_NULL(o->tag_state);
      -	FREE_AND_NULL(o->object_state);
     -+	FREE_AND_NULL(o->blob_pool);
     -+	FREE_AND_NULL(o->tree_pool);
     -+	FREE_AND_NULL(o->commit_pool);
     -+	FREE_AND_NULL(o->tag_pool);
     -+	FREE_AND_NULL(o->object_pool);
     - 	FREE_AND_NULL(o->shallow_stat);
     +-	FREE_AND_NULL(o->shallow_stat);
       }
      
       ## object.h ##
      @@ object.h: struct parsed_object_pool {
     + 	struct object **obj_hash;
       	int nr_objs, obj_hash_size;
       
     - 	/* TODO: migrate alloc_states to mem-pool? */
     +-	/* TODO: migrate alloc_states to mem-pool? */
      -	struct alloc_state *blob_state;
      -	struct alloc_state *tree_state;
      -	struct alloc_state *commit_state;
      -	struct alloc_state *tag_state;
      -	struct alloc_state *object_state;
     -+	struct mem_pool *blob_pool;
     -+	struct mem_pool *tree_pool;
     -+	struct mem_pool *commit_pool;
     -+	struct mem_pool *tag_pool;
     -+	struct mem_pool *object_pool;
     ++	struct mem_pool objects_pool;
       
       	/* parent substitutions from .git/info/grafts and .git/shallow */
       	struct commit_graft **grafts;
     -
     - ## tag.c ##
     -@@ tag.c: struct tag *lookup_tag(struct repository *r, const struct object_id *oid)
     - {
     - 	struct object *obj = lookup_object(r, oid);
     - 	if (!obj)
     --		return create_object(r, oid, alloc_tag_node(r));
     -+		return create_object(r, oid, mem_pool_alloc_tag_node(r));
     - 	return object_as_type(obj, OBJ_TAG, 0);
     - }
     - 
     -
     - ## tree.c ##
     -@@ tree.c: struct tree *lookup_tree(struct repository *r, const struct object_id *oid)
     - {
     - 	struct object *obj = lookup_object(r, oid);
     - 	if (!obj)
     --		return create_object(r, oid, alloc_tree_node(r));
     -+		return create_object(r, oid, mem_pool_alloc_tree_node(r));
     - 	return object_as_type(obj, OBJ_TREE, 0);
     - }
     - 

 alloc.c    | 64 +++++-------------------------------------------------
 alloc.h    |  3 ---
 mem-pool.c |  2 +-
 mem-pool.h |  5 +++++
 object.c   | 22 +++----------------
 object.h   |  7 +-----
 6 files changed, 15 insertions(+), 88 deletions(-)