/*

 * alloc.c  - specialized allocator for internal objects

 *

 * Copyright (C) 2006 Linus Torvalds

 *

 * The standard malloc/free wastes too much space for objects, partly because

 * it maintains all the allocation infrastructure, but even more because it ends

 * up with maximal alignment because it doesn't know what the object alignment

 * for the new allocation is.

 */

#include "git-compat-util.h"

#include "object.h"

#include "blob.h"

#include "tree.h"

#include "commit.h"

#include "repository.h"

#include "tag.h"

#include "alloc.h"

#define BLOCKING 1024

union any_object {

  struct object object;

  struct blob blob;

  struct tree tree;

  struct commit commit;

  struct tag tag;

};

struct alloc_state {

  int nr;    /* number of nodes left in current allocation */

  void *p;   /* first free node in current allocation */

  /* bookkeeping of allocations */

  void **slabs;

  int slab_nr, slab_alloc;

};

struct alloc_state *alloc_state_alloc(void)

{

  return xcalloc(1, sizeof(struct alloc_state));

}

void alloc_state_free_and_null(struct alloc_state **s_)

{

  struct alloc_state *s = *s_;

  if (!s)

    return;

  while (s->slab_nr > 0) {

    s->slab_nr--;

    free(s->slabs[s->slab_nr]);

  }

  FREE_AND_NULL(s->slabs);

  FREE_AND_NULL(*s_);

}

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--;

  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));

  b->object.type = OBJ_BLOB;

  return b;

}

void *alloc_tree_node(struct repository *r)

{

  struct tree *t = alloc_node(r->parsed_objects->tree_state, sizeof(struct tree));

  t->object.type = OBJ_TREE;

  return t;

}

void *alloc_tag_node(struct repository *r)

{

  struct tag *t = alloc_node(r->parsed_objects->tag_state, sizeof(struct tag));

  t->object.type = OBJ_TAG;

  return t;

}

void *alloc_object_node(struct repository *r)

{

  struct object *obj = alloc_node(r->parsed_objects->object_state, sizeof(union any_object));

  obj->type = OBJ_NONE;

  return obj;

}

/*

 * The returned count is to be used as an index into commit slabs,

 * that are *NOT* maintained per repository, and that is why a single

 * global counter is used.

 */

static unsigned int alloc_commit_index(void)

{

  static unsigned int parsed_commits_count;

  return parsed_commits_count++;

}

void init_commit_node(struct commit *c)

{

  c->object.type = OBJ_COMMIT;

  c->index = alloc_commit_index();

}

void *alloc_commit_node(struct repository *r)

{

  struct commit *c = alloc_node(r->parsed_objects->commit_state, sizeof(struct commit));

  init_commit_node(c);

  return c;

}