thodg/libgit2/tests-clar/core/pool.c

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• Hash : 2bc8fa02
  Author :
  Date : 2012-04-17T10:14:24
  

  Implement git_pool paged memory allocator
  
  This adds a `git_pool` object that can do simple paged memory
  allocation with free for the entire pool at once.  Using this,
  you can replace many small allocations with large blocks that
  can then cheaply be doled out in small pieces.  This is best
  used when you plan to free the small blocks all at once - for
  example, if they represent the parsed state from a file or data
  stream that are either all kept or all discarded.
  
  There are two real patterns of usage for `git_pools`: either
  for "string" allocation, where the item size is a single byte
  and you end up just packing the allocations in together, or for
  "fixed size" allocation where you are allocating a large object
  (e.g. a `git_oid`) and you generally just allocation single
  objects that can be tightly packed.  Of course, you can use it
  for other things, but those two cases are the easiest.
  

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• tests-clar/core/pool.c

• #include "clar_libgit2.h"
  #include "pool.h"
  #include "git2/oid.h"
  
  void test_core_pool__0(void)
  {
  	int i;
  	git_pool p;
  	void *ptr;
  
  	cl_git_pass(git_pool_init(&p, 1, 4000));
  
  	for (i = 1; i < 10000; i *= 2) {
  		ptr = git_pool_malloc(&p, i);
  		cl_assert(ptr != NULL);
  		cl_assert(git_pool__ptr_in_pool(&p, ptr));
  		cl_assert(!git_pool__ptr_in_pool(&p, &i));
  	}
  
  	/* 1+2+4+8+16+32+64+128+256+512+1024 -> original block */
  	/* 2048 -> 1 block */
  	/* 4096 -> 1 block */
  	/* 8192 -> 1 block */
  
  	cl_assert(git_pool__open_pages(&p) + git_pool__full_pages(&p) == 4);
  
  	git_pool_clear(&p);
  }
  
  void test_core_pool__1(void)
  {
  	int i;
  	git_pool p;
  
  	cl_git_pass(git_pool_init(&p, 1, 4000));
  
  	for (i = 2010; i > 0; i--)
  		cl_assert(git_pool_malloc(&p, i) != NULL);
  
  	/* with fixed page size, allocation must end up with these values */
  	cl_assert(git_pool__open_pages(&p) == 1);
  	cl_assert(git_pool__full_pages(&p) == 505);
  
  	git_pool_clear(&p);
  
  	cl_git_pass(git_pool_init(&p, 1, 4100));
  
  	for (i = 2010; i > 0; i--)
  		cl_assert(git_pool_malloc(&p, i) != NULL);
  
  	/* with fixed page size, allocation must end up with these values */
  	cl_assert(git_pool__open_pages(&p) == 1);
  	cl_assert(git_pool__full_pages(&p) == 492);
  
  	git_pool_clear(&p);
  }
  
  static char to_hex[] = "0123456789abcdef";
  
  void test_core_pool__2(void)
  {
  	git_pool p;
  	char oid_hex[GIT_OID_HEXSZ];
  	git_oid *oid;
  	int i, j;
  
  	memset(oid_hex, '0', sizeof(oid_hex));
  
  	cl_git_pass(git_pool_init(&p, sizeof(git_oid), 100));
  
  	for (i = 1000; i < 10000; i++) {
  		oid = git_pool_malloc(&p, 1);
  		cl_assert(oid != NULL);
  
  		for (j = 0; j < 8; j++)
  			oid_hex[j] = to_hex[(i >> (4 * j)) & 0x0f];
  		cl_git_pass(git_oid_fromstr(oid, oid_hex));
  	}
  
  	/* with fixed page size, allocation must end up with these values */
  	cl_assert(git_pool__open_pages(&p) == 0);
  	cl_assert(git_pool__full_pages(&p) == 90);
  
  	git_pool_clear(&p);
  }
  

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