thodg/libgit2/src/pack.h

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• Hash : 53607868
  Author :
  Date : 2013-04-15T00:09:03
  

  Further threading fixes This builds on the earlier thread safety work to make it so that setting the odb, index, refdb, or config for a repository is done in a threadsafe manner with minimized locking time. This is done by adding a lock to the repository object and using it to guard the assignment of the above listed pointers. The lock is only held to assign the pointer value. This also contains some minor fixes to the other work with pack files to reduce the time that locks are being held to and fix an apparently memory leak.

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• src/pack.h

• /*
   * Copyright (C) the libgit2 contributors. All rights reserved.
   *
   * This file is part of libgit2, distributed under the GNU GPL v2 with
   * a Linking Exception. For full terms see the included COPYING file.
   */
  
  #ifndef INCLUDE_pack_h__
  #define INCLUDE_pack_h__
  
  #include <zlib.h>
  
  #include "git2/oid.h"
  
  #include "common.h"
  #include "map.h"
  #include "mwindow.h"
  #include "odb.h"
  #include "oidmap.h"
  
  #define GIT_PACK_FILE_MODE 0444
  
  #define PACK_SIGNATURE 0x5041434b	/* "PACK" */
  #define PACK_VERSION 2
  #define pack_version_ok(v) ((v) == htonl(2) || (v) == htonl(3))
  struct git_pack_header {
  	uint32_t hdr_signature;
  	uint32_t hdr_version;
  	uint32_t hdr_entries;
  };
  
  /*
   * The first four bytes of index formats later than version 1 should
   * start with this signature, as all older git binaries would find this
   * value illegal and abort reading the file.
   *
   * This is the case because the number of objects in a packfile
   * cannot exceed 1,431,660,000 as every object would need at least
   * 3 bytes of data and the overall packfile cannot exceed 4 GiB with
   * version 1 of the index file due to the offsets limited to 32 bits.
   * Clearly the signature exceeds this maximum.
   *
   * Very old git binaries will also compare the first 4 bytes to the
   * next 4 bytes in the index and abort with a "non-monotonic index"
   * error if the second 4 byte word is smaller than the first 4
   * byte word. This would be true in the proposed future index
   * format as idx_signature would be greater than idx_version.
   */
  
  #define PACK_IDX_SIGNATURE 0xff744f63	/* "\377tOc" */
  
  struct git_pack_idx_header {
  	uint32_t idx_signature;
  	uint32_t idx_version;
  };
  
  typedef struct git_pack_cache_entry {
  	size_t last_usage; /* enough? */
  	git_atomic refcount;
  	git_rawobj raw;
  } git_pack_cache_entry;
  
  #include "offmap.h"
  
  GIT__USE_OFFMAP;
  GIT__USE_OIDMAP;
  
  #define GIT_PACK_CACHE_MEMORY_LIMIT 16 * 1024 * 1024
  #define GIT_PACK_CACHE_SIZE_LIMIT 1024 * 1024 /* don't bother caching anything over 1MB */
  
  typedef struct {
  	size_t memory_used;
  	size_t memory_limit;
  	size_t use_ctr;
  	git_mutex lock;
  	git_offmap *entries;
  } git_pack_cache;
  
  struct git_pack_file {
  	git_mwindow_file mwf;
  	git_map index_map;
  	git_mutex lock; /* protect updates to mwf and index_map */
  
  	uint32_t num_objects;
  	uint32_t num_bad_objects;
  	git_oid *bad_object_sha1; /* array of git_oid */
  
  	int index_version;
  	git_time_t mtime;
  	unsigned pack_local:1, pack_keep:1, has_cache:1;
  	git_oid sha1;
  	git_oidmap *idx_cache;
  	git_oid **oids;
  
  	git_pack_cache bases; /* delta base cache */
  
  	/* something like ".git/objects/pack/xxxxx.pack" */
  	char pack_name[GIT_FLEX_ARRAY]; /* more */
  };
  
  struct git_pack_entry {
  	git_off_t offset;
  	git_oid sha1;
  	struct git_pack_file *p;
  };
  
  typedef struct git_packfile_stream {
  	git_off_t curpos;
  	int done;
  	z_stream zstream;
  	struct git_pack_file *p;
  	git_mwindow *mw;
  } git_packfile_stream;
  
  int git_packfile_unpack_header(
  		size_t *size_p,
  		git_otype *type_p,
  		git_mwindow_file *mwf,
  		git_mwindow **w_curs,
  		git_off_t *curpos);
  
  int git_packfile_resolve_header(
  		size_t *size_p,
  		git_otype *type_p,
  		struct git_pack_file *p,
  		git_off_t offset);
  
  int git_packfile_unpack(git_rawobj *obj, struct git_pack_file *p, git_off_t *obj_offset);
  int packfile_unpack_compressed(
  	git_rawobj *obj,
  	struct git_pack_file *p,
  	git_mwindow **w_curs,
  	git_off_t *curpos,
  	size_t size,
  	git_otype type);
  
  int git_packfile_stream_open(git_packfile_stream *obj, struct git_pack_file *p, git_off_t curpos);
  ssize_t git_packfile_stream_read(git_packfile_stream *obj, void *buffer, size_t len);
  void git_packfile_stream_free(git_packfile_stream *obj);
  
  git_off_t get_delta_base(struct git_pack_file *p, git_mwindow **w_curs,
  		git_off_t *curpos, git_otype type,
  		git_off_t delta_obj_offset);
  
  void git_packfile_free(struct git_pack_file *p);
  int git_packfile_alloc(struct git_pack_file **pack_out, const char *path);
  
  int git_pack_entry_find(
  		struct git_pack_entry *e,
  		struct git_pack_file *p,
  		const git_oid *short_oid,
  		size_t len);
  int git_pack_foreach_entry(
  		struct git_pack_file *p,
  		git_odb_foreach_cb cb,
  		void *data);
  
  #endif
  

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