thodg/libgit2/include/git2/odb_backend.h

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• Hash : 4a863c06
  Author :
  Date : 2013-01-03T20:36:26
  

  Sane refresh logic All the ODB backends have a specific refresh interface. When reading an object, first we attempt every single backend: if the read fails, then we refresh all the backends and retry the read one more time to see if the object has appeared.

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• include/git2/odb_backend.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_git_odb_backend_h__
  #define INCLUDE_git_odb_backend_h__
  
  #include "common.h"
  #include "types.h"
  #include "oid.h"
  #include "indexer.h"
  
  /**
   * @file git2/backend.h
   * @brief Git custom backend functions
   * @defgroup git_backend Git custom backend API
   * @ingroup Git
   * @{
   */
  GIT_BEGIN_DECL
  
  struct git_odb_stream;
  struct git_odb_writepack;
  
  /**
   * Function type for callbacks from git_odb_foreach.
   */
  typedef int (*git_odb_foreach_cb)(const git_oid *id, void *payload);
  
  /**
   * An instance for a custom backend
   */
  struct git_odb_backend {
  	unsigned int version;
  	git_odb *odb;
  
  	/* read and read_prefix each return to libgit2 a buffer which
  	 * will be freed later. The buffer should be allocated using
  	 * the function git_odb_backend_malloc to ensure that it can
  	 * be safely freed later. */
  	int (* read)(
  			void **, size_t *, git_otype *,
  			struct git_odb_backend *,
  			const git_oid *);
  
  	/* To find a unique object given a prefix
  	 * of its oid.
  	 * The oid given must be so that the
  	 * remaining (GIT_OID_HEXSZ - len)*4 bits
  	 * are 0s.
  	 */
  	int (* read_prefix)(
  			git_oid *,
  			void **, size_t *, git_otype *,
  			struct git_odb_backend *,
  			const git_oid *,
  			size_t);
  
  	int (* read_header)(
  			size_t *, git_otype *,
  			struct git_odb_backend *,
  			const git_oid *);
  
  	/* The writer may assume that the object
  	 * has already been hashed and is passed
  	 * in the first parameter.
  	 */
  	int (* write)(
  			git_oid *,
  			struct git_odb_backend *,
  			const void *,
  			size_t,
  			git_otype);
  
  	int (* writestream)(
  			struct git_odb_stream **,
  			struct git_odb_backend *,
  			size_t,
  			git_otype);
  
  	int (* readstream)(
  			struct git_odb_stream **,
  			struct git_odb_backend *,
  			const git_oid *);
  
  	int (* exists)(
  			struct git_odb_backend *,
  			const git_oid *);
  
  	int (* refresh)(struct git_odb_backend *);
  
  	int (* foreach)(
  			struct git_odb_backend *,
  			git_odb_foreach_cb cb,
  			void *payload);
  
  	int (* writepack)(
  			struct git_odb_writepack **,
  			struct git_odb_backend *,
  			git_transfer_progress_callback progress_cb,
  			void *progress_payload);
  
  	void (* free)(struct git_odb_backend *);
  };
  
  #define GIT_ODB_BACKEND_VERSION 1
  #define GIT_ODB_BACKEND_INIT {GIT_ODB_BACKEND_VERSION}
  
  /** Streaming mode */
  enum {
  	GIT_STREAM_RDONLY = (1 << 1),
  	GIT_STREAM_WRONLY = (1 << 2),
  	GIT_STREAM_RW = (GIT_STREAM_RDONLY | GIT_STREAM_WRONLY),
  };
  
  /** A stream to read/write from a backend */
  struct git_odb_stream {
  	struct git_odb_backend *backend;
  	unsigned int mode;
  
  	int (*read)(struct git_odb_stream *stream, char *buffer, size_t len);
  	int (*write)(struct git_odb_stream *stream, const char *buffer, size_t len);
  	int (*finalize_write)(git_oid *oid_p, struct git_odb_stream *stream);
  	void (*free)(struct git_odb_stream *stream);
  };
  
  /** A stream to write a pack file to the ODB */
  struct git_odb_writepack {
  	struct git_odb_backend *backend;
  
  	int (*add)(struct git_odb_writepack *writepack, const void *data, size_t size, git_transfer_progress *stats);
  	int (*commit)(struct git_odb_writepack *writepack, git_transfer_progress *stats);
  	void (*free)(struct git_odb_writepack *writepack);
  };
  
  GIT_EXTERN(void *) git_odb_backend_malloc(git_odb_backend *backend, size_t len);
  
  /**
   * Constructors for in-box ODB backends.
   */
  GIT_EXTERN(int) git_odb_backend_pack(git_odb_backend **out, const char *objects_dir);
  GIT_EXTERN(int) git_odb_backend_loose(git_odb_backend **out, const char *objects_dir, int compression_level, int do_fsync);
  GIT_EXTERN(int) git_odb_backend_one_pack(git_odb_backend **out, const char *index_file);
  
  GIT_END_DECL
  
  #endif
  

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