thodg/libgit2/include/git2/sys/odb_backend.h

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• Hash : b1a6c316
  Author :
  Date : 2013-08-30T17:36:00
  

  odb: Move the auto refresh logic to the pack backend Previously, `git_object_read()`, `git_object_read_prefix()` and `git_object_exists()` were implementing an auto refresh logic. When the expected object couldn't be found in any backend, a call to `git_odb_refresh()` was triggered and the lookup was once again performed against all backends. This commit removes this auto-refresh logic from the odb layer and pushes it down into the pack-backend (as it's the only one currently exposing a `refresh()` endpoint).

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• include/git2/sys/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_sys_git_odb_backend_h__
  #define INCLUDE_sys_git_odb_backend_h__
  
  #include "git2/common.h"
  #include "git2/types.h"
  #include "git2/oid.h"
  #include "git2/odb.h"
  
  /**
   * @file git2/sys/backend.h
   * @brief Git custom backend implementors functions
   * @defgroup git_backend Git custom backend APIs
   * @ingroup Git
   * @{
   */
  GIT_BEGIN_DECL
  
  /**
   * 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 *, 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 *,
  		git_odb_backend *, const git_oid *, size_t);
  
  	int (* read_header)(
  		size_t *, git_otype *, git_odb_backend *, const git_oid *);
  
  	/**
  	 * Write an object into the backend. The id of the object has
  	 * already been calculated and is passed in.
  	 */
  	int (* write)(
  		git_odb_backend *, const git_oid *, const void *, size_t, git_otype);
  
  	int (* writestream)(
  		git_odb_stream **, git_odb_backend *, size_t, git_otype);
  
  	int (* readstream)(
  		git_odb_stream **, git_odb_backend *, const git_oid *);
  
  	int (* exists)(
  		git_odb_backend *, const git_oid *);
  
  	/**
  	 * If the backend implements a refreshing mechanism, it should be exposed
  	 * through this endpoint. Each call to `git_odb_refresh()` will invoke it.
  	 *
  	 * However, the backend implementation should try to stay up-to-date as much
  	 * as possible by itself as libgit2 will not automatically invoke
  	 * `git_odb_refresh()`. For instance, a potential strategy for the backend
  	 * implementation to achieve this could be to internally invoke this
  	 * endpoint on failed lookups (ie. `exists()`, `read()`, `read_header()`).
  	 */
  	int (* refresh)(git_odb_backend *);
  
  	int (* foreach)(
  		git_odb_backend *, git_odb_foreach_cb cb, void *payload);
  
  	int (* writepack)(
  		git_odb_writepack **, git_odb_backend *,
  		git_transfer_progress_callback progress_cb, void *progress_payload);
  
  	void (* free)(git_odb_backend *);
  };
  
  #define GIT_ODB_BACKEND_VERSION 1
  #define GIT_ODB_BACKEND_INIT {GIT_ODB_BACKEND_VERSION}
  
  GIT_EXTERN(void *) git_odb_backend_malloc(git_odb_backend *backend, size_t len);
  
  GIT_END_DECL
  
  #endif
  

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