include/git2/sys/refdb_backend.h

   1 /*
   2  * Copyright (C) the libgit2 contributors. All rights reserved.
   3  *
   4  * This file is part of libgit2, distributed under the GNU GPL v2 with
   5  * a Linking Exception. For full terms see the included COPYING file.
   6  */
   7 #ifndef INCLUDE_sys_git_refdb_backend_h__
   8 #define INCLUDE_sys_git_refdb_backend_h__
   9
  10 #include "git2/common.h"
  11 #include "git2/types.h"
  12 #include "git2/oid.h"
  13
  14 /**
  15  * @file git2/refdb_backend.h
  16  * @brief Git custom refs backend functions
  17  * @defgroup git_refdb_backend Git custom refs backend API
  18  * @ingroup Git
  19  * @{
  20  */
  21 GIT_BEGIN_DECL
  22
  23
  24 /**
  25  * Every backend's iterator must have a pointer to itself as the first
  26  * element, so the API can talk to it. You'd define your iterator as
  27  *
  28  *     struct my_iterator {
  29  *             git_reference_iterator parent;
  30  *             ...
  31  *     }
  32  *
  33  * and assign `iter->parent.backend` to your `git_refdb_backend`.
  34  */
  35 struct git_reference_iterator {
  36         git_refdb *db;
  37
  38         /**
  39          * Return the current reference and advance the iterator.
  40          */
  41         int (*next)(
  42                 git_reference **ref,
  43                 git_reference_iterator *iter);
  44
  45         /**
  46          * Return the name of the current reference and advance the iterator
  47          */
  48         int (*next_name)(
  49                 const char **ref_name,
  50                 git_reference_iterator *iter);
  51
  52         /**
  53          * Free the iterator
  54          */
  55         void (*free)(
  56                 git_reference_iterator *iter);
  57 };
  58
  59 /** An instance for a custom backend */
  60 struct git_refdb_backend {
  61         unsigned int version;
  62
  63         /**
  64          * Queries the refdb backend to determine if the given ref_name
  65          * exists.  A refdb implementation must provide this function.
  66          */
  67         int (*exists)(
  68                 int *exists,
  69                 git_refdb_backend *backend,
  70                 const char *ref_name);
  71
  72         /**
  73          * Queries the refdb backend for a given reference.  A refdb
  74          * implementation must provide this function.
  75          */
  76         int (*lookup)(
  77                 git_reference **out,
  78                 git_refdb_backend *backend,
  79                 const char *ref_name);
  80
  81         /**
  82          * Allocate an iterator object for the backend.
  83          *
  84          * A refdb implementation must provide this function.
  85          */
  86         int (*iterator)(
  87                 git_reference_iterator **iter,
  88                 struct git_refdb_backend *backend,
  89                 const char *glob);
  90
  91         /*
  92          * Writes the given reference to the refdb.  A refdb implementation
  93          * must provide this function.
  94          */
  95         int (*write)(git_refdb_backend *backend, const git_reference *ref);
  96
  97         /**
  98          * Deletes the given reference from the refdb.  A refdb implementation
  99          * must provide this function.
 100          */
 101         int (*delete)(git_refdb_backend *backend, const git_reference *ref);
 102
 103         /**
 104          * Suggests that the given refdb compress or optimize its references.
 105          * This mechanism is implementation specific.  (For on-disk reference
 106          * databases, this may pack all loose references.)    A refdb
 107          * implementation may provide this function; if it is not provided,
 108          * nothing will be done.
 109          */
 110         int (*compress)(git_refdb_backend *backend);
 111
 112         /**
 113          * Frees any resources held by the refdb.  A refdb implementation may
 114          * provide this function; if it is not provided, nothing will be done.
 115          */
 116         void (*free)(git_refdb_backend *backend);
 117 };
 118
 119 #define GIT_ODB_BACKEND_VERSION 1
 120 #define GIT_ODB_BACKEND_INIT {GIT_ODB_BACKEND_VERSION}
 121
 122 /**
 123  * Constructors for default filesystem-based refdb backend
 124  *
 125  * Under normal usage, this is called for you when the repository is
 126  * opened / created, but you can use this to explicitly construct a
 127  * filesystem refdb backend for a repository.
 128  *
 129  * @param backend_out Output pointer to the git_refdb_backend object
 130  * @param repo Git repository to access
 131  * @return 0 on success, <0 error code on failure
 132  */
 133 GIT_EXTERN(int) git_refdb_backend_fs(
 134         git_refdb_backend **backend_out,
 135         git_repository *repo);
 136
 137 /**
 138  * Sets the custom backend to an existing reference DB
 139  *
 140  * The `git_refdb` will take ownership of the `git_refdb_backend` so you
 141  * should NOT free it after calling this function.
 142  *
 143  * @param refdb database to add the backend to
 144  * @param backend pointer to a git_refdb_backend instance
 145  * @return 0 on success; error code otherwise
 146  */
 147 GIT_EXTERN(int) git_refdb_set_backend(
 148         git_refdb *refdb,
 149         git_refdb_backend *backend);
 150
 151 GIT_END_DECL
 152
 153 #endif