Decouple storage from ODB logic

Comes with two default backends: loose object and packfiles.

Signed-off-by: Vicent Marti <tanoku@gmail.com>

1 files changed, 72 insertions, 57 deletions

diff --git a/src/git/odb.h b/src/git/odb.h
index b4812424c..584a848c5 100644
--- a/src/git/odb.h
+++ b/src/git/odb.h
@@ -17,17 +17,53 @@ GIT_BEGIN_DECL
 /** An open object database handle. */
 typedef struct git_odb git_odb;
 
+/** A custom backend in an ODB */
+typedef struct git_odb_backend git_odb_backend;
+
 /**
- * Open an object database for read/write access.
+ * Create a new object database with no backends.
+ *
+ * Before the ODB can be used for read/writing, a custom database
+ * backend must be manually added using `git_odb_add_backend()`
+ *
+ * @param out location to store the database pointer, if opened.
+ *            Set to NULL if the open failed.
+ * @return GIT_SUCCESS if the database was created; otherwise an error
+ *         code describing why the open was not possible.
+ */
+GIT_EXTERN(int) git_odb_new(git_odb **out);
+
+/**
+ * Create a new object database and automatically add
+ * the two default backends:
+ *
+ *	- git_odb_backend_loose: read and write loose object files
+ *		from disk, assuming `objects_dir` as the Objects folder
+ *
+ *	- git_odb_backend_pack: read objects from packfiles,
+ *		assuming `objects_dir` as the Objects folder which
+ *		contains a 'pack/' folder with the corresponding data
+ *
  * @param out location to store the database pointer, if opened.
  *            Set to NULL if the open failed.
- * @param objects_dir path of the database's "objects" directory.
+ * @param objects_dir path of the backends' "objects" directory.
  * @return GIT_SUCCESS if the database opened; otherwise an error
  *         code describing why the open was not possible.
  */
 GIT_EXTERN(int) git_odb_open(git_odb **out, const char *objects_dir);
 
 /**
+ * Add a custom backend to an existing Object DB
+ *
+ * Read <odb_backends.h> for more information.
+ *
+ * @param odb database to add the backend to
+ * @paramm backend pointer to a git_odb_backend instance
+ * @return 0 on sucess; error code otherwise
+ */
+GIT_EXTERN(int) git_odb_add_backend(git_odb *odb, git_odb_backend *backend);
+
+/**
  * Close an open object database.
  * @param db database pointer to close.  If NULL no action is taken.
  */
@@ -76,7 +112,7 @@ GIT_EXTERN(int) git_odb_read(git_rawobj *out, git_odb *db, const git_oid *id);
  * are filled. The 'data' pointer will always be NULL.
  *
  * The raw object pointed by 'out' doesn't need to be manually
- * closed with git_obj_close().
+ * closed with git_rawobj_close().
  *
  * @param out object descriptor to populate upon reading.
  * @param db database to search for the object in.
@@ -88,44 +124,45 @@ GIT_EXTERN(int) git_odb_read(git_rawobj *out, git_odb *db, const git_oid *id);
 GIT_EXTERN(int) git_odb_read_header(git_rawobj *out, git_odb *db, const git_oid *id);
 
 /**
- * Read an object from the database using only pack files.
- *
- * If GIT_ENOTFOUND then out->data is set to NULL.
+ * Write an object to the database.
  *
- * @param out object descriptor to populate upon reading.
- * @param db database to search for the object in.
- * @param id identity of the object to read.
+ * @param id identity of the object written.
+ * @param db database to which the object should be written.
+ * @param obj object descriptor for the object to write.
  * @return
- * - GIT_SUCCESS if the object was read.
- * - GIT_ENOTFOUND if the object is not in the database.
+ * - GIT_SUCCESS if the object was written;
+ * - GIT_ERROR otherwise.
  */
-GIT_EXTERN(int) git_odb__read_packed(git_rawobj *out, git_odb *db, const git_oid *id);
+GIT_EXTERN(int) git_odb_write(git_oid *id, git_odb *db, git_rawobj *obj);
 
 /**
- * Read an object from the database using only loose object files.
- *
- * If GIT_ENOTFOUND then out->data is set to NULL.
+ * Determine if the given object can be found in the object database.
  *
- * @param out object descriptor to populate upon reading.
- * @param db database to search for the object in.
- * @param id identity of the object to read.
+ * @param db database to be searched for the given object.
+ * @param id the object to search for.
  * @return
- * - GIT_SUCCESS if the object was read.
- * - GIT_ENOTFOUND if the object is not in the database.
+ * - true, if the object was found
+ * - false, otherwise
  */
-GIT_EXTERN(int) git_odb__read_loose(git_rawobj *out, git_odb *db, const git_oid *id);
+GIT_EXTERN(int) git_odb_exists(git_odb *db, const git_oid *id);
+
+
+
+
 
 /**
- * Write an object to the database.
+ * Determine the object-ID (sha1 hash) of the given git_rawobj.
  *
- * @param id identity of the object written.
- * @param db database to which the object should be written.
- * @param obj object descriptor for the object to write.
+ * The input obj must be a valid loose object type and the data
+ * pointer must not be NULL, unless the len field is also zero.
+ *
+ * @param id the resulting object-ID.
+ * @param obj the object whose hash is to be determined.
  * @return
- * - GIT_SUCCESS if the object was written;
- * - GIT_ERROR otherwise.
+ * - GIT_SUCCESS if the object-ID was correctly determined.
+ * - GIT_ERROR if the given object is malformed.
  */
-GIT_EXTERN(int) git_odb_write(git_oid *id, git_odb *db, git_rawobj *obj);
+GIT_EXTERN(int) git_rawobj_hash(git_oid *id, git_rawobj *obj);
 
 /**
  * Release all memory used by the obj structure.
@@ -136,12 +173,15 @@ GIT_EXTERN(int) git_odb_write(git_oid *id, git_odb *db, git_rawobj *obj);
  *
  * @param obj object descriptor to free.
  */
-GIT_INLINE(void) git_obj_close(git_rawobj *obj)
+GIT_INLINE(void) git_rawobj_close(git_rawobj *obj)
 {
 	free(obj->data);
 	obj->data = NULL;
 }
 
+
+
+
 /**
  * Convert an object type to it's string representation.
  *
@@ -151,7 +191,7 @@ GIT_INLINE(void) git_obj_close(git_rawobj *obj)
  * @param type object type to convert.
  * @return the corresponding string representation.
  */
-GIT_EXTERN(const char *) git_obj_type_to_string(git_otype type);
+GIT_EXTERN(const char *) git_otype_tostring(git_otype type);
 
 /**
  * Convert a string object type representation to it's git_otype.
@@ -159,7 +199,7 @@ GIT_EXTERN(const char *) git_obj_type_to_string(git_otype type);
  * @param str the string to convert.
  * @return the corresponding git_otype.
  */
-GIT_EXTERN(git_otype) git_obj_string_to_type(const char *str);
+GIT_EXTERN(git_otype) git_otype_fromstring(const char *str);
 
 /**
  * Determine if the given git_otype is a valid loose object type.
@@ -168,32 +208,7 @@ GIT_EXTERN(git_otype) git_obj_string_to_type(const char *str);
  * @return true if the type represents a valid loose object type,
  * false otherwise.
  */
-GIT_EXTERN(int) git_obj__loose_object_type(git_otype type);
-
-/**
- * Determine the object-ID (sha1 hash) of the given git_rawobj.
- *
- * The input obj must be a valid loose object type and the data
- * pointer must not be NULL, unless the len field is also zero.
- *
- * @param id the resulting object-ID.
- * @param obj the object whose hash is to be determined.
- * @return
- * - GIT_SUCCESS if the object-ID was correctly determined.
- * - GIT_ERROR if the given object is malformed.
- */
-GIT_EXTERN(int) git_obj_hash(git_oid *id, git_rawobj *obj);
-
-/**
- * Determine if the given object can be found in the object database.
- *
- * @param db database to be searched for the given object.
- * @param id the object to search for.
- * @return
- * - true, if the object was found
- * - false, otherwise
- */
-GIT_EXTERN(int) git_odb_exists(git_odb *db, const git_oid *id);
+GIT_EXTERN(int) git_otype_is_loose(git_otype type);
 
 /** @} */
 GIT_END_DECL