streaming: refactor interface to be object-database-centric

Refactor the streaming interface to be centered around object databases
instead of centered around the repository. Rename the functions
accordingly.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: pks-t

archive-tar.c

@@ -135,16 +135,16 @@ static int stream_blocked(struct repository *r, const struct object_id *oid)
 	char buf[BLOCKSIZE];
 	ssize_t readlen;
 
-	st = open_istream(r, oid, &type, &sz, NULL);
+	st = odb_read_object_stream(r->objects, oid, &type, &sz, NULL);
 	if (!st)
 		return error(_("cannot stream blob %s"), oid_to_hex(oid));
 	for (;;) {
-		readlen = read_istream(st, buf, sizeof(buf));
+		readlen = odb_read_stream_read(st, buf, sizeof(buf));
 		if (readlen <= 0)
 			break;
 		do_write_blocked(buf, readlen);
 	}
-	close_istream(st);
+	odb_read_stream_close(st);
 	if (!readlen)
 		finish_record();
 	return readlen;

archive-zip.c

@@ -348,8 +348,8 @@ static int write_zip_entry(struct archiver_args *args,
 
 		if (!buffer) {
 			enum object_type type;
-			stream = open_istream(args->repo, oid, &type, &size,
-					      NULL);
+			stream = odb_read_object_stream(args->repo->objects, oid,
+							&type, &size, NULL);
 			if (!stream)
 				return error(_("cannot stream blob %s"),
 					     oid_to_hex(oid));
@@ -429,7 +429,7 @@ static int write_zip_entry(struct archiver_args *args,
 		ssize_t readlen;
 
 		for (;;) {
-			readlen = read_istream(stream, buf, sizeof(buf));
+			readlen = odb_read_stream_read(stream, buf, sizeof(buf));
 			if (readlen <= 0)
 				break;
 			crc = crc32(crc, buf, readlen);
@@ -439,7 +439,7 @@ static int write_zip_entry(struct archiver_args *args,
 							    buf, readlen);
 			write_or_die(1, buf, readlen);
 		}
-		close_istream(stream);
+		odb_read_stream_close(stream);
 		if (readlen)
 			return readlen;
 
@@ -462,7 +462,7 @@ static int write_zip_entry(struct archiver_args *args,
 		zstream.avail_out = sizeof(compressed);
 
 		for (;;) {
-			readlen = read_istream(stream, buf, sizeof(buf));
+			readlen = odb_read_stream_read(stream, buf, sizeof(buf));
 			if (readlen <= 0)
 				break;
 			crc = crc32(crc, buf, readlen);
@@ -486,7 +486,7 @@ static int write_zip_entry(struct archiver_args *args,
 			}
 
 		}
-		close_istream(stream);
+		odb_read_stream_close(stream);
 		if (readlen)
 			return readlen;
 

builtin/index-pack.c

@@ -779,7 +779,7 @@ static int compare_objects(const unsigned char *buf, unsigned long size,
 	}
 
 	while (size) {
-		ssize_t len = read_istream(data->st, data->buf, size);
+		ssize_t len = odb_read_stream_read(data->st, data->buf, size);
 		if (len == 0)
 			die(_("SHA1 COLLISION FOUND WITH %s !"),
 			    oid_to_hex(&data->entry->idx.oid));
@@ -807,15 +807,15 @@ static int check_collison(struct object_entry *entry)
 
 	memset(&data, 0, sizeof(data));
 	data.entry = entry;
-	data.st = open_istream(the_repository, &entry->idx.oid, &type, &size,
-			       NULL);
+	data.st = odb_read_object_stream(the_repository->objects, &entry->idx.oid,
+					 &type, &size, NULL);
 	if (!data.st)
 		return -1;
 	if (size != entry->size || type != entry->type)
 		die(_("SHA1 COLLISION FOUND WITH %s !"),
 		    oid_to_hex(&entry->idx.oid));
 	unpack_data(entry, compare_objects, &data);
-	close_istream(data.st);
+	odb_read_stream_close(data.st);
 	free(data.buf);
 	return 0;
 }

builtin/pack-objects.c

@@ -417,7 +417,7 @@ static unsigned long write_large_blob_data(struct odb_read_stream *st, struct ha
 	for (;;) {
 		ssize_t readlen;
 		int zret = Z_OK;
-		readlen = read_istream(st, ibuf, sizeof(ibuf));
+		readlen = odb_read_stream_read(st, ibuf, sizeof(ibuf));
 		if (readlen == -1)
 			die(_("unable to read %s"), oid_to_hex(oid));
 
@@ -520,8 +520,8 @@ static unsigned long write_no_reuse_object(struct hashfile *f, struct object_ent
 		if (oe_type(entry) == OBJ_BLOB &&
 		    oe_size_greater_than(&to_pack, entry,
 					 repo_settings_get_big_file_threshold(the_repository)) &&
-		    (st = open_istream(the_repository, &entry->idx.oid, &type,
-				       &size, NULL)) != NULL)
+		    (st = odb_read_object_stream(the_repository->objects, &entry->idx.oid,
+						 &type, &size, NULL)) != NULL)
 			buf = NULL;
 		else {
 			buf = odb_read_object(the_repository->objects,
@@ -577,7 +577,7 @@ static unsigned long write_no_reuse_object(struct hashfile *f, struct object_ent
 			dheader[--pos] = 128 | (--ofs & 127);
 		if (limit && hdrlen + sizeof(dheader) - pos + datalen + hashsz >= limit) {
 			if (st)
-				close_istream(st);
+				odb_read_stream_close(st);
 			free(buf);
 			return 0;
 		}
@@ -591,7 +591,7 @@ static unsigned long write_no_reuse_object(struct hashfile *f, struct object_ent
 		 */
 		if (limit && hdrlen + hashsz + datalen + hashsz >= limit) {
 			if (st)
-				close_istream(st);
+				odb_read_stream_close(st);
 			free(buf);
 			return 0;
 		}
@@ -601,15 +601,15 @@ static unsigned long write_no_reuse_object(struct hashfile *f, struct object_ent
 	} else {
 		if (limit && hdrlen + datalen + hashsz >= limit) {
 			if (st)
-				close_istream(st);
+				odb_read_stream_close(st);
 			free(buf);
 			return 0;
 		}
 		hashwrite(f, header, hdrlen);
 	}
 	if (st) {
 		datalen = write_large_blob_data(st, f, &entry->idx.oid);
-		close_istream(st);
+		odb_read_stream_close(st);
 	} else {
 		hashwrite(f, buf, datalen);
 		free(buf);

object-file.c

@@ -139,7 +139,7 @@ int stream_object_signature(struct repository *r, const struct object_id *oid)
 	char hdr[MAX_HEADER_LEN];
 	int hdrlen;
 
-	st = open_istream(r, oid, &obj_type, &size, NULL);
+	st = odb_read_object_stream(r->objects, oid, &obj_type, &size, NULL);
 	if (!st)
 		return -1;
 
@@ -151,18 +151,18 @@ int stream_object_signature(struct repository *r, const struct object_id *oid)
 	git_hash_update(&c, hdr, hdrlen);
 	for (;;) {
 		char buf[1024 * 16];
-		ssize_t readlen = read_istream(st, buf, sizeof(buf));
+		ssize_t readlen = odb_read_stream_read(st, buf, sizeof(buf));
 
 		if (readlen < 0) {
-			close_istream(st);
+			odb_read_stream_close(st);
 			return -1;
 		}
 		if (!readlen)
 			break;
 		git_hash_update(&c, buf, readlen);
 	}
 	git_hash_final_oid(&real_oid, &c);
-	close_istream(st);
+	odb_read_stream_close(st);
 	return !oideq(oid, &real_oid) ? -1 : 0;
 }
 

streaming.c

@@ -35,7 +35,7 @@ static int close_istream_filtered(struct odb_read_stream *_fs)
 {
 	struct odb_filtered_read_stream *fs = (struct odb_filtered_read_stream *)_fs;
 	free_stream_filter(fs->filter);
-	return close_istream(fs->upstream);
+	return odb_read_stream_close(fs->upstream);
 }
 
 static ssize_t read_istream_filtered(struct odb_read_stream *_fs, char *buf,
@@ -87,7 +87,7 @@ static ssize_t read_istream_filtered(struct odb_read_stream *_fs, char *buf,
 
 		/* refill the input from the upstream */
 		if (!fs->input_finished) {
-			fs->i_end = read_istream(fs->upstream, fs->ibuf, FILTER_BUFFER);
+			fs->i_end = odb_read_stream_read(fs->upstream, fs->ibuf, FILTER_BUFFER);
 			if (fs->i_end < 0)
 				return -1;
 			if (fs->i_end)
@@ -149,7 +149,7 @@ static ssize_t read_istream_incore(struct odb_read_stream *_st, char *buf, size_
 }
 
 static int open_istream_incore(struct odb_read_stream **out,
-			       struct repository *r,
+			       struct object_database *odb,
 			       const struct object_id *oid)
 {
 	struct object_info oi = OBJECT_INFO_INIT;
@@ -162,7 +162,7 @@ static int open_istream_incore(struct odb_read_stream **out,
 	oi.typep = &stream.base.type;
 	oi.sizep = &stream.base.size;
 	oi.contentp = (void **)&stream.buf;
-	ret = odb_read_object_info_extended(r->objects, oid, &oi,
+	ret = odb_read_object_info_extended(odb, oid, &oi,
 					    OBJECT_INFO_DIE_IF_CORRUPT);
 	if (ret)
 		return ret;
@@ -179,57 +179,57 @@ static int open_istream_incore(struct odb_read_stream **out,
  *****************************************************************************/
 
 static int istream_source(struct odb_read_stream **out,
-			  struct repository *r,
+			  struct object_database *odb,
 			  const struct object_id *oid)
 {
 	struct odb_source *source;
 
-	if (!packfile_store_read_object_stream(out, r->objects->packfiles, oid))
+	if (!packfile_store_read_object_stream(out, odb->packfiles, oid))
 		return 0;
 
-	odb_prepare_alternates(r->objects);
-	for (source = r->objects->sources; source; source = source->next)
+	odb_prepare_alternates(odb);
+	for (source = odb->sources; source; source = source->next)
 		if (!odb_source_loose_read_object_stream(out, source, oid))
 			return 0;
 
-	return open_istream_incore(out, r, oid);
+	return open_istream_incore(out, odb, oid);
 }
 
 /****************************************************************
  * Users of streaming interface
  ****************************************************************/
 
-int close_istream(struct odb_read_stream *st)
+int odb_read_stream_close(struct odb_read_stream *st)
 {
 	int r = st->close(st);
 	free(st);
 	return r;
 }
 
-ssize_t read_istream(struct odb_read_stream *st, void *buf, size_t sz)
+ssize_t odb_read_stream_read(struct odb_read_stream *st, void *buf, size_t sz)
 {
 	return st->read(st, buf, sz);
 }
 
-struct odb_read_stream *open_istream(struct repository *r,
-				     const struct object_id *oid,
-				     enum object_type *type,
-				     unsigned long *size,
-				     struct stream_filter *filter)
+struct odb_read_stream *odb_read_object_stream(struct object_database *odb,
+					       const struct object_id *oid,
+					       enum object_type *type,
+					       unsigned long *size,
+					       struct stream_filter *filter)
 {
 	struct odb_read_stream *st;
-	const struct object_id *real = lookup_replace_object(r, oid);
+	const struct object_id *real = lookup_replace_object(odb->repo, oid);
 	int ret;
 
-	ret = istream_source(&st, r, real);
+	ret = istream_source(&st, odb, real);
 	if (ret)
 		return NULL;
 
 	if (filter) {
 		/* Add "&& !is_null_stream_filter(filter)" for performance */
 		struct odb_read_stream *nst = attach_stream_filter(st, filter);
 		if (!nst) {
-			close_istream(st);
+			odb_read_stream_close(st);
 			return NULL;
 		}
 		st = nst;
@@ -252,7 +252,7 @@ int odb_stream_blob_to_fd(struct object_database *odb,
 	ssize_t kept = 0;
 	int result = -1;
 
-	st = open_istream(odb->repo, oid, &type, &sz, filter);
+	st = odb_read_object_stream(odb, oid, &type, &sz, filter);
 	if (!st) {
 		if (filter)
 			free_stream_filter(filter);
@@ -263,7 +263,7 @@ int odb_stream_blob_to_fd(struct object_database *odb,
 	for (;;) {
 		char buf[1024 * 16];
 		ssize_t wrote, holeto;
-		ssize_t readlen = read_istream(st, buf, sizeof(buf));
+		ssize_t readlen = odb_read_stream_read(st, buf, sizeof(buf));
 
 		if (readlen < 0)
 			goto close_and_exit;
@@ -294,6 +294,6 @@ int odb_stream_blob_to_fd(struct object_database *odb,
 	result = 0;
 
  close_and_exit:
-	close_istream(st);
+	odb_read_stream_close(st);
 	return result;
 }

streaming.h

@@ -24,11 +24,31 @@ struct odb_read_stream {
 	unsigned long size; /* inflated size of full object */
 };
 
-struct odb_read_stream *open_istream(struct repository *, const struct object_id *,
-				       enum object_type *, unsigned long *,
-				       struct stream_filter *);
-int close_istream(struct odb_read_stream *);
-ssize_t read_istream(struct odb_read_stream *, void *, size_t);
+/*
+ * Create a new object stream for the given object database. Populates the type
+ * and size pointers with the object's info. An optional filter can be used to
+ * transform the object's content.
+ *
+ * Returns the stream on success, a `NULL` pointer otherwise.
+ */
+struct odb_read_stream *odb_read_object_stream(struct object_database *odb,
+					       const struct object_id *oid,
+					       enum object_type *type,
+					       unsigned long *size,
+					       struct stream_filter *filter);
+
+/*
+ * Close the given read stream and release all resources associated with it.
+ * Returns 0 on success, a negative error code otherwise.
+ */
+int odb_read_stream_close(struct odb_read_stream *stream);
+
+/*
+ * Read data from the stream into the buffer. Returns 0 on EOF and the number
+ * of bytes read on success. Returns a negative error code in case reading from
+ * the stream fails.
+ */
+ssize_t odb_read_stream_read(struct odb_read_stream *stream, void *buf, size_t len);
 
 /*
  * Look up the object by its ID and write the full contents to the file