From: Han Xin <hanxin.hx@xxxxxxxxxxxxxxx>
If we want unpack and write a loose object using "write_loose_object",
we have to feed it with a buffer with the same size of the object, which
will consume lots of memory and may cause OOM. This can be improved by
feeding data to "stream_loose_object()" in a stream.
Add a new function "stream_loose_object()", which is a stream version of
"write_loose_object()" but with a low memory footprint. We will use this
function to unpack large blob object in latter commit.
Another difference with "write_loose_object()" is that we have no chance
to run "write_object_file_prepare()" to calculate the oid in advance.
In "write_loose_object()", we know the oid and we can write the
temporary file in the same directory as the final object, but for an
object with an undetermined oid, we don't know the exact directory for
the object, so we have to save the temporary file in ".git/objects/"
directory instead.
"freshen_packed_object()" or "freshen_loose_object()" will be called
inside "stream_loose_object()" after obtaining the "oid".
Helped-by: René Scharfe <l.s.r@xxxxxx>
Helped-by: Ævar Arnfjörð Bjarmason <avarab@xxxxxxxxx>
Helped-by: Jiang Xin <zhiyou.jx@xxxxxxxxxxxxxxx>
Signed-off-by: Han Xin <hanxin.hx@xxxxxxxxxxxxxxx>
---
object-file.c | 101 +++++++++++++++++++++++++++++++++++++++++++++++++
object-store.h | 9 +++++
2 files changed, 110 insertions(+)
diff --git a/object-file.c b/object-file.c
index 4f0127e823..a462a21629 100644
--- a/object-file.c
+++ b/object-file.c
@@ -2012,6 +2012,107 @@ static int freshen_packed_object(const struct object_id *oid)
return 1;
}
+int stream_loose_object(struct input_stream *in_stream, size_t len,
+ struct object_id *oid)
+{
+ int fd, ret, err = 0, flush = 0;
+ unsigned char compressed[4096];
+ git_zstream stream;
+ git_hash_ctx c;
+ struct strbuf tmp_file = STRBUF_INIT;
+ struct strbuf filename = STRBUF_INIT;
+ int dirlen;
+ char hdr[MAX_HEADER_LEN];
+ int hdrlen;
+
+ /* Since oid is not determined, save tmp file to odb path. */
+ strbuf_addf(&filename, "%s/", get_object_directory());
+ hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %"PRIuMAX, type_name(OBJ_BLOB), len) + 1;
+
+ /* Common steps for write_loose_object and stream_loose_object to
+ * start writing loose oject:
+ *
+ * - Create tmpfile for the loose object.
+ * - Setup zlib stream for compression.
+ * - Start to feed header to zlib stream.
+ */
+ fd = start_loose_object_common(&tmp_file, filename.buf, 0,
+ &stream, compressed, sizeof(compressed),
+ &c, OBJ_BLOB, len, hdr, hdrlen);
+ if (fd < 0) {
+ err = -1;
+ goto cleanup;
+ }
+
+ /* Then the data itself.. */
+ do {
+ unsigned char *in0 = stream.next_in;
+ if (!stream.avail_in && !in_stream->is_finished) {
+ const void *in = in_stream->read(in_stream, &stream.avail_in);
+ stream.next_in = (void *)in;
+ in0 = (unsigned char *)in;
+ /* All data has been read. */
+ if (in_stream->is_finished)
+ flush = Z_FINISH;
+ }
+ ret = git_deflate(&stream, flush);
+ the_hash_algo->update_fn(&c, in0, stream.next_in - in0);
+ if (write_buffer(fd, compressed, stream.next_out - compressed) < 0)
+ die(_("unable to write loose object file"));
+ stream.next_out = compressed;
+ stream.avail_out = sizeof(compressed);
+ /*
+ * Unlike write_loose_object(), we do not have the entire
+ * buffer. If we get Z_BUF_ERROR due to too few input bytes,
+ * then we'll replenish them in the next input_stream->read()
+ * call when we loop.
+ */
+ } while (ret == Z_OK || ret == Z_BUF_ERROR);
+
+ if (stream.total_in != len + hdrlen)
+ die(_("write stream object %ld != %"PRIuMAX), stream.total_in,
+ (uintmax_t)len + hdrlen);
+
+ /* Common steps for write_loose_object and stream_loose_object to
+ * end writing loose oject:
+ *
+ * - End the compression of zlib stream.
+ * - Get the calculated oid.
+ */
+ end_loose_object_common(ret, &c, &stream, oid, NULL,
+ N_("unable to stream deflate new object (%d)"),
+ N_("deflateEnd on stream object failed (%d)"));
+
+ close_loose_object(fd);
+
+ if (freshen_packed_object(oid) || freshen_loose_object(oid)) {
+ unlink_or_warn(tmp_file.buf);
+ goto cleanup;
+ }
+
+ loose_object_path(the_repository, &filename, oid);
+
+ /* We finally know the object path, and create the missing dir. */
+ dirlen = directory_size(filename.buf);
+ if (dirlen) {
+ struct strbuf dir = STRBUF_INIT;
+ strbuf_add(&dir, filename.buf, dirlen);
+
+ if (mkdir_in_gitdir(dir.buf) && errno != EEXIST) {
+ err = error_errno(_("unable to create directory %s"), dir.buf);
+ strbuf_release(&dir);
+ goto cleanup;
+ }
+ strbuf_release(&dir);
+ }
+
+ err = finalize_object_file(tmp_file.buf, filename.buf);
+cleanup:
+ strbuf_release(&tmp_file);
+ strbuf_release(&filename);
+ return err;
+}
+
int write_object_file_flags(const void *buf, unsigned long len,
const char *type, struct object_id *oid,
unsigned flags)
diff --git a/object-store.h b/object-store.h
index 952efb6a4b..cc41c64d69 100644
--- a/object-store.h
+++ b/object-store.h
@@ -34,6 +34,12 @@ struct object_directory {
char *path;
};
+struct input_stream {
+ const void *(*read)(struct input_stream *, unsigned long *len);
+ void *data;
+ int is_finished;
+};
+
KHASH_INIT(odb_path_map, const char * /* key: odb_path */,
struct object_directory *, 1, fspathhash, fspatheq)
@@ -232,6 +238,9 @@ static inline int write_object_file(const void *buf, unsigned long len,
return write_object_file_flags(buf, len, type, oid, 0);
}
+int stream_loose_object(struct input_stream *in_stream, size_t len,
+ struct object_id *oid);
+
int hash_object_file_literally(const void *buf, unsigned long len,
const char *type, struct object_id *oid,
unsigned flags);
--
2.34.1.52.gc288e771b4.agit.6.5.6
