Re: [PATCH v2 1/6] object-file: refactor write_loose_object() to support inputstream

Using "in_stream" instead of "void *buf", we needn't to allocate enough
memory in advance, and only part of the contents will be read when
called "in_stream.read()".

Helped-by: Jiang Xin [off-list ref]
Signed-off-by: Han Xin <redacted>
---
 object-file.c  | 50 ++++++++++++++++++++++++++++++++++++++++++++++----
 object-store.h |  5 +++++
 2 files changed, 51 insertions(+), 4 deletions(-)

diff --git a/object-file.c b/object-file.c
index 02b7970274..1ad2cb579c 100644
--- a/object-file.c
+++ b/object-file.c

@@ -1860,8 +1860,26 @@ static int create_tmpfile(struct strbuf *tmp, const char *filename)
        return fd;
 }

+struct input_data_from_buffer {
+       const char *buf;
+       unsigned long len;
+};
+
+static const char *read_input_stream_from_buffer(void *data, unsigned long *len)

+{
+       struct input_data_from_buffer *input = (struct input_data_from_buffer *)data;
+
+       if (input->len == 0) {
+               *len = 0;
+               return NULL;
+       }
+       *len = input->len;
+       input->len = 0;
+       return input->buf;
+}
+
 static int write_loose_object(const struct object_id *oid, char *hdr,
-                             int hdrlen, const void *buf, unsigned long len,
+                             int hdrlen, struct input_stream *in_stream,
                              time_t mtime, unsigned flags)
 {
        int fd, ret;

@@ -1871,6 +1889,8 @@ static int write_loose_object(const struct object_id *oid, char *hdr,
        struct object_id parano_oid;
        static struct strbuf tmp_file = STRBUF_INIT;
        static struct strbuf filename = STRBUF_INIT;
+       const char *buf;

+       unsigned long len;

        loose_object_path(the_repository, &filename, oid);

@@ -1898,6 +1918,7 @@ static int write_loose_object(const struct object_id *oid, char *hdr,
        the_hash_algo->update_fn(&c, hdr, hdrlen);

        /* Then the data itself.. */
+       buf = in_stream->read(in_stream->data, &len);
        stream.next_in = (void *)buf;
        stream.avail_in = len;
        do {

@@ -1960,6 +1981,13 @@ int write_object_file_flags(const void *buf, unsigned long len,
 {
        char hdr[MAX_HEADER_LEN];
        int hdrlen = sizeof(hdr);
+       struct input_stream in_stream = {
+               .read = read_input_stream_from_buffer,
+               .data = (void *)&(struct input_data_from_buffer) {
+                       .buf = buf,
+                       .len = len,
+               },
+       };

        /* Normally if we have it in the pack then we do not bother writing
         * it out into .git/objects/??/?{38} file.

@@ -1968,7 +1996,7 @@ int write_object_file_flags(const void *buf, unsigned long len,
                                  &hdrlen);
        if (freshen_packed_object(oid) || freshen_loose_object(oid))
                return 0;
-       return write_loose_object(oid, hdr, hdrlen, buf, len, 0, flags);
+       return write_loose_object(oid, hdr, hdrlen, &in_stream, 0, flags);
 }

 int hash_object_file_literally(const void *buf, unsigned long len,

@@ -1977,6 +2005,13 @@ int hash_object_file_literally(const void *buf, unsigned long len,
 {
        char *header;
        int hdrlen, status = 0;
+       struct input_stream in_stream = {
+               .read = read_input_stream_from_buffer,
+               .data = (void *)&(struct input_data_from_buffer) {
+                       .buf = buf,
+                       .len = len,
+               },
+       };

        /* type string, SP, %lu of the length plus NUL must fit this */
        hdrlen = strlen(type) + MAX_HEADER_LEN;

@@ -1988,7 +2023,7 @@ int hash_object_file_literally(const void *buf, unsigned long len,
                goto cleanup;
        if (freshen_packed_object(oid) || freshen_loose_object(oid))
                goto cleanup;
-       status = write_loose_object(oid, header, hdrlen, buf, len, 0, 0);
+       status = write_loose_object(oid, header, hdrlen, &in_stream, 0, 0);

 cleanup:
        free(header);

@@ -2003,14 +2038,21 @@ int force_object_loose(const struct object_id *oid, time_t mtime)
        char hdr[MAX_HEADER_LEN];
        int hdrlen;
        int ret;
+       struct input_data_from_buffer data;
+       struct input_stream in_stream = {
+               .read = read_input_stream_from_buffer,
+               .data = &data,
+       };

        if (has_loose_object(oid))
                return 0;
        buf = read_object(the_repository, oid, &type, &len);
        if (!buf)
                return error(_("cannot read object for %s"), oid_to_hex(oid));
+       data.buf = buf;
+       data.len = len;
        hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %"PRIuMAX , type_name(type), (uintmax_t)len) + 1;
-       ret = write_loose_object(oid, hdr, hdrlen, buf, len, mtime, 0);
+       ret = write_loose_object(oid, hdr, hdrlen, &in_stream, mtime, 0);
        free(buf);

        return ret;

diff --git a/object-store.h b/object-store.h
index 952efb6a4b..f1b67e9100 100644
--- a/object-store.h
+++ b/object-store.h

@@ -34,6 +34,11 @@ struct object_directory {
        char *path;
 };

+struct input_stream {
+       const char *(*read)(void* data, unsigned long *len);
+       void *data;
+};
+
 KHASH_INIT(odb_path_map, const char * /* key: odb_path */,
        struct object_directory *, 1, fspathhash, fspatheq)

--

2.33.1.44.g9344627884.agit.6.5.4