On Sun, 13 Jul 2008, Shawn O. Pearce wrote:
> We need to discard base objects which are not recently used if our
> memory gets low, such as when we are unpacking a long delta chain
> of a very large object.
>
> To support tracking the available base objects we combine the
> pointer and size into a struct. Future changes would allow the
> data pointer to be free'd and marked NULL if memory gets low.
>
> Signed-off-by: Shawn O. Pearce <spearce@xxxxxxxxxxx>
ACK
> ---
> index-pack.c | 60 +++++++++++++++++++++++++++++++--------------------------
> 1 files changed, 33 insertions(+), 27 deletions(-)
>
> diff --git a/index-pack.c b/index-pack.c
> index 25db5db..db03478 100644
> --- a/index-pack.c
> +++ b/index-pack.c
> @@ -26,6 +26,11 @@ union delta_base {
> off_t offset;
> };
>
> +struct base_data {
> + void *data;
> + unsigned long size;
> +};
> +
> /*
> * Even if sizeof(union delta_base) == 24 on 64-bit archs, we really want
> * to memcmp() only the first 20 bytes.
> @@ -426,25 +431,25 @@ static void sha1_object(const void *data, unsigned long size,
> }
> }
>
> -static void resolve_delta(struct object_entry *delta_obj, void *base_data,
> - unsigned long base_size, enum object_type type)
> +static void resolve_delta(struct object_entry *delta_obj,
> + struct base_data *base_obj, enum object_type type)
> {
> void *delta_data;
> unsigned long delta_size;
> - void *result;
> - unsigned long result_size;
> union delta_base delta_base;
> int j, first, last;
> + struct base_data result;
>
> delta_obj->real_type = type;
> delta_data = get_data_from_pack(delta_obj);
> delta_size = delta_obj->size;
> - result = patch_delta(base_data, base_size, delta_data, delta_size,
> - &result_size);
> + result.data = patch_delta(base_obj->data, base_obj->size,
> + delta_data, delta_size,
> + &result.size);
> free(delta_data);
> - if (!result)
> + if (!result.data)
> bad_object(delta_obj->idx.offset, "failed to apply delta");
> - sha1_object(result, result_size, type, delta_obj->idx.sha1);
> + sha1_object(result.data, result.size, type, delta_obj->idx.sha1);
> nr_resolved_deltas++;
>
> hashcpy(delta_base.sha1, delta_obj->idx.sha1);
> @@ -452,7 +457,7 @@ static void resolve_delta(struct object_entry *delta_obj, void *base_data,
> for (j = first; j <= last; j++) {
> struct object_entry *child = objects + deltas[j].obj_no;
> if (child->real_type == OBJ_REF_DELTA)
> - resolve_delta(child, result, result_size, type);
> + resolve_delta(child, &result, type);
> }
> }
>
> @@ -462,11 +467,11 @@ static void resolve_delta(struct object_entry *delta_obj, void *base_data,
> for (j = first; j <= last; j++) {
> struct object_entry *child = objects + deltas[j].obj_no;
> if (child->real_type == OBJ_OFS_DELTA)
> - resolve_delta(child, result, result_size, type);
> + resolve_delta(child, &result, type);
> }
> }
>
> - free(result);
> + free(result.data);
> }
>
> static int compare_delta_entry(const void *a, const void *b)
> @@ -481,7 +486,6 @@ static void parse_pack_objects(unsigned char *sha1)
> {
> int i;
> struct delta_entry *delta = deltas;
> - void *data;
> struct stat st;
>
> /*
> @@ -496,7 +500,7 @@ static void parse_pack_objects(unsigned char *sha1)
> nr_objects);
> for (i = 0; i < nr_objects; i++) {
> struct object_entry *obj = &objects[i];
> - data = unpack_raw_entry(obj, &delta->base);
> + void *data = unpack_raw_entry(obj, &delta->base);
> obj->real_type = obj->type;
> if (obj->type == OBJ_REF_DELTA || obj->type == OBJ_OFS_DELTA) {
> nr_deltas++;
> @@ -545,6 +549,7 @@ static void parse_pack_objects(unsigned char *sha1)
> struct object_entry *obj = &objects[i];
> union delta_base base;
> int j, ref, ref_first, ref_last, ofs, ofs_first, ofs_last;
> + struct base_data base_obj;
>
> if (obj->type == OBJ_REF_DELTA || obj->type == OBJ_OFS_DELTA)
> continue;
> @@ -555,22 +560,22 @@ static void parse_pack_objects(unsigned char *sha1)
> ofs = !find_delta_children(&base, &ofs_first, &ofs_last);
> if (!ref && !ofs)
> continue;
> - data = get_data_from_pack(obj);
> + base_obj.data = get_data_from_pack(obj);
> + base_obj.size = obj->size;
> +
> if (ref)
> for (j = ref_first; j <= ref_last; j++) {
> struct object_entry *child = objects + deltas[j].obj_no;
> if (child->real_type == OBJ_REF_DELTA)
> - resolve_delta(child, data,
> - obj->size, obj->type);
> + resolve_delta(child, &base_obj, obj->type);
> }
> if (ofs)
> for (j = ofs_first; j <= ofs_last; j++) {
> struct object_entry *child = objects + deltas[j].obj_no;
> if (child->real_type == OBJ_OFS_DELTA)
> - resolve_delta(child, data,
> - obj->size, obj->type);
> + resolve_delta(child, &base_obj, obj->type);
> }
> - free(data);
> + free(base_obj.data);
> display_progress(progress, nr_resolved_deltas);
> }
> }
> @@ -656,28 +661,29 @@ static void fix_unresolved_deltas(int nr_unresolved)
>
> for (i = 0; i < n; i++) {
> struct delta_entry *d = sorted_by_pos[i];
> - void *data;
> - unsigned long size;
> enum object_type type;
> int j, first, last;
> + struct base_data base_obj;
>
> if (objects[d->obj_no].real_type != OBJ_REF_DELTA)
> continue;
> - data = read_sha1_file(d->base.sha1, &type, &size);
> - if (!data)
> + base_obj.data = read_sha1_file(d->base.sha1, &type, &base_obj.size);
> + if (!base_obj.data)
> continue;
>
> find_delta_children(&d->base, &first, &last);
> for (j = first; j <= last; j++) {
> struct object_entry *child = objects + deltas[j].obj_no;
> if (child->real_type == OBJ_REF_DELTA)
> - resolve_delta(child, data, size, type);
> + resolve_delta(child, &base_obj, type);
> }
>
> - if (check_sha1_signature(d->base.sha1, data, size, typename(type)))
> + if (check_sha1_signature(d->base.sha1, base_obj.data,
> + base_obj.size, typename(type)))
> die("local object %s is corrupt", sha1_to_hex(d->base.sha1));
> - append_obj_to_pack(d->base.sha1, data, size, type);
> - free(data);
> + append_obj_to_pack(d->base.sha1, base_obj.data,
> + base_obj.size, type);
> + free(base_obj.data);
> display_progress(progress, nr_resolved_deltas);
> }
> free(sorted_by_pos);
> --
> 1.5.6.2.393.g45096
>
Nicolas
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