diff options
Diffstat (limited to 'Documentation/technical')
| -rw-r--r-- | Documentation/technical/pack-format.txt | 17 | ||||
| -rw-r--r-- | Documentation/technical/packfile-uri.txt | 7 | ||||
| -rw-r--r-- | Documentation/technical/reftable.txt | 2 |
3 files changed, 22 insertions, 4 deletions
diff --git a/Documentation/technical/pack-format.txt b/Documentation/technical/pack-format.txt index f96b2e605f..96d2fc589f 100644 --- a/Documentation/technical/pack-format.txt +++ b/Documentation/technical/pack-format.txt @@ -55,6 +55,18 @@ Valid object types are: Type 5 is reserved for future expansion. Type 0 is invalid. +=== Size encoding + +This document uses the following "size encoding" of non-negative +integers: From each byte, the seven least significant bits are +used to form the resulting integer. As long as the most significant +bit is 1, this process continues; the byte with MSB 0 provides the +last seven bits. The seven-bit chunks are concatenated. Later +values are more significant. + +This size encoding should not be confused with the "offset encoding", +which is also used in this document. + === Deltified representation Conceptually there are only four object types: commit, tree, tag and @@ -73,7 +85,10 @@ Ref-delta can also refer to an object outside the pack (i.e. the so-called "thin pack"). When stored on disk however, the pack should be self contained to avoid cyclic dependency. -The delta data is a sequence of instructions to reconstruct an object +The delta data starts with the size of the base object and the +size of the object to be reconstructed. These sizes are +encoded using the size encoding from above. The remainder of +the delta data is a sequence of instructions to reconstruct the object from the base object. If the base object is deltified, it must be converted to canonical form first. Each instruction appends more and more data to the target object until it's complete. There are two diff --git a/Documentation/technical/packfile-uri.txt b/Documentation/technical/packfile-uri.txt index 318713abc3..f7eabc6c76 100644 --- a/Documentation/technical/packfile-uri.txt +++ b/Documentation/technical/packfile-uri.txt @@ -37,8 +37,11 @@ at least so that we can test the client. This is the implementation: a feature, marked experimental, that allows the server to be configured by one or more `uploadpack.blobPackfileUri=<sha1> <uri>` entries. Whenever the list of objects to be sent is assembled, all such -blobs are excluded, replaced with URIs. The client will download those URIs, -expecting them to each point to packfiles containing single blobs. +blobs are excluded, replaced with URIs. As noted in "Future work" below, the +server can evolve in the future to support excluding other objects (or other +implementations of servers could be made that support excluding other objects) +without needing a protocol change, so clients should not expect that packfiles +downloaded in this way only contain single blobs. Client design ------------- diff --git a/Documentation/technical/reftable.txt b/Documentation/technical/reftable.txt index 2951840e9c..8095ab2590 100644 --- a/Documentation/technical/reftable.txt +++ b/Documentation/technical/reftable.txt @@ -446,7 +446,7 @@ especially if readers will not use the object name to ref mapping. Object blocks use unique, abbreviated 2-32 object name keys, mapping to ref blocks containing references pointing to that object directly, or as the peeled value of an annotated tag. Like ref blocks, object blocks use -the file's standard block size. The abbrevation length is available in +the file's standard block size. The abbreviation length is available in the footer as `obj_id_len`. To save space in small files, object blocks may be omitted if the ref |