git/streaming.c, branch main

streaming: move into object database subsystem

2025-11-23T20:56:46Z

The "streaming" terminology is somewhat generic, so it may not be immediately obvious that "streaming.{c,h}" is specific to the object database. Rectify this by moving it into the "odb/" directory so that it can be immediately attributed to the object subsystem. Signed-off-by: Patrick Steinhardt Signed-off-by: Junio C Hamano

streaming: refactor interface to be object-database-centric

2025-11-23T20:56:45Z

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 Signed-off-by: Junio C Hamano

streaming: move logic to read packed objects streams into backend

2025-11-23T20:56:45Z

Move the logic to read packed object streams into the respective subsystem. Signed-off-by: Patrick Steinhardt Signed-off-by: Junio C Hamano

streaming: move logic to read loose objects streams into backend

2025-11-23T20:56:45Z

Move the logic to read loose object streams into the respective subsystem. This allows us to make a couple of function declarations private. Signed-off-by: Patrick Steinhardt Signed-off-by: Junio C Hamano

streaming: make the `odb_read_stream` definition public

2025-11-23T20:56:45Z

Subsequent commits will move the backend-specific logic of setting up an object read stream into the specific subsystems. As the backends are now the ones that are responsible for allocating the stream they'll need to have the stream definition available to them. Make the stream definition public to prepare for this. Signed-off-by: Patrick Steinhardt Signed-off-by: Junio C Hamano

streaming: get rid of `the_repository`

2025-11-23T20:56:45Z

Subsequent commits will move the backend-specific logic of object streaming into their respective subsystems. These subsystems have gotten rid of `the_repository` already, but we still use it in two locations in the streaming subsystem. Prepare for the move by fixing those two cases. Converting the logic in `open_istream_pack_non_delta()` is trivial as we already got the object database as input. But for `stream_blob_to_fd()` we have to add a new parameter to make it accessible. So, as we already have to adjust all callers anyway, rename the function to `odb_stream_blob_to_fd()` to indicate it's part of the object subsystem. Signed-off-by: Patrick Steinhardt Signed-off-by: Junio C Hamano

streaming: rely on object sources to create object stream

2025-11-23T20:56:45Z

When creating an object stream we first look up the object info and, if it's present, we call into the respective backend that contains the object to create a new stream for it. This has the consequence that, for loose object source, we basically iterate through the object sources twice: we first discover that the file exists as a loose object in the first place by iterating through all sources. And, once we have discovered it, we again walk through all sources to try and map the object. The same issue will eventually also surface once the packfile store becomes per-object-source. Furthermore, it feels rather pointless to first look up the object only to then try and read it. Refactor the logic to be centered around sources instead. Instead of first reading the object, we immediately ask the source to create the object stream for us. If the object exists we get stream, otherwise we'll try the next source. Like this we only have to iterate through sources once. But even more importantly, this change also helps us to make the whole logic pluggable. The object read stream subsystem does not need to be aware of the different source backends anymore, but eventually it'll only have to call the source's callback function. Note that at the current point in time we aren't fully there yet: - The packfile store still sits on the object database level and is thus agnostic of the sources. - We still have to call into both the packfile store and the loose object source. But both of these issues will soon be addressed. This refactoring results in a slight change to semantics: previously, it was `odb_read_object_info_extended()` that picked the source for us, and it would have favored packed (non-deltified) objects over loose objects. And while we still favor packed over loose objects for a single source with the new logic, we'll now favor a loose object from an earlier source over a packed object from a later source. Ultimately this shouldn't matter though: the stream doesn't indicate to the caller which source it is from and whether it was created from a packed or loose object, so such details are opaque to the caller. And other than that we should be able to assume that two objects with the same object ID should refer to the same content, so the streamed data would be the same, too. Signed-off-by: Patrick Steinhardt Signed-off-by: Junio C Hamano

streaming: move zlib stream into backends

2025-11-23T20:56:45Z

While all backend-specific data is now contained in a backend-specific structure, we still share the zlib stream across the loose and packed objects. Refactor the code and move it into the specific structures so that we fully detangle the different backends from one another. Signed-off-by: Patrick Steinhardt Signed-off-by: Junio C Hamano

streaming: create structure for filtered object streams

2025-11-23T20:56:45Z

As explained in a preceding commit, we want to get rid of the union of stream-type specific data in `struct odb_read_stream`. Create a new structure for filtered object streams to move towards this design. Signed-off-by: Patrick Steinhardt Signed-off-by: Junio C Hamano

streaming: create structure for packed object streams

2025-11-23T20:56:45Z

As explained in a preceding commit, we want to get rid of the union of stream-type specific data in `struct odb_read_stream`. Create a new structure for packed object streams to move towards this design. Signed-off-by: Patrick Steinhardt Signed-off-by: Junio C Hamano