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diff --git a/doc/developer-notes.rst b/doc/developer-notes.rst index 4e9b31a..1df082a 100644 --- a/doc/developer-notes.rst +++ b/doc/developer-notes.rst @@ -5,31 +5,3 @@ If you are working on libfuse itself (rather than using it for a different project) this file should be of interest to you. Otherwise you should ignore it entirely. - -Channel Interface -================= - -From the API, it may appear as if every fuse session (`struct -fuse_session`) is associated with a single fuse channel (`struct -fuse_chan`) that is created by `fuse_mount()` and assigned to the -session in `fuse_session_add_chan()`. Therefore, one may wonder why -there are two separate structs in the first place, and why the channel -structure has a reference counter and mutex. - -The answer is that when using the multi-threaded session loop with the -*clone_fd* option enabled, there are actually multiple channel objects -per session. The session only holds a reference to the first one, and -the additional channel objects don't actually hold references to the -session object -- but they still exist. The additional channels are -created by duplicating the fd (in `fuse_clone_chan()`, called by -`fuse_loop_start_thread`). When processing a request, -`fuse_session_process_buf()` records the active channel in the request -object (`struct fuse_req`) so that it can be retrieved by e.g. the -``fuse_reply_*`` functions. Since the request object can potentially -live longer than the worker thread that created it, we need to keep a -reference count for the channel. - -The reason for not having references to the session object from the -extra channels is not clear, but with the current implementation this -would not work because `fuse_session_remove_chan` always attempts to -remove the channel from the session. |