Commit @264e0d872c("Remove automatic event deferral") removed the immediate
event queue because event deferral now had to be explicit. The problem is that
while some events don't need to be deferred, they still can result in recursive
`event_poll` calls, and recursion is not supported by libuv. Examples of those
are msgpack-rpc requests while a server->client request is pending, or signals
which can call `mch_exit`(and that will result in `uv_run` calls).
To fix the problem, this reintroduces the immediate event queue for events that
can potentially result in event loop recursion. The non-deferred events are
still processed in `event_poll`, but only after `uv_run` returns.
This is how asynchronous events are currently handled by Nvim:
- Libuv event loop is entered when Nvim blocks for user input(os_inchar is
called)
- Any event delivered by libuv that is not user input is queued for processing
- The `K_EVENT` special key code is returned by os_inchar
- `K_EVENT` is returned to a loop that is reading keys for the current Nvim
mode, which will be handled by calling event_process()
This approach has the advantage of integrating nicely with the current
codebase, eg: vimscript code can be executed asynchronously with little
surprises(Its the same as if the user typed a key).
The problem with using keys to represent any event is that it also interferes with
operators, and not every event needs or should do that. For example, consider
this scenario:
- A msgpack-rpc client calls vim_feedkeys("d")
- Nvim processes K_EVENT, pushing "d" to the input queue
- Nvim processes "d", entering operator-pending mode to wait for a motion
- The client calls vim_feedkeys("w"), expecting Nvim to delete a word
- Nvim processes K_EVENT, breaking out of operator-pending and pushing "w"
- Nvim processes "w", moving a word
This commit fixes the above problem by removing all automatic calls to
`event_push`(which is what generates K_EVENT input). Right now this also breaks
redrawing initiated by asynchronous events(and possibly other stuff too, Nvim is
a complex state machine and we can't simply run vimscript code anywhere).
In future commits the calls to `event_push` will be inserted only where it's
absolutely necessary to run code in "key reading loops", such as when executing
vimscript code or mutating editor data structures in ways that currently can
only be done by the user.
This approach is more flexible because we don't need to support a fixed set of
"event types", any module can push events to be handled in main loop by simply
passing a callback to the Event structure.
- Remove all *_set_defer methods and the 'defer' flag from rstream/jobs
- Added {signal,rstream,job}_event_source functions. Each return a pointer that
represent the event source for the object in question(For signals, a static
pointer is returned)
- Added a 'source' field to the Event struct, which is set to the appropriate
value by the code that created the event.
- Added a 'sources' parameter to `event_poll`. It should point to a
NULL-terminated array of event sources that will be used to decide which
events should be processed immediately
- Added a 'source_override' parameter to `rstream_new`. This was required to use
jobs as event sources of RStream instances(When "focusing" on a job, for
example).
- Extracted `process_from` static function from `event_process`.
- Remove 'defer' parameter from `event_process`, which now operates only on
deferred events.
- Refactor `channel_send_call` to use the new lock mechanism
What changed in a single sentence: Code that calls `event_poll` have to specify
which event sources should NOT be deferred. This change was necessary for a
number of reasons:
- To fix a bug where due to race conditions, a client request
could end in the deferred queue in the middle of a `channel_send_call`
invocation, resulting in a deadlock since the client process would never
receive a response, and channel_send_call would never return because
the client would still be waiting for the response.
- To handle "event locking" correctly in recursive `channel_send_call`
invocations when the frames are waiting for responses from different
clients. Not much of an issue now since there's only a python client, but
could break things later.
- To simplify the process of implementing synchronous functions that depend on
asynchronous events.
`-Wstrict-prototypes` warn if a function is declared or defined without
specifying the argument types.
This warning disallow function prototypes with empty parameter list.
In C, a function declared with an empty parameter list accepts an
arbitrary number of arguments when being called. This is for historic
reasons; originally, C functions didn't have prototypes, as C evolved
from B, a typeless language. When prototypes were added, the original
typeless declarations were left in the language for backwards
compatibility.
Instead we should provide `void` in argument list to state
that function doesn't have arguments.
Also this warning disallow declaring type of the parameters after the
parentheses because Neovim header generator produce no declarations for
old-stlyle prototypes: it expects to find `{` after prototype.
To make it possible reuse `event_poll` recursively and in other blocking
function calls, this changes how deferred/immediate events are processed:
- There are two queues in event.c, one for immediate events and another for
deferred events. The queue used when pushing/processing events is determined
with boolean arguments passed to `event_push`/`event_process` respectively.
- Events pushed to the immediate queue are processed inside `event_poll` but
after the `uv_run` call. This is required because libuv event loop does not
support recursion, and processing events may result in other `event_poll`
calls.
- Events pushed to the deferred queue are processed later by calling
`event_process(true)`. This is required to "trick" vim into treating all
asynchronous events as special keypresses, which is the least obtrusive
way of introducing asynchronicity into the editor.
- RStream instances will now forward the `defer` flag to the `event_push` call.
- The 'stripdecls.py' script replaces declarations in all headers by includes to
generated headers.
`ag '#\s*if(?!ndef NEOVIM_).*((?!#\s*endif).*\n)*#ifdef INCLUDE_GENERATED'`
was used for this.
- Add and integrate gendeclarations.lua into the build system to generate the
required includes.
- Add -Wno-unused-function
- Made a bunch of old-style definitions ANSI
This adds a requirement: all type and structure definitions must be present
before INCLUDE_GENERATED_DECLARATIONS-protected include.
Warning: mch_expandpath (path.h.generated.h) was moved manually. So far it is
the only exception.
Move files from src/ to src/nvim/.
- src/nvim/ becomes the new root dir for nvim executable sources.
- src/libnvim/ is planned to become root dir of the neovim library.
