This PR adds the `Context` type for cancellation with context
propagation. It works by storing a tree of forks of the main context,
providing a way to control cancellation.
This PR adds the StreamMap type that enables multiplexing in
asynchronous streams.
This PR depends on: #10366, #10367 and #10370.
---------
Co-authored-by: Markus Himmel <markus@lean-fro.org>
This PR adds a multi-consumer, multi-producer channel to Std.Sync.
This PR depends on: #10366, #10367 and #10370.
---------
Co-authored-by: Markus Himmel <markus@lean-fro.org>
This PR adds `Notify` that is a structure that is similar to `CondVar`
but it's used for concurrency. The main difference between
`Std.Sync.Notify` and `Std.Condvar` is that depends on a `Std.Mutex` and
blocks the entire thread that the `Task` is using while waiting. If I
try to use it with async and a lot of `Task`s like this:
```lean
def condvar : Async Unit := do
let condvar ← Std.Condvar.new
let mutex ← Std.Mutex.new false
for i in [0:threads] do
background do
IO.println s!"start {i + 1}"
await =<< (show IO (ETask _ _) from IO.asTask (mutex.atomically (condvar.wait mutex)))
IO.println s!"end {i + 1}"
IO.sleep 2000
condvar.notifyAll
```
It causes some weird behavior because some tasks start running and get
notified, while others don’t, because `condvar.wait` blocks the `Task`
entire task and right now afaik it blocks an entire thread and cannot be
paused while doing blocking operations like that.
`Notify` uses `Promise`s so it’s better suited for concurrency. The
`Task` is not blocked while waiting for a notification which makes it
simpler for use cases that just involve notifying:
```lean
def notify : Async Unit := do
let notify ← Std.Notify.new
for i in [0:threads] do
background do
IO.println s!"start {i}"
notify.wait
IO.println s!"end {i}"
IO.sleep 2000
notify.notify
```
This PR depends on: #10366, #10367 and #10370.
This PR adds a shared mutex (or read-write lock) as `Std.SharedMutex`.
In order to easily migrate a `Std.Mutex` to `Std.SharedMutex` if
necessary, the functions for obtaining exclusive access are named the
same, allowing a correct drop in to be done by just swapping types.
This PR moves `IO.Channel` and `IO.Mutex` from `Init` to `Std.Sync` and
renames them to `Std.Channel` and `Std.Mutex`.
Note that the original files are retained and the deprecation is written
manually as we cannot import `Std` from `Init` so this is the only way
to deprecate without a hard breaking change. In particular we do not yet
move `Std.Queue` from `Init` to `Std` both because it needs to be
retained for this deprecation to work but also because it is already
within the `Std` namespace and as such we cannot maintain two copies of
the file at once. After the deprecation period is finished `Std.Queue`
will find a new home in `Std.Data.Queue`.
