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runtime: cleanup and add config options (#1807)

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* runtime: cleanup and add config options

This patch finishes the cleanup as part of the transition to Tokio 0.2.
A number of changes were made to take advantage of having all Tokio
types in a single crate. Also, fixes using Tokio types from
`spawn_blocking`.

* Many threads, one resource driver

Previously, in the threaded scheduler, a resource driver (mio::Poll /
timer combo) was created per thread. This was more or less fine, except
it required balancing across the available drivers. When using a
resource driver from **outside** of the thread pool, balancing is
tricky. The change was original done to avoid having a dedicated driver
thread.

Now, instead of creating many resource drivers, a single resource driver
is used. Each scheduler thread will attempt to "lock" the resource
driver before parking on it. If the resource driver is already locked,
the thread uses a condition variable to park. Contention should remain
low as, under load, the scheduler avoids using the drivers.

* Add configuration options to enable I/O / time

New configuration options are added to `runtime::Builder` to allow
enabling I/O and time drivers on a runtime instance basis. This is
useful when wanting to create lightweight runtime instances to execute
compute only tasks.

* Bug fixes

The condition variable parker is updated to the same algorithm used in
`std`. This is motivated by some potential deadlock cases discovered by
`loom`.

The basic scheduler is fixed to fairly schedule tasks. `push_front` was
accidentally used instead of `push_back`.

I/O, time, and spawning now work from within `spawn_blocking` closures.

* Misc cleanup

The threaded scheduler is no longer generic over `P :Park`. Instead, it
is hard coded to a specific parker. Tests, including loom tests, are
updated to use `Runtime` directly. This provides greater coverage.

The `blocking` module is moved back into `runtime` as all usage is
within `runtime` itself.
This commit is contained in:
Carl Lerche
2019-11-21 23:28:39 -08:00
committed by GitHub
parent 6866fe426c
commit 8546ff826d
67 changed files with 1658 additions and 1359 deletions
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tokio/tests/rt_threaded.rs
+8 -5
View File
@@ -18,6 +18,7 @@ fn single_thread() {
// No panic when starting a runtime w/ a single thread
let _ = runtime::Builder::new()
.threaded_scheduler()
.enable_all()
.num_threads(1)
.build();
}
@@ -189,10 +190,11 @@ fn drop_threadpool_drops_futures() {
let rt = runtime::Builder::new()
.threaded_scheduler()
.after_start(move || {
.enable_all()
.on_thread_start(move || {
a.fetch_add(1, Relaxed);
})
.before_stop(move || {
.on_thread_stop(move || {
b.fetch_add(1, Relaxed);
})
.build()
@@ -218,7 +220,7 @@ fn drop_threadpool_drops_futures() {
}
#[test]
fn after_start_and_before_stop_is_called() {
fn start_stop_callbacks_called() {
use std::sync::atomic::{AtomicUsize, Ordering};
let after_start = Arc::new(AtomicUsize::new(0));
@@ -228,10 +230,11 @@ fn after_start_and_before_stop_is_called() {
let before_inner = before_stop.clone();
let mut rt = tokio::runtime::Builder::new()
.threaded_scheduler()
.after_start(move || {
.enable_all()
.on_thread_start(move || {
after_inner.clone().fetch_add(1, Ordering::Relaxed);
})
.before_stop(move || {
.on_thread_stop(move || {
before_inner.clone().fetch_add(1, Ordering::Relaxed);
})
.build()