289 lines
8.4 KiB
Rust
289 lines
8.4 KiB
Rust
// Copyright 2015-2019 Parity Technologies (UK) Ltd.
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// This file is part of Parity Ethereum.
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// Parity Ethereum is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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// Parity Ethereum is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with Parity Ethereum. If not, see <http://www.gnu.org/licenses/>.
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//! Tokio Runtime wrapper.
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pub extern crate futures;
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pub extern crate tokio;
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use futures::{future, Future, IntoFuture};
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use std::{
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fmt,
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sync::mpsc,
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thread,
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time::{Duration, Instant},
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};
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pub use tokio::{
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runtime::{Builder as TokioRuntimeBuilder, Runtime as TokioRuntime, TaskExecutor},
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timer::Delay,
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};
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/// Runtime for futures.
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///
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/// Runs in a separate thread.
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pub struct Runtime {
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executor: Executor,
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handle: RuntimeHandle,
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}
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impl Runtime {
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fn new(runtime_bldr: &mut TokioRuntimeBuilder) -> Self {
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let mut runtime = runtime_bldr.build().expect(
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"Building a Tokio runtime will only fail when mio components \
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cannot be initialized (catastrophic)",
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);
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let (stop, stopped) = futures::oneshot();
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let (tx, rx) = mpsc::channel();
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let handle = thread::spawn(move || {
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tx.send(runtime.executor())
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.expect("Rx is blocking upper thread.");
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runtime
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.block_on(futures::empty().select(stopped).map(|_| ()).map_err(|_| ()))
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.expect("Tokio runtime should not have unhandled errors.");
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});
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let executor = rx
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.recv()
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.expect("tx is transfered to a newly spawned thread.");
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Runtime {
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executor: Executor {
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inner: Mode::Tokio(executor),
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},
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handle: RuntimeHandle {
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close: Some(stop),
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handle: Some(handle),
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},
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}
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}
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/// Spawns a new tokio runtime with a default thread count on a background
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/// thread and returns a `Runtime` which can be used to spawn tasks via
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/// its executor.
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pub fn with_default_thread_count() -> Self {
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let mut runtime_bldr = TokioRuntimeBuilder::new();
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Self::new(&mut runtime_bldr)
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}
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/// Spawns a new tokio runtime with a the specified thread count on a
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/// background thread and returns a `Runtime` which can be used to spawn
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/// tasks via its executor.
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pub fn with_thread_count(thread_count: usize) -> Self {
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let mut runtime_bldr = TokioRuntimeBuilder::new();
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runtime_bldr.core_threads(thread_count);
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Self::new(&mut runtime_bldr)
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}
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/// Returns this runtime raw executor.
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///
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/// Deprecated: Exists only to connect with current JSONRPC implementation.
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pub fn raw_executor(&self) -> TaskExecutor {
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if let Mode::Tokio(ref executor) = self.executor.inner {
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executor.clone()
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} else {
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panic!("Runtime is not initialized in Tokio mode.")
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}
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}
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/// Returns runtime executor.
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pub fn executor(&self) -> Executor {
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self.executor.clone()
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}
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}
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#[derive(Clone)]
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enum Mode {
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Tokio(TaskExecutor),
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Sync,
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ThreadPerFuture,
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}
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impl fmt::Debug for Mode {
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fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
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use self::Mode::*;
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match *self {
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Tokio(_) => write!(fmt, "tokio"),
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Sync => write!(fmt, "synchronous"),
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ThreadPerFuture => write!(fmt, "thread per future"),
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}
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}
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}
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/// Returns a future which runs `f` until `duration` has elapsed, at which
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/// time `on_timeout` is run and the future resolves.
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fn timeout<F, R, T>(
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f: F,
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duration: Duration,
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on_timeout: T,
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) -> impl Future<Item = (), Error = ()> + Send + 'static
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where
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T: FnOnce() -> () + Send + 'static,
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F: FnOnce() -> R + Send + 'static,
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R: IntoFuture<Item = (), Error = ()> + Send + 'static,
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R::Future: Send + 'static,
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{
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let future = future::lazy(f);
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let timeout = Delay::new(Instant::now() + duration).then(move |_| {
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on_timeout();
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Ok(())
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});
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future.select(timeout).then(|_| Ok(()))
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}
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#[derive(Debug, Clone)]
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pub struct Executor {
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inner: Mode,
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}
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impl Executor {
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/// Executor for existing runtime.
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///
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/// Deprecated: Exists only to connect with current JSONRPC implementation.
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pub fn new(executor: TaskExecutor) -> Self {
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Executor {
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inner: Mode::Tokio(executor),
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}
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}
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/// Synchronous executor, used mostly for tests.
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pub fn new_sync() -> Self {
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Executor { inner: Mode::Sync }
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}
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/// Spawns a new thread for each future (use only for tests).
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pub fn new_thread_per_future() -> Self {
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Executor {
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inner: Mode::ThreadPerFuture,
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}
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}
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/// Spawn a future to this runtime
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pub fn spawn<R>(&self, r: R)
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where
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R: IntoFuture<Item = (), Error = ()> + Send + 'static,
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R::Future: Send + 'static,
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{
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match self.inner {
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Mode::Tokio(ref executor) => executor.spawn(r.into_future()),
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Mode::Sync => {
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let _ = r.into_future().wait();
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}
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Mode::ThreadPerFuture => {
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thread::spawn(move || {
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let _ = r.into_future().wait();
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});
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}
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}
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}
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/// Spawn a new future returned by given closure.
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pub fn spawn_fn<F, R>(&self, f: F)
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where
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F: FnOnce() -> R + Send + 'static,
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R: IntoFuture<Item = (), Error = ()> + Send + 'static,
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R::Future: Send + 'static,
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{
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match self.inner {
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Mode::Tokio(ref executor) => executor.spawn(future::lazy(f)),
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Mode::Sync => {
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let _ = future::lazy(f).wait();
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}
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Mode::ThreadPerFuture => {
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thread::spawn(move || {
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let _ = f().into_future().wait();
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});
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}
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}
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}
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/// Spawn a new future and wait for it or for a timeout to occur.
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pub fn spawn_with_timeout<F, R, T>(&self, f: F, duration: Duration, on_timeout: T)
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where
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T: FnOnce() -> () + Send + 'static,
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F: FnOnce() -> R + Send + 'static,
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R: IntoFuture<Item = (), Error = ()> + Send + 'static,
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R::Future: Send + 'static,
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{
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match self.inner {
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Mode::Tokio(ref executor) => executor.spawn(timeout(f, duration, on_timeout)),
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Mode::Sync => {
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let _ = timeout(f, duration, on_timeout).wait();
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}
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Mode::ThreadPerFuture => {
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thread::spawn(move || {
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let _ = timeout(f, duration, on_timeout).wait();
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});
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}
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}
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}
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}
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impl<F: Future<Item = (), Error = ()> + Send + 'static> future::Executor<F> for Executor {
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fn execute(&self, future: F) -> Result<(), future::ExecuteError<F>> {
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match self.inner {
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Mode::Tokio(ref executor) => executor.execute(future),
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Mode::Sync => {
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let _ = future.wait();
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Ok(())
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}
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Mode::ThreadPerFuture => {
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thread::spawn(move || {
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let _ = future.wait();
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});
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Ok(())
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}
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}
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}
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}
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/// A handle to a runtime. Dropping the handle will cause runtime to shutdown.
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pub struct RuntimeHandle {
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close: Option<futures::Complete<()>>,
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handle: Option<thread::JoinHandle<()>>,
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}
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impl From<Runtime> for RuntimeHandle {
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fn from(el: Runtime) -> Self {
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el.handle
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}
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}
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impl Drop for RuntimeHandle {
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fn drop(&mut self) {
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self.close.take().map(|v| v.send(()));
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}
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}
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impl RuntimeHandle {
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/// Blocks current thread and waits until the runtime is finished.
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pub fn wait(mut self) -> thread::Result<()> {
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self.handle
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.take()
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.expect("Handle is taken only in `wait`, `wait` is consuming; qed")
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.join()
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}
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/// Finishes this runtime.
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pub fn close(mut self) {
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let _ = self
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.close
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.take()
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.expect("Close is taken only in `close` and `drop`. `close` is consuming; qed")
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.send(());
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}
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}
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