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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
use ipc_channel::ipc::IpcSender;
use panicking;
use serde::Serialize;
use std::any::Any;
use std::borrow::ToOwned;
use std::sync::mpsc::Sender;
use std::thread;
use thread_state;
pub type PanicReason = Option<String>;
pub fn spawn_named<F>(name: String, f: F)
where F: FnOnce() + Send + 'static
{
spawn_named_with_send_on_failure_maybe(name, None, f, |_| {});
}
pub trait AddFailureDetails {
fn add_panic_message(&mut self, message: String);
fn add_panic_object(&mut self, object: &Any) {
if let Some(message) = object.downcast_ref::<String>() {
self.add_panic_message(message.to_owned());
} else if let Some(&message) = object.downcast_ref::<&'static str>() {
self.add_panic_message(message.to_owned());
}
}
}
/// An abstraction over `Sender<T>` and `IpcSender<T>`, for use in
/// `spawn_named_with_send_on_failure`.
pub trait SendOnFailure {
type Value;
fn send_on_failure(&mut self, value: Self::Value);
}
impl<T> SendOnFailure for Sender<T> where T: Send + 'static {
type Value = T;
fn send_on_failure(&mut self, value: T) {
// Discard any errors to avoid double-panic
let _ = self.send(value);
}
}
impl<T> SendOnFailure for IpcSender<T> where T: Send + Serialize + 'static {
type Value = T;
fn send_on_failure(&mut self, value: T) {
// Discard any errors to avoid double-panic
let _ = self.send(value);
}
}
/// Arrange to send a particular message to a channel if the thread fails.
pub fn spawn_named_with_send_on_failure<F, T, S>(name: String,
state: thread_state::ThreadState,
f: F,
mut msg: T,
mut dest: S)
where F: FnOnce() + Send + 'static,
T: Send + AddFailureDetails + 'static,
S: Send + SendOnFailure + 'static,
S::Value: From<T>,
{
spawn_named_with_send_on_failure_maybe(name, Some(state), f,
move |err| {
msg.add_panic_object(err);
dest.send_on_failure(S::Value::from(msg));
});
}
fn spawn_named_with_send_on_failure_maybe<F, G>(name: String,
state: Option<thread_state::ThreadState>,
f: F,
fail: G)
where F: FnOnce() + Send + 'static,
G: FnOnce(&(Any + Send)) + Send + 'static {
let builder = thread::Builder::new().name(name.clone());
let local = panicking::PanicHandlerLocal {
fail: Box::new(fail),
};
let f_with_state = move || {
if let Some(state) = state {
thread_state::initialize(state);
}
// set the handler
panicking::LOCAL_INFO.with(|i| {
*i.borrow_mut() = Some(local);
});
f();
};
builder.spawn(f_with_state).unwrap();
}
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