1207 lines
40 KiB
Rust
1207 lines
40 KiB
Rust
// Copyright 2013-2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! Communication primitives for concurrent tasks (`Chan` and `Port` types)
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//!
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//! Rust makes it very difficult to share data among tasks to prevent race
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//! conditions and to improve parallelism, but there is often a need for
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//! communication between concurrent tasks. The primitives defined in this
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//! module are the building blocks for synchronization in rust.
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//!
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//! This module currently provides two types:
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//!
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//! * `Chan`
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//! * `Port`
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//!
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//! `Chan` is used to send data to a `Port`. A `Chan` is clone-able such that
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//! many tasks can send simultaneously to one receiving port. These
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//! communication primitives are *task blocking*, not *thread blocking*. This
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//! means that if one task is blocked on a channel, other tasks can continue to
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//! make progress.
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//!
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//! Rust channels can be used as if they have an infinite internal buffer. What
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//! this means is that the `send` operation will never block. `Port`s, on the
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//! other hand, will block the task if there is no data to be received.
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//!
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//! ## Failure Propagation
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//!
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//! In addition to being a core primitive for communicating in rust, channels
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//! and ports are the points at which failure is propagated among tasks.
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//! Whenever the one half of channel is closed, the other half will have its
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//! next operation `fail!`. The purpose of this is to allow propagation of
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//! failure among tasks that are linked to one another via channels.
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//!
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//! There are methods on both of `Chan` and `Port` to perform their respective
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//! operations without failing, however.
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//!
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//! ## Outside the Runtime
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//!
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//! All channels and ports work seamlessly inside and outside of the rust
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//! runtime. This means that code may use channels to communicate information
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//! inside and outside of the runtime. For example, if rust were embedded as an
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//! FFI module in another application, the rust runtime would probably be
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//! running in its own external thread pool. Channels created can communicate
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//! from the native application threads to the rust threads through the use of
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//! native mutexes and condition variables.
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//!
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//! What this means is that if a native thread is using a channel, execution
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//! will be blocked accordingly by blocking the OS thread.
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//!
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//! # Example
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//!
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//! ```rust,should_fail
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//! // Create a simple streaming channel
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//! let (port, chan) = Chan::new();
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//! spawn(proc() {
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//! chan.send(10);
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//! })
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//! assert_eq!(port.recv(), 10);
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//!
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//! // Create a shared channel which can be sent along from many tasks
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//! let (port, chan) = Chan::new();
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//! for i in range(0, 10) {
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//! let chan = chan.clone();
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//! spawn(proc() {
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//! chan.send(i);
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//! })
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//! }
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//!
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//! for _ in range(0, 10) {
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//! let j = port.recv();
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//! assert!(0 <= j && j < 10);
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//! }
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//!
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//! // The call to recv() will fail!() because the channel has already hung
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//! // up (or been deallocated)
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//! let (port, chan) = Chan::<int>::new();
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//! drop(chan);
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//! port.recv();
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//! ```
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// A description of how Rust's channel implementation works
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//
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// Channels are supposed to be the basic building block for all other
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// concurrent primitives that are used in Rust. As a result, the channel type
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// needs to be highly optimized, flexible, and broad enough for use everywhere.
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//
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// The choice of implementation of all channels is to be built on lock-free data
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// structures. The channels themselves are then consequently also lock-free data
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// structures. As always with lock-free code, this is a very "here be dragons"
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// territory, especially because I'm unaware of any academic papers which have
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// gone into great length about channels of these flavors.
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//
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// ## Flavors of channels
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//
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// From the perspective of a consumer of this library, there is only one flavor
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// of channel. This channel can be used as a stream and cloned to allow multiple
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// senders. Under the hood, however, there are actually three flavors of
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// channels in play.
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//
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// * Oneshots - these channels are highly optimized for the one-send use case.
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// They contain as few atomics as possible and involve one and
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// exactly one allocation.
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// * Streams - these channels are optimized for the non-shared use case. They
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// use a different concurrent queue which is more tailored for this
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// use case. The initial allocation of this flavor of channel is not
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// optimized.
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// * Shared - this is the most general form of channel that this module offers,
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// a channel with multiple senders. This type is as optimized as it
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// can be, but the previous two types mentioned are much faster for
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// their use-cases.
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//
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// ## Concurrent queues
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//
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// The basic idea of Rust's Chan/Port types is that send() never blocks, but
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// recv() obviously blocks. This means that under the hood there must be some
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// shared and concurrent queue holding all of the actual data.
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//
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// With two flavors of channels, two flavors of queues are also used. We have
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// chosen to use queues from a well-known author which are abbreviated as SPSC
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// and MPSC (single producer, single consumer and multiple producer, single
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// consumer). SPSC queues are used for streams while MPSC queues are used for
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// shared channels.
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//
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// ### SPSC optimizations
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//
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// The SPSC queue found online is essentially a linked list of nodes where one
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// half of the nodes are the "queue of data" and the other half of nodes are a
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// cache of unused nodes. The unused nodes are used such that an allocation is
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// not required on every push() and a free doesn't need to happen on every
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// pop().
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//
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// As found online, however, the cache of nodes is of an infinite size. This
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// means that if a channel at one point in its life had 50k items in the queue,
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// then the queue will always have the capacity for 50k items. I believed that
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// this was an unnecessary limitation of the implementation, so I have altered
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// the queue to optionally have a bound on the cache size.
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//
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// By default, streams will have an unbounded SPSC queue with a small-ish cache
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// size. The hope is that the cache is still large enough to have very fast
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// send() operations while not too large such that millions of channels can
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// coexist at once.
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//
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// ### MPSC optimizations
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//
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// Right now the MPSC queue has not been optimized. Like the SPSC queue, it uses
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// a linked list under the hood to earn its unboundedness, but I have not put
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// forth much effort into having a cache of nodes similar to the SPSC queue.
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//
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// For now, I believe that this is "ok" because shared channels are not the most
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// common type, but soon we may wish to revisit this queue choice and determine
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// another candidate for backend storage of shared channels.
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//
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// ## Overview of the Implementation
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//
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// Now that there's a little background on the concurrent queues used, it's
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// worth going into much more detail about the channels themselves. The basic
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// pseudocode for a send/recv are:
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//
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//
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// send(t) recv()
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// queue.push(t) return if queue.pop()
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// if increment() == -1 deschedule {
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// wakeup() if decrement() > 0
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// cancel_deschedule()
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// }
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// queue.pop()
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//
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// As mentioned before, there are no locks in this implementation, only atomic
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// instructions are used.
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//
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// ### The internal atomic counter
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//
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// Every channel/port/shared channel have a shared counter with their
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// counterparts to keep track of the size of the queue. This counter is used to
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// abort descheduling by the receiver and to know when to wake up on the sending
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// side.
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//
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// As seen in the pseudocode, senders will increment this count and receivers
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// will decrement the count. The theory behind this is that if a sender sees a
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// -1 count, it will wake up the receiver, and if the receiver sees a 1+ count,
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// then it doesn't need to block.
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//
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// The recv() method has a beginning call to pop(), and if successful, it needs
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// to decrement the count. It is a crucial implementation detail that this
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// decrement does *not* happen to the shared counter. If this were the case,
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// then it would be possible for the counter to be very negative when there were
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// no receivers waiting, in which case the senders would have to determine when
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// it was actually appropriate to wake up a receiver.
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//
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// Instead, the "steal count" is kept track of separately (not atomically
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// because it's only used by ports), and then the decrement() call when
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// descheduling will lump in all of the recent steals into one large decrement.
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//
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// The implication of this is that if a sender sees a -1 count, then there's
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// guaranteed to be a waiter waiting!
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//
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// ## Native Implementation
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//
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// A major goal of these channels is to work seamlessly on and off the runtime.
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// All of the previous race conditions have been worded in terms of
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// scheduler-isms (which is obviously not available without the runtime).
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//
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// For now, native usage of channels (off the runtime) will fall back onto
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// mutexes/cond vars for descheduling/atomic decisions. The no-contention path
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// is still entirely lock-free, the "deschedule" blocks above are surrounded by
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// a mutex and the "wakeup" blocks involve grabbing a mutex and signaling on a
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// condition variable.
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//
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// ## Select
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//
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// Being able to support selection over channels has greatly influenced this
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// design, and not only does selection need to work inside the runtime, but also
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// outside the runtime.
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//
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// The implementation is fairly straightforward. The goal of select() is not to
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// return some data, but only to return which channel can receive data without
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// blocking. The implementation is essentially the entire blocking procedure
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// followed by an increment as soon as its woken up. The cancellation procedure
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// involves an increment and swapping out of to_wake to acquire ownership of the
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// task to unblock.
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//
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// Sadly this current implementation requires multiple allocations, so I have
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// seen the throughput of select() be much worse than it should be. I do not
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// believe that there is anything fundamental which needs to change about these
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// channels, however, in order to support a more efficient select().
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//
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// # Conclusion
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//
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// And now that you've seen all the races that I found and attempted to fix,
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// here's the code for you to find some more!
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use cast;
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use cell::Cell;
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use clone::Clone;
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use iter::Iterator;
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use kinds::Send;
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use kinds::marker;
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use mem;
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use ops::Drop;
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use option::{Some, None, Option};
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use result::{Ok, Err, Result};
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use rt::local::Local;
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use rt::task::{Task, BlockedTask};
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use sync::arc::UnsafeArc;
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pub use comm::select::{Select, Handle};
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macro_rules! test (
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{ fn $name:ident() $b:block $($a:attr)*} => (
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mod $name {
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#[allow(unused_imports)];
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use native;
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use comm::*;
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use prelude::*;
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use super::*;
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use super::super::*;
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use task;
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fn f() $b
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$($a)* #[test] fn uv() { f() }
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$($a)* #[test] fn native() {
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use native;
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let (p, c) = Chan::new();
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native::task::spawn(proc() { c.send(f()) });
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p.recv();
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}
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}
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)
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)
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mod select;
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mod oneshot;
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mod stream;
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mod shared;
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// Use a power of 2 to allow LLVM to optimize to something that's not a
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// division, this is hit pretty regularly.
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static RESCHED_FREQ: int = 256;
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/// The receiving-half of Rust's channel type. This half can only be owned by
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/// one task
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pub struct Port<T> {
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priv inner: Flavor<T>,
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priv receives: Cell<uint>,
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// can't share in an arc
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priv marker: marker::NoFreeze,
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}
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/// An iterator over messages received on a port, this iterator will block
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/// whenever `next` is called, waiting for a new message, and `None` will be
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/// returned when the corresponding channel has hung up.
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pub struct Messages<'a, T> {
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priv port: &'a Port<T>
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}
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/// The sending-half of Rust's channel type. This half can only be owned by one
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/// task
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pub struct Chan<T> {
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priv inner: Flavor<T>,
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priv sends: Cell<uint>,
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// can't share in an arc
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priv marker: marker::NoFreeze,
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}
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/// This enumeration is the list of the possible reasons that try_recv could not
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/// return data when called.
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#[deriving(Eq, Clone)]
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pub enum TryRecvResult<T> {
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/// This channel is currently empty, but the sender(s) have not yet
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/// disconnected, so data may yet become available.
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Empty,
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/// This channel's sending half has become disconnected, and there will
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/// never be any more data received on this channel
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Disconnected,
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/// The channel had some data and we successfully popped it
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Data(T),
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}
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enum Flavor<T> {
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Oneshot(UnsafeArc<oneshot::Packet<T>>),
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Stream(UnsafeArc<stream::Packet<T>>),
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Shared(UnsafeArc<shared::Packet<T>>),
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}
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impl<T: Send> Chan<T> {
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/// Creates a new port/channel pair. All data send on the channel returned
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/// will become available on the port as well. See the documentation of
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/// `Port` and `Chan` to see what's possible with them.
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pub fn new() -> (Port<T>, Chan<T>) {
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let (a, b) = UnsafeArc::new2(oneshot::Packet::new());
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(Port::my_new(Oneshot(a)), Chan::my_new(Oneshot(b)))
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}
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fn my_new(inner: Flavor<T>) -> Chan<T> {
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Chan { inner: inner, sends: Cell::new(0), marker: marker::NoFreeze }
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}
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/// Sends a value along this channel to be received by the corresponding
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/// port.
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///
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/// Rust channels are infinitely buffered so this method will never block.
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///
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/// # Failure
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///
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/// This function will fail if the other end of the channel has hung up.
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/// This means that if the corresponding port has fallen out of scope, this
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/// function will trigger a fail message saying that a message is being sent
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/// on a closed channel.
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///
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/// Note that if this function does *not* fail, it does not mean that the
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/// data will be successfully received. All sends are placed into a queue,
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/// so it is possible for a send to succeed (the other end is alive), but
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/// then the other end could immediately disconnect.
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///
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/// The purpose of this functionality is to propagate failure among tasks.
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/// If failure is not desired, then consider using the `try_send` method
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pub fn send(&self, t: T) {
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if !self.try_send(t) {
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fail!("sending on a closed channel");
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}
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}
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/// Attempts to send a value on this channel, returning whether it was
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/// successfully sent.
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///
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/// A successful send occurs when it is determined that the other end of the
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/// channel has not hung up already. An unsuccessful send would be one where
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/// the corresponding port has already been deallocated. Note that a return
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/// value of `false` means that the data will never be received, but a
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/// return value of `true` does *not* mean that the data will be received.
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/// It is possible for the corresponding port to hang up immediately after
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/// this function returns `true`.
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///
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/// Like `send`, this method will never block. If the failure of send cannot
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/// be tolerated, then this method should be used instead.
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pub fn try_send(&self, t: T) -> bool {
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// In order to prevent starvation of other tasks in situations where
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// a task sends repeatedly without ever receiving, we occassionally
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// yield instead of doing a send immediately. Only doing this if
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// we're doing a rescheduling send, otherwise the caller is
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// expecting not to context switch.
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//
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// Note that we don't unconditionally attempt to yield because the
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// TLS overhead can be a bit much.
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let cnt = self.sends.get() + 1;
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self.sends.set(cnt);
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if cnt % (RESCHED_FREQ as uint) == 0 {
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let task: ~Task = Local::take();
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task.maybe_yield();
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}
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let (new_inner, ret) = match self.inner {
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Oneshot(ref p) => {
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let p = p.get();
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unsafe {
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if !(*p).sent() {
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return (*p).send(t);
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} else {
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let (a, b) = UnsafeArc::new2(stream::Packet::new());
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match (*p).upgrade(Port::my_new(Stream(b))) {
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oneshot::UpSuccess => {
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(*a.get()).send(t);
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(a, true)
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}
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oneshot::UpDisconnected => (a, false),
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oneshot::UpWoke(task) => {
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(*a.get()).send(t);
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task.wake().map(|t| t.reawaken());
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(a, true)
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}
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}
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}
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}
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}
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Stream(ref p) => return unsafe { (*p.get()).send(t) },
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Shared(ref p) => return unsafe { (*p.get()).send(t) },
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};
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unsafe {
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let mut tmp = Chan::my_new(Stream(new_inner));
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mem::swap(&mut cast::transmute_mut(self).inner, &mut tmp.inner);
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}
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return ret;
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}
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}
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impl<T: Send> Clone for Chan<T> {
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fn clone(&self) -> Chan<T> {
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let (packet, sleeper) = match self.inner {
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Oneshot(ref p) => {
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let (a, b) = UnsafeArc::new2(shared::Packet::new());
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match unsafe { (*p.get()).upgrade(Port::my_new(Shared(a))) } {
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oneshot::UpSuccess | oneshot::UpDisconnected => (b, None),
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oneshot::UpWoke(task) => (b, Some(task))
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}
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}
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Stream(ref p) => {
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let (a, b) = UnsafeArc::new2(shared::Packet::new());
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match unsafe { (*p.get()).upgrade(Port::my_new(Shared(a))) } {
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stream::UpSuccess | stream::UpDisconnected => (b, None),
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stream::UpWoke(task) => (b, Some(task)),
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}
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}
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Shared(ref p) => {
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unsafe { (*p.get()).clone_chan(); }
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return Chan::my_new(Shared(p.clone()));
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}
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};
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unsafe {
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(*packet.get()).inherit_blocker(sleeper);
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let mut tmp = Chan::my_new(Shared(packet.clone()));
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mem::swap(&mut cast::transmute_mut(self).inner, &mut tmp.inner);
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}
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Chan::my_new(Shared(packet))
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}
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}
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#[unsafe_destructor]
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impl<T: Send> Drop for Chan<T> {
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fn drop(&mut self) {
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match self.inner {
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Oneshot(ref mut p) => unsafe { (*p.get()).drop_chan(); },
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Stream(ref mut p) => unsafe { (*p.get()).drop_chan(); },
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Shared(ref mut p) => unsafe { (*p.get()).drop_chan(); },
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}
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}
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}
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impl<T: Send> Port<T> {
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fn my_new(inner: Flavor<T>) -> Port<T> {
|
|
Port { inner: inner, receives: Cell::new(0), marker: marker::NoFreeze }
|
|
}
|
|
|
|
/// Blocks waiting for a value on this port
|
|
///
|
|
/// This function will block if necessary to wait for a corresponding send
|
|
/// on the channel from its paired `Chan` structure. This port will be woken
|
|
/// up when data is ready, and the data will be returned.
|
|
///
|
|
/// # Failure
|
|
///
|
|
/// Similar to channels, this method will trigger a task failure if the
|
|
/// other end of the channel has hung up (been deallocated). The purpose of
|
|
/// this is to propagate failure among tasks.
|
|
///
|
|
/// If failure is not desired, then there are two options:
|
|
///
|
|
/// * If blocking is still desired, the `recv_opt` method will return `None`
|
|
/// when the other end hangs up
|
|
///
|
|
/// * If blocking is not desired, then the `try_recv` method will attempt to
|
|
/// peek at a value on this port.
|
|
pub fn recv(&self) -> T {
|
|
match self.recv_opt() {
|
|
Some(t) => t,
|
|
None => fail!("receiving on a closed channel"),
|
|
}
|
|
}
|
|
|
|
/// Attempts to return a pending value on this port without blocking
|
|
///
|
|
/// This method will never block the caller in order to wait for data to
|
|
/// become available. Instead, this will always return immediately with a
|
|
/// possible option of pending data on the channel.
|
|
///
|
|
/// This is useful for a flavor of "optimistic check" before deciding to
|
|
/// block on a port.
|
|
///
|
|
/// This function cannot fail.
|
|
pub fn try_recv(&self) -> TryRecvResult<T> {
|
|
// If a thread is spinning in try_recv, we should take the opportunity
|
|
// to reschedule things occasionally. See notes above in scheduling on
|
|
// sends for why this doesn't always hit TLS.
|
|
let cnt = self.receives.get() + 1;
|
|
self.receives.set(cnt);
|
|
if cnt % (RESCHED_FREQ as uint) == 0 {
|
|
let task: ~Task = Local::take();
|
|
task.maybe_yield();
|
|
}
|
|
|
|
loop {
|
|
let mut new_port = match self.inner {
|
|
Oneshot(ref p) => {
|
|
match unsafe { (*p.get()).try_recv() } {
|
|
Ok(t) => return Data(t),
|
|
Err(oneshot::Empty) => return Empty,
|
|
Err(oneshot::Disconnected) => return Disconnected,
|
|
Err(oneshot::Upgraded(port)) => port,
|
|
}
|
|
}
|
|
Stream(ref p) => {
|
|
match unsafe { (*p.get()).try_recv() } {
|
|
Ok(t) => return Data(t),
|
|
Err(stream::Empty) => return Empty,
|
|
Err(stream::Disconnected) => return Disconnected,
|
|
Err(stream::Upgraded(port)) => port,
|
|
}
|
|
}
|
|
Shared(ref p) => {
|
|
match unsafe { (*p.get()).try_recv() } {
|
|
Ok(t) => return Data(t),
|
|
Err(shared::Empty) => return Empty,
|
|
Err(shared::Disconnected) => return Disconnected,
|
|
}
|
|
}
|
|
};
|
|
unsafe {
|
|
mem::swap(&mut cast::transmute_mut(self).inner,
|
|
&mut new_port.inner);
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Attempt to wait for a value on this port, but does not fail if the
|
|
/// corresponding channel has hung up.
|
|
///
|
|
/// This implementation of iterators for ports will always block if there is
|
|
/// not data available on the port, but it will not fail in the case that
|
|
/// the channel has been deallocated.
|
|
///
|
|
/// In other words, this function has the same semantics as the `recv`
|
|
/// method except for the failure aspect.
|
|
///
|
|
/// If the channel has hung up, then `None` is returned. Otherwise `Some` of
|
|
/// the value found on the port is returned.
|
|
pub fn recv_opt(&self) -> Option<T> {
|
|
loop {
|
|
let mut new_port = match self.inner {
|
|
Oneshot(ref p) => {
|
|
match unsafe { (*p.get()).recv() } {
|
|
Ok(t) => return Some(t),
|
|
Err(oneshot::Empty) => return unreachable!(),
|
|
Err(oneshot::Disconnected) => return None,
|
|
Err(oneshot::Upgraded(port)) => port,
|
|
}
|
|
}
|
|
Stream(ref p) => {
|
|
match unsafe { (*p.get()).recv() } {
|
|
Ok(t) => return Some(t),
|
|
Err(stream::Empty) => return unreachable!(),
|
|
Err(stream::Disconnected) => return None,
|
|
Err(stream::Upgraded(port)) => port,
|
|
}
|
|
}
|
|
Shared(ref p) => {
|
|
match unsafe { (*p.get()).recv() } {
|
|
Ok(t) => return Some(t),
|
|
Err(shared::Empty) => return unreachable!(),
|
|
Err(shared::Disconnected) => return None,
|
|
}
|
|
}
|
|
};
|
|
unsafe {
|
|
mem::swap(&mut cast::transmute_mut(self).inner,
|
|
&mut new_port.inner);
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Returns an iterator which will block waiting for messages, but never
|
|
/// `fail!`. It will return `None` when the channel has hung up.
|
|
pub fn iter<'a>(&'a self) -> Messages<'a, T> {
|
|
Messages { port: self }
|
|
}
|
|
}
|
|
|
|
impl<T: Send> select::Packet for Port<T> {
|
|
fn can_recv(&self) -> bool {
|
|
loop {
|
|
let mut new_port = match self.inner {
|
|
Oneshot(ref p) => {
|
|
match unsafe { (*p.get()).can_recv() } {
|
|
Ok(ret) => return ret,
|
|
Err(upgrade) => upgrade,
|
|
}
|
|
}
|
|
Stream(ref p) => {
|
|
match unsafe { (*p.get()).can_recv() } {
|
|
Ok(ret) => return ret,
|
|
Err(upgrade) => upgrade,
|
|
}
|
|
}
|
|
Shared(ref p) => {
|
|
return unsafe { (*p.get()).can_recv() };
|
|
}
|
|
};
|
|
unsafe {
|
|
mem::swap(&mut cast::transmute_mut(self).inner,
|
|
&mut new_port.inner);
|
|
}
|
|
}
|
|
}
|
|
|
|
fn start_selection(&self, mut task: BlockedTask) -> Result<(), BlockedTask>{
|
|
loop {
|
|
let (t, mut new_port) = match self.inner {
|
|
Oneshot(ref p) => {
|
|
match unsafe { (*p.get()).start_selection(task) } {
|
|
oneshot::SelSuccess => return Ok(()),
|
|
oneshot::SelCanceled(task) => return Err(task),
|
|
oneshot::SelUpgraded(t, port) => (t, port),
|
|
}
|
|
}
|
|
Stream(ref p) => {
|
|
match unsafe { (*p.get()).start_selection(task) } {
|
|
stream::SelSuccess => return Ok(()),
|
|
stream::SelCanceled(task) => return Err(task),
|
|
stream::SelUpgraded(t, port) => (t, port),
|
|
}
|
|
}
|
|
Shared(ref p) => {
|
|
return unsafe { (*p.get()).start_selection(task) };
|
|
}
|
|
};
|
|
task = t;
|
|
unsafe {
|
|
mem::swap(&mut cast::transmute_mut(self).inner,
|
|
&mut new_port.inner);
|
|
}
|
|
}
|
|
}
|
|
|
|
fn abort_selection(&self) -> bool {
|
|
let mut was_upgrade = false;
|
|
loop {
|
|
let result = match self.inner {
|
|
Oneshot(ref p) => unsafe { (*p.get()).abort_selection() },
|
|
Stream(ref p) => unsafe {
|
|
(*p.get()).abort_selection(was_upgrade)
|
|
},
|
|
Shared(ref p) => return unsafe {
|
|
(*p.get()).abort_selection(was_upgrade)
|
|
},
|
|
};
|
|
let mut new_port = match result { Ok(b) => return b, Err(p) => p };
|
|
was_upgrade = true;
|
|
unsafe {
|
|
mem::swap(&mut cast::transmute_mut(self).inner,
|
|
&mut new_port.inner);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'a, T: Send> Iterator<T> for Messages<'a, T> {
|
|
fn next(&mut self) -> Option<T> { self.port.recv_opt() }
|
|
}
|
|
|
|
#[unsafe_destructor]
|
|
impl<T: Send> Drop for Port<T> {
|
|
fn drop(&mut self) {
|
|
match self.inner {
|
|
Oneshot(ref mut p) => unsafe { (*p.get()).drop_port(); },
|
|
Stream(ref mut p) => unsafe { (*p.get()).drop_port(); },
|
|
Shared(ref mut p) => unsafe { (*p.get()).drop_port(); },
|
|
}
|
|
}
|
|
}
|
|
|
|
#[cfg(test)]
|
|
mod test {
|
|
use prelude::*;
|
|
|
|
use native;
|
|
use os;
|
|
use super::*;
|
|
|
|
pub fn stress_factor() -> uint {
|
|
match os::getenv("RUST_TEST_STRESS") {
|
|
Some(val) => from_str::<uint>(val).unwrap(),
|
|
None => 1,
|
|
}
|
|
}
|
|
|
|
test!(fn smoke() {
|
|
let (p, c) = Chan::new();
|
|
c.send(1);
|
|
assert_eq!(p.recv(), 1);
|
|
})
|
|
|
|
test!(fn drop_full() {
|
|
let (_p, c) = Chan::new();
|
|
c.send(~1);
|
|
})
|
|
|
|
test!(fn drop_full_shared() {
|
|
let (_p, c) = Chan::new();
|
|
c.send(~1);
|
|
})
|
|
|
|
test!(fn smoke_shared() {
|
|
let (p, c) = Chan::new();
|
|
c.send(1);
|
|
assert_eq!(p.recv(), 1);
|
|
let c = c.clone();
|
|
c.send(1);
|
|
assert_eq!(p.recv(), 1);
|
|
})
|
|
|
|
test!(fn smoke_threads() {
|
|
let (p, c) = Chan::new();
|
|
spawn(proc() {
|
|
c.send(1);
|
|
});
|
|
assert_eq!(p.recv(), 1);
|
|
})
|
|
|
|
test!(fn smoke_port_gone() {
|
|
let (p, c) = Chan::new();
|
|
drop(p);
|
|
c.send(1);
|
|
} #[should_fail])
|
|
|
|
test!(fn smoke_shared_port_gone() {
|
|
let (p, c) = Chan::new();
|
|
drop(p);
|
|
c.send(1);
|
|
} #[should_fail])
|
|
|
|
test!(fn smoke_shared_port_gone2() {
|
|
let (p, c) = Chan::new();
|
|
drop(p);
|
|
let c2 = c.clone();
|
|
drop(c);
|
|
c2.send(1);
|
|
} #[should_fail])
|
|
|
|
test!(fn port_gone_concurrent() {
|
|
let (p, c) = Chan::new();
|
|
spawn(proc() {
|
|
p.recv();
|
|
});
|
|
loop { c.send(1) }
|
|
} #[should_fail])
|
|
|
|
test!(fn port_gone_concurrent_shared() {
|
|
let (p, c) = Chan::new();
|
|
let c1 = c.clone();
|
|
spawn(proc() {
|
|
p.recv();
|
|
});
|
|
loop {
|
|
c.send(1);
|
|
c1.send(1);
|
|
}
|
|
} #[should_fail])
|
|
|
|
test!(fn smoke_chan_gone() {
|
|
let (p, c) = Chan::<int>::new();
|
|
drop(c);
|
|
p.recv();
|
|
} #[should_fail])
|
|
|
|
test!(fn smoke_chan_gone_shared() {
|
|
let (p, c) = Chan::<()>::new();
|
|
let c2 = c.clone();
|
|
drop(c);
|
|
drop(c2);
|
|
p.recv();
|
|
} #[should_fail])
|
|
|
|
test!(fn chan_gone_concurrent() {
|
|
let (p, c) = Chan::new();
|
|
spawn(proc() {
|
|
c.send(1);
|
|
c.send(1);
|
|
});
|
|
loop { p.recv(); }
|
|
} #[should_fail])
|
|
|
|
test!(fn stress() {
|
|
let (p, c) = Chan::new();
|
|
spawn(proc() {
|
|
for _ in range(0, 10000) { c.send(1); }
|
|
});
|
|
for _ in range(0, 10000) {
|
|
assert_eq!(p.recv(), 1);
|
|
}
|
|
})
|
|
|
|
test!(fn stress_shared() {
|
|
static AMT: uint = 10000;
|
|
static NTHREADS: uint = 8;
|
|
let (p, c) = Chan::<int>::new();
|
|
let (p1, c1) = Chan::new();
|
|
|
|
spawn(proc() {
|
|
for _ in range(0, AMT * NTHREADS) {
|
|
assert_eq!(p.recv(), 1);
|
|
}
|
|
match p.try_recv() {
|
|
Data(..) => fail!(),
|
|
_ => {}
|
|
}
|
|
c1.send(());
|
|
});
|
|
|
|
for _ in range(0, NTHREADS) {
|
|
let c = c.clone();
|
|
spawn(proc() {
|
|
for _ in range(0, AMT) { c.send(1); }
|
|
});
|
|
}
|
|
p1.recv();
|
|
})
|
|
|
|
#[test]
|
|
fn send_from_outside_runtime() {
|
|
let (p, c) = Chan::<int>::new();
|
|
let (p1, c1) = Chan::new();
|
|
let (port, chan) = Chan::new();
|
|
let chan2 = chan.clone();
|
|
spawn(proc() {
|
|
c1.send(());
|
|
for _ in range(0, 40) {
|
|
assert_eq!(p.recv(), 1);
|
|
}
|
|
chan2.send(());
|
|
});
|
|
p1.recv();
|
|
native::task::spawn(proc() {
|
|
for _ in range(0, 40) {
|
|
c.send(1);
|
|
}
|
|
chan.send(());
|
|
});
|
|
port.recv();
|
|
port.recv();
|
|
}
|
|
|
|
#[test]
|
|
fn recv_from_outside_runtime() {
|
|
let (p, c) = Chan::<int>::new();
|
|
let (dp, dc) = Chan::new();
|
|
native::task::spawn(proc() {
|
|
for _ in range(0, 40) {
|
|
assert_eq!(p.recv(), 1);
|
|
}
|
|
dc.send(());
|
|
});
|
|
for _ in range(0, 40) {
|
|
c.send(1);
|
|
}
|
|
dp.recv();
|
|
}
|
|
|
|
#[test]
|
|
fn no_runtime() {
|
|
let (p1, c1) = Chan::<int>::new();
|
|
let (p2, c2) = Chan::<int>::new();
|
|
let (port, chan) = Chan::new();
|
|
let chan2 = chan.clone();
|
|
native::task::spawn(proc() {
|
|
assert_eq!(p1.recv(), 1);
|
|
c2.send(2);
|
|
chan2.send(());
|
|
});
|
|
native::task::spawn(proc() {
|
|
c1.send(1);
|
|
assert_eq!(p2.recv(), 2);
|
|
chan.send(());
|
|
});
|
|
port.recv();
|
|
port.recv();
|
|
}
|
|
|
|
test!(fn oneshot_single_thread_close_port_first() {
|
|
// Simple test of closing without sending
|
|
let (port, _chan) = Chan::<int>::new();
|
|
{ let _p = port; }
|
|
})
|
|
|
|
test!(fn oneshot_single_thread_close_chan_first() {
|
|
// Simple test of closing without sending
|
|
let (_port, chan) = Chan::<int>::new();
|
|
{ let _c = chan; }
|
|
})
|
|
|
|
test!(fn oneshot_single_thread_send_port_close() {
|
|
// Testing that the sender cleans up the payload if receiver is closed
|
|
let (port, chan) = Chan::<~int>::new();
|
|
{ let _p = port; }
|
|
chan.send(~0);
|
|
} #[should_fail])
|
|
|
|
test!(fn oneshot_single_thread_recv_chan_close() {
|
|
// Receiving on a closed chan will fail
|
|
let res = task::try(proc() {
|
|
let (port, chan) = Chan::<~int>::new();
|
|
{ let _c = chan; }
|
|
port.recv();
|
|
});
|
|
// What is our res?
|
|
assert!(res.is_err());
|
|
})
|
|
|
|
test!(fn oneshot_single_thread_send_then_recv() {
|
|
let (port, chan) = Chan::<~int>::new();
|
|
chan.send(~10);
|
|
assert!(port.recv() == ~10);
|
|
})
|
|
|
|
test!(fn oneshot_single_thread_try_send_open() {
|
|
let (port, chan) = Chan::<int>::new();
|
|
assert!(chan.try_send(10));
|
|
assert!(port.recv() == 10);
|
|
})
|
|
|
|
test!(fn oneshot_single_thread_try_send_closed() {
|
|
let (port, chan) = Chan::<int>::new();
|
|
{ let _p = port; }
|
|
assert!(!chan.try_send(10));
|
|
})
|
|
|
|
test!(fn oneshot_single_thread_try_recv_open() {
|
|
let (port, chan) = Chan::<int>::new();
|
|
chan.send(10);
|
|
assert!(port.recv_opt() == Some(10));
|
|
})
|
|
|
|
test!(fn oneshot_single_thread_try_recv_closed() {
|
|
let (port, chan) = Chan::<int>::new();
|
|
{ let _c = chan; }
|
|
assert!(port.recv_opt() == None);
|
|
})
|
|
|
|
test!(fn oneshot_single_thread_peek_data() {
|
|
let (port, chan) = Chan::<int>::new();
|
|
assert_eq!(port.try_recv(), Empty)
|
|
chan.send(10);
|
|
assert_eq!(port.try_recv(), Data(10));
|
|
})
|
|
|
|
test!(fn oneshot_single_thread_peek_close() {
|
|
let (port, chan) = Chan::<int>::new();
|
|
{ let _c = chan; }
|
|
assert_eq!(port.try_recv(), Disconnected);
|
|
assert_eq!(port.try_recv(), Disconnected);
|
|
})
|
|
|
|
test!(fn oneshot_single_thread_peek_open() {
|
|
let (port, _chan) = Chan::<int>::new();
|
|
assert_eq!(port.try_recv(), Empty);
|
|
})
|
|
|
|
test!(fn oneshot_multi_task_recv_then_send() {
|
|
let (port, chan) = Chan::<~int>::new();
|
|
spawn(proc() {
|
|
assert!(port.recv() == ~10);
|
|
});
|
|
|
|
chan.send(~10);
|
|
})
|
|
|
|
test!(fn oneshot_multi_task_recv_then_close() {
|
|
let (port, chan) = Chan::<~int>::new();
|
|
spawn(proc() {
|
|
let _chan = chan;
|
|
});
|
|
let res = task::try(proc() {
|
|
assert!(port.recv() == ~10);
|
|
});
|
|
assert!(res.is_err());
|
|
})
|
|
|
|
test!(fn oneshot_multi_thread_close_stress() {
|
|
for _ in range(0, stress_factor()) {
|
|
let (port, chan) = Chan::<int>::new();
|
|
spawn(proc() {
|
|
let _p = port;
|
|
});
|
|
let _chan = chan;
|
|
}
|
|
})
|
|
|
|
test!(fn oneshot_multi_thread_send_close_stress() {
|
|
for _ in range(0, stress_factor()) {
|
|
let (port, chan) = Chan::<int>::new();
|
|
spawn(proc() {
|
|
let _p = port;
|
|
});
|
|
let _ = task::try(proc() {
|
|
chan.send(1);
|
|
});
|
|
}
|
|
})
|
|
|
|
test!(fn oneshot_multi_thread_recv_close_stress() {
|
|
for _ in range(0, stress_factor()) {
|
|
let (port, chan) = Chan::<int>::new();
|
|
spawn(proc() {
|
|
let port = port;
|
|
let res = task::try(proc() {
|
|
port.recv();
|
|
});
|
|
assert!(res.is_err());
|
|
});
|
|
spawn(proc() {
|
|
let chan = chan;
|
|
spawn(proc() {
|
|
let _chan = chan;
|
|
});
|
|
});
|
|
}
|
|
})
|
|
|
|
test!(fn oneshot_multi_thread_send_recv_stress() {
|
|
for _ in range(0, stress_factor()) {
|
|
let (port, chan) = Chan::<~int>::new();
|
|
spawn(proc() {
|
|
chan.send(~10);
|
|
});
|
|
spawn(proc() {
|
|
assert!(port.recv() == ~10);
|
|
});
|
|
}
|
|
})
|
|
|
|
test!(fn stream_send_recv_stress() {
|
|
for _ in range(0, stress_factor()) {
|
|
let (port, chan) = Chan::<~int>::new();
|
|
|
|
send(chan, 0);
|
|
recv(port, 0);
|
|
|
|
fn send(chan: Chan<~int>, i: int) {
|
|
if i == 10 { return }
|
|
|
|
spawn(proc() {
|
|
chan.send(~i);
|
|
send(chan, i + 1);
|
|
});
|
|
}
|
|
|
|
fn recv(port: Port<~int>, i: int) {
|
|
if i == 10 { return }
|
|
|
|
spawn(proc() {
|
|
assert!(port.recv() == ~i);
|
|
recv(port, i + 1);
|
|
});
|
|
}
|
|
}
|
|
})
|
|
|
|
test!(fn recv_a_lot() {
|
|
// Regression test that we don't run out of stack in scheduler context
|
|
let (port, chan) = Chan::new();
|
|
for _ in range(0, 10000) { chan.send(()); }
|
|
for _ in range(0, 10000) { port.recv(); }
|
|
})
|
|
|
|
test!(fn shared_chan_stress() {
|
|
let (port, chan) = Chan::new();
|
|
let total = stress_factor() + 100;
|
|
for _ in range(0, total) {
|
|
let chan_clone = chan.clone();
|
|
spawn(proc() {
|
|
chan_clone.send(());
|
|
});
|
|
}
|
|
|
|
for _ in range(0, total) {
|
|
port.recv();
|
|
}
|
|
})
|
|
|
|
test!(fn test_nested_recv_iter() {
|
|
let (port, chan) = Chan::<int>::new();
|
|
let (total_port, total_chan) = Chan::<int>::new();
|
|
|
|
spawn(proc() {
|
|
let mut acc = 0;
|
|
for x in port.iter() {
|
|
acc += x;
|
|
}
|
|
total_chan.send(acc);
|
|
});
|
|
|
|
chan.send(3);
|
|
chan.send(1);
|
|
chan.send(2);
|
|
drop(chan);
|
|
assert_eq!(total_port.recv(), 6);
|
|
})
|
|
|
|
test!(fn test_recv_iter_break() {
|
|
let (port, chan) = Chan::<int>::new();
|
|
let (count_port, count_chan) = Chan::<int>::new();
|
|
|
|
spawn(proc() {
|
|
let mut count = 0;
|
|
for x in port.iter() {
|
|
if count >= 3 {
|
|
break;
|
|
} else {
|
|
count += x;
|
|
}
|
|
}
|
|
count_chan.send(count);
|
|
});
|
|
|
|
chan.send(2);
|
|
chan.send(2);
|
|
chan.send(2);
|
|
chan.try_send(2);
|
|
drop(chan);
|
|
assert_eq!(count_port.recv(), 4);
|
|
})
|
|
|
|
test!(fn try_recv_states() {
|
|
let (p, c) = Chan::<int>::new();
|
|
let (p1, c1) = Chan::<()>::new();
|
|
let (p2, c2) = Chan::<()>::new();
|
|
spawn(proc() {
|
|
p1.recv();
|
|
c.send(1);
|
|
c2.send(());
|
|
p1.recv();
|
|
drop(c);
|
|
c2.send(());
|
|
});
|
|
|
|
assert_eq!(p.try_recv(), Empty);
|
|
c1.send(());
|
|
p2.recv();
|
|
assert_eq!(p.try_recv(), Data(1));
|
|
assert_eq!(p.try_recv(), Empty);
|
|
c1.send(());
|
|
p2.recv();
|
|
assert_eq!(p.try_recv(), Disconnected);
|
|
})
|
|
|
|
// This bug used to end up in a livelock inside of the Port destructor
|
|
// because the internal state of the Shared port was corrupted
|
|
test!(fn destroy_upgraded_shared_port_when_sender_still_active() {
|
|
let (p, c) = Chan::new();
|
|
let (p1, c2) = Chan::new();
|
|
spawn(proc() {
|
|
p.recv(); // wait on a oneshot port
|
|
drop(p); // destroy a shared port
|
|
c2.send(());
|
|
});
|
|
// make sure the other task has gone to sleep
|
|
for _ in range(0, 5000) { task::deschedule(); }
|
|
|
|
// upgrade to a shared chan and send a message
|
|
let t = c.clone();
|
|
drop(c);
|
|
t.send(());
|
|
|
|
// wait for the child task to exit before we exit
|
|
p1.recv();
|
|
})
|
|
}
|