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discuss joinable tasks

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Niko Matsakis 2012-01-11 13:12:34 -08:00
parent 46664c1af2
commit 79d489cedf
1 changed files with 20 additions and 1 deletions
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doc/tutorial/task.md
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@ -14,7 +14,7 @@ somewhat. The tutorial documents the API as it exists today.
## Spawning a task
Spawning a task is done using the various spawn functions in the
module task. Let's begin with the simplest one, `task::spawn()`, and
module `task`. We will Let's begin with the simplest one, `task::spawn()`, and
later move on to the others:
let some_value = 22;
@ -122,4 +122,23 @@ addition to the task id of the child, this record defines two fields,
respectively for communicating with the child. Those fields are used
here to send and receive three messages from the child task.
## Joining a task
The function `spawn_joinable()` is used to spawn a task that can later
be joined. This is implemented by having the child task send a
message when it has completed (either successfully or by failing).
Therefore, `spawn_joinable()` returns a structure containing both the
task ID and the port where this message will be sent---this structure
type is called `task::joinable_task`. The structure can be passed to
`task::join()`, which simply blocks on the port, waiting to receive
the message from the child task.
## The supervisor relationship
By default, failures in Rust propagate upward through the task tree.
We say that each task is supervised by its parent, meaning that if the
task fails, that failure is propagated to the parent task, which will
fail sometime later. This propagation can be disabled by using the
function `task::unsupervise()`, which disables error propagation from
the current task to its parent.