at:tutorial:actors
Differences
This shows you the differences between two versions of the page.
Both sides previous revisionPrevious revisionNext revision | Previous revisionNext revisionBoth sides next revision | ||
at:tutorial:actors [2007/07/18 11:11] – elisag | at:tutorial:actors [2008/06/18 19:22] – install tvcutsem | ||
---|---|---|---|
Line 201: | Line 201: | ||
We have described a future as a placeholder for the return value of an asynchronous message send which is eventually // | We have described a future as a placeholder for the return value of an asynchronous message send which is eventually // | ||
- | Blocking a thread on a future can be a major source of deadlocks, like any form of blocking, of course. In the actor paradigm where communication between actors should remain strictly asynchronous, | + | Blocking a thread on a future can be a major source of deadlocks, like any form of blocking. In the actor paradigm where communication between actors should remain strictly asynchronous, |
- | The solution proposed in the [[http:// | + | The solution proposed in the [[http:// |
+ | |||
+ | As an example of a pipeline of message sends, consider the following code: | ||
+ | |||
+ | < | ||
+ | def booleanFuture := remoteObject< | ||
+ | booleanFuture< | ||
+ | ... | ||
+ | } ifFalse: { | ||
+ | ... | ||
+ | } | ||
+ | </ | ||
+ | |||
+ | In this example, the message '' | ||
+ | |||
+ | ==== Working with Resolved Futures ==== | ||
When a future eventually becomes resolved with a value, any messages that were accumulated by the future are forwarded asynchronously to the actual return value, such that it appears as if the original object had sent the messages to the actual return value in the first place. | When a future eventually becomes resolved with a value, any messages that were accumulated by the future are forwarded asynchronously to the actual return value, such that it appears as if the original object had sent the messages to the actual return value in the first place. | ||
Line 210: | Line 225: | ||
AmbientTalk only allows one method to be synchronously invoked on a future, the '' | AmbientTalk only allows one method to be synchronously invoked on a future, the '' | ||
</ | </ | ||
- | |||
- | ==== Working with Resolved Futures ==== | ||
As explained above, it is always correct to use asynchronous message sends to communicate with a future. Sometimes, however, we may want to perform some operation on the return value other than message sending, for example, printing it to the screen. If you print the future directly, you get the following: | As explained above, it is always correct to use asynchronous message sends to communicate with a future. Sometimes, however, we may want to perform some operation on the return value other than message sending, for example, printing it to the screen. If you print the future directly, you get the following: | ||
Line 271: | Line 284: | ||
</ | </ | ||
- | Finally, it is useful to know that '' | + | Finally, it is useful to know that '' |
< | < | ||
Line 279: | Line 292: | ||
</ | </ | ||
- | When the future for ''< | + | When the future for ''< |
==== Futures and Annotated Messages ==== | ==== Futures and Annotated Messages ==== | ||
Line 320: | Line 333: | ||
Some operations, such as creating and sending asynchronous messages are useful to reify at the //actor level//. With such a reification, | Some operations, such as creating and sending asynchronous messages are useful to reify at the //actor level//. With such a reification, | ||
- | Overriding the actor' | + | Overriding the actor' |
< | < | ||
- | def oldmirror := actor.install: (extend: actor with: { | + | def oldmirror := actor.replaceMirror: (extend: actor with: { |
def send(msg) { | def send(msg) { | ||
log(msg); | log(msg); | ||
Line 331: | Line 344: | ||
</ | </ | ||
- | Notice that, in this example, the new metaobject protocol is an extension of the old protocol. This enables it to invoke its parent' | + | Notice that, in this example, the new metaobject protocol is an extension of the old protocol. This enables it to invoke its parent' |
+ | < | ||
For a good use case of actor mirrors, see the '' | For a good use case of actor mirrors, see the '' | ||
+ | </ | ||
Other methods that can be overridden are '' | Other methods that can be overridden are '' |
at/tutorial/actors.txt · Last modified: 2020/02/05 21:26 by elisag