Add vicious cycle and self-resolution detection #223

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domenic opened this Issue Feb 28, 2013 · 2 comments

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domenic commented Feb 28, 2013

This seems like a better solution to the test case in #221.

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kriskowal commented Feb 28, 2013

Vicious cycle detection would entail a check in deferred.resolve(value) to verify that Q.resolve(value).mostResolved() is not equal to deferred.

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domenic commented Jul 9, 2013

This is a small backward-compat hazard; tagging it as such. Also I'd like to point out that the upcoming Promises/A+ 1.1 revision requires self-resolution detection. (It encourages, but does not mandate, vicious cycle detection.) Search for "if x and promise" at https://github.com/promises-aplus/promises-spec.

@kriskowal kriskowal added a commit that referenced this issue Oct 21, 2013

@kriskowal kriskowal Rearchitect Q for closure avoidance and WeakMap
Implement the `Promise` constructor.  The promise constructor serves
both as a deferred promise constructor that accepts a function, and a
new kind of promise constructor that accepts a backing handler object.
The backing handler object must implement `dispatch(resolve, op,
operands)` and `inspect()`.  The new promise constructor replaces the
`Q.promise` function, which is deprecated.  The new promise constructor
replaces `makePromise`, which has been removed entirely.  As such,
Q-Connection will have to be rearchitected to provide a custom promise
handler for remote objects instead of using `makePromise`. Fixes #346.

Postpone calling `then` on a thenable until a message is dispatched to
the coerced promise.  Fixes #372.

When coercing a thenable, memoize the resulting promise to avoid
re-starting a lazy promise.

Add support for vicious cycle detection.  Fixes #223.

This change request also reviews the Q API, deprecating many interfaces
that remain from legacy designs.  Fixes #215.

Factor most Node.js tools into `q/node` module.  Mirror deprecated
interfaces in Q.

Support for `close` and `closed` has been removed from `Queue`, which
has additional ramifications for Q-Connection.  I intend to use Q-IO
streams in Q-Connection instead of raw queues.

Most of the Q specifications continue to work after these changes, but
with many deprecation warnings.  The specs have been revised to appease
the deprecation warnings.

⚠️ However, the specifications for "progress" have all been
disabled pending a closer investigation to decide whether to fix Q or
fix the specs.

The promise protocol no longer supports "set" and "delete" operations.
Function application is a special case of "post", and for support of
"fbind", it is now possible to pass a "thisp" as a final argument.  The
"when" message is now called simply "then".

Support for pre-ECMAScript 5 has been abandoned outright, pending
review.

Removed:

-   Q.set, promise.set
-   Q.delete, promise.delete
-   Q.nearer
-   Q.master

The following methods of `Q` are deprecated in favor of their
equivalents on the `promise` prototype:

-   `progress`, `thenResolve`, `thenReject`, `isPending`, `isFulfilled`,
    `isRejected`, `dispatch`, `get`, `post`, `invoke`, `keys`

Other deprecations:

-   Q.resolve in favor of Q
-   Q.fulfill in favor of Q
-   Q.isPromiseAlike in favor of Q.isThenable
-   Q.when in favor of Q().then
-   Q.fail and promise.fail in favor of promise.catch
-   Q.fin and promise.fin in favor of promise.finally
-   Q.mapply and promise.mapply in favor of promise.post
-   Q.send and promise.send in favor of promise.invoke
-   Q.mcall and promise.mcall in favor of promise.invoke
-   Q.promise in favor of new Q.Promise with a resolver function
-   Q.makePromise in favor of new Q.Promise with a handler object
-   promise.fbind in favor of Q.fbind
-   deferred.makeNodeResolver() in favor of
    require("q/node").makeNodeResolver(deferred.resolve)
-   promise.passByCopy() in favor of Q.passByCopy(promise),
    provisionally

Node.js wrappers that have been moved into their own module have a
deprecated interface in Q proper:

-   `nodeify`, `denodify`, `nfbind`, `nbind`, `npost`, `ninvoke`

But the following experimental aliases are deprecated and do not exist
in `q/node`:

-   `nsend` for `ninvoke`
-   `nmcall` for `ninvoke`
-   `nmapply` for `npost`
d93f938

@kriskowal kriskowal added a commit that referenced this issue Oct 30, 2013

@kriskowal kriskowal Rearchitect Q for closure avoidance and WeakMap
Implement the `Promise` constructor.  The promise constructor serves
both as a deferred promise constructor that accepts a function, and a
new kind of promise constructor that accepts a backing handler object.
The backing handler object must implement `dispatch(resolve, op,
operands)` and `inspect()`.  The new promise constructor replaces the
`Q.promise` function, which is deprecated.  The new promise constructor
replaces `makePromise`, which has been removed entirely.  As such,
Q-Connection will have to be rearchitected to provide a custom promise
handler for remote objects instead of using `makePromise`. Fixes #346.

Postpone calling `then` on a thenable until a message is dispatched to
the coerced promise.  Fixes #372. Fixes #369.

When coercing a thenable, memoize the resulting promise to avoid
re-starting a lazy promise.

Add support for vicious cycle detection.  Fixes #223.

This change request also reviews the Q API, deprecating many interfaces
that remain from legacy designs.  Fixes #215.

Factor most Node.js tools into `q/node` module.  Mirror deprecated
interfaces in Q.

Support for `close` and `closed` has been removed from `Queue`, which
has additional ramifications for Q-Connection.  I intend to use Q-IO
streams in Q-Connection instead of raw queues.

Most of the Q specifications continue to work after these changes, but
with many deprecation warnings.  The specs have been revised to appease
the deprecation warnings.

⚠️ However, the specifications for "progress" have all been
disabled pending a closer investigation to decide whether to fix Q or
fix the specs.

The promise protocol no longer supports "set" and "delete" operations.
Function application is a special case of "post", and for support of
"fbind", it is now possible to pass a "thisp" as a final argument.  The
"when" message is now called simply "then".

Support for pre-ECMAScript 5 has been abandoned outright, pending
review.

Removed:

-   Q.set, promise.set
-   Q.delete, promise.delete
-   Q.nearer
-   Q.master

The following methods of `Q` are deprecated in favor of their
equivalents on the `promise` prototype:

-   `progress`, `thenResolve`, `thenReject`, `isPending`, `isFulfilled`,
    `isRejected`, `dispatch`, `get`, `post`, `invoke`, `keys`

Other deprecations:

-   Q.resolve in favor of Q
-   Q.fulfill in favor of Q
-   Q.isPromiseAlike in favor of Q.isThenable
-   Q.when in favor of Q().then
-   Q.fail and promise.fail in favor of promise.catch
-   Q.fin and promise.fin in favor of promise.finally
-   Q.mapply and promise.mapply in favor of promise.post
-   Q.send and promise.send in favor of promise.invoke
-   Q.mcall and promise.mcall in favor of promise.invoke
-   Q.promise in favor of new Q.Promise with a resolver function
-   Q.makePromise in favor of new Q.Promise with a handler object
-   promise.fbind in favor of Q.fbind
-   deferred.makeNodeResolver() in favor of
    require("q/node").makeNodeResolver(deferred.resolve)
-   promise.passByCopy() in favor of Q.passByCopy(promise),
    provisionally

Node.js wrappers that have been moved into their own module have a
deprecated interface in Q proper:

-   `nodeify`, `denodify`, `nfbind`, `nbind`, `npost`, `ninvoke`

But the following experimental aliases are deprecated and do not exist
in `q/node`:

-   `nsend` for `ninvoke`
-   `nmcall` for `ninvoke`
-   `nmapply` for `npost`
bbc7db1

kriskowal closed this in 67cfb6e Oct 30, 2013

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