With Mark’s direction, the v2 branch of Q handles "vicious cycles" through the WeakMap that maps promises to their underlying handler. Whenever a promise is resolved with another promise, it walks forward through the chain of promises that the promise handler "became" through resolution. The first promise’s initial handler is a "vicious cycle" rejected promise handler, so if the walk forward through the resolution returns to itself, it remains resolved to the vicious cycle.
https://github.com/kriskowal/q/blob/v2/q.js#L181-L204 On Wed, Feb 24, 2016 at 11:38 AM Bradley Meck <bradley.m...@gmail.com> wrote: > I was doing some recursive data structure work and ended up with a > cyclical promise that did not use a direct self reference. It can be > reduced down to: > > ```javascript > var af, a = new Promise(f=>af=f); > var bf, b = new Promise(f=>bf=f); > > af(b);bf(a); // the problem > > a.then(_=>_) // some env/libs need this to start checking status > ``` > > According to https://tc39.github.io/ecma262/#sec-promise-resolve-functions > it looks like this should cause a recursive and infinite set of > `EnqueueJob("PromiseJobs",...)` > > This code currently does strange things in stable browsers, but doesn't > seem to always cause infinite loops in the nightly builds of some things. I > was wondering what the expected behavior is here because I am having > trouble making sense of things. > _______________________________________________ > es-discuss mailing list > es-discuss@mozilla.org > https://mail.mozilla.org/listinfo/es-discuss >
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