Created
September 1, 2016 14:47
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Promise.eachLimit
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| function createArrayIterator(coll) { | |
| var i = -1; | |
| var len = coll.length; | |
| return function next() { | |
| return ++i < len ? {value: coll[i], key: i} : null; | |
| } | |
| } | |
| function eachLimit(coll, limit, iteratee) { | |
| if (limit <= 0 || !coll) return Promise.resolve(); | |
| var done = false; | |
| var running = 0; | |
| var nextElem = createArrayIterator(coll); | |
| function replenish() { | |
| return new Promise(function(resolve, reject) { | |
| while (running < limit && !done) { | |
| var elem = nextElem(); | |
| if (elem === null) { | |
| done = true; | |
| if (running <= 0) { | |
| resolve(); | |
| } | |
| return; | |
| } | |
| running++; | |
| iteratee(elem.value, elem.key).then(function() { | |
| running--; | |
| if (done && running <= 0) { | |
| resolve(); | |
| } else { | |
| replenish().then(resolve, reject) | |
| } | |
| }).catch(function(e) { | |
| running--; | |
| done = true; | |
| reject(e); | |
| }); | |
| } | |
| }); | |
| } | |
| return replenish(); | |
| } |
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