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Add descriptions for demux and compose

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This commit is contained in:
Jerry Kurian
2019-09-09 15:54:29 -04:00
parent d33d8dcad3
commit 7aeea4815a
5 changed files with 60 additions and 134 deletions
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9
src/functions/demux.ts
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@@ -57,9 +57,7 @@ class Demux extends Writable {
) {
super(options);
if (demuxBy.keyBy === undefined && demuxBy.key === undefined) {
throw new Error(
"keyBy or key must be provided in second parameter",
);
throw new Error("keyBy or key must be provided in second argument");
}
this.demuxer = demuxBy.keyBy || ((chunk: any) => chunk[demuxBy.key!]);
this.construct = construct;
@@ -68,6 +66,7 @@ class Demux extends Writable {
this.nonWritableStreams = [];
}
// Throttles when one stream is not writable
public _write(chunk: any, encoding?: any, cb?: any) {
const destKey = this.demuxer(chunk);
if (this.streamsByKey[destKey] === undefined) {
@@ -76,10 +75,6 @@ class Demux extends Writable {
writable: true,
};
}
// Throttle when one stream is not writable anymore
// Set writable to false
// keep state of all the streams, if one is not writable demux shouldnt be writable
// Small optimization is to keep writing until you get a following event to the unwritable destination
let res = false;
if (this.streamsByKey[destKey].writable && this.isWritable) {
res = this.streamsByKey[destKey].stream.write(chunk, encoding, cb);