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1 | // Licensed to the Apache Software Foundation (ASF) under one |
2 | // or more contributor license agreements. See the NOTICE file | |
3 | // distributed with this work for additional information | |
4 | // regarding copyright ownership. The ASF licenses this file | |
5 | // to you under the Apache License, Version 2.0 (the | |
6 | // "License"); you may not use this file except in compliance | |
7 | // with the License. You may obtain a copy of the License at | |
8 | // | |
9 | // http://www.apache.org/licenses/LICENSE-2.0 | |
10 | // | |
11 | // Unless required by applicable law or agreed to in writing, | |
12 | // software distributed under the License is distributed on an | |
13 | // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY | |
14 | // KIND, either express or implied. See the License for the | |
15 | // specific language governing permissions and limitations | |
16 | // under the License. | |
17 | ||
18 | import { DataType } from '../../type'; | |
19 | import { RecordBatch } from '../../recordbatch'; | |
20 | import { AsyncByteQueue } from '../../io/stream'; | |
21 | import { RecordBatchReader } from '../../ipc/reader'; | |
22 | ||
23 | /** @ignore */ | |
24 | export function recordBatchReaderThroughDOMStream<T extends { [key: string]: DataType } = any>(writableStrategy?: ByteLengthQueuingStrategy, readableStrategy?: { autoDestroy: boolean }) { | |
25 | ||
26 | const queue = new AsyncByteQueue(); | |
27 | let reader: RecordBatchReader<T> | null = null; | |
28 | ||
29 | const readable = new ReadableStream<RecordBatch<T>>({ | |
30 | async cancel() { await queue.close(); }, | |
31 | async start(controller) { await next(controller, reader || (reader = await open())); }, | |
32 | async pull(controller) { reader ? await next(controller, reader) : controller.close(); } | |
33 | }); | |
34 | ||
35 | return { writable: new WritableStream(queue, { 'highWaterMark': 2 ** 14, ...writableStrategy }), readable }; | |
36 | ||
37 | async function open() { | |
38 | return await (await RecordBatchReader.from<T>(queue)).open(readableStrategy); | |
39 | } | |
40 | ||
41 | async function next(controller: ReadableStreamDefaultController<RecordBatch<T>>, reader: RecordBatchReader<T>) { | |
42 | let size = controller.desiredSize; | |
43 | let r: IteratorResult<RecordBatch<T>> | null = null; | |
44 | while (!(r = await reader.next()).done) { | |
45 | controller.enqueue(r.value); | |
46 | if (size != null && --size <= 0) { | |
47 | return; | |
48 | } | |
49 | } | |
50 | controller.close(); | |
51 | } | |
52 | } |