etcher-sdk
Version:
84 lines • 3.42 kB
JavaScript
"use strict";
/*
* Copyright 2018 balena.io
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
Object.defineProperty(exports, "__esModule", { value: true });
exports.ProgressBlockReadStream = exports.BlockReadStream = void 0;
const stream_1 = require("stream");
const aligned_lockable_buffer_1 = require("./aligned-lockable-buffer");
const constants_1 = require("./constants");
const errors_1 = require("./errors");
const progress_1 = require("./source-destination/progress");
class BlockReadStream extends stream_1.Readable {
constructor({ source, alignment, start = 0, end = Infinity, chunkSize = constants_1.CHUNK_SIZE, maxRetries = 5, numBuffers = 2, }) {
super({ objectMode: true, highWaterMark: numBuffers - 1 });
this.bytesRead = 0;
this.source = source;
this.alignment = alignment;
this.bytesRead = start;
this.end = end;
this.chunkSize = chunkSize;
this.maxRetries = maxRetries;
if (alignment !== undefined) {
this.chunkSize = Math.max(Math.floor(chunkSize / alignment) * alignment, alignment);
this.alignedReadableState = new aligned_lockable_buffer_1.AlignedReadableState(chunkSize, alignment, numBuffers);
}
}
async tryRead(buffer) {
// Tries to read `this.maxRetries` times if the error is transient.
return await (0, errors_1.retryOnTransientError)(async () => {
return await this.source.read(buffer, 0, buffer.length, this.bytesRead);
}, this.maxRetries, constants_1.RETRY_BASE_TIMEOUT);
}
async _read() {
if (this.bytesRead > this.end) {
this.push(null);
return;
}
let buffer = this.alignment !== undefined
? this.alignedReadableState.getCurrentBuffer()
: Buffer.allocUnsafe(this.chunkSize);
const toRead = this.end - this.bytesRead + 1;
if (toRead < buffer.length) {
buffer = buffer.slice(0, toRead);
}
try {
let unlock;
if ((0, aligned_lockable_buffer_1.isAlignedLockableBuffer)(buffer)) {
unlock = await buffer.lock();
}
let bytesRead;
try {
({ bytesRead } = await this.tryRead(buffer));
}
finally {
unlock === null || unlock === void 0 ? void 0 : unlock();
}
this.bytesRead += bytesRead;
if (bytesRead !== 0) {
this.push(buffer.slice(0, bytesRead));
}
else {
this.push(null);
}
}
catch (error) {
this.emit('error', error);
}
}
}
exports.BlockReadStream = BlockReadStream;
exports.ProgressBlockReadStream = (0, progress_1.makeClassEmitProgressEvents)(BlockReadStream, 'bytesRead', 'bytesRead');
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