etcher-sdk
Version:
80 lines • 3.14 kB
JavaScript
"use strict";
/*
* Copyright 2019 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.SparseReadStream = void 0;
const stream_1 = require("stream");
const aligned_lockable_buffer_1 = require("../aligned-lockable-buffer");
const shared_1 = require("./shared");
class SparseReadStream extends stream_1.Readable {
constructor({ source, blocks, chunkSize, verify, generateChecksums, alignment, numBuffers = 2, }) {
super({ objectMode: true, highWaterMark: numBuffers - 1 });
this.positionInBlock = 0;
this.source = source;
this.blocks = blocks;
this.chunkSize = chunkSize;
if (alignment !== undefined) {
this.alignedReadableState = new aligned_lockable_buffer_1.AlignedReadableState(chunkSize, alignment, numBuffers);
}
this.stateIterator = (0, shared_1.createSparseReaderStateIterator)(blocks, verify, generateChecksums);
this.nextBlock();
}
async _read() {
try {
this.push(await this.__read());
}
catch (error) {
this.emit('error', error);
this.push(null);
}
}
nextBlock() {
this.state = this.stateIterator.next().value;
this.positionInBlock = 0;
}
async __read() {
var _a;
if (this.state === undefined) {
// No current block means we're done reading
return null;
}
const length = Math.min(this.chunkSize, this.state.subBlock.length - this.positionInBlock);
const buffer = this.alignedReadableState !== undefined
? this.alignedReadableState.getCurrentBuffer().slice(0, length)
: Buffer.allocUnsafe(length);
const unlock = (0, aligned_lockable_buffer_1.isAlignedLockableBuffer)(buffer)
? await buffer.lock()
: undefined;
try {
await this.source.read(buffer, 0, length, this.state.subBlock.offset + this.positionInBlock);
(_a = this.state.hasher) === null || _a === void 0 ? void 0 : _a.update(buffer);
}
finally {
unlock === null || unlock === void 0 ? void 0 : unlock();
}
const chunk = {
buffer,
position: this.state.subBlock.offset + this.positionInBlock,
};
this.positionInBlock += length;
if (this.positionInBlock === this.state.subBlock.length) {
this.nextBlock();
}
return chunk;
}
}
exports.SparseReadStream = SparseReadStream;
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