etcher-sdk
Version:
92 lines • 3.68 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.BlockTransformStream = void 0;
const stream_1 = require("stream");
const aligned_lockable_buffer_1 = require("./aligned-lockable-buffer");
const constants_1 = require("./constants");
const utils_1 = require("./utils");
class BlockTransformStream extends stream_1.Transform {
constructor({ chunkSize, alignment, numBuffers = 2, }) {
super({ objectMode: true, highWaterMark: numBuffers - 1 });
this.bytesRead = 0;
this.bytesWritten = 0;
this.currentBufferPosition = 0;
this.alignedReadableState = new aligned_lockable_buffer_1.AlignedReadableState(chunkSize, alignment, numBuffers);
}
__flush() {
this.unlockCurrentBuffer();
if (this.currentBufferPosition !== this.currentBuffer.length) {
this.push(this.currentBuffer.slice(0, this.currentBufferPosition));
}
else {
this.push(this.currentBuffer);
}
this.bytesWritten += this.currentBufferPosition;
this.currentBufferPosition = 0;
}
async pushChunk(chunk) {
if (chunk.length === 0) {
return;
}
// Get an aligned buffer and lock it when starting or when the last aligned buffer was just flushed
if (this.currentBufferPosition === 0) {
this.currentBuffer = this.alignedReadableState.getCurrentBuffer();
this.unlockCurrentBuffer = await this.currentBuffer.lock();
}
// Copy the current chunk into the current aligned buffer
const lengthToCopy = Math.min(chunk.length, this.currentBuffer.length - this.currentBufferPosition);
chunk.copy(this.currentBuffer, this.currentBufferPosition, 0, lengthToCopy);
this.currentBufferPosition += lengthToCopy;
this.bytesRead += lengthToCopy;
// If the current aligned buffer is full, push it
if (this.currentBufferPosition === this.currentBuffer.length) {
this.__flush();
}
// If the chunk did not fit in the last aligned buffer, copy the remaining part into the next aligned buffer
if (lengthToCopy < chunk.length) {
await this.pushChunk(chunk.slice(lengthToCopy));
}
}
_transform(chunk, _encoding, callback) {
(0, utils_1.asCallback)(this.pushChunk(chunk), callback);
}
_flush(callback) {
try {
this.__flush();
callback();
}
catch (error) {
callback(error);
}
}
static alignIfNeeded(stream, alignment, numBuffers) {
if (alignment === undefined) {
return stream;
}
const transform = new BlockTransformStream({
chunkSize: constants_1.CHUNK_SIZE,
alignment,
numBuffers,
});
stream.on('error', transform.emit.bind(transform, 'error'));
stream.pipe(transform);
return transform;
}
}
exports.BlockTransformStream = BlockTransformStream;
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