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313 lines
12 KiB
313 lines
12 KiB
3 years ago
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"use strict";
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Object.defineProperty(exports, "__esModule", { value: true });
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exports.GridFSBucketReadStream = void 0;
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const stream_1 = require("stream");
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const error_1 = require("../error");
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/**
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* A readable stream that enables you to read buffers from GridFS.
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*
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* Do not instantiate this class directly. Use `openDownloadStream()` instead.
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* @public
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*/
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class GridFSBucketReadStream extends stream_1.Readable {
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/**
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* @param chunks - Handle for chunks collection
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* @param files - Handle for files collection
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* @param readPreference - The read preference to use
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* @param filter - The filter to use to find the file document
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* @internal
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*/
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constructor(chunks, files, readPreference, filter, options) {
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super();
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this.s = {
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bytesToTrim: 0,
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bytesToSkip: 0,
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bytesRead: 0,
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chunks,
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expected: 0,
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files,
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filter,
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init: false,
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expectedEnd: 0,
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options: {
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start: 0,
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end: 0,
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...options
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},
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readPreference
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};
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}
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/**
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* Reads from the cursor and pushes to the stream.
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* Private Impl, do not call directly
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* @internal
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*/
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_read() {
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if (this.destroyed)
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return;
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waitForFile(this, () => doRead(this));
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}
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/**
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* Sets the 0-based offset in bytes to start streaming from. Throws
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* an error if this stream has entered flowing mode
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* (e.g. if you've already called `on('data')`)
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*
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* @param start - 0-based offset in bytes to start streaming from
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*/
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start(start = 0) {
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throwIfInitialized(this);
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this.s.options.start = start;
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return this;
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}
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/**
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* Sets the 0-based offset in bytes to start streaming from. Throws
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* an error if this stream has entered flowing mode
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* (e.g. if you've already called `on('data')`)
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*
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* @param end - Offset in bytes to stop reading at
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*/
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end(end = 0) {
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throwIfInitialized(this);
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this.s.options.end = end;
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return this;
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}
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/**
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* Marks this stream as aborted (will never push another `data` event)
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* and kills the underlying cursor. Will emit the 'end' event, and then
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* the 'close' event once the cursor is successfully killed.
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*/
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async abort() {
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this.push(null);
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this.destroyed = true;
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if (this.s.cursor) {
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try {
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await this.s.cursor.close();
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}
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finally {
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this.emit(GridFSBucketReadStream.CLOSE);
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}
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}
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else {
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if (!this.s.init) {
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// If not initialized, fire close event because we will never
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// get a cursor
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this.emit(GridFSBucketReadStream.CLOSE);
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}
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}
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}
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}
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exports.GridFSBucketReadStream = GridFSBucketReadStream;
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/**
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* An error occurred
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* @event
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*/
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GridFSBucketReadStream.ERROR = 'error';
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/**
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* Fires when the stream loaded the file document corresponding to the provided id.
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* @event
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*/
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GridFSBucketReadStream.FILE = 'file';
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/**
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* Emitted when a chunk of data is available to be consumed.
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* @event
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*/
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GridFSBucketReadStream.DATA = 'data';
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/**
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* Fired when the stream is exhausted (no more data events).
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* @event
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*/
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GridFSBucketReadStream.END = 'end';
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/**
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* Fired when the stream is exhausted and the underlying cursor is killed
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* @event
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*/
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GridFSBucketReadStream.CLOSE = 'close';
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function throwIfInitialized(stream) {
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if (stream.s.init) {
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throw new error_1.MongoGridFSStreamError('Options cannot be changed after the stream is initialized');
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}
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}
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function doRead(stream) {
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if (stream.destroyed)
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return;
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if (!stream.s.cursor)
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return;
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if (!stream.s.file)
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return;
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const handleReadResult = ({ error, doc }) => {
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if (stream.destroyed) {
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return;
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}
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if (error) {
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stream.emit(GridFSBucketReadStream.ERROR, error);
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return;
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}
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if (!doc) {
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stream.push(null);
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stream.s.cursor?.close().then(() => {
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stream.emit(GridFSBucketReadStream.CLOSE);
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}, error => {
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stream.emit(GridFSBucketReadStream.ERROR, error);
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});
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return;
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}
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if (!stream.s.file)
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return;
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const bytesRemaining = stream.s.file.length - stream.s.bytesRead;
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const expectedN = stream.s.expected++;
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const expectedLength = Math.min(stream.s.file.chunkSize, bytesRemaining);
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if (doc.n > expectedN) {
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return stream.emit(GridFSBucketReadStream.ERROR, new error_1.MongoGridFSChunkError(`ChunkIsMissing: Got unexpected n: ${doc.n}, expected: ${expectedN}`));
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}
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if (doc.n < expectedN) {
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return stream.emit(GridFSBucketReadStream.ERROR, new error_1.MongoGridFSChunkError(`ExtraChunk: Got unexpected n: ${doc.n}, expected: ${expectedN}`));
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}
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let buf = Buffer.isBuffer(doc.data) ? doc.data : doc.data.buffer;
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if (buf.byteLength !== expectedLength) {
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if (bytesRemaining <= 0) {
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return stream.emit(GridFSBucketReadStream.ERROR, new error_1.MongoGridFSChunkError(`ExtraChunk: Got unexpected n: ${doc.n}, expected file length ${stream.s.file.length} bytes but already read ${stream.s.bytesRead} bytes`));
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}
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return stream.emit(GridFSBucketReadStream.ERROR, new error_1.MongoGridFSChunkError(`ChunkIsWrongSize: Got unexpected length: ${buf.byteLength}, expected: ${expectedLength}`));
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}
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stream.s.bytesRead += buf.byteLength;
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if (buf.byteLength === 0) {
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return stream.push(null);
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}
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let sliceStart = null;
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let sliceEnd = null;
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if (stream.s.bytesToSkip != null) {
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sliceStart = stream.s.bytesToSkip;
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stream.s.bytesToSkip = 0;
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}
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const atEndOfStream = expectedN === stream.s.expectedEnd - 1;
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const bytesLeftToRead = stream.s.options.end - stream.s.bytesToSkip;
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if (atEndOfStream && stream.s.bytesToTrim != null) {
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sliceEnd = stream.s.file.chunkSize - stream.s.bytesToTrim;
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}
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else if (stream.s.options.end && bytesLeftToRead < doc.data.byteLength) {
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sliceEnd = bytesLeftToRead;
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}
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if (sliceStart != null || sliceEnd != null) {
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buf = buf.slice(sliceStart || 0, sliceEnd || buf.byteLength);
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}
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stream.push(buf);
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return;
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};
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stream.s.cursor.next().then(doc => handleReadResult({ error: null, doc }), error => handleReadResult({ error, doc: null }));
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}
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function init(stream) {
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const findOneOptions = {};
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if (stream.s.readPreference) {
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findOneOptions.readPreference = stream.s.readPreference;
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}
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if (stream.s.options && stream.s.options.sort) {
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findOneOptions.sort = stream.s.options.sort;
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}
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if (stream.s.options && stream.s.options.skip) {
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findOneOptions.skip = stream.s.options.skip;
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}
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const handleReadResult = ({ error, doc }) => {
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if (error) {
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return stream.emit(GridFSBucketReadStream.ERROR, error);
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}
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if (!doc) {
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const identifier = stream.s.filter._id
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? stream.s.filter._id.toString()
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: stream.s.filter.filename;
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const errmsg = `FileNotFound: file ${identifier} was not found`;
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// TODO(NODE-3483)
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const err = new error_1.MongoRuntimeError(errmsg);
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err.code = 'ENOENT'; // TODO: NODE-3338 set property as part of constructor
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return stream.emit(GridFSBucketReadStream.ERROR, err);
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}
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// If document is empty, kill the stream immediately and don't
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// execute any reads
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if (doc.length <= 0) {
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stream.push(null);
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return;
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}
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if (stream.destroyed) {
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// If user destroys the stream before we have a cursor, wait
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// until the query is done to say we're 'closed' because we can't
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// cancel a query.
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stream.emit(GridFSBucketReadStream.CLOSE);
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return;
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}
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try {
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stream.s.bytesToSkip = handleStartOption(stream, doc, stream.s.options);
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}
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catch (error) {
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return stream.emit(GridFSBucketReadStream.ERROR, error);
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}
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const filter = { files_id: doc._id };
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// Currently (MongoDB 3.4.4) skip function does not support the index,
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// it needs to retrieve all the documents first and then skip them. (CS-25811)
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// As work around we use $gte on the "n" field.
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if (stream.s.options && stream.s.options.start != null) {
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const skip = Math.floor(stream.s.options.start / doc.chunkSize);
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if (skip > 0) {
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filter['n'] = { $gte: skip };
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}
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}
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stream.s.cursor = stream.s.chunks.find(filter).sort({ n: 1 });
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if (stream.s.readPreference) {
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stream.s.cursor.withReadPreference(stream.s.readPreference);
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}
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stream.s.expectedEnd = Math.ceil(doc.length / doc.chunkSize);
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stream.s.file = doc;
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try {
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stream.s.bytesToTrim = handleEndOption(stream, doc, stream.s.cursor, stream.s.options);
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}
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catch (error) {
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return stream.emit(GridFSBucketReadStream.ERROR, error);
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}
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stream.emit(GridFSBucketReadStream.FILE, doc);
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return;
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};
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stream.s.files.findOne(stream.s.filter, findOneOptions).then(doc => handleReadResult({ error: null, doc }), error => handleReadResult({ error, doc: null }));
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}
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function waitForFile(stream, callback) {
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if (stream.s.file) {
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return callback();
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}
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if (!stream.s.init) {
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init(stream);
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stream.s.init = true;
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}
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stream.once('file', () => {
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callback();
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});
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}
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function handleStartOption(stream, doc, options) {
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if (options && options.start != null) {
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if (options.start > doc.length) {
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throw new error_1.MongoInvalidArgumentError(`Stream start (${options.start}) must not be more than the length of the file (${doc.length})`);
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}
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if (options.start < 0) {
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throw new error_1.MongoInvalidArgumentError(`Stream start (${options.start}) must not be negative`);
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}
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if (options.end != null && options.end < options.start) {
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throw new error_1.MongoInvalidArgumentError(`Stream start (${options.start}) must not be greater than stream end (${options.end})`);
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}
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stream.s.bytesRead = Math.floor(options.start / doc.chunkSize) * doc.chunkSize;
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stream.s.expected = Math.floor(options.start / doc.chunkSize);
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return options.start - stream.s.bytesRead;
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}
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throw new error_1.MongoInvalidArgumentError('Start option must be defined');
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}
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function handleEndOption(stream, doc, cursor, options) {
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if (options && options.end != null) {
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if (options.end > doc.length) {
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throw new error_1.MongoInvalidArgumentError(`Stream end (${options.end}) must not be more than the length of the file (${doc.length})`);
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}
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if (options.start == null || options.start < 0) {
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throw new error_1.MongoInvalidArgumentError(`Stream end (${options.end}) must not be negative`);
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}
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const start = options.start != null ? Math.floor(options.start / doc.chunkSize) : 0;
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cursor.limit(Math.ceil(options.end / doc.chunkSize) - start);
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stream.s.expectedEnd = Math.ceil(options.end / doc.chunkSize);
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return Math.ceil(options.end / doc.chunkSize) * doc.chunkSize - options.end;
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}
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throw new error_1.MongoInvalidArgumentError('End option must be defined');
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}
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//# sourceMappingURL=download.js.map
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