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| 'use strict';
|
| const Snappy = require('../connection/utils').retrieveSnappy();
| const zlib = require('zlib');
|
| const compressorIDs = {
| snappy: 1,
| zlib: 2
| };
|
| const uncompressibleCommands = new Set([
| 'ismaster',
| 'saslStart',
| 'saslContinue',
| 'getnonce',
| 'authenticate',
| 'createUser',
| 'updateUser',
| 'copydbSaslStart',
| 'copydbgetnonce',
| 'copydb'
| ]);
|
| // Facilitate compressing a message using an agreed compressor
| function compress(self, dataToBeCompressed, callback) {
| switch (self.options.agreedCompressor) {
| case 'snappy':
| Snappy.compress(dataToBeCompressed, callback);
| break;
| case 'zlib':
| // Determine zlibCompressionLevel
| var zlibOptions = {};
| if (self.options.zlibCompressionLevel) {
| zlibOptions.level = self.options.zlibCompressionLevel;
| }
| zlib.deflate(dataToBeCompressed, zlibOptions, callback);
| break;
| default:
| throw new Error(
| 'Attempt to compress message using unknown compressor "' +
| self.options.agreedCompressor +
| '".'
| );
| }
| }
|
| // Decompress a message using the given compressor
| function decompress(compressorID, compressedData, callback) {
| if (compressorID < 0 || compressorID > compressorIDs.length) {
| throw new Error(
| 'Server sent message compressed using an unsupported compressor. (Received compressor ID ' +
| compressorID +
| ')'
| );
| }
| switch (compressorID) {
| case compressorIDs.snappy:
| Snappy.uncompress(compressedData, callback);
| break;
| case compressorIDs.zlib:
| zlib.inflate(compressedData, callback);
| break;
| default:
| callback(null, compressedData);
| }
| }
|
| module.exports = {
| compressorIDs,
| uncompressibleCommands,
| compress,
| decompress
| };
|
|
