This repository has been archived by the owner on Feb 4, 2022. It is now read-only.
-
Notifications
You must be signed in to change notification settings - Fork 108
/
compression.js
64 lines (58 loc) · 1.71 KB
/
compression.js
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
var Snappy = require('../connection/utils').retrieveSnappy(),
zlib = require('zlib');
var compressorIDs = {
snappy: 1,
zlib: 2
}
var uncompressibleCommands = [
'ismaster',
'saslStart',
'saslContinue',
'getnonce',
'authenticate',
'createUser',
'updateUser',
'copydbSaslStart',
'copydbgetnonce',
'copydb'
];
// Facilitate compressing a message using an agreed compressor
var compress = function(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
var decompress = function(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: compressorIDs,
uncompressibleCommands: uncompressibleCommands,
compress: compress,
decompress: decompress
}