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50 lines
1.3 KiB
50 lines
1.3 KiB
'use strict';
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var optional = require('optional');
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var async = require('async');
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var snappy = optional('snappy');
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if (snappy == null) {
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var unavailableCodec = function unavailableCodec () {
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throw new Error('Snappy codec is not installed');
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};
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module.exports = {
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encode: unavailableCodec,
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decode: unavailableCodec
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};
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} else {
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var SNAPPY_MAGIC_BYTES = [130, 83, 78, 65, 80, 80, 89, 0];
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var SNAPPY_MAGIC_BYTES_LEN = SNAPPY_MAGIC_BYTES.length;
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var SNAPPY_MAGIC = Buffer.from(SNAPPY_MAGIC_BYTES).toString('hex');
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exports.encode = snappy.compress;
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exports.decode = decodeSnappy;
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}
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function isChunked (buffer) {
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var prefix = buffer.toString('hex', 0, SNAPPY_MAGIC_BYTES_LEN);
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return prefix === SNAPPY_MAGIC;
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}
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// Ported from:
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// https://github.com/Shopify/sarama/blob/a3e2437d6d26cda6b2dc501dbdab4d3f6befa295/snappy.go
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function decodeSnappy (buffer, cb) {
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if (isChunked(buffer)) {
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var pos = 16;
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var max = buffer.length;
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var encoded = [];
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var size;
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while (pos < max) {
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size = buffer.readUInt32BE(pos);
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pos += 4;
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encoded.push(buffer.slice(pos, pos + size));
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pos += size;
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}
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return async.mapSeries(encoded, snappy.uncompress, function (err, decodedChunks) {
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if (err) return cb(err);
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return cb(null, Buffer.concat(decodedChunks));
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});
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}
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return snappy.uncompress(buffer, cb);
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}
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