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Perf: cache iconv decoder #2391

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merged 3 commits into from
Jan 23, 2024
Merged

Perf: cache iconv decoder #2391

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93c1fac
Cache with Map.
sandinmyjoints Jan 22, 2024
5f4ed84
Cache with lru-cache.
sandinmyjoints Jan 22, 2024
15eec77
Require default explicitly.
sandinmyjoints Jan 23, 2024
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27 changes: 24 additions & 3 deletions lib/parsers/string.js
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Original file line number Diff line number Diff line change
@@ -1,21 +1,42 @@
'use strict';

const Iconv = require('iconv-lite');
const LRU = require('lru-cache');

exports.decode = function(buffer, encoding, start, end, options) {
const decoderCache = new LRU({
max: 500,
});

exports.decode = function (buffer, encoding, start, end, options) {
if (Buffer.isEncoding(encoding)) {
return buffer.toString(encoding, start, end);
}

const decoder = Iconv.getDecoder(encoding, options || {});
// Optimize for common case: encoding="short_string", options=undefined.
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@sandinmyjoints sandinmyjoints Jan 22, 2024 •
edited
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I figure encoding is probably constant for most users. For my use case, it's always "cesu8" (for utf8mb3).

let decoder;
if (!options) {
decoder = decoderCache.get(encoding);
if (!decoder) {
decoder = Iconv.getDecoder(encoding);
decoderCache.set(encoding, decoder);
}
} else {
const decoderArgs = { encoding, options };
const decoderKey = JSON.stringify(decoderArgs);
decoder = decoderCache.get(decoderKey);
if (!decoder) {
decoder = Iconv.getDecoder(decoderArgs.encoding, decoderArgs.options);
decoderCache.set(decoderKey, decoder);
}
}

const res = decoder.write(buffer.slice(start, end));
const trail = decoder.end();

return trail ? res + trail : res;
};

exports.encode = function(string, encoding, options) {
exports.encode = function (string, encoding, options) {
if (Buffer.isEncoding(encoding)) {
return Buffer.from(string, encoding);
}
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