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Alan Shaw
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May 4, 2019
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,70 +1,35 @@ | ||
| 'use strict' | ||
|
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| const Buffer = require('safe-buffer').Buffer | ||
| const Varint = require('varint') | ||
| const BufferList = require('bl') | ||
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| module.exports = encode | ||
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| const poolSize = 10 * 1024 | ||
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| function encode (opts) { | ||
| opts = Object.assign({ | ||
| fixed: false | ||
| }, opts || {}) | ||
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| // Only needed for varint | ||
| const varint = require('varint') | ||
| let pool = opts.fixed ? null : createPool() | ||
| let used = 0 | ||
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| let ended = false | ||
| let first = true | ||
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| return (read) => (end, cb) => { | ||
| if (end) ended = end | ||
| if (ended) return cb(ended) | ||
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| read(null, (end, data) => { | ||
| if (end) ended = end | ||
| if (ended && !first) { | ||
| return cb(ended) | ||
| } | ||
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| first = false | ||
| const MIN_POOL_SIZE = 147 // Varint.encode(Number.MAX_VALUE).length | ||
| const DEFAULT_POOL_SIZE = 10 * 1024 | ||
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| if (!ended && !Buffer.isBuffer(data)) { | ||
| ended = new Error('data must be a buffer') | ||
| return cb(ended) | ||
| } | ||
| function encode (options) { | ||
| options = options || {} | ||
| options.poolSize = Math.max(options.poolSize || DEFAULT_POOL_SIZE, MIN_POOL_SIZE) | ||
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| const dataLength = ended ? 0 : data.length | ||
| return source => (async function * () { | ||
| let pool = Buffer.alloc(options.poolSize) | ||
| let poolOffset = 0 | ||
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| let encodedLength | ||
| if (opts.fixed) { | ||
| encodedLength = Buffer.alloc(4) | ||
| encodedLength.writeInt32BE(dataLength, 0) // writes exactly 4 bytes | ||
| } else { | ||
| varint.encode(dataLength, pool, used) | ||
| used += varint.encode.bytes | ||
| encodedLength = pool.slice(used - varint.encode.bytes, used) | ||
| for await (const chunk of source) { | ||
| Varint.encode(chunk.length, pool, poolOffset) | ||
| poolOffset += Varint.encode.bytes | ||
| const encodedLength = pool.slice(poolOffset - Varint.encode.bytes, poolOffset) | ||
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| if (pool.length - used < 100) { | ||
| pool = createPool() | ||
| used = 0 | ||
| } | ||
| if (pool.length - poolOffset < MIN_POOL_SIZE) { | ||
| pool = Buffer.alloc(options.poolSize) | ||
| poolOffset = 0 | ||
| } | ||
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| if (ended) { | ||
| return cb(null, encodedLength) | ||
| } | ||
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| cb(null, Buffer.concat([ | ||
| encodedLength, | ||
| data | ||
| ], (opts.fixed ? 4 : varint.encode.bytes) + dataLength)) | ||
| }) | ||
| } | ||
| yield new BufferList().append(encodedLength).append(chunk) | ||
| // yield Buffer.concat([encodedLength, chunk]) | ||
| } | ||
| })() | ||
| } | ||
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| function createPool () { | ||
| return Buffer.alloc(poolSize) | ||
| } | ||
| module.exports = encode | ||
| module.exports.MIN_POOL_SIZE = MIN_POOL_SIZE | ||
| module.exports.DEFAULT_POOL_SIZE = DEFAULT_POOL_SIZE |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,52 @@ | ||
| /* eslint-env mocha */ | ||
| 'use strict' | ||
|
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| const pipe = require('it-pipe') | ||
| const { expect } = require('chai') | ||
| const randomInt = require('random-int') | ||
| const randomBytes = require('random-bytes') | ||
| const { map, collect } = require('streaming-iterables') | ||
| const Varint = require('varint') | ||
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| const lp = require('../') | ||
| const { MIN_POOL_SIZE } = lp.encode | ||
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| const times = (n, fn) => Array.from(Array(n), fn) | ||
| const someBytes = n => randomBytes(randomInt(1, n || 32)) | ||
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| describe('encode', () => { | ||
| it('should encode length as prefix', async () => { | ||
| const input = await Promise.all(times(randomInt(1, 10), someBytes)) | ||
| const output = await pipe(input, lp.encode(), map(c => c.slice()), collect) | ||
| output.forEach((o, i) => { | ||
| const length = Varint.decode(o) | ||
| expect(length).to.equal(input[i].length) | ||
| expect(o.slice(Varint.decode.bytes)).to.deep.equal(input[i]) | ||
| }) | ||
| }) | ||
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| it('should encode zero length as prefix', async () => { | ||
| const input = [Buffer.alloc(0)] | ||
| const output = await pipe(input, lp.encode(), map(c => c.slice()), collect) | ||
| output.forEach((o, i) => { | ||
| const length = Varint.decode(o) | ||
| expect(length).to.equal(input[i].length) | ||
| expect(o.slice(Varint.decode.bytes)).to.deep.equal(input[i]) | ||
| }) | ||
| }) | ||
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| it('should re-allocate buffer pool when empty', async () => { | ||
| const input = await Promise.all(times(MIN_POOL_SIZE * 2, someBytes)) | ||
| const output = await pipe( | ||
| input, | ||
| lp.encode({ poolSize: MIN_POOL_SIZE * 1.5 }), | ||
| map(c => c.slice()), | ||
| collect | ||
| ) | ||
| output.forEach((o, i) => { | ||
| const length = Varint.decode(o) | ||
| expect(length).to.equal(input[i].length) | ||
| expect(o.slice(Varint.decode.bytes)).to.deep.equal(input[i]) | ||
| }) | ||
| }) | ||
| }) |