51 lines
1.3 KiB
Go
51 lines
1.3 KiB
Go
package cryptocore
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import (
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"bytes"
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"log"
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"sync"
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)
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/*
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Number of bytes to prefetch.
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512 looks like a good compromise between throughput and latency:
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Benchmark16-2 3000000 567 ns/op 28.18 MB/s
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Benchmark64-2 5000000 293 ns/op 54.51 MB/s
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Benchmark128-2 10000000 220 ns/op 72.48 MB/s
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Benchmark256-2 10000000 210 ns/op 76.17 MB/s
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Benchmark512-2 10000000 191 ns/op 83.75 MB/s
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Benchmark1024-2 10000000 171 ns/op 93.48 MB/s
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Benchmark2048-2 10000000 165 ns/op 96.45 MB/s
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Benchmark4096-2 10000000 165 ns/op 96.58 MB/s
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Benchmark40960-2 10000000 147 ns/op 108.82 MB/s
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*/
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const prefetchN = 512
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type randPrefetcherT struct {
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sync.Mutex
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buf bytes.Buffer
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}
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func (r *randPrefetcherT) read(want int) (out []byte) {
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out = make([]byte, want)
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r.Lock()
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// Note: don't use defer, it slows us down!
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have, err := r.buf.Read(out)
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if have == want && err == nil {
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r.Unlock()
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return out
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}
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// Buffer was empty -> re-fill
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r.buf.Reset()
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r.buf.Write(RandBytes(prefetchN))
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have, err = r.buf.Read(out)
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if have != want || err != nil {
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log.Panicf("randPrefetcher could not satisfy read: have=%d want=%d err=%v", have, want, err)
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}
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r.Unlock()
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return out
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}
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var randPrefetcher randPrefetcherT
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