Add vendoring

vendor/github.com/valyala/fastrand/README.md

@@ -0,0 +1,76 @@
+[![Build Status](https://travis-ci.org/valyala/fastrand.svg)](https://travis-ci.org/valyala/fastrand)
+[![GoDoc](https://godoc.org/github.com/valyala/fastrand?status.svg)](http://godoc.org/github.com/valyala/fastrand)
+[![Go Report](https://goreportcard.com/badge/github.com/valyala/fastrand)](https://goreportcard.com/report/github.com/valyala/fastrand)
+
+
+# fastrand
+
+Fast pseudorandom number generator.
+
+
+# Features
+
+- Optimized for speed.
+- Performance scales on multiple CPUs.
+
+# How does it work?
+
+It abuses [sync.Pool](https://golang.org/pkg/sync/#Pool) for maintaining
+"per-CPU" pseudorandom number generators.
+
+TODO: firgure out how to use real per-CPU pseudorandom number generators.
+
+
+# Benchmark results
+
+
+```
+$ GOMAXPROCS=1 go test -bench=. github.com/valyala/fastrand
+goos: linux
+goarch: amd64
+pkg: github.com/valyala/fastrand
+BenchmarkUint32n                   	50000000	        29.7 ns/op
+BenchmarkRNGUint32n                	200000000	         6.50 ns/op
+BenchmarkRNGUint32nWithLock        	100000000	        21.5 ns/op
+BenchmarkMathRandInt31n            	50000000	        31.8 ns/op
+BenchmarkMathRandRNGInt31n         	100000000	        17.9 ns/op
+BenchmarkMathRandRNGInt31nWithLock 	50000000	        30.2 ns/op
+PASS
+ok  	github.com/valyala/fastrand	10.634s
+```
+
+```
+$ GOMAXPROCS=2 go test -bench=. github.com/valyala/fastrand
+goos: linux
+goarch: amd64
+pkg: github.com/valyala/fastrand
+BenchmarkUint32n-2                     	100000000	        17.6 ns/op
+BenchmarkRNGUint32n-2                  	500000000	         3.36 ns/op
+BenchmarkRNGUint32nWithLock-2          	50000000	        32.0 ns/op
+BenchmarkMathRandInt31n-2              	20000000	        51.2 ns/op
+BenchmarkMathRandRNGInt31n-2           	100000000	        11.0 ns/op
+BenchmarkMathRandRNGInt31nWithLock-2   	20000000	        91.0 ns/op
+PASS
+ok  	github.com/valyala/fastrand	9.543s
+```
+
+```
+$ GOMAXPROCS=4 go test -bench=. github.com/valyala/fastrand
+goos: linux
+goarch: amd64
+pkg: github.com/valyala/fastrand
+BenchmarkUint32n-4                     	100000000	        14.2 ns/op
+BenchmarkRNGUint32n-4                  	500000000	         3.30 ns/op
+BenchmarkRNGUint32nWithLock-4          	20000000	        88.7 ns/op
+BenchmarkMathRandInt31n-4              	10000000	       145 ns/op
+BenchmarkMathRandRNGInt31n-4           	200000000	         8.35 ns/op
+BenchmarkMathRandRNGInt31nWithLock-4   	20000000	       102 ns/op
+PASS
+ok  	github.com/valyala/fastrand	11.534s
+```
+
+As you can see, [fastrand.Uint32n](https://godoc.org/github.com/valyala/fastrand#Uint32n)
+scales on multiple CPUs, while [rand.Int31n](https://golang.org/pkg/math/rand/#Int31n)
+doesn't scale. Their performance is comparable on `GOMAXPROCS=1`,
+but `fastrand.Uint32n` runs 3x faster than `rand.Int31n` on `GOMAXPROCS=2`
+and 10x faster than `rand.Int31n` on `GOMAXPROCS=4`.