move all files to common/ to begin repo merge

common/random.go

@@ -0,0 +1,138 @@
+package common
+
+import (
+	crand "crypto/rand"
+	"math/rand"
+	"time"
+)
+
+const (
+	strChars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz" // 62 characters
+)
+
+func init() {
+	b := cRandBytes(8)
+	var seed uint64
+	for i := 0; i < 8; i++ {
+		seed |= uint64(b[i])
+		seed <<= 8
+	}
+	rand.Seed(int64(seed))
+}
+
+// Constructs an alphanumeric string of given length.
+func RandStr(length int) string {
+	chars := []byte{}
+MAIN_LOOP:
+	for {
+		val := rand.Int63()
+		for i := 0; i < 10; i++ {
+			v := int(val & 0x3f) // rightmost 6 bits
+			if v >= 62 {         // only 62 characters in strChars
+				val >>= 6
+				continue
+			} else {
+				chars = append(chars, strChars[v])
+				if len(chars) == length {
+					break MAIN_LOOP
+				}
+				val >>= 6
+			}
+		}
+	}
+
+	return string(chars)
+}
+
+func RandUint16() uint16 {
+	return uint16(rand.Uint32() & (1<<16 - 1))
+}
+
+func RandUint32() uint32 {
+	return rand.Uint32()
+}
+
+func RandUint64() uint64 {
+	return uint64(rand.Uint32())<<32 + uint64(rand.Uint32())
+}
+
+func RandUint() uint {
+	return uint(rand.Int())
+}
+
+func RandInt16() int16 {
+	return int16(rand.Uint32() & (1<<16 - 1))
+}
+
+func RandInt32() int32 {
+	return int32(rand.Uint32())
+}
+
+func RandInt64() int64 {
+	return int64(rand.Uint32())<<32 + int64(rand.Uint32())
+}
+
+func RandInt() int {
+	return rand.Int()
+}
+
+// Distributed pseudo-exponentially to test for various cases
+func RandUint16Exp() uint16 {
+	bits := rand.Uint32() % 16
+	if bits == 0 {
+		return 0
+	}
+	n := uint16(1 << (bits - 1))
+	n += uint16(rand.Int31()) & ((1 << (bits - 1)) - 1)
+	return n
+}
+
+// Distributed pseudo-exponentially to test for various cases
+func RandUint32Exp() uint32 {
+	bits := rand.Uint32() % 32
+	if bits == 0 {
+		return 0
+	}
+	n := uint32(1 << (bits - 1))
+	n += uint32(rand.Int31()) & ((1 << (bits - 1)) - 1)
+	return n
+}
+
+// Distributed pseudo-exponentially to test for various cases
+func RandUint64Exp() uint64 {
+	bits := rand.Uint32() % 64
+	if bits == 0 {
+		return 0
+	}
+	n := uint64(1 << (bits - 1))
+	n += uint64(rand.Int63()) & ((1 << (bits - 1)) - 1)
+	return n
+}
+
+func RandFloat32() float32 {
+	return rand.Float32()
+}
+
+func RandTime() time.Time {
+	return time.Unix(int64(RandUint64Exp()), 0)
+}
+
+func RandBytes(n int) []byte {
+	bs := make([]byte, n)
+	for i := 0; i < n; i++ {
+		bs[i] = byte(rand.Intn(256))
+	}
+	return bs
+}
+
+// NOTE: This relies on the os's random number generator.
+// For real security, we should salt that with some seed.
+// See github.com/tendermint/go-crypto for a more secure reader.
+func cRandBytes(numBytes int) []byte {
+	b := make([]byte, numBytes)
+	_, err := crand.Read(b)
+	if err != nil {
+		PanicCrisis(err)
+	}
+	return b
+}