diff options
Diffstat (limited to 'uuid.go')
| -rw-r--r-- | uuid.go | 39 |
1 files changed, 38 insertions, 1 deletions
@@ -12,6 +12,7 @@ import ( "fmt" "io" "strings" + "sync" ) // A UUID is a 128 bit (16 byte) Universal Unique IDentifier as defined in RFC @@ -33,7 +34,15 @@ const ( Future // Reserved for future definition. ) -var rander = rand.Reader // random function +const randPoolSize = 16 * 16 + +var ( + rander = rand.Reader // random function + poolEnabled = false + poolMu sync.Mutex + poolPos = randPoolSize // protected with poolMu + pool [randPoolSize]byte // protected with poolMu +) type invalidLengthError struct{ len int } @@ -255,3 +264,31 @@ func SetRand(r io.Reader) { } rander = r } + +// EnableRandPool enables internal randomness pool used for Random +// (Version 4) UUID generation. The pool contains random bytes read from +// the random number generator on demand in batches. Enabling the pool +// may improve the UUID generation throughput significantly. +// +// Since the pool is stored on the Go heap, this feature may be a bad fit +// for security sensitive applications. +// +// Both EnableRandPool and DisableRandPool are not thread-safe and should +// only be called when there is no possibility that New or any other +// UUID Version 4 generation function will be called concurrently. +func EnableRandPool() { + poolEnabled = true +} + +// DisableRandPool disables the randomness pool if it was previously +// enabled with EnableRandPool. +// +// Both EnableRandPool and DisableRandPool are not thread-safe and should +// only be called when there is no possibility that New or any other +// UUID Version 4 generation function will be called concurrently. +func DisableRandPool() { + poolEnabled = false + defer poolMu.Unlock() + poolMu.Lock() + poolPos = randPoolSize +} |