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moving from uint64 to int64. allows use of snowflakes id in databases

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This commit is contained in:
Colin Henry 2020-07-09 20:02:23 -07:00
parent 852a57d9b3
commit 3991c52689
1 changed files with 21 additions and 20 deletions
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41
snowflake/snowflake.go
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@ -16,30 +16,30 @@ const (
sequenceBits = 12 sequenceBits = 12
// Custom Epoch (January 1, 2015 Midnight UTC = 2015-01-01T00:00:00Z) // Custom Epoch (January 1, 2015 Midnight UTC = 2015-01-01T00:00:00Z)
customEpoch uint64 = 1420070400000 customEpoch int64 = 1420070400000
) )
var maxNodeID uint64 var maxNodeID int64
var maxSequence uint64 var maxSequence int64
var nodeID uint64 var nodeID int64
var lastTimestamp uint64 = 0 var lastTimestamp int64 = 0
var sequence uint64 var sequence int64
func init() { func init() {
maxNodeID = uint64(math.Pow(2, nodeIDBits) - 1) maxNodeID = int64(math.Pow(2, nodeIDBits) - 1)
maxSequence = uint64(math.Pow(2, sequenceBits) - 1) maxSequence = int64(math.Pow(2, sequenceBits) - 1)
nodeID = generateNodeID() nodeID = generateNodeID()
} }
func generateNodeID() uint64 { func generateNodeID() int64 {
var nodeID uint64 var nodeID int64
if interfaces, err := net.Interfaces(); err == nil { if interfaces, err := net.Interfaces(); err == nil {
h := fnv.New32a() h := fnv.New32a()
for _, i := range interfaces { for _, i := range interfaces {
h.Write(i.HardwareAddr) h.Write(i.HardwareAddr)
} }
nodeID = uint64(h.Sum32()) nodeID = int64(h.Sum32())
} else { } else {
panic("interfaces not available") panic("interfaces not available")
} }
@ -51,7 +51,7 @@ var timestampMutex sync.Mutex
var sequenceMutex sync.Mutex var sequenceMutex sync.Mutex
// Next returns the next logical snowflake // Next returns the next logical snowflake
func Next() uint64 { func Next() int64 {
timestampMutex.Lock() timestampMutex.Lock()
currentTimestamp := ts() currentTimestamp := ts()
timestampMutex.Unlock() timestampMutex.Unlock()
@ -69,21 +69,22 @@ func Next() uint64 {
sequenceMutex.Unlock() sequenceMutex.Unlock()
lastTimestamp = currentTimestamp lastTimestamp = currentTimestamp
id := currentTimestamp << (totalBits - epochBits) // id := currentTimestamp << (totalBits - epochBits)
fmt.Printf("%b\n", id) // id |= (nodeID << (totalBits - epochBits - nodeIDBits))
id |= (nodeID << (totalBits - epochBits - nodeIDBits)) // id |= sequence
fmt.Printf("%b\n", id) var id int64 = currentTimestamp << (nodeIDBits + sequenceBits)
id |= (nodeID << sequenceBits)
id |= sequence id |= sequence
fmt.Printf("%b\n", id) fmt.Printf("%b\n", id)
return id return id
} }
func ts() uint64 { func ts() int64 {
return uint64(time.Now().UnixNano()/1000000) - customEpoch return int64(time.Now().UnixNano()/1000000) - customEpoch
} }
func waitNextMillis(currentTimestamp uint64) uint64 { func waitNextMillis(currentTimestamp int64) int64 {
for currentTimestamp == lastTimestamp { for currentTimestamp == lastTimestamp {
currentTimestamp = ts() currentTimestamp = ts()
} }