b6a95a8cb3
* Dropped unused codekit config * Integrated dynamic and static bindata for public * Ignore public bindata * Add a general generate make task * Integrated flexible public assets into web command * Updated vendoring, added all missiong govendor deps * Made the linter happy with the bindata and dynamic code * Moved public bindata definition to modules directory * Ignoring the new bindata path now * Updated to the new public modules import path * Updated public bindata command and drop the new prefix
138 lines
3.4 KiB
Go
138 lines
3.4 KiB
Go
package uuid
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/****************
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* Date: 14/02/14
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* Time: 7:43 PM
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***************/
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import (
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"bytes"
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"log"
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seed "math/rand"
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"net"
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"sync"
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)
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// **************************************************** State
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func SetupCustomStateSaver(pSaver StateSaver) {
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state.Lock()
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pSaver.Init(&state)
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state.init()
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state.Unlock()
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}
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// Holds package information about the current
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// state of the UUID generator
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type State struct {
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// A flag which informs whether to
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// randomly create a node id
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randomNode bool
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// A flag which informs whether to
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// randomly create the sequence
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randomSequence bool
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// the last time UUID was saved
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past Timestamp
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// the next time the state will be saved
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next Timestamp
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// the last node which saved a UUID
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node []byte
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// An iterated value to help ensure different
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// values across the same domain
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sequence uint16
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sync.Mutex
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// save state interface
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saver StateSaver
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}
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// Changes the state with current data
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// Compares the current found node to the last node stored,
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// If they are the same or randomSequence is already set due
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// to an earlier read issue then the sequence is randomly generated
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// else if there is an issue with the time the sequence is incremented
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func (o *State) read(pNow Timestamp, pNode net.HardwareAddr) {
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if bytes.Equal([]byte(pNode), o.node) || o.randomSequence {
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o.sequence = uint16(seed.Int()) & 0x3FFF
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} else if pNow < o.past {
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o.sequence++
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}
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o.past = pNow
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o.node = pNode
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}
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func (o *State) persist() {
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if o.saver != nil {
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o.saver.Save(o)
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}
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}
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// Initialises the UUID state when the package is first loaded
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// it first attempts to decode the file state into State
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// if this file does not exist it will create the file and do a flush
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// of the random state which gets loaded at package runtime
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// second it will attempt to resolve the current hardware address nodeId
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// thirdly it will check the state of the clock
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func (o *State) init() {
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if o.saver != nil {
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intfcs, err := net.Interfaces()
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if err != nil {
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log.Println("uuid.State.init: address error: will generate random node id instead", err)
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return
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}
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a := getHardwareAddress(intfcs)
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if a == nil {
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log.Println("uuid.State.init: address error: will generate random node id instead", err)
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return
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}
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// Don't use random as we have a real address
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o.randomSequence = false
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if bytes.Equal([]byte(a), state.node) {
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state.sequence++
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}
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state.node = a
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state.randomNode = false
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}
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}
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func getHardwareAddress(pInterfaces []net.Interface) net.HardwareAddr {
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for _, inter := range pInterfaces {
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// Initially I could multicast out the Flags to get
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// whether the interface was up but started failing
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if (inter.Flags & (1 << net.FlagUp)) != 0 {
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//if inter.Flags.String() != "0" {
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if addrs, err := inter.Addrs(); err == nil {
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for _, addr := range addrs {
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if addr.String() != "0.0.0.0" && !bytes.Equal([]byte(inter.HardwareAddr), make([]byte, len(inter.HardwareAddr))) {
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return inter.HardwareAddr
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}
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}
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}
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}
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}
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return nil
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}
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// *********************************************** StateSaver interface
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// Use this interface to setup a custom state saver if you wish to have
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// v1 UUIDs based on your node id and constant time.
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type StateSaver interface {
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// Init is run if Setup() is false
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// Init should setup the system to save the state
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Init(*State)
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// Save saves the state and is called only if const V1Save and
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// Setup() is true
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Save(*State)
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}
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