200 lines
3.1 KiB
Go
200 lines
3.1 KiB
Go
package sync
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import (
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gosync "sync"
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"time"
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)
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type memorySync struct {
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options Options
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locks map[string]*memoryLock
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mtx gosync.RWMutex
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}
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type memoryLock struct {
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time time.Time
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release chan bool
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id string
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ttl time.Duration
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}
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type memoryLeader struct {
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opts LeaderOptions
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resign func(id string) error
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status chan bool
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id string
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}
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func (m *memoryLeader) Resign() error {
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return m.resign(m.id)
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}
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func (m *memoryLeader) Status() chan bool {
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return m.status
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}
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func (m *memorySync) Leader(id string, opts ...LeaderOption) (Leader, error) {
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var once gosync.Once
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var options LeaderOptions
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for _, o := range opts {
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o(&options)
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}
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// acquire a lock for the id
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if err := m.Lock(id); err != nil {
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return nil, err
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}
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// return the leader
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return &memoryLeader{
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opts: options,
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id: id,
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resign: func(id string) error {
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once.Do(func() {
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m.Unlock(id)
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})
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return nil
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},
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// TODO: signal when Unlock is called
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status: make(chan bool, 1),
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}, nil
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}
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func (m *memorySync) Init(opts ...Option) error {
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for _, o := range opts {
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o(&m.options)
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}
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return nil
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}
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func (m *memorySync) Options() Options {
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return m.options
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}
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func (m *memorySync) Lock(id string, opts ...LockOption) error {
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// lock our access
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m.mtx.Lock()
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var options LockOptions
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for _, o := range opts {
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o(&options)
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}
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lk, ok := m.locks[id]
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if !ok {
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m.locks[id] = &memoryLock{
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id: id,
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time: time.Now(),
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ttl: options.TTL,
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release: make(chan bool),
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}
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// unlock
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m.mtx.Unlock()
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return nil
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}
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m.mtx.Unlock()
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// set wait time
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var wait <-chan time.Time
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var ttl <-chan time.Time
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// decide if we should wait
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if options.Wait > time.Duration(0) {
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wait = time.After(options.Wait)
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}
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// check the ttl of the lock
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if lk.ttl > time.Duration(0) {
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// time lived for the lock
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live := time.Since(lk.time)
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// set a timer for the leftover ttl
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if live > lk.ttl {
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// release the lock if it expired
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_ = m.Unlock(id)
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} else {
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ttl = time.After(live)
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}
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}
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lockLoop:
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for {
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// wait for the lock to be released
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select {
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case <-lk.release:
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m.mtx.Lock()
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// someone locked before us
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lk, ok = m.locks[id]
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if ok {
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m.mtx.Unlock()
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continue
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}
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// got chance to lock
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m.locks[id] = &memoryLock{
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id: id,
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time: time.Now(),
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ttl: options.TTL,
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release: make(chan bool),
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}
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m.mtx.Unlock()
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break lockLoop
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case <-ttl:
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// ttl exceeded
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_ = m.Unlock(id)
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// TODO: check the ttl again above
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ttl = nil
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// try acquire
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continue
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case <-wait:
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return ErrLockTimeout
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}
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}
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return nil
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}
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func (m *memorySync) Unlock(id string) error {
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m.mtx.Lock()
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defer m.mtx.Unlock()
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lk, ok := m.locks[id]
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// no lock exists
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if !ok {
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return nil
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}
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// delete the lock
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delete(m.locks, id)
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select {
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case <-lk.release:
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return nil
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default:
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close(lk.release)
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}
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return nil
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}
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func (m *memorySync) String() string {
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return "memory"
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}
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// NewSync return new memory sync
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func NewSync(opts ...Option) Sync {
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options := Options{}
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for _, o := range opts {
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o(&options)
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}
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return &memorySync{
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options: options,
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locks: make(map[string]*memoryLock),
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}
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}
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