dendrite/internal/mutex.go

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package internal
import "sync"
type MutexByRoom struct {
mu *sync.Mutex // protects the map
roomToMu map[string]*sync.Mutex
}
func NewMutexByRoom() *MutexByRoom {
return &MutexByRoom{
mu: &sync.Mutex{},
roomToMu: make(map[string]*sync.Mutex),
}
}
func (m *MutexByRoom) Lock(roomID string) {
m.mu.Lock()
roomMu := m.roomToMu[roomID]
if roomMu == nil {
roomMu = &sync.Mutex{}
}
m.roomToMu[roomID] = roomMu
m.mu.Unlock()
// don't lock inside m.mu else we can deadlock
roomMu.Lock()
}
func (m *MutexByRoom) Unlock(roomID string) {
m.mu.Lock()
roomMu := m.roomToMu[roomID]
if roomMu == nil {
panic("MutexByRoom: Unlock before Lock")
}
m.mu.Unlock()
roomMu.Unlock()
}