package sync

import (
	"sync"
	"amuz.es/src/infra/goutils/runtime"
	"sync/atomic"
	"fmt"
)

type ReentrantMutex struct {
	lock      sync.Mutex
	owner     int64 // current lock owner
	recursion int64 //current recursion level
}

func (r *ReentrantMutex) Lock() {
	caller := runtime.GOID()
	// fast path
	if atomic.LoadInt64(&r.owner) == caller {
		r.recursion++
		return
	}

	r.lock.Lock()
	// we are now inside the lock
	atomic.StoreInt64(&r.owner, caller)
	r.recursion = 1
}

func (r *ReentrantMutex) Unlock() {
	caller := runtime.GOID()
	if atomic.LoadInt64(&r.owner) != caller {
		panic(fmt.Sprintf("you are not the owner(%d): %d!", r.owner, caller))
	}

	r.recursion--
	// fast path
	if r.recursion != 0 {
		return
	}

	// we are going to release the lock
	atomic.StoreInt64(&r.owner, 0)
	r.lock.Unlock()
}