阻塞lock的基本流程
if(cas(0,acquire))
setExclusiveOwnerThread
else if(current==getExclusiveOnwerThread) {
setState(c+acquires)
}
addWaiter
park
........................
for(;;) {
p = node.predecessorif(p==head&&tryAcquire(arg)){
setHead(node)return
}park
}
阻塞release的基本流程
if(current!=getExclusiveOnwerThread){
IllegalMonitorStateException
}
if(c == 0){
setExclusive(null)
free = true
}
setState(c)
return free
unparkSuccessor(LockSupport.unpark(thread))
非阻塞lock的基本流程
if(cas(0,acquire))
setExclusiveOwnerThread true
else if(current==getExclusiveOwnerThread)
setState(c+acquire) true
false
非阻塞的release的基本流程
與阻塞的release流程相同
阻塞共享lock的基本流程
tryAcquireShared(acquires){
for(;;) {
remaining = state-acquires
if(remaining<0 || CAS(state,remaining))
return remaining
}
}
if(tryAcquireShared(arg)<0){
node = addWaiter(Node.SHARED)
for(;;) {
p = node.predecessorpropagate = tryAcquireShared(arg)if(p==head&&propagate>=0){
setHead(node)if(propagate>0||next==null||next.isShared())//如果還有剩餘,繼續喚醒接下來一個節點doReleaseShared()return
}park
}
}
阻塞共享release的基本流程
tryReleaseShared(acquires){
for(;;){if(cas(state,state+acquires))return true}
}
if(tryReleaseShared(acquires)) {
unparkSuccessor(h)
}
共享lock的基本模式
覆蓋tryAcquireShared方法
for(;;) {
if(state-acquire<0) {
false
}
if(cas(state,state-acquires)) {
true
}
}
共享lock的release的基本模式
覆蓋tryReleaseShared方法
for(;;) {
if(cas(state,state+acquires)) {
true
}
}
排它lock的基本模式
覆蓋tryAcquire方法
if(state==0) {
if(cas(state, state+acquire)) {
setExclusiveOwnerThread(current)
return true
}
} else if(current==getExclusiveOwnerThread) {
if(cas(state, state+acquire)) {
return true
}
}
return flase
排它lock的release基本模式
覆蓋tryRelease方法
if(current != getExclusiveThread) {
throw new IllegalMonitorStateException()
}
nextc = state-release
if(nextc == 0) {
setState(nextc)
setExclusiveOwnerThread(current)
return true
} else {
setState(nextc)
return false
}