public virtual PredicateResults GetTheLock(ZooKeeper client, List <string> sortedChildren, string sequenceNodePath, int maxLeases)
{
var sequenceNodeName = ZKPaths.GetNodeFromPath(sequenceNodePath);
var ourIndex = sortedChildren.IndexOf(sequenceNodeName);
if (ourIndex < 0)
{
throw new KeeperException.NoNodeException(sequenceNodePath);
}
var locked = ourIndex < maxLeases;
var nodeToWatch = locked ? null : sortedChildren[ourIndex - maxLeases];
return(new PredicateResults(nodeToWatch, locked));
}
private PredicateResults ReadLockPredicate(List <string> children, string sequenceNodePath)
{
// 已获取写锁可以直接获取读锁
if (_writeLock.IsAcquiredLock())
{
return(new PredicateResults(null, true));
}
int watchWriteIndex = int.MaxValue;
int ourIndex = -1;
var sequenceNodeName = ZKPaths.GetNodeFromPath(sequenceNodePath);
for (int index = 0; index < children.Count; index++)
{
var node = children[index];
// 写锁节点
if (node.Contains(ZookeeperReadWriteLock.WRITE_LOCK_NAME))
{
watchWriteIndex = index;
}
// 当前读锁节点
else if (node == sequenceNodeName)
{
ourIndex = index;
break;
}
}
if (ourIndex < 0)
{
throw new KeeperException.NoNodeException(sequenceNodePath);
}
var locked = (ourIndex < watchWriteIndex);
var pathToWatch = locked ? null : children[watchWriteIndex];
return(new PredicateResults(pathToWatch, locked));
}
/// <summary>
/// 获取一个Lease
/// </summary>
/// <param name="startMs">开始毫秒数</param>
/// <param name="waitMs">等待毫秒数</param>
/// <returns>Lease节点名称</returns>
private async Task <string> InternalAcquireOneLeaseAsync(long startMs, long waitMs)
{
// 获取剩余等待时间
var remainingTime = GetRemainingWaitMs(startMs, waitMs);
if (remainingTime <= 0)
{
new TimeoutException("等待超时");
}
// 获取分布式锁
await _lock.AcquireAsync(remainingTime);
string leasePath;
var success = false;
try
{
// 创建Lease临时有序节点
leasePath = await _zkClient.createAsync(ZKPaths.MakePath(_leasesPath, LEASE_BASE_NAME), null,
ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL);
// 节点名称
var leaseNodeName = ZKPaths.GetNodeFromPath(leasePath);
try
{
while (true)
{
var childrenResult = await _zkClient.getChildrenAsync(_leasesPath, _watcher);
// 找不到刚创建的Lease节点
if (!childrenResult.Children.Contains(leaseNodeName))
{
throw new KeeperException.NoNodeException("Sequential path not found - possible session loss");
}
// 成功获取一个Lease
if (childrenResult.Children.Count <= _maxLeases)
{
break;
}
// 剩余等待时间
remainingTime = GetRemainingWaitMs(startMs, waitMs);
if (remainingTime <= 0)
{
throw new TimeoutException("等待超时");
}
// 等待被唤醒
var result = await _signal.WaitAsync(remainingTime);
if (!result)
{
throw new TimeoutException("等待超时");
}
}
success = true;
}
finally
{
if (!success)
{
await DeleteLease(leasePath);
}
}
}
finally
{
await _lock.ReleaseAsync();
}
return(leasePath);
}
