public async Task IsEncapsulated()
{
using var s1 = new SemaphoreWrapper(1);
using var s2 = new SemaphoreWrapper(1);
await s1.EnterQueue().OrTimeout();
await s2.EnterQueue().OrTimeout();
}
public async Task WaitsIfNoSpaceAvailible()
{
using var s = new SemaphoreWrapper(1);
await s.EnterQueue().OrTimeout();
var waitingTask = s.EnterQueue();
Assert.False(waitingTask.IsCompleted);
s.LeaveQueue();
await waitingTask.OrTimeout();
}
public async Task TracksQueueLength()
{
using var s = new SemaphoreWrapper(1);
Assert.Equal(1, s.Count);
await s.EnterQueue().OrTimeout();
Assert.Equal(0, s.Count);
s.LeaveQueue();
Assert.Equal(1, s.Count);
}
private void Release(SemaphoreWrapper wrapper)
{
lock (_lock)
{
var isEmpty = wrapper.Release();
if (!isEmpty)
{
return;
}
_wrapperMap.Remove(wrapper.Key);
}
}
public void DoesNotWaitIfSpaceAvailible()
{
using var s = new SemaphoreWrapper(2);
var t1 = s.EnterQueue();
Assert.True(t1.IsCompleted);
var t2 = s.EnterQueue();
Assert.True(t2.IsCompleted);
var t3 = s.EnterQueue();
Assert.False(t3.IsCompleted);
}
public Task <IDisposable> WaitAsync(
string key,
CancellationToken cancelToken = default(CancellationToken))
{
lock (_lock)
{
SemaphoreWrapper wrapper;
if (_wrapperMap.ContainsKey(key))
{
wrapper = _wrapperMap[key];
}
else
{
wrapper = _wrapperMap[key] = new SemaphoreWrapper(Release);
wrapper.Key = key;
}
return(wrapper.WaitAsync(cancelToken));
}
}
public async static Task <T> ExecuteWithFileLocked <T>(string filePath, Func <bool, Task <T> > action)
{
bool completed = false;
while (!completed)
{
var createdNew = false;
using (var fileLock = SemaphoreWrapper.Create(initialCount: 0, maximumCount: 1, name: FilePathToLockName(filePath),
createdNew: out createdNew))
{
try
{
// If this lock is already acquired by another process, wait until we can acquire it
if (!createdNew)
{
var signaled = fileLock.WaitOne(TimeSpan.FromSeconds(5));
if (!signaled)
{
// Timeout and retry
continue;
}
}
completed = true;
return(await action(createdNew));
}
finally
{
if (completed)
{
fileLock.Release();
}
}
}
}
// should never get here
throw new TaskCanceledException($"Failed to acquire semaphore for file: {filePath}");
}
