Added LeaseId property to expose fencing token

src/DotNext.Tests/Threading/Leases/LeaseTests.cs

@@ -90,7 +90,8 @@ public static async Task ConsumerTokenState()
         True(consumer.Token.IsCancellationRequested);
         True(consumer.Expiration.IsExpired);
 
-        True((await consumer.TryAcquireAsync()));
+        True(await consumer.TryAcquireAsync());
+        Equal(1UL, consumer.LeaseId.Version);
         False(consumer.Token.IsCancellationRequested);
         False(consumer.Expiration.IsExpired);
 

src/DotNext.Threading/Threading/Leases/LeaseConsumer.cs

@@ -78,6 +78,12 @@ private TimeSpan AdjustTimeToLive(TimeSpan originalTtl)
     /// Gets lease expiration timeout.
     /// </summary>
     public ref readonly Timeout Expiration => ref timeout;
+
+    /// <summary>
+    /// Gets the lease version.
+    /// </summary>
+    /// <remarks>The returned value can be used as a fencing token.</remarks>
+    public LeaseIdentity LeaseId => identity;
 
     private ValueTask CancelAndStopTimerAsync()
     {
@@ -181,7 +187,7 @@ public async Task<TResult> ExecuteAsync<TResult>(Func<CancellationToken, Task<TR
         var leaseToken = Token;
         var operationToken = token;
         var cts = operationToken.LinkTo(leaseToken);
-        
+
         var task = Fork(worker, operationToken);
         try
         {
@@ -216,10 +222,10 @@ public async Task<TResult> ExecuteAsync<TResult>(Func<CancellationToken, Task<TR
         {
             cts?.Dispose();
         }
-    }
 
-    private static Task<TResult> Fork<TResult>(Func<CancellationToken, Task<TResult>> function, CancellationToken token)
-        => Task.Run(() => function(token), token);
+        static Task<TResult> Fork(Func<CancellationToken, Task<TResult>> function, CancellationToken token)
+            => Task.Run(() => function(token), token);
+    }
 
     /// <summary>
     /// Performs a call to <see cref="LeaseProvider{TMetadata}.TryAcquireAsync(CancellationToken)"/> across the application boundaries.