feat(client): add rendezvous traversal coordinators (#12)

src/FinalFactory.Rendezvous.Client/RendezvousClientAbstractions.cs

@@ -42,6 +42,10 @@ public static class RendezvousClientResult
 
 public sealed class PublishedSession
 {
+    private readonly object _timingGate = new();
+    private DateTimeOffset _expiresAt;
+    private int _leaseRenewAfterSeconds;
+
     internal PublishedSession(RegisterSessionResponse response)
     {
         ListingId = response.ListingId;
@@ -49,8 +53,8 @@ public sealed class PublishedSession
         LeaseToken = response.LeaseToken;
         HostPresenceHandle = response.HostPresenceHandle;
         HostPresenceCapability = response.HostPresenceCapability;
-        ExpiresAt = response.ExpiresAt;
-        LeaseRenewAfterSeconds = response.LeaseRenewAfterSeconds;
+        _expiresAt = response.ExpiresAt;
+        _leaseRenewAfterSeconds = response.LeaseRenewAfterSeconds;
         HostPresenceRefreshAfterSeconds = response.HostPresenceRefreshAfterSeconds;
     }
 
@@ -59,8 +63,41 @@ public sealed class PublishedSession
     public string LeaseToken { get; }
     public MediationHandle HostPresenceHandle { get; }
     public string HostPresenceCapability { get; }
-    public DateTimeOffset ExpiresAt { get; internal set; }
-    public int LeaseRenewAfterSeconds { get; internal set; }
+    public DateTimeOffset ExpiresAt
+    {
+        get
+        {
+            lock (_timingGate)
+            {
+                return _expiresAt;
+            }
+        }
+        internal set
+        {
+            lock (_timingGate)
+            {
+                _expiresAt = value;
+            }
+        }
+    }
+
+    public int LeaseRenewAfterSeconds
+    {
+        get
+        {
+            lock (_timingGate)
+            {
+                return _leaseRenewAfterSeconds;
+            }
+        }
+        internal set
+        {
+            lock (_timingGate)
+            {
+                _leaseRenewAfterSeconds = value;
+            }
+        }
+    }
     public int HostPresenceRefreshAfterSeconds { get; }
 
     public override string ToString() => $"[PublishedSession {ListingId}; credentials redacted]";
@@ -109,6 +146,28 @@ public interface IRendezvousSessionBrowserClient
         CancellationToken cancellationToken = default);
 }
 
+public interface IRendezvousJoinClient
+{
+    Task<RendezvousClientResult<CreateJoinAttemptResponse>> CreateAsync(
+        CreateJoinAttemptRequest request,
+        CancellationToken cancellationToken = default);
+
+    Task<RendezvousClientResult<bool>> CancelAsync(
+        CreateJoinAttemptResponse attempt,
+        CancellationToken cancellationToken = default);
+
+    Task<RendezvousClientResult<BrowseHostJoinAttemptsResponse>> BrowseForHostAsync(
+        PublishedSession session,
+        int pageSize = ContractLimits.BrowserPageMaxItems,
+        string? cursor = null,
+        CancellationToken cancellationToken = default);
+
+    Task<RendezvousClientResult<IReadOnlyList<HostJoinAttempt>>> BrowseAllForHostAsync(
+        PublishedSession session,
+        int maximumPages = 100,
+        CancellationToken cancellationToken = default);
+}
+
 public interface IRendezvousDelay
 {
     Task DelayAsync(TimeSpan delay, CancellationToken cancellationToken);