More efficient session validity checks. Jellyfin session detection.

CinemaLib/Webshare/Session.cs

@@ -1,7 +1,5 @@
 using System;
 using System.Globalization;
-using System.Security.Cryptography;
-using System.Text;
 using System.Xml;
 using Cinema.Webshare;
 
@@ -17,6 +15,7 @@ public sealed class Session
   private static readonly Uri WebshareApiUri = LinkGenerator.WebshareApiUri;
   private static readonly TimeSpan InitialLoginBackoff = new TimeSpan(4 * TimeSpan.TicksPerSecond);
   private static readonly TimeSpan MaxLoginBackoff = new TimeSpan(8 * TimeSpan.TicksPerMinute);
+  private static readonly TimeSpan TokenValidPeriod = new TimeSpan(120 * TimeSpan.TicksPerSecond);
 
   private readonly string _userName;
   private readonly string _password;
@@ -26,6 +25,7 @@ public sealed class Session
 
   private DateTime _nextLoginTrial;
   private TimeSpan _nextLoginBackoff;
+  private DateTime _nextValidTrial;
 
   /// <summary>
   /// Constructs a session from credentials and optionally a possibly live token.
@@ -74,52 +74,62 @@ public sealed class Session
   /// <returns>True if the local instance data are valid. -or- False otherwise.</returns>
   private async Task<bool> EnsureValidAsync(CancellationToken cancel)
   {
-    if (!await RefreshUserDataAsync(cancel))
+    DateTime now = DateTime.Now;
+
+    if (_token != null && (_isVip ?? false) && now < _nextValidTrial)
+      // Fast track positive check
+      return true;
+
+    if (await RefreshUserDataAsync(cancel) && (_isVip ?? false))
     {
-      DateTime now = DateTime.Now;
-      if (now > _nextLoginTrial)
+      // Valid VIP (slower with API check)
+      _nextValidTrial = now + TokenValidPeriod;
+      return true;
+    }
+
+    if (now > _nextLoginTrial)
+    {
+      // Try to log in again
+      string? token;
+      try
       {
-        // Try to login again
-        string? token;
-        try
-        {
-          string? salt;
-          if ((salt = await GetSaltAsync(_userName, cancel)) == null
-            || (token = await GetTokenAsync(_userName, _password.HashPassword(salt), cancel)) == null)
-          {
-            // Login failed
-            token = null;
-          }
-        }
-        catch
+        string? salt;
+        if ((salt = await GetSaltAsync(_userName, cancel)) == null
+          || (token = await GetTokenAsync(_userName, _password.HashPassword(salt), cancel)) == null)
         {
+          // Login failed
           token = null;
         }
-
-        if (token != null)
-        {
-          _nextLoginBackoff = InitialLoginBackoff;
-          _token = token;
-          if (await RefreshUserDataAsync(cancel))
-            return true;
-
-        }
-        else
-        {
-          TimeSpan nextBackoff = new TimeSpan(2 * _nextLoginBackoff.Ticks);
-          if (nextBackoff > MaxLoginBackoff)
-            nextBackoff = MaxLoginBackoff;
-          _nextLoginTrial = now + nextBackoff;
-        }
+      }
+      catch
+      {
+        token = null;
       }
 
-      _token = null;
-      _isVip = null;
-      _vipDaysLeft = null;
-      return false;
+      if (token != null && await RefreshUserDataAsync(cancel) && (_isVip ?? false))
+      {
+        // Valid token with VIP
+        _nextLoginBackoff = InitialLoginBackoff;
+        _token = token;
+        _nextValidTrial = now + TokenValidPeriod;
+        return true;
+
+      }
+      else
+      {
+        // Invalid, no token or not VIP ...
+        TimeSpan nextBackoff = new TimeSpan(2 * _nextLoginBackoff.Ticks);
+        if (nextBackoff > MaxLoginBackoff)
+          nextBackoff = MaxLoginBackoff;
+        _nextLoginTrial = now + nextBackoff;
+      }
     }
-    else
-      return true;
+
+    // ... still invalid, no token or not VIP
+    _token = null;
+    _isVip = null;
+    _vipDaysLeft = null;
+    return false;
   }
 
   /// <summary>