feat: Add Processing Time stat field (#218)

Co-authored-by: James Rodewig <[email protected]>

Fauna.Test/Integration.Tests.cs

@@ -649,10 +649,8 @@ await _client.QueryAsync(
         int pages = 0;
         await foreach (var page in feed)
         {
-            if (page.HasNext)
-            {
-                Assert.AreEqual(pageSize, page.Events.Count);
-            }
+            if (page.Events.Count > 0) Assert.NotNull(page.Events[0].Stats.ProcessingTimeMs);
+            if (page.HasNext) Assert.AreEqual(pageSize, page.Events.Count);
 
             pages++;
         }

Fauna/Core/QueryStats.cs

@@ -56,6 +56,12 @@ public readonly struct QueryStats
     [JsonPropertyName(Stats_RateLimitsHit)]
     public List<string> RateLimitsHit { get; init; }
 
+    /// <summary>
+    /// Processing time in milliseconds. Only returned on Events.
+    /// </summary>
+    [JsonPropertyName(Stats_ProcessingTimeMs)]
+    public int? ProcessingTimeMs { get; init; }
+
     /// <summary>
     /// Returns a string representation of the query statistics.
     /// </summary>
@@ -65,6 +71,7 @@ public override string ToString()
         return $"compute: {ComputeOps}, read: {ReadOps}, write: {WriteOps}, " +
                $"queryTime: {QueryTimeMs}, retries: {ContentionRetries}, " +
                $"storageRead: {StorageBytesRead}, storageWrite: {StorageBytesWrite}, " +
+               $"{(ProcessingTimeMs.HasValue ? $"processingTime: {ProcessingTimeMs}, " : "")}" +
                $"limits: [{string.Join(',', RateLimitsHit)}]";
     }
 }

Fauna/Core/ResponseFields.cs

@@ -106,6 +106,11 @@ internal readonly struct ResponseFields
     /// </summary>
     public const string Stats_RateLimitsHit = "rate_limits_hit";
 
+    /// <summary>
+    /// Field name for the processing time in milliseconds.
+    /// </summary>
+    public const string Stats_ProcessingTimeMs = "processing_time_ms";
+
     #endregion
 
     #region "error" block