CSHARP-1834: Make minimum value of MaxStaleness 90 seconds.

Author: rstam

src/MongoDB.Driver.Core/Core/Clusters/ServerSelectors/ReadPreferenceServerSelector.cs

@@ -255,42 +255,30 @@ private void EnsureMaxStalenessIsValid(ClusterDescription cluster)
         {
             if (_maxStaleness.HasValue)
             {
-                TimeSpan heartbeatInterval;
-                TimeSpan idleWritePeriod;
-
-                var primary = SelectPrimary(cluster.Servers).SingleOrDefault();
-                if (primary != null)
+                if (_maxStaleness.Value < TimeSpan.FromSeconds(90))
                 {
-                    heartbeatInterval = primary.HeartbeatInterval;
-                    idleWritePeriod = primary.IdleWritePeriod;
+                    var message = string.Format(
+                        "Max staleness ({0} seconds) must greater than or equal to 90 seconds.",
+                        (int)_maxStaleness.Value.TotalSeconds);
+                    throw new Exception(message);
                 }
-                else
-                {
-                    ServerDescription secondaryWithGreatestLastUpdateTime = null;
-                    foreach (var secondary in SelectSecondaries(cluster.Servers))
-                    {
-                        if (secondaryWithGreatestLastUpdateTime == null || secondary.LastUpdateTimestamp > secondaryWithGreatestLastUpdateTime.LastUpdateTimestamp)
-                        {
-                            secondaryWithGreatestLastUpdateTime = secondary;
-                        }
-                    }
-
-                    if (secondaryWithGreatestLastUpdateTime == null)
-                    {
-                        return;
-                    }
 
-                    heartbeatInterval = secondaryWithGreatestLastUpdateTime.HeartbeatInterval;
-                    idleWritePeriod = secondaryWithGreatestLastUpdateTime.IdleWritePeriod;
+                var anyServer = cluster.Servers.FirstOrDefault();
+                if (anyServer == null)
+                {
+                    return;
                 }
 
+                var heartbeatInterval = anyServer.HeartbeatInterval; // all servers have the same HeartbeatInterval
+                var idleWritePeriod = TimeSpan.FromSeconds(10);
+
                 if (_maxStaleness.Value < heartbeatInterval + idleWritePeriod)
                 {
                     var message = string.Format(
-                        "Max staleness ({0} ms) must greater than or equal to heartbeat interval ({1} ms) plus idle write period ({2} ms).",
-                        (int)_maxStaleness.Value.TotalMilliseconds,
-                        (int)heartbeatInterval.TotalMilliseconds,
-                        (int)idleWritePeriod.TotalMilliseconds);
+                        "Max staleness ({0} seconds) must greater than or equal to heartbeat interval ({1} seconds) plus idle write period ({2} seconds).",
+                        (int)_maxStaleness.Value.TotalSeconds,
+                        (int)heartbeatInterval.TotalSeconds,
+                        (int)idleWritePeriod.TotalSeconds);
                     throw new Exception(message);
                 }
             }

src/MongoDB.Driver.Core/Core/Connections/IsMasterResult.cs

@@ -63,25 +63,6 @@ public ElectionId ElectionId
             }
         }
 
-        /// <summary>
-        /// Gets the idle write period.
-        /// </summary>
-        public TimeSpan IdleWritePeriod
-        {
-            get
-            {
-                BsonValue value;
-                if (_wrapped.TryGetValue("idleWritePeriodMS", out value))
-                {
-                    return TimeSpan.FromMilliseconds(value.ToDouble());
-                }
-                else
-                {
-                    return TimeSpan.FromSeconds(10);
-                }
-            }
-        }
-
         /// <summary>
         /// Gets a value indicating whether this instance is an arbiter.
         /// </summary>

src/MongoDB.Driver.Core/Core/Operations/QueryHelper.cs

@@ -81,7 +81,7 @@ public static BsonDocument CreateReadPreferenceDocument(ServerType serverType, R
             {
                 { "mode", modeString },
                 { "tags", tagSets, tagSets != null },
-                { "maxStalenessSeconds", () => readPreference.MaxStaleness.Value.TotalSeconds, readPreference.MaxStaleness.HasValue }
+                { "maxStalenessSeconds", () => (int)readPreference.MaxStaleness.Value.TotalSeconds, readPreference.MaxStaleness.HasValue }
             };
         }
     }

src/MongoDB.Driver.Core/Core/Servers/ServerDescription.cs

@@ -40,7 +40,6 @@ public sealed class ServerDescription : IEquatable<ServerDescription>
         private readonly EndPoint _endPoint;
         private readonly Exception _heartbeatException;
         private readonly TimeSpan _heartbeatInterval;
-        private readonly TimeSpan _idleWritePeriod;
         private readonly DateTime _lastUpdateTimestamp;
         private readonly DateTime? _lastWriteTimestamp;
         private readonly int _maxBatchCount;
@@ -66,7 +65,6 @@ public sealed class ServerDescription : IEquatable<ServerDescription>
         /// <param name="electionId">The election identifier.</param>
         /// <param name="heartbeatException">The heartbeat exception.</param>
         /// <param name="heartbeatInterval">The heartbeat interval.</param>
-        /// <param name="idleWritePeriod">The idle write period.</param>
         /// <param name="lastUpdateTimestamp">The last update timestamp.</param>
         /// <param name="lastWriteTimestamp">The last write timestamp.</param>
         /// <param name="maxBatchCount">The maximum batch count.</param>
@@ -87,7 +85,6 @@ public ServerDescription(
             Optional<ElectionId> electionId = default(Optional<ElectionId>),
             Optional<Exception> heartbeatException = default(Optional<Exception>),
             Optional<TimeSpan> heartbeatInterval = default(Optional<TimeSpan>),
-            Optional<TimeSpan> idleWritePeriod = default(Optional<TimeSpan>),
             Optional<DateTime> lastUpdateTimestamp = default(Optional<DateTime>),
             Optional<DateTime?> lastWriteTimestamp = default(Optional<DateTime?>),
             Optional<int> maxBatchCount = default(Optional<int>),
@@ -114,7 +111,6 @@ public ServerDescription(
             _endPoint = endPoint;
             _heartbeatException = heartbeatException.WithDefault(null);
             _heartbeatInterval = heartbeatInterval.WithDefault(TimeSpan.Zero);
-            _idleWritePeriod = idleWritePeriod.WithDefault(TimeSpan.FromSeconds(10));
             _lastUpdateTimestamp = lastUpdateTimestamp.WithDefault(DateTime.UtcNow);
             _lastWriteTimestamp = lastWriteTimestamp.WithDefault(null);
             _maxBatchCount = maxBatchCount.WithDefault(1000);
@@ -193,17 +189,6 @@ public TimeSpan HeartbeatInterval
             get { return _heartbeatInterval; }
         }
 
-        /// <summary>
-        /// Gets the idle write period.
-        /// </summary>
-        /// <value>
-        /// The idle write period.
-        /// </value>
-        public TimeSpan IdleWritePeriod
-        {
-            get { return _idleWritePeriod; }
-        }
-
         /// <summary>
         /// Gets the last update timestamp (when the ServerDescription itself was last updated).
         /// </summary>
@@ -369,7 +354,6 @@ public bool Equals(ServerDescription other)
                 EndPointHelper.Equals(_endPoint, other._endPoint) &&
                 object.Equals(_heartbeatException, other._heartbeatException) &&
                 _heartbeatInterval == other._heartbeatInterval &&
-                _idleWritePeriod == other._idleWritePeriod &&
                 _lastUpdateTimestamp == other._lastUpdateTimestamp &&
                 _lastWriteTimestamp == other._lastWriteTimestamp &&
                 _maxBatchCount == other._maxBatchCount &&
@@ -396,7 +380,6 @@ public override int GetHashCode()
                 .Hash(_endPoint)
                 .Hash(_heartbeatException)
                 .Hash(_heartbeatInterval)
-                .Hash(_idleWritePeriod)
                 .Hash(_lastUpdateTimestamp)
                 .Hash(_lastWriteTimestamp)
                 .Hash(_maxBatchCount)
@@ -438,7 +421,6 @@ public override string ToString()
         /// <param name="electionId">The election identifier.</param>
         /// <param name="heartbeatException">The heartbeat exception.</param>
         /// <param name="heartbeatInterval">The heartbeat interval.</param>
-        /// <param name="idleWritePeriod">The idle write period.</param>
         /// <param name="lastUpdateTimestamp">The last update timestamp.</param>
         /// <param name="lastWriteTimestamp">The last write timestamp.</param>
         /// <param name="maxBatchCount">The maximum batch count.</param>
@@ -460,7 +442,6 @@ public ServerDescription With(
             Optional<ElectionId> electionId = default(Optional<ElectionId>),
             Optional<Exception> heartbeatException = default(Optional<Exception>),
             Optional<TimeSpan> heartbeatInterval = default(Optional<TimeSpan>),
-            Optional<TimeSpan> idleWritePeriod = default(Optional<TimeSpan>),
             Optional<DateTime> lastUpdateTimestamp = default(Optional<DateTime>),
             Optional<DateTime?> lastWriteTimestamp = default(Optional<DateTime?>),
             Optional<int> maxBatchCount = default(Optional<int>),
@@ -485,7 +466,6 @@ public ServerDescription With(
                 electionId.Replaces(_electionId) ||
                 heartbeatException.Replaces(_heartbeatException) ||
                 heartbeatInterval.Replaces(_heartbeatInterval) ||
-                idleWritePeriod.Replaces(_idleWritePeriod) ||
                 lastUpdateTimestamp.Replaces(_lastUpdateTimestamp) ||
                 lastWriteTimestamp.Replaces(_lastWriteTimestamp) ||
                 maxBatchCount.Replaces(_maxBatchCount) ||
@@ -507,7 +487,6 @@ public ServerDescription With(
                     electionId: electionId.WithDefault(_electionId),
                     heartbeatException: heartbeatException.WithDefault(_heartbeatException),
                     heartbeatInterval: heartbeatInterval.WithDefault(_heartbeatInterval),
-                    idleWritePeriod: idleWritePeriod.WithDefault(_idleWritePeriod),
                     lastUpdateTimestamp: lastUpdateTimestamp.WithDefault(_lastUpdateTimestamp),
                     lastWriteTimestamp: lastWriteTimestamp.WithDefault(_lastWriteTimestamp),
                     maxBatchCount: maxBatchCount.WithDefault(_maxBatchCount),

src/MongoDB.Driver.Core/Core/Servers/ServerMonitor.cs

@@ -177,7 +177,6 @@ private async Task<bool> HeartbeatAsync(CancellationToken cancellationToken)
                     canonicalEndPoint: isMasterResult.Me,
                     electionId: isMasterResult.ElectionId,
                     lastWriteTimestamp: isMasterResult.LastWriteTimestamp,
-                    idleWritePeriod: isMasterResult.IdleWritePeriod,
                     maxBatchCount: isMasterResult.MaxBatchCount,
                     maxDocumentSize: isMasterResult.MaxDocumentSize,
                     maxMessageSize: isMasterResult.MaxMessageSize,

src/MongoDB.Driver.Core/ReadPreference.cs

@@ -119,6 +119,10 @@ public ReadPreference(
             if (maxStaleness.HasValue)
             {
                 Ensure.IsInfiniteOrGreaterThanZero(maxStaleness.Value, nameof(maxStaleness));
+                if (maxStaleness.Value > TimeSpan.Zero)
+                {
+                    Ensure.That(maxStaleness.Value.Ticks % TimeSpan.TicksPerMillisecond == 0, "MaxStaleness must not have fractional seconds.", nameof(maxStaleness));
+                }
                 Ensure.That(mode != ReadPreferenceMode.Primary, "MaxStaleness cannot be used with ReadPreferenceMode Primary.", nameof(maxStaleness));
             }
 

tests/MongoDB.Driver.Core.Tests.Dotnet/Specifications/max-staleness/tests/ReplicaSetNoPrimary/IdleWritePeriod.json

@@ -1,6 +1,6 @@
-# During server selection,
-# clients (drivers or mongos) MUST raise an error if ``maxStalenessSeconds`` is not zero or null,
-# and any server's ``maxWireVersion`` is less than 5 (`SERVER-23893`_).
+# During server selection, clients (drivers or mongos) MUST raise an error if
+# maxStalenessSeconds is defined and not -1 and any server's ``maxWireVersion``
+# is less than 5 (`SERVER-23893`_).
 ---
 topology_description:
   type: ReplicaSetNoPrimary