Implemented Spinwaiting on sequence overflow (see #24). Moved MockTimeSource and new MockAutoIncrementingIntervalTimeSource to new namespace. Added spinwait to configuration. Added a bunch of constructor overloads. Upped versions.

Author: RobThree

IdGen.Configuration/AppConfigFactory.cs

@@ -37,7 +37,7 @@ public static IdGenerator GetFromConfig(string name)
                 if (idgen != null)
                 {
                     var ts = idgen.TickDuration == TimeSpan.Zero ? defaulttimesource : new DefaultTimeSource(idgen.Epoch, idgen.TickDuration);
-                    return new IdGenerator(idgen.Id, new MaskConfig(idgen.TimestampBits, idgen.GeneratorIdBits, idgen.SequenceBits), ts);
+                    return new IdGenerator(idgen.Id, new MaskConfig(idgen.TimestampBits, idgen.GeneratorIdBits, idgen.SequenceBits), ts, idgen.UseSpinWait);
                 }
 
                 throw new KeyNotFoundException();

IdGen.Configuration/IdGen.Configuration.csproj

@@ -12,9 +12,9 @@
     <PackageLicenseExpression>MIT</PackageLicenseExpression>
     <PackageProjectUrl>https://github.com/RobThree/IdGen</PackageProjectUrl>
     <PackageTags>idgen configuration</PackageTags>
-    <PackageReleaseNotes></PackageReleaseNotes>
+    <PackageReleaseNotes>Added spinwait option (see #24)</PackageReleaseNotes>
     <Description>Configuration support for IdGen</Description>
-    <Version>1.0</Version>
+    <Version>1.0.1</Version>
     <RootNamespace>IdGen.Configuration</RootNamespace>
     <PackageIcon>logo.png</PackageIcon>
     <PackageIconUrl />

IdGen.Configuration/IdGeneratorElement.cs

@@ -39,6 +39,16 @@ private string StringEpoch
             set => this["epoch"] = value;
         }
 
+        /// <summary>
+        /// Gets/sets the spinwait option of the <see cref="IdGeneratorElement"/>.
+        /// </summary>
+        [ConfigurationProperty("useSpinWait", IsRequired = false)]
+        public bool UseSpinWait
+        {
+            get => (bool)this["useSpinWait"];
+            set => this["useSpinWait"] = value;
+        }
+
         /// <summary>
         /// Gets/sets the Epoch of the <see cref="IdGeneratorElement"/>.
         /// </summary>

IdGen/IdGen.csproj

@@ -12,9 +12,9 @@
     <PackageLicenseExpression>MIT</PackageLicenseExpression>
     <PackageProjectUrl>https://github.com/RobThree/IdGen</PackageProjectUrl>
     <PackageTags>scalable unique id generator distributed</PackageTags>
-    <PackageReleaseNotes>Fix concurrency issue (see PR #23)</PackageReleaseNotes>
+    <PackageReleaseNotes>Added spinwait option (see #24)</PackageReleaseNotes>
     <Description>Twitter Snowflake-alike ID generator for .Net</Description>
-    <Version>2.4</Version>
+    <Version>2.4.1</Version>
     <RootNamespace>IdGen</RootNamespace>
     <PackageIcon>logo.png</PackageIcon>
     <PackageIconUrl />

IdGen/IdGenerator.cs

@@ -2,6 +2,7 @@
 using System.Collections;
 using System.Collections.Generic;
 using System.Runtime.CompilerServices;
+using System.Threading;
 
 namespace IdGen
 {
@@ -17,9 +18,12 @@ public class IdGenerator : IIdGenerator<long>
         /// </summary>
         public static readonly DateTime DefaultEpoch = new DateTime(2015, 1, 1, 0, 0, 0, DateTimeKind.Utc);
 
+        private const bool DEFAULTSPINWAIT = false;
+
         private int _sequence = 0;
         private long _lastgen = -1;
         private readonly long _generatorId;
+        private readonly bool _usespinwait;
 
         private readonly long MASK_SEQUENCE;
         private readonly long MASK_TIME;
@@ -52,6 +56,17 @@ public class IdGenerator : IIdGenerator<long>
         /// </summary>
         public ITimeSource TimeSource { get; private set; }
 
+        /// <summary>
+        /// Gets wether the <see cref="IdGenerator"/> uses <see cref="SpinWait">spinwaiting</see> when a
+        /// sequenceoverflow occurs.
+        /// </summary>
+        /// <remarks>
+        /// When true, the <see cref="IdGenerator"/> won't throw a <see cref="SequenceOverflowException"/> when a 
+        /// sequence overflows; rather it will wait (using a spinwait) for the next tick and then return a new Id.
+        /// </remarks>
+        public bool UseSpinWait => _usespinwait;
+
+
         /// <summary>
         /// Initializes a new instance of the <see cref="IdGenerator"/> class, 2015-01-01 0:00:00Z is used as default 
         /// epoch and the <see cref="IdGen.MaskConfig.Default"/> value is used for the <see cref="MaskConfig"/>. The
@@ -60,7 +75,19 @@ public class IdGenerator : IIdGenerator<long>
         /// <param name="generatorId">The Id of the generator.</param>
         /// <exception cref="ArgumentOutOfRangeException">Thrown when GeneratorId exceeds maximum value.</exception>
         public IdGenerator(int generatorId)
-            : this(generatorId, DefaultEpoch) { }
+            : this(generatorId, DefaultEpoch, DEFAULTSPINWAIT) { }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="IdGenerator"/> class, 2015-01-01 0:00:00Z is used as default 
+        /// epoch and the <see cref="IdGen.MaskConfig.Default"/> value is used for the <see cref="MaskConfig"/>. The
+        /// <see cref="DefaultTimeSource"/> is used to retrieve timestamp information.
+        /// </summary>
+        /// <param name="generatorId">The Id of the generator.</param>
+        /// <param name="useSpinWait">Whether to use spinwaiting when a sequenceoverflow occurs.</param>
+        /// <exception cref="ArgumentOutOfRangeException">Thrown when GeneratorId exceeds maximum value.</exception>
+        public IdGenerator(int generatorId, bool useSpinWait)
+            : this(generatorId, DefaultEpoch, useSpinWait) { }
+
 
         /// <summary>
         /// Initializes a new instance of the <see cref="IdGenerator"/> class. The <see cref="IdGen.MaskConfig.Default"/> 
@@ -73,7 +100,21 @@ public IdGenerator(int generatorId)
         /// Thrown when GeneratorId exceeds maximum value or epoch in future.
         /// </exception>
         public IdGenerator(int generatorId, DateTimeOffset epoch)
-            : this(generatorId, epoch, MaskConfig.Default) { }
+            : this(generatorId, epoch, MaskConfig.Default, DEFAULTSPINWAIT) { }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="IdGenerator"/> class. The <see cref="IdGen.MaskConfig.Default"/> 
+        /// value is used for the <see cref="MaskConfig"/>.  The <see cref="DefaultTimeSource"/> is used to retrieve
+        /// timestamp information.
+        /// </summary>
+        /// <param name="generatorId">The Id of the generator.</param>
+        /// <param name="epoch">The Epoch of the generator.</param>
+        /// <param name="useSpinWait">Whether to use spinwaiting when a sequenceoverflow occurs.</param>
+        /// <exception cref="ArgumentOutOfRangeException">
+        /// Thrown when GeneratorId exceeds maximum value or epoch in future.
+        /// </exception>
+        public IdGenerator(int generatorId, DateTimeOffset epoch, bool useSpinWait)
+            : this(generatorId, epoch, MaskConfig.Default, useSpinWait) { }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="IdGenerator"/> class.  The <see cref="DefaultTimeSource"/> is
@@ -87,7 +128,22 @@ public IdGenerator(int generatorId, DateTimeOffset epoch)
         /// Thrown when GeneratorId or Sequence masks are >31 bit, GeneratorId exceeds maximum value or epoch in future.
         /// </exception>
         public IdGenerator(int generatorId, MaskConfig maskConfig)
-            : this(generatorId, maskConfig, new DefaultTimeSource(DefaultEpoch)) { }
+            : this(generatorId, maskConfig, new DefaultTimeSource(DefaultEpoch), DEFAULTSPINWAIT) { }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="IdGenerator"/> class.  The <see cref="DefaultTimeSource"/> is
+        /// used to retrieve timestamp information.
+        /// </summary>
+        /// <param name="generatorId">The Id of the generator.</param>
+        /// <param name="maskConfig">The <see cref="MaskConfig"/> of the generator.</param>
+        /// <param name="useSpinWait">Whether to use spinwaiting when a sequenceoverflow occurs.</param>
+        /// <exception cref="ArgumentNullException">Thrown when maskConfig is null.</exception>
+        /// <exception cref="InvalidOperationException">Thrown when maskConfig defines a non-63 bit bitmask.</exception>
+        /// <exception cref="ArgumentOutOfRangeException">
+        /// Thrown when GeneratorId or Sequence masks are >31 bit, GeneratorId exceeds maximum value or epoch in future.
+        /// </exception>
+        public IdGenerator(int generatorId, MaskConfig maskConfig, bool useSpinWait)
+            : this(generatorId, maskConfig, new DefaultTimeSource(DefaultEpoch), useSpinWait) { }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="IdGenerator"/> class.  The <see cref="DefaultTimeSource"/> is
@@ -102,7 +158,23 @@ public IdGenerator(int generatorId, MaskConfig maskConfig)
         /// Thrown when GeneratorId or Sequence masks are >31 bit, GeneratorId exceeds maximum value or epoch in future.
         /// </exception>
         public IdGenerator(int generatorId, DateTimeOffset epoch, MaskConfig maskConfig)
-            : this(generatorId, maskConfig, new DefaultTimeSource(epoch)) { }
+            : this(generatorId, maskConfig, new DefaultTimeSource(epoch), DEFAULTSPINWAIT) { }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="IdGenerator"/> class.  The <see cref="DefaultTimeSource"/> is
+        /// used to retrieve timestamp information.
+        /// </summary>
+        /// <param name="generatorId">The Id of the generator.</param>
+        /// <param name="epoch">The Epoch of the generator.</param>
+        /// <param name="maskConfig">The <see cref="MaskConfig"/> of the generator.</param>
+        /// <param name="useSpinWait">Whether to use spinwaiting when a sequenceoverflow occurs.</param>
+        /// <exception cref="ArgumentNullException">Thrown when maskConfig is null.</exception>
+        /// <exception cref="InvalidOperationException">Thrown when maskConfig defines a non-63 bit bitmask.</exception>
+        /// <exception cref="ArgumentOutOfRangeException">
+        /// Thrown when GeneratorId or Sequence masks are >31 bit, GeneratorId exceeds maximum value or epoch in future.
+        /// </exception>
+        public IdGenerator(int generatorId, DateTimeOffset epoch, MaskConfig maskConfig, bool useSpinWait)
+            : this(generatorId, maskConfig, new DefaultTimeSource(epoch), useSpinWait) { }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="IdGenerator"/> class.
@@ -115,7 +187,22 @@ public IdGenerator(int generatorId, DateTimeOffset epoch, MaskConfig maskConfig)
         /// Thrown when GeneratorId or Sequence masks are >31 bit, GeneratorId exceeds maximum value or epoch in future.
         /// </exception>
         public IdGenerator(int generatorId, ITimeSource timeSource)
-            : this(generatorId, MaskConfig.Default, timeSource) { }
+            : this(generatorId, MaskConfig.Default, timeSource, DEFAULTSPINWAIT) { }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="IdGenerator"/> class.
+        /// </summary>
+        /// <param name="generatorId">The Id of the generator.</param>
+        /// <param name="timeSource">The time-source to use when acquiring time data.</param>
+        /// <param name="useSpinWait">Whether to use spinwaiting when a sequenceoverflow occurs.</param>
+        /// <exception cref="ArgumentNullException">Thrown when either maskConfig or timeSource is null.</exception>
+        /// <exception cref="InvalidOperationException">Thrown when maskConfig defines a non-63 bit bitmask.</exception>
+        /// <exception cref="ArgumentOutOfRangeException">
+        /// Thrown when GeneratorId or Sequence masks are >31 bit, GeneratorId exceeds maximum value or epoch in future.
+        /// </exception>
+        public IdGenerator(int generatorId, ITimeSource timeSource, bool useSpinWait)
+            : this(generatorId, MaskConfig.Default, timeSource, useSpinWait) { }
+
 
         /// <summary>
         /// Initializes a new instance of the <see cref="IdGenerator"/> class.
@@ -129,6 +216,21 @@ public IdGenerator(int generatorId, ITimeSource timeSource)
         /// Thrown when GeneratorId or Sequence masks are >31 bit, GeneratorId exceeds maximum value or epoch in future.
         /// </exception>
         public IdGenerator(int generatorId, MaskConfig maskConfig, ITimeSource timeSource)
+            : this(generatorId, maskConfig, timeSource, DEFAULTSPINWAIT) { }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="IdGenerator"/> class.
+        /// </summary>
+        /// <param name="generatorId">The Id of the generator.</param>
+        /// <param name="maskConfig">The <see cref="MaskConfig"/> of the generator.</param>
+        /// <param name="timeSource">The time-source to use when acquiring time data.</param>
+        /// <param name="useSpinWait">Whether to use spinwaiting when a sequenceoverflow occurs.</param>
+        /// <exception cref="ArgumentNullException">Thrown when either maskConfig or timeSource is null.</exception>
+        /// <exception cref="InvalidOperationException">Thrown when maskConfig defines a non-63 bit bitmask.</exception>
+        /// <exception cref="ArgumentOutOfRangeException">
+        /// Thrown when GeneratorId or Sequence masks are >31 bit, GeneratorId exceeds maximum value or epoch in future.
+        /// </exception>
+        public IdGenerator(int generatorId, MaskConfig maskConfig, ITimeSource timeSource, bool useSpinWait)
         {
             if (maskConfig == null)
                 throw new ArgumentNullException(nameof(maskConfig));
@@ -160,6 +262,7 @@ public IdGenerator(int generatorId, MaskConfig maskConfig, ITimeSource timeSourc
             MaskConfig = maskConfig;
             TimeSource = timeSource;
             _generatorId = generatorId;
+            _usespinwait = useSpinWait;
         }
 
         /// <summary>
@@ -221,13 +324,21 @@ private long CreateIdImpl(out Exception exception)
                 if (timestamp == _lastgen)
                 {
                     if (_sequence >= MASK_SEQUENCE)
-                    { 
-                        exception = new SequenceOverflowException("Sequence overflow. Refusing to generate id for rest of tick");
-                        return -1;
+                    {
+                        if (_usespinwait)
+                        {
+                            SpinWait.SpinUntil(() => _lastgen != GetTicks());
+                            return CreateIdImpl(out exception); // Try again
+                        }
+                        else
+                        {
+                            exception = new SequenceOverflowException("Sequence overflow. Refusing to generate id for rest of tick");
+                            return -1;
+                        }
                     }
                     _sequence++;
                 }
-                else // If we're in a new(er) "timeslot", so we can reset the sequence and store the new(er) "timeslot"
+                else // We're in a new(er) "timeslot", so we can reset the sequence and store the new(er) "timeslot"
                 {
                     _sequence = 0;
                     _lastgen = timestamp;

IdGenDocumentation/Content/VersionHistory/v2.4.0.0.aml

@@ -3,7 +3,7 @@
   <developerConceptualDocument xmlns="http://ddue.schemas.microsoft.com/authoring/2003/5" xmlns:xlink="http://www.w3.org/1999/xlink">
     <introduction>
       <para>
-        Version 2.3.0.0 was released on 2020-04-18.
+        Version 2.4.0.0 was released on 2020-04-18.
       </para>
     </introduction>
 

IdGenDocumentation/Content/VersionHistory/v2.4.1.0.aml

@@ -0,0 +1,32 @@
+<?xml version="1.0" encoding="utf-8"?>
+<topic id="941bdc70-cff6-4a4d-80b6-509114890f14" revisionNumber="1">
+  <developerConceptualDocument xmlns="http://ddue.schemas.microsoft.com/authoring/2003/5" xmlns:xlink="http://www.w3.org/1999/xlink">
+    <introduction>
+      <para>
+        Version 2.4.1.0 was released on 2020-07-02.
+      </para>
+    </introduction>
+
+    <section>
+      <title>Changes in This Release</title>
+      <content>
+
+        <list class="bullet">
+          <listItem>
+            <para>
+              Implemented spinwait (see <externalLink>
+                <linkText>#24</linkText>
+                <linkUri>https://github.com/RobThree/IdGen/pull/24</linkUri>
+              </externalLink>).
+            </para>
+          </listItem>
+        </list>
+      </content>
+    </section>
+
+    <relatedTopics>
+      <link xlink:href="4491ec46-0001-46c1-88b7-3dd2ee8472f3" />
+    </relatedTopics>
+
+  </developerConceptualDocument>
+</topic>