Merge pull request #439 from ipdae/issues-371

Implement deterministic Guid
planetarium · Aug 16, 2019 · f46dfd6 · f46dfd6
2 parents 52e9107 + e68b2b9
commit f46dfd6
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diff --git a/CHANGES.md b/CHANGES.md
@@ -29,6 +29,7 @@ To be released.
  -  Removed `IRandom.NextDouble()` method, because [floating-point arithmetics,
     which is underspecified, likely introduce
     indeterminism][floating-point determinism].  [[#410], [#419]]
+ -  Added `IActionContext.NewGuId()` method.  [[#371], [#439]]
 
 ### Added interfaces
 
@@ -118,6 +119,7 @@ To be released.
 [#366]: https://github.com/planetarium/libplanet/pull/366
 [#367]: https://github.com/planetarium/libplanet/pull/367
 [#369]: https://github.com/planetarium/libplanet/pull/369
+[#371]: https://github.com/planetarium/libplanet/issues/371
 [#375]: https://github.com/planetarium/libplanet/pull/375
 [#377]: https://github.com/planetarium/libplanet/issues/377
 [#378]: https://github.com/planetarium/libplanet/pull/378
@@ -146,6 +148,7 @@ To be released.
 [#426]: https://github.com/planetarium/libplanet/pull/426
 [#434]: https://github.com/planetarium/libplanet/pull/434
 [#438]: https://github.com/planetarium/libplanet/pull/438
+[#439]: https://github.com/planetarium/libplanet/pull/439
 [LiteDB #1268]: https://github.com/mbdavid/LiteDB/issues/1268
 [floating-point determinism]: https://wp.me/p1fTCO-kT
 

diff --git a/Libplanet.Tests/Action/ActionContextTest.cs b/Libplanet.Tests/Action/ActionContextTest.cs
@@ -1,3 +1,4 @@
+using System;
 using System.Collections.Immutable;
 using Libplanet.Action;
 using Xunit;
@@ -29,6 +30,54 @@ public void RandomShouldBeDeterministic()
             }
         }
 
+        [Fact]
+        public void GuidShouldBeDeterministic()
+        {
+            var address = new Address("21744f4f08db23e044178dafb8273aeb5ebe6644");
+            var context1 = new ActionContext(
+                signer: address,
+                miner: address,
+                blockIndex: 1,
+                previousStates: new DumbAccountStateDelta(),
+                randomSeed: 0
+            );
+
+            var context2 = new ActionContext(
+                signer: address,
+                miner: address,
+                blockIndex: 1,
+                previousStates: new DumbAccountStateDelta(),
+                randomSeed: 0
+            );
+
+            var context3 = new ActionContext(
+                signer: address,
+                miner: address,
+                blockIndex: 1,
+                previousStates: new DumbAccountStateDelta(),
+                randomSeed: 1
+            );
+
+            (Guid expected, Guid diff)[] testCases =
+            {
+                (
+                    new Guid("6f460c1a-755d-d8e4-ad67-65d5f519dbc8"),
+                    new Guid("8286d046-9740-a3e4-95cf-ff46699c73c4")
+                ),
+                (
+                    new Guid("3b347c2b-f837-0085-ec5e-64005393b30d"),
+                    new Guid("3410cda1-5b13-a34e-6f84-a54adf7a0ea0")
+                ),
+            };
+
+            foreach (var (expected, diff) in testCases)
+            {
+                Assert.Equal(expected, context1.NewGuid());
+                Assert.Equal(expected, context2.NewGuid());
+                Assert.Equal(diff, context3.NewGuid());
+            }
+        }
+
         private class DumbAccountStateDelta : IAccountStateDelta
         {
             public IImmutableSet<Address> UpdatedAddresses =>

diff --git a/Libplanet/Action/ActionContext.cs b/Libplanet/Action/ActionContext.cs
@@ -1,3 +1,5 @@
+using System;
+
 namespace Libplanet.Action
 {
     internal class ActionContext : IActionContext
@@ -30,5 +32,13 @@ public ActionContext(
         public IAccountStateDelta PreviousStates { get; }
 
         public IRandom Random { get; }
+
+        public Guid NewGuid()
+        {
+            // FIXME implement rfc4122 https://www.ietf.org/rfc/rfc4122.txt
+            var b = new byte[16];
+            Random.NextBytes(b);
+            return new Guid(b);
+        }
     }
 }
diff --git a/Libplanet/Action/IActionContext.cs b/Libplanet/Action/IActionContext.cs
@@ -1,3 +1,5 @@
+using System;
+
 namespace Libplanet.Action
 {
     /// <summary>
@@ -53,5 +55,12 @@ public interface IActionContext
         /// <returns>A random object that shares interface mostly equivalent
         /// to <see cref="System.Random"/>.</returns>
         IRandom Random { get; }
+
+        /// <summary>
+        /// Creates new <see cref="Guid"/>.  Its seed (state) is determined by a block and
+        /// a transaction, which is deterministic as like <see cref="Random"/>.
+        /// </summary>
+        /// <returns>A deterministic guid.</returns>
+        Guid NewGuid();
     }
 }