Add Transaction Conditions for List Index

StackExchange.Redis.Tests/Transactions.cs

@@ -207,6 +207,96 @@ public void BasicTranWithHashEqualsCondition(string expected, string value, bool
             }
         }
 
+        [Test]
+        [TestCase(false, false, true)]
+        [TestCase(false, true, false)]
+        [TestCase(true, false, false)]
+        [TestCase(true, true, true)]
+        public void BasicTranWithListExistsCondition(bool demandKeyExists, bool keyExists, bool expectTran)
+        {
+            using (var muxer = Create(disabledCommands: new[] { "info", "config" }))
+            {
+                RedisKey key = Me(), key2 = Me() + "2";
+                var db = muxer.GetDatabase();
+                db.KeyDelete(key, CommandFlags.FireAndForget);
+                db.KeyDelete(key2, CommandFlags.FireAndForget);
+                if (keyExists) db.ListRightPush(key2, "any value", flags:  CommandFlags.FireAndForget);
+                Assert.IsFalse(db.KeyExists(key));
+                Assert.AreEqual(keyExists, db.KeyExists(key2));
+
+                var tran = db.CreateTransaction();
+                var cond = tran.AddCondition(demandKeyExists ? Condition.ListIndexExists(key2, 0) : Condition.ListIndexNotExists(key2, 0));
+                var push = tran.ListRightPushAsync(key, "any value");
+                var exec = tran.ExecuteAsync();
+                var get = db.ListGetByIndex(key, 0);
+
+                Assert.AreEqual(expectTran, db.Wait(exec), "expected tran result");
+                if (demandKeyExists == keyExists)
+                {
+                    Assert.IsTrue(db.Wait(exec), "eq: exec");
+                    Assert.IsTrue(cond.WasSatisfied, "eq: was satisfied");
+                    Assert.AreEqual(1, db.Wait(push), "eq: push");
+                    Assert.AreEqual("any value", (string)get, "eq: get");
+                }
+                else
+                {
+                    Assert.IsFalse(db.Wait(exec), "neq: exec");
+                    Assert.False(cond.WasSatisfied, "neq: was satisfied");
+                    Assert.AreEqual(TaskStatus.Canceled, push.Status, "neq: push");
+                    Assert.AreEqual(null, (string)get, "neq: get");
+                }
+            }
+        }
+
+        [Test]
+        [TestCase("same", "same", true, true)]
+        [TestCase("x", "y", true, false)]
+        [TestCase("x", null, true, false)]
+        [TestCase(null, "y", true, false)]
+        [TestCase(null, null, true, true)]
+
+        [TestCase("same", "same", false, false)]
+        [TestCase("x", "y", false, true)]
+        [TestCase("x", null, false, true)]
+        [TestCase(null, "y", false, true)]
+        [TestCase(null, null, false, false)]
+        public void BasicTranWithListEqualsCondition(string expected, string value, bool expectEqual, bool expectTran)
+        {
+            using (var muxer = Create())
+            {
+                RedisKey key = Me(), key2 = Me() + "2";
+                var db = muxer.GetDatabase();
+                db.KeyDelete(key, CommandFlags.FireAndForget);
+                db.KeyDelete(key2, CommandFlags.FireAndForget);
+
+                if (value != null) db.ListRightPush(key2, value, flags: CommandFlags.FireAndForget);
+                Assert.IsFalse(db.KeyExists(key));
+                Assert.AreEqual(value, (string)db.ListGetByIndex(key2, 0));
+
+                var tran = db.CreateTransaction();
+                var cond = tran.AddCondition(expectEqual ? Condition.ListIndexEqual(key2, 0, expected) : Condition.ListIndexNotEqual(key2, 0, expected));
+                var push = tran.ListRightPushAsync(key, "any value");
+                var exec = tran.ExecuteAsync();
+                var get = db.ListGetByIndex(key, 0);
+
+                Assert.AreEqual(expectTran, db.Wait(exec), "expected tran result");
+                if (expectEqual == (value == expected))
+                {
+                    Assert.IsTrue(db.Wait(exec), "eq: exec");
+                    Assert.IsTrue(cond.WasSatisfied, "eq: was satisfied");
+                    Assert.AreEqual(1, db.Wait(push), "eq: push");
+                    Assert.AreEqual("any value", (string)get, "eq: get");
+                }
+                else
+                {
+                    Assert.IsFalse(db.Wait(exec), "neq: exec");
+                    Assert.False(cond.WasSatisfied, "neq: was satisfied");
+                    Assert.AreEqual(TaskStatus.Canceled, push.Status, "neq: push");
+                    Assert.AreEqual(null, (string)get, "neq: get");
+                }
+            }
+        }
+
         [Test]
         public async void BasicTran()
         {

StackExchange.Redis/StackExchange/Redis/Condition.cs

@@ -67,6 +67,38 @@ public static Condition KeyNotExists(RedisKey key)
             return new ExistsCondition(key, RedisValue.Null, false);
         }
 
+        /// <summary>
+        /// Enforces that the given list index must have the specified value 
+        /// </summary>
+        public static Condition ListIndexEqual(RedisKey key, long index, RedisValue value)
+        {
+            return new ListCondition(key, index, true, value);
+        }
+
+        /// <summary>
+        /// Enforces that the given list index must exist
+        /// </summary>
+        public static Condition ListIndexExists(RedisKey key, long index)
+        {
+            return new ListCondition(key, index, true, null);
+        }
+
+        /// <summary>
+        /// Enforces that the given list index must not have the specified value 
+        /// </summary>
+        public static Condition ListIndexNotEqual(RedisKey key, long index, RedisValue value)
+        {
+            return new ListCondition(key, index, false, value);
+        }
+
+        /// <summary>
+        /// Enforces that the given list index must not exist
+        /// </summary>
+        public static Condition ListIndexNotExists(RedisKey key, long index)
+        {
+            return new ListCondition(key, index, false, null);
+        }
+
         /// <summary>
         /// Enforces that the given key must have the specified value
         /// </summary>
@@ -262,6 +294,76 @@ internal override bool TryValidate(RawResult result, out bool value)
                 return false;
             }
         }
+
+        internal class ListCondition : Condition
+        {
+            internal override Condition MapKeys(Func<RedisKey,RedisKey> map)
+            {
+                return new ListCondition(map(key), index, expectedResult, expectedValue);
+            }
+            private readonly bool expectedResult;
+            private readonly long index;
+            private readonly RedisValue? expectedValue;
+            private readonly RedisKey key;
+            public ListCondition(RedisKey key, long index, bool expectedResult, RedisValue? expectedValue)
+            {
+                if (key.IsNull) throw new ArgumentException("key");
+                this.key = key;
+                this.index = index;
+                this.expectedResult = expectedResult;
+                this.expectedValue = expectedValue;
+            }
+
+            public override string ToString()
+            {
+                return ((string)key) + "[" + index.ToString() + "]"
+                    + (expectedValue.HasValue ? (expectedResult ? " == " : " != ") + expectedValue.Value : (expectedResult ? " exists" : " does not exist"));
+            }
+
+            internal override void CheckCommands(CommandMap commandMap)
+            {
+                commandMap.AssertAvailable(RedisCommand.LINDEX);
+            }
+
+            internal sealed override IEnumerable<Message> CreateMessages(int db, ResultBox resultBox)
+            {
+                yield return Message.Create(db, CommandFlags.None, RedisCommand.WATCH, key);
+
+                var message = ConditionProcessor.CreateMessage(this, db, CommandFlags.None, RedisCommand.LINDEX, key, index);
+                message.SetSource(ConditionProcessor.Default, resultBox);
+                yield return message;
+            }
+
+            internal override int GetHashSlot(ServerSelectionStrategy serverSelectionStrategy)
+            {
+                return serverSelectionStrategy.HashSlot(key);
+            }
+            internal override bool TryValidate(RawResult result, out bool value)
+            {
+                switch (result.Type)
+                {
+                    case ResultType.BulkString:
+                    case ResultType.SimpleString:
+                    case ResultType.Integer:
+                        var parsed = result.AsRedisValue();
+                        if (expectedValue.HasValue)
+                        {
+                            value = (parsed == expectedValue.Value) == expectedResult;
+                            ConnectionMultiplexer.TraceWithoutContext("actual: " + (string)parsed + "; expected: " + (string)expectedValue.Value +
+                                "; wanted: " + (expectedResult ? "==" : "!=") + "; voting: " + value);
+                        }
+                        else
+                        {
+                            value = (parsed.IsNull != expectedResult);
+                            ConnectionMultiplexer.TraceWithoutContext("exists: " + parsed + "; expected: " + expectedResult + "; voting: " + value);
+                        }
+                        return true;
+                }
+                value = false;
+                return false;
+            }
+        }
+
     }
 
     /// <summary>