Merge pull request #6 from kemitix/value-deadlock-fix

Value: Avoid danger of JVM-level deadlock during initialisation

CHANGELOG

@@ -5,6 +5,7 @@ CHANGELOG
 -----
 
 * Add `.travis-support`
+* Avoid danger of JVM-level deadlock during `Value` initialisation
 * Avoid danger of JVM-level deadlock during `Condition` initialisation
 * Upgrade `kemitix-parent` to 3.2.0
 * Upgrade `kemitix-checkstyle-parent` to 3.2.0

src/main/java/net/kemitix/conditional/FalseCondition.java

@@ -26,7 +26,7 @@ package net.kemitix.conditional;
  *
  * @author Paul Campbell (pcampbell@kemitix.net).
  */
-public final class FalseCondition implements Condition {
+final class FalseCondition implements Condition {
 
     protected static final Condition FALSE = new net.kemitix.conditional.FalseCondition();
 

src/main/java/net/kemitix/conditional/FalseValueClause.java

@@ -0,0 +1,64 @@
+/**
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017 Paul Campbell
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of this software
+ * and associated documentation files (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all copies
+ * or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+ * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
+ * AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+package net.kemitix.conditional;
+
+import java.util.function.Supplier;
+
+/**
+ * An intermediate state where the clause has evaluated to false.
+ *
+ * @param <T> the type of the value
+ *
+ * @author Paul Campbell (pcampbell@kemitix.net).
+ */
+class FalseValueClause<T> implements Value.ValueClause<T> {
+
+    protected static final Value.ValueClause FALSE = new FalseValueClause();
+
+    @Override
+    public ValueSupplier<T> then(final Supplier<T> trueSupplier) {
+        return new FalseValueSupplier();
+    }
+
+    @Override
+    public Value.ValueClause<T> and(final boolean clause) {
+        return this;
+    }
+
+    @Override
+    public Value.ValueClause<T> or(final boolean clause) {
+        return Value.where(clause);
+    }
+
+    /**
+     * An intermediate result of the {@link Value} where the clause has evaluated to false.
+     */
+    private class FalseValueSupplier implements ValueSupplier<T> {
+
+        @Override
+        public T otherwise(final Supplier<T> falseSupplier) {
+            return falseSupplier.get();
+        }
+
+    }
+
+}

src/main/java/net/kemitix/conditional/TrueCondition.java

@@ -26,7 +26,7 @@ package net.kemitix.conditional;
  *
  * @author Paul Campbell (pcampbell@kemitix.net).
  */
-public final class TrueCondition implements Condition {
+final class TrueCondition implements Condition {
 
     protected static final Condition TRUE = new net.kemitix.conditional.TrueCondition();
 

src/main/java/net/kemitix/conditional/TrueValueClause.java

@@ -0,0 +1,69 @@
+/**
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017 Paul Campbell
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of this software
+ * and associated documentation files (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all copies
+ * or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+ * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
+ * AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+package net.kemitix.conditional;
+
+import lombok.RequiredArgsConstructor;
+
+import java.util.function.Supplier;
+
+/**
+ * An intermediate state where the clause has evaluated to true.
+ *
+ * @param <T> the type of the value
+ *
+ * @author Paul Campbell (pcampbell@kemitix.net).
+ */
+class TrueValueClause<T> implements Value.ValueClause<T> {
+
+    protected static final Value.ValueClause TRUE = new TrueValueClause();
+
+    @Override
+    public ValueSupplier<T> then(final Supplier<T> trueSupplier) {
+        return new TrueValueSupplier(trueSupplier);
+    }
+
+    @Override
+    public Value.ValueClause<T> and(final boolean clause) {
+        return Value.where(clause);
+    }
+
+    @Override
+    public Value.ValueClause<T> or(final boolean clause) {
+        return this;
+    }
+
+    /**
+     * An intermediate result of the {@link Value} where the clause has evaluated to true.
+     */
+    @RequiredArgsConstructor
+    private class TrueValueSupplier implements ValueSupplier<T> {
+
+        private final Supplier<T> valueSupplier;
+
+        @Override
+        public T otherwise(final Supplier<T> falseSupplier) {
+            return valueSupplier.get();
+        }
+
+    }
+
+}

src/main/java/net/kemitix/conditional/Value.java

@@ -21,14 +21,7 @@
 
 package net.kemitix.conditional;
 
-import lombok.RequiredArgsConstructor;
-
-import java.util.AbstractMap.SimpleEntry;
-import java.util.Collections;
-import java.util.Map;
 import java.util.function.Supplier;
-import java.util.stream.Collectors;
-import java.util.stream.Stream;
 
 /**
  * A Value from an if-then-else in a functional-style.
@@ -37,14 +30,6 @@ import java.util.stream.Stream;
  */
 public interface Value {
 
-    ValueClause TRUE = new TrueValueClause();
-
-    ValueClause FALSE = new FalseValueClause();
-
-    Map<Boolean, ValueClause> VALUE_CLAUSES = Collections.unmodifiableMap(
-            Stream.of(new SimpleEntry<>(true, TRUE), new SimpleEntry<>(false, FALSE))
-                  .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue)));
-
     /**
      * Create a new {@link ValueClause} for the clause.
      *
@@ -53,9 +38,9 @@ public interface Value {
      *
      * @return a true or false value clause
      */
-    @SuppressWarnings("unchecked")
+    @SuppressWarnings({"unchecked", "avoidinlineconditionals"})
     static <T> ValueClause<T> where(final boolean clause) {
-        return (ValueClause<T>) VALUE_CLAUSES.get(clause);
+        return (ValueClause<T>) (clause ? TrueValueClause.TRUE : FalseValueClause.FALSE);
     }
 
     /**
@@ -146,79 +131,4 @@ public interface Value {
 
     }
 
-    /**
-     * An intermediate state where the clause has evaluated to true.
-     *
-     * @param <T> the type of the value
-     */
-    class TrueValueClause<T> implements ValueClause<T> {
-
-        @Override
-        public ValueSupplier<T> then(final Supplier<T> trueSupplier) {
-            return new TrueValueSupplier(trueSupplier);
-        }
-
-        @Override
-        public ValueClause<T> and(final boolean clause) {
-            return Value.where(clause);
-        }
-
-        @Override
-        public ValueClause<T> or(final boolean clause) {
-            return this;
-        }
-
-        /**
-         * An intermediate result of the {@link Value} where the clause has evaluated to true.
-         */
-        @RequiredArgsConstructor
-        private class TrueValueSupplier implements ValueSupplier<T> {
-
-            private final Supplier<T> valueSupplier;
-
-            @Override
-            public T otherwise(final Supplier<T> falseSupplier) {
-                return valueSupplier.get();
-            }
-
-        }
-
-    }
-
-    /**
-     * An intermediate state where the clause has evaluated to false.
-     *
-     * @param <T> the type of the value
-     */
-    class FalseValueClause<T> implements ValueClause<T> {
-
-        @Override
-        public ValueSupplier<T> then(final Supplier<T> trueSupplier) {
-            return new FalseValueSupplier();
-        }
-
-        @Override
-        public ValueClause<T> and(final boolean clause) {
-            return this;
-        }
-
-        @Override
-        public ValueClause<T> or(final boolean clause) {
-            return Value.where(clause);
-        }
-
-        /**
-         * An intermediate result of the {@link Value} where the clause has evaluated to false.
-         */
-        private class FalseValueSupplier implements ValueSupplier<T> {
-
-            @Override
-            public T otherwise(final Supplier<T> falseSupplier) {
-                return falseSupplier.get();
-            }
-
-        }
-
-    }
-
 }