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Condition: avoid danger of JVM-level deadlock during initialisation

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Paul Campbell 2017-08-26 19:13:36 +01:00
parent 5cd4f5e78a
commit 62e4d56c9a
4 changed files with 110 additions and 70 deletions
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1
CHANGELOG
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@ -4,6 +4,7 @@ CHANGELOG
0.3.0
-----
* Avoid danger of JVM-level deadlock during `Condition` initialisation
* Upgrade `kemitix-parent` to 3.2.0
* Upgrade `kemitix-checkstyle-parent` to 3.2.0
* Upgrade `assertj` to 3.8.0

72
src/main/java/net/kemitix/conditional/Condition.java
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@ -21,12 +21,6 @@
package net.kemitix.conditional;
import java.util.AbstractMap.SimpleEntry;
import java.util.Collections;
import java.util.Map;
import java.util.stream.Collectors;
import java.util.stream.Stream;
/**
* If-then-else in a functional-style.
*
@ -34,14 +28,6 @@ import java.util.stream.Stream;
*/
public interface Condition {
Condition TRUE = new TrueCondition();
Condition FALSE = new FalseCondition();
Map<Boolean, Condition> CONDITIONS = Collections.unmodifiableMap(
Stream.of(new SimpleEntry<>(true, TRUE), new SimpleEntry<>(false, FALSE))
.collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue)));
/**
* Create a new {@code Condition} for the clause.
*
@ -49,8 +35,9 @@ public interface Condition {
*
* @return the Condition
*/
@SuppressWarnings("avoidinlineconditionals")
static Condition where(final boolean clause) {
return CONDITIONS.get(clause);
return clause ? TrueCondition.TRUE : FalseCondition.FALSE;
}
/**
@ -131,59 +118,4 @@ public interface Condition {
return where(clause);
}
/**
* A {@code Condition} that has evaluated to {@code true}.
*/
class TrueCondition implements Condition {
@Override
public Condition and(final boolean clause) {
return where(clause);
}
@Override
public Condition or(final boolean secondClause) {
return TRUE;
}
@Override
public Condition then(final Runnable response) {
response.run();
return TRUE;
}
@Override
public void otherwise(final Runnable response) {
// do nothing
}
}
/**
* A {@code Condition} that has evaluated to {@code false}.
*/
class FalseCondition implements Condition {
@Override
public Condition and(final boolean clause) {
return FALSE;
}
@Override
public Condition or(final boolean secondClause) {
return where(secondClause);
}
@Override
public Condition then(final Runnable response) {
return FALSE;
}
@Override
public void otherwise(final Runnable response) {
response.run();
}
}
}

53
src/main/java/net/kemitix/conditional/FalseCondition.java Normal file
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@ -0,0 +1,53 @@
/**
* 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;
/**
* A {@code Condition} that has evaluated to {@code false}.
*
* @author Paul Campbell (pcampbell@kemitix.net).
*/
public final class FalseCondition implements Condition {
protected static final Condition FALSE = new net.kemitix.conditional.FalseCondition();
@Override
public Condition and(final boolean clause) {
return FALSE;
}
@Override
public Condition or(final boolean secondClause) {
return Condition.where(secondClause);
}
@Override
public Condition then(final Runnable response) {
return FALSE;
}
@Override
public void otherwise(final Runnable response) {
response.run();
}
}

54
src/main/java/net/kemitix/conditional/TrueCondition.java Normal file
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@ -0,0 +1,54 @@
/**
* 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;
/**
* A {@code Condition} that has evaluated to {@code true}.
*
* @author Paul Campbell (pcampbell@kemitix.net).
*/
public final class TrueCondition implements Condition {
protected static final Condition TRUE = new net.kemitix.conditional.TrueCondition();
@Override
public Condition and(final boolean clause) {
return Condition.where(clause);
}
@Override
public Condition or(final boolean secondClause) {
return TRUE;
}
@Override
public Condition then(final Runnable response) {
response.run();
return TRUE;
}
@Override
public void otherwise(final Runnable response) {
// do nothing
}
}