ARTEMIS-1783 Remove need for guava in client

Refactor away from Guava memorize based on Guava Supplier to using java.util.Supplier and our own memorizer code.
This commit is contained in:
Michael André Pearce 2018-05-11 07:24:35 +01:00 committed by Clebert Suconic
parent 6904af82d4
commit 19418630d4
2 changed files with 99 additions and 2 deletions

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@ -0,0 +1,95 @@
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.activemq.artemis.utils;
import java.io.Serializable;
import java.util.function.Supplier;
public class Suppliers {
/**
* Returns a supplier which caches the instance retrieved during the first
* call to {@code get()} and returns that value on subsequent calls to
* {@code get()}. See:
* <a href="http://en.wikipedia.org/wiki/Memoization">memoization</a>
*
* <p>The returned supplier is thread-safe. The delegate's {@code get()}
* method will be invoked at most once. The supplier's serialized form does
* not contain the cached value, which will be recalculated when {@code get()}
* is called on the reserialized instance.
*
* <p>If {@code delegate} is an instance created by an earlier call to {@code
* memoize}, it is returned directly.
*/
public static <T> Supplier<T> memoize(Supplier<T> delegate) {
return (delegate instanceof MemoizingSupplier)
? delegate
: new MemoizingSupplier<T>(checkNotNull(delegate));
}
private static class MemoizingSupplier<T> implements Supplier<T>, Serializable {
final Supplier<T> delegate;
transient volatile boolean initialized;
// "value" does not need to be volatile; visibility piggy-backs
// on volatile read of "initialized".
transient T value;
MemoizingSupplier(Supplier<T> delegate) {
this.delegate = delegate;
}
@Override
public T get() {
// A 2-field variant of Double Checked Locking.
if (!initialized) {
synchronized (this) {
if (!initialized) {
T t = delegate.get();
value = t;
initialized = true;
return t;
}
}
}
return value;
}
@Override
public String toString() {
return "Suppliers.memoize(" + delegate + ")";
}
private static final long serialVersionUID = 0;
}
/**
* Ensures that an object reference passed as a parameter to the calling method is not null.
*
* @param reference an object reference
* @return the non-null reference that was validated
* @throws NullPointerException if {@code reference} is null
*/
public static <T> T checkNotNull(T reference) {
if (reference == null) {
throw new NullPointerException();
}
return reference;
}
}

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@ -16,11 +16,13 @@
*/
package org.apache.activemq.artemis.core.message.impl;
import com.google.common.base.Supplier;
import com.google.common.base.Suppliers;
import org.apache.activemq.artemis.api.core.SimpleString;
import org.apache.activemq.artemis.utils.Suppliers;
import org.apache.activemq.artemis.utils.collections.TypedProperties;
import java.util.function.Supplier;
public class CoreMessageObjectPools {
private Supplier<SimpleString.ByteBufSimpleStringPool> addressDecoderPool = Suppliers.memoize(SimpleString.ByteBufSimpleStringPool::new);