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/*
* Copyright (C) 2011 The Guava Authors
*
* Licensed 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 com.google.common.cache;
import static com.google.common.base.Preconditions.checkNotNull;
import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.collect.Maps;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ListenableFuture;
import java.util.Map;
import java.util.concurrent.atomic.AtomicInteger;
import javax.annotation.CheckForNull;
/**
* Utility {@link CacheLoader} implementations intended for use in testing.
*
* @author mike nonemacher
*/
@GwtCompatible(emulated = true)
class TestingCacheLoaders {
/**
* Returns a {@link CacheLoader} that implements a naive {@link CacheLoader#loadAll}, delegating
* {@link CacheLoader#load} calls to {@code loader}.
*/
static <K, V> CacheLoader<K, V> bulkLoader(final CacheLoader<K, V> loader) {
checkNotNull(loader);
return new CacheLoader<K, V>() {
@Override
public V load(K key) throws Exception {
return loader.load(key);
}
@Override
public Map<K, V> loadAll(Iterable<? extends K> keys) throws Exception {
Map<K, V> result = Maps.newHashMap(); // allow nulls
for (K key : keys) {
result.put(key, load(key));
}
return result;
}
};
}
/** Returns a {@link CacheLoader} that returns the given {@code constant} for every request. */
static <K, V> ConstantLoader<K, V> constantLoader(@CheckForNull V constant) {
return new ConstantLoader<>(constant);
}
/** Returns a {@link CacheLoader} that returns the given {@code constant} for every request. */
static IncrementingLoader incrementingLoader() {
return new IncrementingLoader();
}
/** Returns a {@link CacheLoader} that throws the given error for every request. */
static <K, V> CacheLoader<K, V> errorLoader(final Error e) {
checkNotNull(e);
return new CacheLoader<K, V>() {
@Override
public V load(K key) {
throw e;
}
};
}
/** Returns a {@link CacheLoader} that throws the given exception for every request. */
static <K, V> CacheLoader<K, V> exceptionLoader(final Exception e) {
checkNotNull(e);
return new CacheLoader<K, V>() {
@Override
public V load(K key) throws Exception {
throw e;
}
};
}
/** Returns a {@link CacheLoader} that returns the key for every request. */
static <T> IdentityLoader<T> identityLoader() {
return new IdentityLoader<T>();
}
/**
* Returns a {@code new Object()} for every request, and increments a counter for every request.
* The count is accessible via {@link #getCount}.
*/
static class CountingLoader extends CacheLoader<Object, Object> {
private final AtomicInteger count = new AtomicInteger();
@Override
public Object load(Object from) {
count.incrementAndGet();
return new Object();
}
public int getCount() {
return count.get();
}
}
static final class ConstantLoader<K, V> extends CacheLoader<K, V> {
private final V constant;
ConstantLoader(V constant) {
this.constant = constant;
}
@Override
public V load(K key) {
return constant;
}
}
/**
* Returns a {@code new Object()} for every request, and increments a counter for every request.
* An {@code Integer} loader that returns the key for {@code load} requests, and increments the
* old value on {@code reload} requests. The load counts are accessible via {@link #getLoadCount}
* and {@link #getReloadCount}.
*/
static class IncrementingLoader extends CacheLoader<Integer, Integer> {
private final AtomicInteger countLoad = new AtomicInteger();
private final AtomicInteger countReload = new AtomicInteger();
@Override
public Integer load(Integer key) {
countLoad.incrementAndGet();
return key;
}
@GwtIncompatible // reload
@Override
public ListenableFuture<Integer> reload(Integer key, Integer oldValue) {
countReload.incrementAndGet();
return Futures.immediateFuture(oldValue + 1);
}
public int getLoadCount() {
return countLoad.get();
}
public int getReloadCount() {
return countReload.get();
}
}
static final class IdentityLoader<T> extends CacheLoader<T, T> {
@Override
public T load(T key) {
return key;
}
}
}
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