/*
 * Copyright (C) 2009 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 com.google.common.annotations.GwtIncompatible;
import com.google.common.cache.LocalCache.ValueReference;
import org.checkerframework.checker.nullness.qual.Nullable;

An entry in a reference map.

Entries in the map can be in the following states:

Valid:

  • Live: valid key/value are set
  • Loading: loading is pending

Invalid:

  • Expired: time expired (key/value may still be set)
  • Collected: key/value was partially collected, but not yet cleaned up
  • Unset: marked as unset, awaiting cleanup or reuse
/** * An entry in a reference map. * * <p>Entries in the map can be in the following states: * * <p>Valid: * * <ul> * <li>Live: valid key/value are set * <li>Loading: loading is pending * </ul> * * <p>Invalid: * * <ul> * <li>Expired: time expired (key/value may still be set) * <li>Collected: key/value was partially collected, but not yet cleaned up * <li>Unset: marked as unset, awaiting cleanup or reuse * </ul> */
@GwtIncompatible interface ReferenceEntry<K, V> {
Returns the value reference from this entry.
/** Returns the value reference from this entry. */
ValueReference<K, V> getValueReference();
Sets the value reference for this entry.
/** Sets the value reference for this entry. */
void setValueReference(ValueReference<K, V> valueReference);
Returns the next entry in the chain.
/** Returns the next entry in the chain. */
@Nullable ReferenceEntry<K, V> getNext();
Returns the entry's hash.
/** Returns the entry's hash. */
int getHash();
Returns the key for this entry.
/** Returns the key for this entry. */
@Nullable K getKey(); /* * Used by entries that use access order. Access entries are maintained in a doubly-linked list. * New entries are added at the tail of the list at write time; stale entries are expired from * the head of the list. */
Returns the time that this entry was last accessed, in ns.
/** Returns the time that this entry was last accessed, in ns. */
long getAccessTime();
Sets the entry access time in ns.
/** Sets the entry access time in ns. */
void setAccessTime(long time);
Returns the next entry in the access queue.
/** Returns the next entry in the access queue. */
ReferenceEntry<K, V> getNextInAccessQueue();
Sets the next entry in the access queue.
/** Sets the next entry in the access queue. */
void setNextInAccessQueue(ReferenceEntry<K, V> next);
Returns the previous entry in the access queue.
/** Returns the previous entry in the access queue. */
ReferenceEntry<K, V> getPreviousInAccessQueue();
Sets the previous entry in the access queue.
/** Sets the previous entry in the access queue. */
void setPreviousInAccessQueue(ReferenceEntry<K, V> previous); /* * Implemented by entries that use write order. Write entries are maintained in a doubly-linked * list. New entries are added at the tail of the list at write time and stale entries are * expired from the head of the list. */
Returns the time that this entry was last written, in ns.
/** Returns the time that this entry was last written, in ns. */
long getWriteTime();
Sets the entry write time in ns.
/** Sets the entry write time in ns. */
void setWriteTime(long time);
Returns the next entry in the write queue.
/** Returns the next entry in the write queue. */
ReferenceEntry<K, V> getNextInWriteQueue();
Sets the next entry in the write queue.
/** Sets the next entry in the write queue. */
void setNextInWriteQueue(ReferenceEntry<K, V> next);
Returns the previous entry in the write queue.
/** Returns the previous entry in the write queue. */
ReferenceEntry<K, V> getPreviousInWriteQueue();
Sets the previous entry in the write queue.
/** Sets the previous entry in the write queue. */
void setPreviousInWriteQueue(ReferenceEntry<K, V> previous); }