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rajender |
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/*
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* Copyright (C) 2011 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.android.volley;
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import java.util.Collections;
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import java.util.Map;
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/**
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* An interface for a cache keyed by a String with a byte array as data.
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*/
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public interface Cache {
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/**
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* Retrieves an entry from the cache.
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* @param key Cache key
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* @return An {@link Entry} or null in the event of a cache miss
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*/
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Entry get(String key);
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/**
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* Adds or replaces an entry to the cache.
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* @param key Cache key
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* @param entry Data to store and metadata for cache coherency, TTL, etc.
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*/
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void put(String key, Entry entry);
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/**
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* Performs any potentially long-running actions needed to initialize the cache;
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* will be called from a worker thread.
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*/
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void initialize();
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/**
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* Invalidates an entry in the cache.
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* @param key Cache key
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* @param fullExpire True to fully expire the entry, false to soft expire
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*/
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void invalidate(String key, boolean fullExpire);
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/**
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* Removes an entry from the cache.
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* @param key Cache key
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*/
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void remove(String key);
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/**
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* Empties the cache.
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*/
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void clear();
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/**
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* Data and metadata for an entry returned by the cache.
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*/
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class Entry {
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/** The data returned from cache. */
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public byte[] data;
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/** ETag for cache coherency. */
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public String etag;
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/** Date of this response as reported by the server. */
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public long serverDate;
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/** The last modified date for the requested object. */
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public long lastModified;
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/** TTL for this record. */
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public long ttl;
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/** Soft TTL for this record. */
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public long softTtl;
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/** Immutable response headers as received from server; must be non-null. */
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public Map<String, String> responseHeaders = Collections.emptyMap();
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/** True if the entry is expired. */
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public boolean isExpired() {
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return this.ttl < System.currentTimeMillis();
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}
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/** True if a refresh is needed from the original data source. */
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public boolean refreshNeeded() {
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return this.softTtl < System.currentTimeMillis();
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}
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}
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}
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