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      1 /*
      2  * Copyright (C) 2011 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.volley;
     18 
     19 /**
     20  * Default retry policy for requests.
     21  */
     22 public class DefaultRetryPolicy implements RetryPolicy {
     23     /** The current timeout in milliseconds. */
     24     private int mCurrentTimeoutMs;
     25 
     26     /** The current retry count. */
     27     private int mCurrentRetryCount;
     28 
     29     /** The maximum number of attempts. */
     30     private final int mMaxNumRetries;
     31 
     32     /** The backoff multiplier for for the policy. */
     33     private final float mBackoffMultiplier;
     34 
     35     /** The default socket timeout in milliseconds */
     36     public static final int DEFAULT_TIMEOUT_MS = 2500;
     37 
     38     /** The default number of retries */
     39     public static final int DEFAULT_MAX_RETRIES = 1;
     40 
     41     /** The default backoff multiplier */
     42     public static final float DEFAULT_BACKOFF_MULT = 1f;
     43 
     44     /**
     45      * Constructs a new retry policy using the default timeouts.
     46      */
     47     public DefaultRetryPolicy() {
     48         this(DEFAULT_TIMEOUT_MS, DEFAULT_MAX_RETRIES, DEFAULT_BACKOFF_MULT);
     49     }
     50 
     51     /**
     52      * Constructs a new retry policy.
     53      * @param initialTimeoutMs The initial timeout for the policy.
     54      * @param maxNumRetries The maximum number of retries.
     55      * @param backoffMultiplier Backoff multiplier for the policy.
     56      */
     57     public DefaultRetryPolicy(int initialTimeoutMs, int maxNumRetries, float backoffMultiplier) {
     58         mCurrentTimeoutMs = initialTimeoutMs;
     59         mMaxNumRetries = maxNumRetries;
     60         mBackoffMultiplier = backoffMultiplier;
     61     }
     62 
     63     /**
     64      * Returns the current timeout.
     65      */
     66     @Override
     67     public int getCurrentTimeout() {
     68         return mCurrentTimeoutMs;
     69     }
     70 
     71     /**
     72      * Returns the current retry count.
     73      */
     74     @Override
     75     public int getCurrentRetryCount() {
     76         return mCurrentRetryCount;
     77     }
     78 
     79     /**
     80      * Prepares for the next retry by applying a backoff to the timeout.
     81      * @param error The error code of the last attempt.
     82      */
     83     @Override
     84     public void retry(VolleyError error) throws VolleyError {
     85         mCurrentRetryCount++;
     86         mCurrentTimeoutMs += (mCurrentTimeoutMs * mBackoffMultiplier);
     87         if (!hasAttemptRemaining()) {
     88             throw error;
     89         }
     90     }
     91 
     92     /**
     93      * Returns true if this policy has attempts remaining, false otherwise.
     94      */
     95     protected boolean hasAttemptRemaining() {
     96         return mCurrentRetryCount <= mMaxNumRetries;
     97     }
     98 }
     99