com.enjoy.nerd.http.RetryHandler.java Source code

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Here is the source code for com.enjoy.nerd.http.RetryHandler.java

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/*
Android Asynchronous Http Client
Copyright (c) 2011 James Smith <james@loopj.com>
http://loopj.com
    
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.
*/

/*
Some of the retry logic in this class is heavily borrowed from the
fantastic droid-fu project: https://github.com/donnfelker/droid-fu
*/

package com.enjoy.nerd.http;

import java.io.IOException;
import java.io.InterruptedIOException;
import java.net.SocketException;
import java.net.UnknownHostException;
import java.util.HashSet;

import javax.net.ssl.SSLException;

import org.apache.http.NoHttpResponseException;
import org.apache.http.client.HttpRequestRetryHandler;
import org.apache.http.client.HttpResponseException;
import org.apache.http.protocol.ExecutionContext;
import org.apache.http.protocol.HttpContext;

import android.os.SystemClock;

class RetryHandler implements HttpRequestRetryHandler {
    private static HashSet<Class<?>> exceptionWhitelist = new HashSet<Class<?>>();
    private static HashSet<Class<?>> exceptionBlacklist = new HashSet<Class<?>>();

    static {
        // Retry if the server dropped connection on us
        exceptionWhitelist.add(NoHttpResponseException.class);
        // retry-this, since it may happens as part of a Wi-Fi to 3G failover
        exceptionWhitelist.add(UnknownHostException.class);
        // retry-this, since it may happens as part of a Wi-Fi to 3G failover
        exceptionWhitelist.add(SocketException.class);
        exceptionWhitelist.add(InterruptedIOException.class);

        // never retry timeouts
        //exceptionBlacklist.add(InterruptedIOException.class);
        exceptionBlacklist.add(HttpResponseException.class);
        // never retry SSL handshake failures
        exceptionBlacklist.add(SSLException.class);
    }

    private final int maxRetries;
    private final int retrySleepTimeMS;

    public RetryHandler(int maxRetries, int retrySleepTimeMS) {
        this.maxRetries = maxRetries;
        this.retrySleepTimeMS = retrySleepTimeMS;
    }

    @Override
    public boolean retryRequest(IOException exception, int executionCount, HttpContext context) {
        boolean retry = true;

        Boolean b = (Boolean) context.getAttribute(ExecutionContext.HTTP_REQ_SENT);
        boolean sent = (b != null && b);

        if (executionCount > maxRetries) {
            // Do not retry if over max retry count
            retry = false;
        } else if (isInList(exceptionBlacklist, exception)) {
            // immediately cancel retry if the error is blacklisted
            retry = false;
        } else if (isInList(exceptionWhitelist, exception)) {
            // immediately retry if error is whitelisted
            retry = true;
        } else if (!sent) {
            // for most other errors, retry only if request hasn't been fully sent yet
            retry = true;
        }

        /*
        if (retry) {
        // resend all idempotent requests
        HttpUriRequest currentReq = (HttpUriRequest) context.getAttribute(ExecutionContext.HTTP_REQUEST);
        if (currentReq == null) {
             return false;
        }
        }
        */

        if (retry) {
            SystemClock.sleep(retrySleepTimeMS);
        } else {
            exception.printStackTrace();
        }

        return retry;
    }

    static void addClassToWhitelist(Class<?> cls) {
        exceptionWhitelist.add(cls);
    }

    static void addClassToBlacklist(Class<?> cls) {
        exceptionBlacklist.add(cls);
    }

    protected boolean isInList(HashSet<Class<?>> list, Throwable error) {
        for (Class<?> aList : list) {
            if (aList.isInstance(error)) {
                return true;
            }
        }
        return false;
    }
}