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Commit ce522835 authored by Daichi Hirono's avatar Daichi Hirono
Browse files

Stop holding mProxyLock while downloading PAC script data. 

Holding PacManager#mProxyLock for long time eventually causes ANR when
launching new applications.

1. ActivityThread#handleBindApplication blocks until

   ActivityThread#handleBindApplication
   -> ConnectivityService#getProxyForNetwork()
   -> ConnectivityService#getDefaultProxy()

  obtains the lock of ConnectivityService#mProxyLock

2. ConnectivityService#mProxyLock can be held by
   ConnectivityService#setGlobalProxy() running on another thread until

   ConnectivityService#setGlobalProxy()
   -> ConnectivityService#sendProxyBroadcast()
   -> PacManager#setCurrentProxyScriptUrl()

  obtains the lock of PacManager#mProxyLock

3. Before the CL, PacManager#mProxyLock could be held by
   mPacDownloader#run() on mNetThread until downloading a PAC script
   completed.

The CL fixes the step 3 so that mPacDownloader#run does not keep the
lock of PacManager#mProxyLock. It eventually fixes long blocking at
ActivityThread#handleBindApplication and ANR when launching an
application.

Bug: 36317236
Test: Build succeeded
Merged-In: I864e41e1142178681f8f1b4fb7750d37e3ab2076
Change-Id: I864e41e1142178681f8f1b4fb7750d37e3ab2076
parent 58ba53bd

services/core/java/com/android/server/connectivity/PacManager.java

+19 −15
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 
 */

package com.android.server.connectivity;



import android.annotation.WorkerThread;

import android.app.AlarmManager;

import android.app.PendingIntent;

import android.content.BroadcastReceiver;
@@ -73,7 +74,7 @@ public class PacManager { 
    public static final String KEY_PROXY = "keyProxy";

    private String mCurrentPac;

    @GuardedBy("mProxyLock")

    private Uri mPacUrl = Uri.EMPTY;

    private volatile Uri mPacUrl = Uri.EMPTY;



    private AlarmManager mAlarmManager;

    @GuardedBy("mProxyLock")
@@ -86,30 +87,35 @@ public class PacManager { 
    private int mCurrentDelay;

    private int mLastPort;



    private boolean mHasSentBroadcast;

    private boolean mHasDownloaded;

    private volatile boolean mHasSentBroadcast;

    private volatile boolean mHasDownloaded;



    private Handler mConnectivityHandler;

    private int mProxyMessage;



    /**

     * Used for locking when setting mProxyService and all references to mPacUrl or mCurrentPac.

     * Used for locking when setting mProxyService and all references to mCurrentPac.

     */

    private final Object mProxyLock = new Object();



    /**

     * Runnable to download PAC script.

     * The behavior relies on the assamption it always run on mNetThread to guarantee that the

     * latest data fetched from mPacUrl is stored in mProxyService.

     */

    private Runnable mPacDownloader = new Runnable() {

        @Override

        @WorkerThread

        public void run() {

            String file;

            synchronized (mProxyLock) {

                if (Uri.EMPTY.equals(mPacUrl)) return;

            final Uri pacUrl = mPacUrl;

            if (Uri.EMPTY.equals(pacUrl)) return;

            try {

                    file = get(mPacUrl);

                file = get(pacUrl);

            } catch (IOException ioe) {

                file = null;

                Log.w(TAG, "Failed to load PAC file: " + ioe);

            }

            }

            if (file != null) {

                synchronized (mProxyLock) {

                    if (!file.equals(mCurrentPac)) {
@@ -171,9 +177,7 @@ public class PacManager { 
                // Allow to send broadcast, nothing to do.

                return false;

            }

            synchronized (mProxyLock) {

            mPacUrl = proxy.getPacFileUrl();

            }

            mCurrentDelay = DELAY_1;

            mHasSentBroadcast = false;

            mHasDownloaded = false;