From 2e8d5ed7768f905e77780c3d7e8a88d07e5d91b3 Mon Sep 17 00:00:00 2001
From: yinxu <yinxu@google.com>
Date: Thu, 15 Mar 2018 11:39:15 -0700
Subject: [PATCH] Use AsyncTask.SERIAL_EXECUTOR as the default executor for
 scan

Because there will be multiple callbacks for each scan and they must be
invoked with the same order as they are received by the platform, we
should use AsyncTask.SERIAL_EXECUTOR instead of
AsyncTask.THREAD_POOL_EXECUTOR as the default executor.

Bug:74840070
Test: Unit Test, CTS Test
Change-Id: I7333940dad38f7e400a4124486bdb21cea0d5220
---
 .../java/android/telephony/TelephonyManager.java |  7 +++++--
 .../android/telephony/TelephonyScanManager.java  | 16 ++++++++++++----
 2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/telephony/java/android/telephony/TelephonyManager.java b/telephony/java/android/telephony/TelephonyManager.java
index 37db96344d1c4..0b7fa64af7d7e 100644
--- a/telephony/java/android/telephony/TelephonyManager.java
+++ b/telephony/java/android/telephony/TelephonyManager.java
@@ -5425,7 +5425,10 @@ public class TelephonyManager {
      * app has carrier privileges (see {@link #hasCarrierPrivileges}).
      *
      * @param request Contains all the RAT with bands/channels that need to be scanned.
-     * @param executor The executor through which the callback should be invoked.
+     * @param executor The executor through which the callback should be invoked. Since the scan
+     *        request may trigger multiple callbacks and they must be invoked in the same order as
+     *        they are received by the platform, the user should provide an executor which executes
+     *        tasks one at a time in serial order. For example AsyncTask.SERIAL_EXECUTOR.
      * @param callback Returns network scan results or errors.
      * @return A NetworkScan obj which contains a callback which can be used to stop the scan.
      */
@@ -5451,7 +5454,7 @@ public class TelephonyManager {
     @RequiresPermission(android.Manifest.permission.MODIFY_PHONE_STATE)
     public NetworkScan requestNetworkScan(
         NetworkScanRequest request, TelephonyScanManager.NetworkScanCallback callback) {
-        return requestNetworkScan(request, AsyncTask.THREAD_POOL_EXECUTOR, callback);
+        return requestNetworkScan(request, AsyncTask.SERIAL_EXECUTOR, callback);
     }
 
     /**
diff --git a/telephony/java/android/telephony/TelephonyScanManager.java b/telephony/java/android/telephony/TelephonyScanManager.java
index 99e2db883e524..96ff33255b535 100644
--- a/telephony/java/android/telephony/TelephonyScanManager.java
+++ b/telephony/java/android/telephony/TelephonyScanManager.java
@@ -137,8 +137,10 @@ public final class TelephonyScanManager {
                             for (int i = 0; i < parcelables.length; i++) {
                                 ci[i] = (CellInfo) parcelables[i];
                             }
-                            executor.execute(() ->
-                                    callback.onResults((List<CellInfo>) Arrays.asList(ci)));
+                            executor.execute(() ->{
+                                Rlog.d(TAG, "onResults: " + ci.toString());
+                                callback.onResults((List<CellInfo>) Arrays.asList(ci));
+                            });
                         } catch (Exception e) {
                             Rlog.e(TAG, "Exception in networkscan callback onResults", e);
                         }
@@ -146,14 +148,20 @@ public final class TelephonyScanManager {
                     case CALLBACK_SCAN_ERROR:
                         try {
                             final int errorCode = message.arg1;
-                            executor.execute(() -> callback.onError(errorCode));
+                            executor.execute(() -> {
+                                Rlog.d(TAG, "onError: " + errorCode);
+                                callback.onError(errorCode);
+                            });
                         } catch (Exception e) {
                             Rlog.e(TAG, "Exception in networkscan callback onError", e);
                         }
                         break;
                     case CALLBACK_SCAN_COMPLETE:
                         try {
-                            executor.execute(() -> callback.onComplete());
+                            executor.execute(() -> {
+                                Rlog.d(TAG, "onComplete");
+                                callback.onComplete();
+                            });
                             mScanInfo.remove(message.arg2);
                         } catch (Exception e) {
                             Rlog.e(TAG, "Exception in networkscan callback onComplete", e);