Defer post-install resource clean up for 5 seconds

There is an inherent problem with deleting files on disk while an
app is running, since it might still try to access code/resources
in the deleted files.

We cannot instantaneously update all application threads to the
new paths without blocking the world, so keep the old ones around
for an arbitrary amount of time.

As mentioned in the linked bug, if PackageManager boots with
duplicated app directories, it will automatically clean itself up,
so we are not concerned with the case where the deferred delete
message doesn't get executed in the current device boot cycle.

5 seconds was chosen with no reasoning beyond it feels safe.

Bug: 129291162

Test: manual reboot device with invalid dirs on disk
Test: manual dynamic feature delivery app with --dont-kill split

Merged-In: Id249a185a8556ebf133be3c36b1fec3f14b588ac
Change-Id: Id249a185a8556ebf133be3c36b1fec3f14b588ac
(cherry picked from commit 87380366ecf60f2cb2697cb26e07ccaf666b45e6)

1 files changed, 26 insertions, 5 deletions

diff --git a/services/core/java/com/android/server/pm/PackageManagerService.java b/services/core/java/com/android/server/pm/PackageManagerService.java
index c4d4106804e1..f03240072807 100644
--- a/services/core/java/com/android/server/pm/PackageManagerService.java
+++ b/services/core/java/com/android/server/pm/PackageManagerService.java
@@ -1319,6 +1319,9 @@ public class PackageManagerService extends IPackageManager.Stub
     static final int INSTANT_APP_RESOLUTION_PHASE_TWO = 20;
     static final int ENABLE_ROLLBACK_STATUS = 21;
     static final int ENABLE_ROLLBACK_TIMEOUT = 22;
+    static final int DEFERRED_NO_KILL_POST_DELETE = 23;
+
+    static final int DEFERRED_NO_KILL_POST_DELETE_DELAY_MS = 5 * 1000;
 
     static final int WRITE_SETTINGS_DELAY = 10*1000;  // 10 seconds
 
@@ -1525,6 +1528,12 @@ public class PackageManagerService extends IPackageManager.Stub
 
                     Trace.asyncTraceEnd(TRACE_TAG_PACKAGE_MANAGER, "postInstall", msg.arg1);
                 } break;
+                case DEFERRED_NO_KILL_POST_DELETE: {
+                    synchronized (mInstallLock) {
+                        InstallArgs args = (InstallArgs) msg.obj;
+                        args.doPostDeleteLI(true);
+                    }
+                } break;
                 case WRITE_SETTINGS: {
                     Process.setThreadPriority(Process.THREAD_PRIORITY_DEFAULT);
                     synchronized (mPackages) {
@@ -2029,11 +2038,18 @@ public class PackageManagerService extends IPackageManager.Stub
                     getUnknownSourcesSettings());
 
             // Remove the replaced package's older resources safely now
-            // We delete after a gc for applications  on sdcard.
-            if (res.removedInfo != null && res.removedInfo.args != null) {
-                Runtime.getRuntime().gc();
-                synchronized (mInstallLock) {
-                    res.removedInfo.args.doPostDeleteLI(true);
+            InstallArgs args = res.removedInfo != null ? res.removedInfo.args : null;
+            if (args != null) {
+                if (!killApp) {
+                    // If we didn't kill the app, defer the deletion of code/resource files, since
+                    // they may still be in use by the running application. This mitigates problems
+                    // in cases where resources or code is loaded by a new Activity before
+                    // ApplicationInfo changes have propagated to all application threads.
+                    scheduleDeferredNoKillPostDelete(args);
+                } else {
+                    synchronized (mInstallLock) {
+                        args.doPostDeleteLI(true);
+                    }
                 }
             } else {
                 // Force a gc to clear up things. Ask for a background one, it's fine to go on
@@ -2068,6 +2084,11 @@ public class PackageManagerService extends IPackageManager.Stub
         }
     }
 
+    private void scheduleDeferredNoKillPostDelete(InstallArgs args) {
+        Message message = mHandler.obtainMessage(DEFERRED_NO_KILL_POST_DELETE, args);
+        mHandler.sendMessageDelayed(message, DEFERRED_NO_KILL_POST_DELETE_DELAY_MS);
+    }
+
     /**
      * Gets the type of the external storage a package is installed on.
      * @param packageVolume The storage volume of the package.