From be70384952d3371d73bf058ab1a789b087b2cb45 Mon Sep 17 00:00:00 2001
From: JW Wang <wangchun@google.com>
Date: Fri, 24 Jul 2020 12:13:14 +0800
Subject: [PATCH] Persist sessions on the handler thread after sealing

So we won't block the binder thread by doing IO. It also
simplifies the code because this is always done at the beginning
of the install flow no matter it is a transferred session or not.

Bug: 162037825
Test: atest StagedInstallTest AtomicInstallTest
Change-Id: Ie041370320923d76d60748b19b1982306c053862
---
 .../server/pm/PackageInstallerSession.java    | 42 ++++++++++++-------
 1 file changed, 26 insertions(+), 16 deletions(-)

diff --git a/services/core/java/com/android/server/pm/PackageInstallerSession.java b/services/core/java/com/android/server/pm/PackageInstallerSession.java
index 391a08db6716a..92da005babfa0 100644
--- a/services/core/java/com/android/server/pm/PackageInstallerSession.java
+++ b/services/core/java/com/android/server/pm/PackageInstallerSession.java
@@ -164,10 +164,11 @@ public class PackageInstallerSession extends IPackageInstallerSession.Stub {
     private static final boolean LOGD = true;
     private static final String REMOVE_MARKER_EXTENSION = ".removed";
 
-    private static final int MSG_STREAM_VALIDATE_AND_COMMIT = 1;
-    private static final int MSG_INSTALL = 2;
-    private static final int MSG_ON_PACKAGE_INSTALLED = 3;
-    private static final int MSG_SESSION_VERIFICATION_FAILURE = 4;
+    private static final int MSG_ON_SESSION_SEALED = 1;
+    private static final int MSG_STREAM_VALIDATE_AND_COMMIT = 2;
+    private static final int MSG_INSTALL = 3;
+    private static final int MSG_ON_PACKAGE_INSTALLED = 4;
+    private static final int MSG_SESSION_VERIFICATION_FAILURE = 5;
 
     /** XML constants used for persisting a session */
     static final String TAG_SESSION = "session";
@@ -444,6 +445,9 @@ public class PackageInstallerSession extends IPackageInstallerSession.Stub {
         @Override
         public boolean handleMessage(Message msg) {
             switch (msg.what) {
+                case MSG_ON_SESSION_SEALED:
+                    handleSessionSealed();
+                    break;
                 case MSG_STREAM_VALIDATE_AND_COMMIT:
                     handleStreamValidateAndCommit();
                     break;
@@ -1172,6 +1176,22 @@ public class PackageInstallerSession extends IPackageInstallerSession.Stub {
             }
         }
 
+        dispatchSessionSealed();
+    }
+
+    /**
+     * Kicks off the install flow. The first step is to persist 'sealed' flags
+     * to prevent mutations of hard links created later.
+     */
+    private void dispatchSessionSealed() {
+        mHandler.obtainMessage(MSG_ON_SESSION_SEALED).sendToTarget();
+    }
+
+    private void handleSessionSealed() {
+        assertSealed("dispatchSessionSealed");
+        // Persist the fact that we've sealed ourselves to prevent
+        // mutations of any hard links we create.
+        mCallback.onSessionSealedBlocking(this);
         dispatchStreamValidateAndCommit();
     }
 
@@ -1425,11 +1445,6 @@ public class PackageInstallerSession extends IPackageInstallerSession.Stub {
             }
         }
 
-        // Persist the fact that we've sealed ourselves to prevent
-        // mutations of any hard links we create. We do this without holding
-        // the session lock, since otherwise it's a lock inversion.
-        mCallback.onSessionSealedBlocking(this);
-
         return true;
     }
 
@@ -1701,11 +1716,6 @@ public class PackageInstallerSession extends IPackageInstallerSession.Stub {
             mInstallerUid = newOwnerAppInfo.uid;
             mInstallSource = InstallSource.create(packageName, null, packageName, null);
         }
-
-        // Persist the fact that we've sealed ourselves to prevent
-        // mutations of any hard links we create. We do this without holding
-        // the session lock, since otherwise it's a lock inversion.
-        mCallback.onSessionSealedBlocking(this);
     }
 
     private void handleInstall() {
@@ -2923,9 +2933,9 @@ public class PackageInstallerSession extends IPackageInstallerSession.Stub {
                             }
                             if (hasParentSessionId()) {
                                 mSessionProvider.getSession(
-                                        getParentSessionId()).dispatchStreamValidateAndCommit();
+                                        getParentSessionId()).dispatchSessionSealed();
                             } else {
-                                dispatchStreamValidateAndCommit();
+                                dispatchSessionSealed();
                             }
                             if (manualStartAndDestroy) {
                                 dataLoader.destroy(dataLoaderId);