From 3fa0ce99ac29df436d1f69b520492178d255d6c2 Mon Sep 17 00:00:00 2001
From: JW Wang <wangchun@google.com>
Date: Fri, 20 Dec 2019 14:34:40 +0800
Subject: [PATCH] Enable a new rollback only when all child sessions succeeded
 (1/n)

Don't enable a new rollback until all its child sessions are
notified with success by SessionCallback#onFinished.

This change allows us to delete/remove a new rollback if any of its
child sessions failed before enabling it.

Bug: 134652027
Test: atest RollbackTest

Change-Id: Ie7cee8b0998a1df381a83219988a3876629fbcbb
---
 .../rollback/RollbackManagerServiceImpl.java  | 50 +++++++++++++++----
 1 file changed, 39 insertions(+), 11 deletions(-)

diff --git a/services/core/java/com/android/server/rollback/RollbackManagerServiceImpl.java b/services/core/java/com/android/server/rollback/RollbackManagerServiceImpl.java
index 9a65ae6dba4dc..c21c0a99f822d 100644
--- a/services/core/java/com/android/server/rollback/RollbackManagerServiceImpl.java
+++ b/services/core/java/com/android/server/rollback/RollbackManagerServiceImpl.java
@@ -1089,19 +1089,28 @@ class RollbackManagerServiceImpl extends IRollbackManager.Stub {
             if (LOCAL_LOGV) {
                 Slog.v(TAG, "SessionCallback.onFinished id=" + sessionId + " success=" + success);
             }
-            NewRollback newRollback;
-            synchronized (mLock) {
-                newRollback = getNewRollbackForPackageSessionLocked(sessionId);
-                if (newRollback != null) {
-                    mNewRollbacks.remove(newRollback);
-                }
-            }
 
-            if (newRollback != null) {
-                Rollback rollback = completeEnableRollback(newRollback, success);
-                if (rollback != null && !rollback.isStaged()) {
-                    makeRollbackAvailable(rollback);
+            if (success) {
+                NewRollback newRollback;
+                synchronized (mLock) {
+                    newRollback = getNewRollbackForPackageSessionLocked(sessionId);
+                    if (newRollback != null && newRollback.notifySessionWithSuccess()) {
+                        mNewRollbacks.remove(newRollback);
+                    } else {
+                        // Not all child sessions finished with success.
+                        // Don't enable the rollback yet.
+                        newRollback = null;
+                    }
                 }
+
+                if (newRollback != null) {
+                    Rollback rollback = completeEnableRollback(newRollback, success);
+                    if (rollback != null && !rollback.isStaged()) {
+                        makeRollbackAvailable(rollback);
+                    }
+                }
+            } else {
+                // TODO: delete rollbacks for this failed session
             }
 
             // Clear the queue so it will never be leaked to next tests.
@@ -1251,6 +1260,14 @@ class RollbackManagerServiceImpl extends IRollbackManager.Stub {
         @GuardedBy("mNewRollbackLock")
         private boolean mIsCancelled = false;
 
+        /**
+         * The number of sessions in the install which are notified with success by
+         * {@link PackageInstaller.SessionCallback#onFinished(int, boolean)}.
+         * This NewRollback will be enabled only after all child sessions finished with success.
+         */
+        @GuardedBy("mNewRollbackLock")
+        private int mNumPackageSessionsWithSuccess;
+
         private final Object mNewRollbackLock = new Object();
 
         NewRollback(Rollback rollback, int[] packageSessionIds) {
@@ -1322,6 +1339,17 @@ class RollbackManagerServiceImpl extends IRollbackManager.Stub {
         int getPackageSessionIdCount() {
             return mPackageSessionIds.length;
         }
+
+        /**
+         * Called when a child session finished with success.
+         * Returns true when all child sessions are notified with success. This NewRollback will be
+         * enabled only after all child sessions finished with success.
+         */
+        boolean notifySessionWithSuccess() {
+            synchronized (mNewRollbackLock) {
+                return ++mNumPackageSessionsWithSuccess == mPackageSessionIds.length;
+            }
+        }
     }
 
     @GuardedBy("mLock")