From 8846e4d0899e69b110d28dd4dfb7c33fb0e87407 Mon Sep 17 00:00:00 2001
From: Louis Chang <louischang@google.com>
Date: Sat, 20 Feb 2021 15:05:30 +0800
Subject: [PATCH] New activity launch mode - singleInstancePerTask

Adding a new activity launch mode `singleInstancePerTask` which
is similar to singleTask that the activity is single instance and
can only be created in task root, but still allowed to be created
in multiple documents or tasks.

Also adding meta-data support of apps that targeting on previous SDK.

Bug: 175354896
Test: IntentTests

Change-Id: I4ba3b2ba6d619677f03e67d3b7da1b5d2a79907f
---
 core/api/current.txt                          |  1 +
 .../java/android/content/pm/ActivityInfo.java | 26 +++++++++++++++----
 .../android/content/pm/PackageParser.java     |  1 +
 .../component/ParsedActivityUtils.java        | 12 +++++++++
 core/res/res/values/attrs_manifest.xml        |  6 +++++
 .../android/server/wm/ActivityStarter.java    | 22 +++++++++++++++-
 6 files changed, 62 insertions(+), 6 deletions(-)

diff --git a/core/api/current.txt b/core/api/current.txt
index b1e8645a2ae33..469bcffd0f4b2 100644
--- a/core/api/current.txt
+++ b/core/api/current.txt
@@ -11719,6 +11719,7 @@ package android.content.pm {
     field public static final int FLAG_STATE_NOT_NEEDED = 16; // 0x10
     field public static final int LAUNCH_MULTIPLE = 0; // 0x0
     field public static final int LAUNCH_SINGLE_INSTANCE = 3; // 0x3
+    field public static final int LAUNCH_SINGLE_INSTANCE_PER_TASK = 4; // 0x4
     field public static final int LAUNCH_SINGLE_TASK = 2; // 0x2
     field public static final int LAUNCH_SINGLE_TOP = 1; // 0x1
     field public static final int PERSIST_ACROSS_REBOOTS = 2; // 0x2
diff --git a/core/java/android/content/pm/ActivityInfo.java b/core/java/android/content/pm/ActivityInfo.java
index b1ca12cde8577..1660c9d23002a 100644
--- a/core/java/android/content/pm/ActivityInfo.java
+++ b/core/java/android/content/pm/ActivityInfo.java
@@ -74,12 +74,28 @@ public class ActivityInfo extends ComponentInfo implements Parcelable {
      */
     public static final int LAUNCH_SINGLE_INSTANCE = 3;
     /**
-     * The launch mode style requested by the activity.  From the
-     * {@link android.R.attr#launchMode} attribute, one of
-     * {@link #LAUNCH_MULTIPLE},
-     * {@link #LAUNCH_SINGLE_TOP}, {@link #LAUNCH_SINGLE_TASK}, or
-     * {@link #LAUNCH_SINGLE_INSTANCE}.
+     * Constant corresponding to <code>singleInstancePerTask</code> in
+     * the {@link android.R.attr#launchMode} attribute.
      */
+    public static final int LAUNCH_SINGLE_INSTANCE_PER_TASK = 4;
+
+    /** @hide */
+    @IntDef(prefix = "LAUNCH_", value = {
+            LAUNCH_MULTIPLE,
+            LAUNCH_SINGLE_TOP,
+            LAUNCH_SINGLE_TASK,
+            LAUNCH_SINGLE_INSTANCE,
+            LAUNCH_SINGLE_INSTANCE_PER_TASK
+    })
+    @Retention(RetentionPolicy.SOURCE)
+    public @interface LaunchMode {
+    }
+
+    /**
+     * The launch mode style requested by the activity.  From the
+     * {@link android.R.attr#launchMode} attribute.
+     */
+    @LaunchMode
     public int launchMode;
 
     /**
diff --git a/core/java/android/content/pm/PackageParser.java b/core/java/android/content/pm/PackageParser.java
index bf8d1f6ab07b1..5e08399f8abb8 100644
--- a/core/java/android/content/pm/PackageParser.java
+++ b/core/java/android/content/pm/PackageParser.java
@@ -214,6 +214,7 @@ public class PackageParser {
     public static final String METADATA_SUPPORTS_SIZE_CHANGES = "android.supports_size_changes";
     public static final String METADATA_ACTIVITY_WINDOW_LAYOUT_AFFINITY =
             "android.activity_window_layout_affinity";
+    public static final String METADATA_ACTIVITY_LAUNCH_MODE = "android.activity.launch_mode";
 
     /**
      * Bit mask of all the valid bits that can be set in recreateOnConfigChanges.
diff --git a/core/java/android/content/pm/parsing/component/ParsedActivityUtils.java b/core/java/android/content/pm/parsing/component/ParsedActivityUtils.java
index f821e081fc66b..0f4aa061b72d0 100644
--- a/core/java/android/content/pm/parsing/component/ParsedActivityUtils.java
+++ b/core/java/android/content/pm/parsing/component/ParsedActivityUtils.java
@@ -16,6 +16,7 @@
 
 package android.content.pm.parsing.component;
 
+import static android.content.pm.ActivityInfo.LAUNCH_SINGLE_INSTANCE_PER_TASK;
 import static android.content.pm.ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED;
 import static android.content.pm.parsing.component.ComponentParseUtils.flag;
 
@@ -23,6 +24,7 @@ import android.annotation.NonNull;
 import android.app.ActivityTaskManager;
 import android.content.Intent;
 import android.content.pm.ActivityInfo;
+import android.content.pm.PackageParser;
 import android.content.pm.parsing.ParsingPackage;
 import android.content.pm.parsing.ParsingPackageUtils;
 import android.content.pm.parsing.ParsingUtils;
@@ -402,6 +404,16 @@ public class ParsedActivityUtils {
             }
         }
 
+        if (!isAlias && activity.launchMode != LAUNCH_SINGLE_INSTANCE_PER_TASK
+                && activity.metaData != null && activity.metaData.containsKey(
+                PackageParser.METADATA_ACTIVITY_LAUNCH_MODE)) {
+            final String launchMode = activity.metaData.getString(
+                    PackageParser.METADATA_ACTIVITY_LAUNCH_MODE);
+            if (launchMode != null && launchMode.equals("singleInstancePerTask")) {
+                activity.launchMode = LAUNCH_SINGLE_INSTANCE_PER_TASK;
+            }
+        }
+
         ParseResult<ActivityInfo.WindowLayout> layoutResult =
                 resolveActivityWindowLayout(activity, input);
         if (layoutResult.isError()) {
diff --git a/core/res/res/values/attrs_manifest.xml b/core/res/res/values/attrs_manifest.xml
index bed5c31bd3274..3c703fc47c559 100644
--- a/core/res/res/values/attrs_manifest.xml
+++ b/core/res/res/values/attrs_manifest.xml
@@ -825,6 +825,12 @@
             <a href="{@docRoot}guide/topics/fundamentals/tasks-and-back-stack.html">Tasks and Back
             Stack</a> document for more details about tasks.-->
         <enum name="singleInstance" value="3" />
+        <!-- The activity can only be running as the root activity of the task, the first activity
+            that created the task, and therefore there will only be one instance of this activity
+            in a task. In constrast to the {@code singleTask} launch mode, this activity can be
+            started in multiple instances in different tasks if the
+            {@code FLAG_ACTIVITY_MULTIPLE_TASK} is set.-->
+        <enum name="singleInstancePerTask" value="4" />
     </attr>
 
     <!-- Specify the orientation an activity should be run in.  If not
diff --git a/services/core/java/com/android/server/wm/ActivityStarter.java b/services/core/java/com/android/server/wm/ActivityStarter.java
index 6ce9048d79e29..da49fa72dc50c 100644
--- a/services/core/java/com/android/server/wm/ActivityStarter.java
+++ b/services/core/java/com/android/server/wm/ActivityStarter.java
@@ -48,6 +48,7 @@ import static android.content.Intent.FLAG_ACTIVITY_TASK_ON_HOME;
 import static android.content.pm.ActivityInfo.DOCUMENT_LAUNCH_ALWAYS;
 import static android.content.pm.ActivityInfo.FLAG_SHOW_FOR_ALL_USERS;
 import static android.content.pm.ActivityInfo.LAUNCH_SINGLE_INSTANCE;
+import static android.content.pm.ActivityInfo.LAUNCH_SINGLE_INSTANCE_PER_TASK;
 import static android.content.pm.ActivityInfo.LAUNCH_SINGLE_TASK;
 import static android.content.pm.ActivityInfo.LAUNCH_SINGLE_TOP;
 import static android.content.pm.PackageManager.PERMISSION_GRANTED;
@@ -2093,7 +2094,8 @@ class ActivityStarter {
             mAddingToTask = true;
         } else if ((mLaunchFlags & FLAG_ACTIVITY_CLEAR_TOP) != 0
                 || isDocumentLaunchesIntoExisting(mLaunchFlags)
-                || isLaunchModeOneOf(LAUNCH_SINGLE_INSTANCE, LAUNCH_SINGLE_TASK)) {
+                || isLaunchModeOneOf(LAUNCH_SINGLE_INSTANCE, LAUNCH_SINGLE_TASK,
+                        LAUNCH_SINGLE_INSTANCE_PER_TASK)) {
             // In this situation we want to remove all activities from the task up to the one
             // being started. In most cases this means we are resetting the task to its initial
             // state.
@@ -2261,6 +2263,12 @@ class ActivityStarter {
                 && !isLaunchModeOneOf(LAUNCH_SINGLE_TASK, LAUNCH_SINGLE_INSTANCE)
                 && (mLaunchFlags & FLAG_ACTIVITY_NEW_DOCUMENT) != 0;
 
+        if (mLaunchMode == LAUNCH_SINGLE_INSTANCE_PER_TASK) {
+            // Adding NEW_TASK flag for singleInstancePerTask launch mode activity, so that the
+            // activity won't be launched in source record's task.
+            mLaunchFlags |= FLAG_ACTIVITY_NEW_TASK;
+        }
+
         sendNewTaskResultRequestIfNeeded();
 
         if ((mLaunchFlags & FLAG_ACTIVITY_NEW_DOCUMENT) != 0 && r.resultTo == null) {
@@ -2529,6 +2537,14 @@ class ActivityStarter {
             }
         }
 
+        if (intentActivity != null && mLaunchMode == LAUNCH_SINGLE_INSTANCE_PER_TASK
+                && !intentActivity.getTask().getRootActivity().mActivityComponent.equals(
+                mStartActivity.mActivityComponent)) {
+            // The task could be selected due to same task affinity. Do not reuse the task while
+            // starting the singleInstancePerTask activity if it is not the task root activity.
+            intentActivity = null;
+        }
+
         if (intentActivity != null
                 && (mStartActivity.isActivityTypeHome() || intentActivity.isActivityTypeHome())
                 && intentActivity.getDisplayArea() != mPreferredTaskDisplayArea) {
@@ -2715,6 +2731,10 @@ class ActivityStarter {
         return mode1 == mLaunchMode || mode2 == mLaunchMode;
     }
 
+    private boolean isLaunchModeOneOf(int mode1, int mode2, int mode3) {
+        return mode1 == mLaunchMode || mode2 == mLaunchMode || mode3 == mLaunchMode;
+    }
+
     static boolean isDocumentLaunchesIntoExisting(int flags) {
         return (flags & Intent.FLAG_ACTIVITY_NEW_DOCUMENT) != 0 &&
                 (flags & Intent.FLAG_ACTIVITY_MULTIPLE_TASK) == 0;