Finally

app/src/main/java/nep/timeline/cirno/entity/AppRecord.java

@@ -30,6 +30,12 @@ public boolean isSystem() {
         return packageName == null || packageName.equals("android") || PKGUtils.isSystemApp(applicationInfo);
     }
 
+    public String getPackageNameWithUser() {
+        if (userId == 0)
+            return packageName;
+        return packageName + ":" + userId;
+    }
+
     public void reset() {
         this.frozen = false;
         this.appState = new AppState(this);

app/src/main/java/nep/timeline/cirno/entity/AppState.java

@@ -1,12 +1,26 @@
 package nep.timeline.cirno.entity;
 
+import android.os.IBinder;
+
+import java.util.HashSet;
+import java.util.Set;
+
 import lombok.Getter;
 
 @Getter
 public class AppState {
     private final AppRecord parent;
+    private boolean visible = false;
+    private final Set<IBinder> activities = new HashSet<>();
 
     public AppState(AppRecord appRecord) {
         this.parent = appRecord;
     }
+
+    public synchronized boolean setVisible(boolean value) {
+        if (visible == value)
+            return false;
+        visible = value;
+        return true;
+    }
 }

app/src/main/java/nep/timeline/cirno/entity/ProcessRecord.java

@@ -3,7 +3,9 @@
 import android.content.pm.ApplicationInfo;
 
 import de.robv.android.xposed.XposedHelpers;
+import lombok.AccessLevel;
 import lombok.Getter;
+import lombok.Setter;
 import nep.timeline.cirno.services.AppService;
 
 @Getter
@@ -15,7 +17,10 @@ public class ProcessRecord {
     private final int uid;
     private final String packageName;
     private final String processName;
+    @Getter(AccessLevel.NONE)
     private AppRecord appRecord;
+    @Setter
+    private boolean frozen;
 
     public ProcessRecord(Object instance) {
         this.instance = instance;

app/src/main/java/nep/timeline/cirno/hooks/android/activity/ActivityStatsHook.java

@@ -12,6 +12,9 @@
 import nep.timeline.cirno.entity.AppRecord;
 import nep.timeline.cirno.framework.AbstractMethodHook;
 import nep.timeline.cirno.framework.MethodHook;
+import nep.timeline.cirno.log.Log;
+import nep.timeline.cirno.services.FreezerService;
+import nep.timeline.cirno.threads.FreezerHandler;
 
 public class ActivityStatsHook extends MethodHook {
     private final Map<IBinder, ActivityRecord> activityRecords = new ConcurrentHashMap<>();
@@ -62,6 +65,20 @@ protected void beforeMethod(MethodHookParam param) {
                 if (appRecord == null)
                     return;
 
+                if (event == UsageEvents.Event.ACTIVITY_RESUMED)
+                    appRecord.getAppState().getActivities().add(activityRecord.getToken());
+                else
+                    appRecord.getAppState().getActivities().remove(activityRecord.getToken());
+
+                if (appRecord.getAppState().getActivities().isEmpty()) {
+                    if (appRecord.getAppState().setVisible(false)) {
+                        Log.d(appRecord.getPackageNameWithUser() + " 进入后台");
+                        FreezerHandler.sendFreezeMessage(appRecord, 3000);
+                    }
+                } else if (appRecord.getAppState().setVisible(true)) {
+                    Log.d(appRecord.getPackageNameWithUser() + " 进入前台");
+                    FreezerService.thaw(appRecord);
+                }
             }
         };
     }

app/src/main/java/nep/timeline/cirno/services/FreezerService.java

@@ -1,15 +1,34 @@
 package nep.timeline.cirno.services;
 
-import nep.timeline.cirno.utils.RWUtils;
+import nep.timeline.cirno.entity.AppRecord;
+import nep.timeline.cirno.entity.ProcessRecord;
+import nep.timeline.cirno.utils.FrozenRW;
 
 public class FreezerService {
-    public static final String cgroupV2 = "/sys/fs/cgroup/";
+    public static void freezer(AppRecord appRecord) {
+        if (appRecord.isFrozen() || appRecord.isSystem() || appRecord.getAppState().isVisible())
+            return;
 
-    public static void frozen(int uid, int pid) {
-        RWUtils.writeFrozen(cgroupV2 + "/uid_" + uid + "/pid_" + pid + "/cgroup.freeze", 1);
+        for (ProcessRecord processRecord : appRecord.getProcessRecords()) {
+            if (processRecord.isDeathProcess() || processRecord.isFrozen())
+                continue;
+
+            FrozenRW.frozen(processRecord.getRunningUid(), processRecord.getPid());
+            processRecord.setFrozen(true);
+        }
     }
 
-    public static void thaw(int uid, int pid) {
-        RWUtils.writeFrozen(cgroupV2 + "/uid_" + uid + "/pid_" + pid + "/cgroup.freeze", 0);
+
+    public static void thaw(AppRecord appRecord) {
+        if (!appRecord.isFrozen() || appRecord.isSystem())
+            return;
+
+        for (ProcessRecord processRecord : appRecord.getProcessRecords()) {
+            if (processRecord.isDeathProcess() || !processRecord.isFrozen())
+                continue;
+
+            FrozenRW.thaw(processRecord.getRunningUid(), processRecord.getPid());
+            processRecord.setFrozen(false);
+        }
     }
 }

app/src/main/java/nep/timeline/cirno/threads/FreezerHandler.java

@@ -0,0 +1,32 @@
+package nep.timeline.cirno.threads;
+
+import android.os.Handler;
+import android.os.Message;
+
+import nep.timeline.cirno.entity.AppRecord;
+
+public class FreezerHandler {
+    public static final Handler handler = new FreezerMessageHandler(Handlers.makeLooper("Freezer"));
+
+    public static void removeAppMessage(AppRecord appRecord) {
+        if (handler.hasMessages(0, appRecord))
+            handler.removeMessages(0, appRecord);
+    }
+
+    public static void sendFreezeMessage(AppRecord appRecord, long delay) {
+        if (handler.hasMessages(0, appRecord))
+            return;
+
+        sendFreezeMessageIgnoreMessages(appRecord, delay);
+    }
+
+    public static void sendFreezeMessageIgnoreMessages(AppRecord appRecord, long delay) {
+        removeAppMessage(appRecord);
+
+        Message obtain = handler.obtainMessage(0, appRecord);
+        if (delay < 1)
+            handler.sendMessage(obtain);
+        else
+            handler.sendMessageDelayed(obtain, delay);
+    }
+}

app/src/main/java/nep/timeline/cirno/threads/FreezerMessageHandler.java

@@ -0,0 +1,27 @@
+package nep.timeline.cirno.threads;
+
+import android.os.Handler;
+import android.os.Looper;
+import android.os.Message;
+
+import androidx.annotation.NonNull;
+
+import nep.timeline.cirno.entity.AppRecord;
+import nep.timeline.cirno.log.Log;
+import nep.timeline.cirno.services.FreezerService;
+
+public class FreezerMessageHandler extends Handler {
+    public FreezerMessageHandler(Looper looper) {
+        super(looper);
+    }
+
+    @Override
+    public void handleMessage(@NonNull Message message) {
+        super.handleMessage(message);
+        try {
+            FreezerService.freezer((AppRecord) message.obj);
+        } catch (Throwable th) {
+            Log.e("Freezer", th);
+        }
+    }
+}

app/src/main/java/nep/timeline/cirno/utils/FrozenRW.java

@@ -0,0 +1,13 @@
+package nep.timeline.cirno.utils;
+
+public class FrozenRW {
+    public static final String cgroupV2 = "/sys/fs/cgroup/";
+
+    public static void frozen(int uid, int pid) {
+        RWUtils.writeFrozen(cgroupV2 + "/uid_" + uid + "/pid_" + pid + "/cgroup.freeze", 1);
+    }
+
+    public static void thaw(int uid, int pid) {
+        RWUtils.writeFrozen(cgroupV2 + "/uid_" + uid + "/pid_" + pid + "/cgroup.freeze", 0);
+    }
+}