Migrate Tethering#dump to use runWithScissorsForDump

This change includes:
  1. Refactor the logic in Tethering#dump into utils class.
  2. Move the utils class to a common place which could be referenced
     from other sub-modules.
  3. Add @MonitorThreadLeak annotation to enforce
     there is no thread leak problem.

Test: atest FrameworksNetTests NetworkStaticLibTests
Test: atest ConnectivityCoverageTests:com.android.networkstack.tethering.TetheringTest#testDumpTetheringLog
Test: adb shell dumpsys tethering (with hardcoded exception)
Fix: 312669345

Change-Id: Ia6fdfeeec2110afa0ec9e056e9db3843748845c3
diff --git a/service/src/com/android/server/ConnectivityService.java b/service/src/com/android/server/ConnectivityService.java
index b4efa34..31b14ef 100755
--- a/service/src/com/android/server/ConnectivityService.java
+++ b/service/src/com/android/server/ConnectivityService.java
@@ -291,6 +291,7 @@
 import com.android.net.module.util.BpfUtils;
 import com.android.net.module.util.CollectionUtils;
 import com.android.net.module.util.DeviceConfigUtils;
+import com.android.net.module.util.HandlerUtils;
 import com.android.net.module.util.InterfaceParams;
 import com.android.net.module.util.LinkPropertiesUtils.CompareOrUpdateResult;
 import com.android.net.module.util.LinkPropertiesUtils.CompareResult;
@@ -315,7 +316,6 @@
 import com.android.server.connectivity.DnsManager.PrivateDnsValidationUpdate;
 import com.android.server.connectivity.DscpPolicyTracker;
 import com.android.server.connectivity.FullScore;
-import com.android.server.connectivity.HandlerUtils;
 import com.android.server.connectivity.InvalidTagException;
 import com.android.server.connectivity.KeepaliveResourceUtil;
 import com.android.server.connectivity.KeepaliveTracker;
@@ -1280,7 +1280,7 @@
         LocalPriorityDump() {}
 
         private void dumpHigh(FileDescriptor fd, PrintWriter pw) {
-            if (!HandlerUtils.runWithScissors(mHandler, () -> {
+            if (!HandlerUtils.runWithScissorsForDump(mHandler, () -> {
                 doDump(fd, pw, new String[]{DIAG_ARG});
                 doDump(fd, pw, new String[]{SHORT_ARG});
             }, DUMPSYS_DEFAULT_TIMEOUT_MS)) {
@@ -1289,7 +1289,7 @@
         }
 
         private void dumpNormal(FileDescriptor fd, PrintWriter pw, String[] args) {
-            if (!HandlerUtils.runWithScissors(mHandler, () -> doDump(fd, pw, args),
+            if (!HandlerUtils.runWithScissorsForDump(mHandler, () -> doDump(fd, pw, args),
                     DUMPSYS_DEFAULT_TIMEOUT_MS)) {
                 pw.println("dumpNormal timeout");
             }
diff --git a/service/src/com/android/server/connectivity/HandlerUtils.java b/service/src/com/android/server/connectivity/HandlerUtils.java
deleted file mode 100644
index 997ecbf..0000000
--- a/service/src/com/android/server/connectivity/HandlerUtils.java
+++ /dev/null
@@ -1,139 +0,0 @@
-/*
- * Copyright (C) 2023 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package com.android.server.connectivity;
-
-import android.annotation.NonNull;
-import android.os.Handler;
-import android.os.Looper;
-import android.os.SystemClock;
-
-/**
- * Helper class for Handler related utilities.
- *
- * @hide
- */
-public class HandlerUtils {
-    // Note: @hide methods copied from android.os.Handler
-    /**
-     * Runs the specified task synchronously.
-     * <p>
-     * If the current thread is the same as the handler thread, then the runnable
-     * runs immediately without being enqueued.  Otherwise, posts the runnable
-     * to the handler and waits for it to complete before returning.
-     * </p><p>
-     * This method is dangerous!  Improper use can result in deadlocks.
-     * Never call this method while any locks are held or use it in a
-     * possibly re-entrant manner.
-     * </p><p>
-     * This method is occasionally useful in situations where a background thread
-     * must synchronously await completion of a task that must run on the
-     * handler's thread.  However, this problem is often a symptom of bad design.
-     * Consider improving the design (if possible) before resorting to this method.
-     * </p><p>
-     * One example of where you might want to use this method is when you just
-     * set up a Handler thread and need to perform some initialization steps on
-     * it before continuing execution.
-     * </p><p>
-     * If timeout occurs then this method returns <code>false</code> but the runnable
-     * will remain posted on the handler and may already be in progress or
-     * complete at a later time.
-     * </p><p>
-     * When using this method, be sure to use {@link Looper#quitSafely} when
-     * quitting the looper.  Otherwise {@link #runWithScissors} may hang indefinitely.
-     * (TODO: We should fix this by making MessageQueue aware of blocking runnables.)
-     * </p>
-     *
-     * @param h The target handler.
-     * @param r The Runnable that will be executed synchronously.
-     * @param timeout The timeout in milliseconds, or 0 to wait indefinitely.
-     *
-     * @return Returns true if the Runnable was successfully executed.
-     *         Returns false on failure, usually because the
-     *         looper processing the message queue is exiting.
-     *
-     * @hide This method is prone to abuse and should probably not be in the API.
-     * If we ever do make it part of the API, we might want to rename it to something
-     * less funny like runUnsafe().
-     */
-    public static boolean runWithScissors(@NonNull Handler h, @NonNull Runnable r, long timeout) {
-        if (r == null) {
-            throw new IllegalArgumentException("runnable must not be null");
-        }
-        if (timeout < 0) {
-            throw new IllegalArgumentException("timeout must be non-negative");
-        }
-
-        if (Looper.myLooper() == h.getLooper()) {
-            r.run();
-            return true;
-        }
-
-        BlockingRunnable br = new BlockingRunnable(r);
-        return br.postAndWait(h, timeout);
-    }
-
-    private static final class BlockingRunnable implements Runnable {
-        private final Runnable mTask;
-        private boolean mDone;
-
-        BlockingRunnable(Runnable task) {
-            mTask = task;
-        }
-
-        @Override
-        public void run() {
-            try {
-                mTask.run();
-            } finally {
-                synchronized (this) {
-                    mDone = true;
-                    notifyAll();
-                }
-            }
-        }
-
-        public boolean postAndWait(Handler handler, long timeout) {
-            if (!handler.post(this)) {
-                return false;
-            }
-
-            synchronized (this) {
-                if (timeout > 0) {
-                    final long expirationTime = SystemClock.uptimeMillis() + timeout;
-                    while (!mDone) {
-                        long delay = expirationTime - SystemClock.uptimeMillis();
-                        if (delay <= 0) {
-                            return false; // timeout
-                        }
-                        try {
-                            wait(delay);
-                        } catch (InterruptedException ex) {
-                        }
-                    }
-                } else {
-                    while (!mDone) {
-                        try {
-                            wait();
-                        } catch (InterruptedException ex) {
-                        }
-                    }
-                }
-            }
-            return true;
-        }
-    }
-}