1/*
2 * Copyright (C) 2012 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.android.internal.util;
18
19import android.os.Handler;
20
21import java.io.PrintWriter;
22import java.io.StringWriter;
23
24/**
25 * Helper functions for dumping the state of system services.
26 */
27public final class DumpUtils {
28    private DumpUtils() {
29    }
30
31    /**
32     * Helper for dumping state owned by a handler thread.
33     *
34     * Because the caller might be holding an important lock that the handler is
35     * trying to acquire, we use a short timeout to avoid deadlocks.  The process
36     * is inelegant but this function is only used for debugging purposes.
37     */
38    public static void dumpAsync(Handler handler, final Dump dump, PrintWriter pw,
39            final String prefix, long timeout) {
40        final StringWriter sw = new StringWriter();
41        if (handler.runWithScissors(new Runnable() {
42            @Override
43            public void run() {
44                PrintWriter lpw = new FastPrintWriter(sw);
45                dump.dump(lpw, prefix);
46                lpw.close();
47            }
48        }, timeout)) {
49            pw.print(sw.toString());
50        } else {
51            pw.println("... timed out");
52        }
53    }
54
55    public interface Dump {
56        void dump(PrintWriter pw, String prefix);
57    }
58}
59