1 /*
2  * Copyright (C) 2020 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 
17 #pragma once
18 
19 #include <binder/IBinder.h>
20 #include <utils/Timers.h>
21 #include <set>
22 
23 namespace android::inputdispatcher {
24 
25 /**
26  * Keeps track of the times when each connection is going to ANR.
27  * Provides the ability to quickly find the connection that is going to cause ANR next.
28  */
29 class AnrTracker {
30 public:
31     void insert(nsecs_t timeoutTime, sp<IBinder> token);
32     void erase(nsecs_t timeoutTime, const sp<IBinder>& token);
33     void eraseToken(const sp<IBinder>& token);
34     void clear();
35 
36     bool empty() const;
37     // If empty() is false, return the time at which the next connection should cause an ANR
38     // If empty() is true, return LLONG_MAX
39     nsecs_t firstTimeout() const;
40     // Return the token of the next connection that should cause an ANR.
41     // Do not call this unless empty() is false, you will encounter undefined behaviour.
42     const sp<IBinder>& firstToken() const;
43 
44 private:
45     // Optimization: use a multiset to keep track of the event timeouts. When an event is sent
46     // to the InputConsumer, we add an entry to this structure. We look at the smallest value to
47     // determine if any of the connections is unresponsive, and to determine when we should wake
48     // next for the future ANR check.
49     // Using a multiset helps quickly look up the next timeout due.
50     //
51     // We must use a multi-set, because it is plausible (although highly unlikely) to have entries
52     // from the same connection and same timestamp, but different sequence numbers.
53     // We are not tracking sequence numbers, and just allow duplicates to exist.
54     std::multiset<std::pair<nsecs_t /*timeoutTime*/, sp<IBinder> /*connectionToken*/>> mAnrTimeouts;
55 };
56 
57 } // namespace android::inputdispatcher
58