1 /*
2  * Copyright 2019 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 #include <android-base/stringprintf.h>
19 #include <cutils/compiler.h>
20 #include <utils/Trace.h>
21 #include <cmath>
22 #include <string>
23 
24 namespace android {
25 
26 template <typename T>
27 class TracedOrdinal {
28 public:
29     static_assert(std::is_same<bool, T>() || (std::is_signed<T>() && std::is_integral<T>()),
30                   "Type is not supported. Please test it with systrace before adding "
31                   "it to the list.");
32 
TracedOrdinal(std::string name,T initialValue)33     TracedOrdinal(std::string name, T initialValue)
34           : mName(std::move(name)),
35             mHasGoneNegative(std::signbit(initialValue)),
36             mData(initialValue) {
37         trace();
38     }
39 
T()40     operator T() const { return mData; }
41 
42     TracedOrdinal& operator=(T other) {
43         mData = other;
44         mHasGoneNegative = mHasGoneNegative || std::signbit(mData);
45         trace();
46         return *this;
47     }
48 
49 private:
trace()50     void trace() {
51         if (CC_LIKELY(!ATRACE_ENABLED())) {
52             return;
53         }
54 
55         if (mNameNegative.empty()) {
56             mNameNegative = base::StringPrintf("%sNegative", mName.c_str());
57         }
58 
59         if (!std::signbit(mData)) {
60             ATRACE_INT64(mName.c_str(), int64_t(mData));
61             if (mHasGoneNegative) {
62                 ATRACE_INT64(mNameNegative.c_str(), 0);
63             }
64         } else {
65             ATRACE_INT64(mNameNegative.c_str(), -int64_t(mData));
66             ATRACE_INT64(mName.c_str(), 0);
67         }
68     }
69 
70     const std::string mName;
71     std::string mNameNegative;
72     bool mHasGoneNegative;
73     T mData;
74 };
75 
76 } // namespace android
77