1 // Copyright (C) 2018 The Android Open Source Project 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 #include <ostream> 16 17 namespace iorap { 18 19 // kIsDebugBuild is special. 20 // It gets to be in the 'iorap' namespace 21 // so that different modules don't need to qualify it. 22 #ifndef NDEBUG 23 static constexpr bool kIsDebugBuild = true; 24 #else 25 static constexpr bool kIsDebugBuild = false; 26 #endif 27 28 namespace common { 29 30 // TODO: move below code to helpers. 31 template <typename T, bool> 32 struct base_if_condition {}; 33 34 template <typename T> 35 struct base_if_condition<T, true> : public T {}; 36 37 template <typename T> 38 using base_if_debug = base_if_condition<T, kIsDebugBuild>; 39 40 namespace detail { 41 // "if constexpr" doesn't allow us to exclude fields from a struct/class, 42 // and also "if constexpr" doesn't allow us to reference a field that does not 43 // exist. 44 // so we must move everything into a separate base class. 45 template <bool kIsDebug = kIsDebugBuild> 46 struct DebugCounterBase { 47 constexpr size_t value() const { 48 return counter; 49 } 50 51 constexpr void set_value(size_t value) { 52 counter = value; 53 } 54 55 size_t counter{1}; // Don't start with 0. 56 }; 57 58 template <> 59 struct DebugCounterBase<false /*kIsDebug*/> { 60 constexpr size_t value() const { 61 return 0; 62 } 63 64 constexpr void set_value(size_t value) { 65 } 66 }; 67 } // namespace detail 68 69 // This counter does absolutely nothing, the code compiles to no-ops 70 // when debugging is disabled. 71 struct DebugCounter : detail::DebugCounterBase<> { 72 constexpr DebugCounter& operator++() { 73 set_value(value() + 1); 74 return *this; 75 } 76 77 constexpr DebugCounter operator++(int) { 78 DebugCounter now = *this; 79 set_value(value() + 1); 80 return now; 81 } 82 83 constexpr operator size_t() const { 84 return value(); 85 } 86 87 friend std::ostream& operator<<(std::ostream& os, DebugCounter counter); 88 }; 89 90 inline std::ostream& operator<<(std::ostream& os, DebugCounter counter) { 91 os << counter.value(); 92 return os; 93 } 94 95 // TODO: refactor DebugCounter and base traits into their own files? 96 97 } // namespace common 98 } // namespace iorap 99