| /* |
| * Copyright (C) 2021 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. |
| */ |
| |
| #ifndef INCLUDE_PERFETTO_TRACING_STRING_HELPERS_H_ |
| #define INCLUDE_PERFETTO_TRACING_STRING_HELPERS_H_ |
| |
| #include "perfetto/base/export.h" |
| |
| #include <cstddef> |
| #include <string> |
| |
| namespace perfetto { |
| |
| // A wrapper for marking strings that can't be determined to be static at build |
| // time, but are in fact static. |
| class PERFETTO_EXPORT StaticString { |
| public: |
| // Implicit constructor for string literals. |
| template <size_t N> |
| constexpr StaticString(const char (&str)[N]) : value(str) {} |
| |
| // Implicit constructor for null strings. |
| constexpr StaticString(std::nullptr_t) : value(nullptr) {} |
| |
| constexpr explicit StaticString(const char* str) : value(str) {} |
| |
| const char* value; |
| }; |
| |
| namespace internal { |
| |
| // Ensure that |string| is a static constant string. |
| // |
| // If you get a compiler failure here, you are most likely trying to use |
| // TRACE_EVENT with a dynamic event name. There are two ways to fix this: |
| // |
| // 1) If the event name is actually dynamic (e.g., std::string), write it into |
| // the event manually: |
| // |
| // TRACE_EVENT("category", nullptr, [&](perfetto::EventContext ctx) { |
| // ctx.event()->set_name(dynamic_name); |
| // }); |
| // |
| // 2) If the name is static, but the pointer is computed at runtime, wrap it |
| // with perfetto::StaticString: |
| // |
| // TRACE_EVENT("category", perfetto::StaticString{name}); |
| // |
| // DANGER: Using perfetto::StaticString with strings whose contents change |
| // dynamically can cause silent trace data corruption. |
| // |
| constexpr const char* GetStaticString(StaticString string) { |
| return string.value; |
| } |
| |
| } // namespace internal |
| |
| // A explicit wrapper for marking strings as dynamic to ensure that perfetto |
| // doesn't try to cache the pointer value. |
| class PERFETTO_EXPORT DynamicString { |
| public: |
| explicit DynamicString(const std::string& str) |
| : value(str.data()), length(str.length()) {} |
| explicit DynamicString(const char* str) : value(str), length(strlen(str)) {} |
| DynamicString(const char* str, size_t len) : value(str), length(len) {} |
| |
| const char* value; |
| size_t length; |
| }; |
| |
| } // namespace perfetto |
| |
| #endif // INCLUDE_PERFETTO_TRACING_STRING_HELPERS_H_ |