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| 1 // Copyright 2016 The Chromium Authors. All rights reserved. |
| 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. |
| 4 |
| 5 #ifndef BASE_TRACE_EVENT_CATEGORY_H_ |
| 6 #define BASE_TRACE_EVENT_CATEGORY_H_ |
| 7 |
| 8 #include <stddef.h> |
| 9 #include <stdint.h> |
| 10 |
| 11 #include "base/base_export.h" |
| 12 #include "base/logging.h" |
| 13 |
| 14 namespace base { |
| 15 namespace trace_event { |
| 16 |
| 17 struct TraceCategory; |
| 18 class TraceCategoryTest; |
| 19 class TraceLog; |
| 20 |
| 21 // Keeps track of the state of all tracing categories. The reason why this |
| 22 // is a fully static class with global state is to allow to statically define |
| 23 // known categories as global linker-initialized structs, without requiring |
| 24 // static initializers. |
| 25 class BASE_EXPORT CategoryRegistry { |
| 26 public: |
| 27 // Allows for-each iterations over a slice of the categories array. |
| 28 class Range { |
| 29 public: |
| 30 Range(TraceCategory* begin, TraceCategory* end) : begin_(begin), end_(end) { |
| 31 DCHECK_LE(begin, end); |
| 32 } |
| 33 TraceCategory* begin() const { return begin_; } |
| 34 TraceCategory* end() const { return end_; } |
| 35 |
| 36 private: |
| 37 TraceCategory* const begin_; |
| 38 TraceCategory* const end_; |
| 39 }; |
| 40 |
| 41 // Known categories. |
| 42 static TraceCategory* const kCategoryExhausted; |
| 43 static TraceCategory* const kCategoryMetadata; |
| 44 static TraceCategory* const kCategoryAlreadyShutdown; |
| 45 |
| 46 // Returns a category entry from the Category.state_ptr() pointer. |
| 47 // TODO(primiano): trace macros should just keep a pointer to the entire |
| 48 // TraceCategory, not just the enabled state pointer. That would remove the |
| 49 // need for this function and make everything cleaner at no extra cost (as |
| 50 // long as the |state_| is the first field of the struct, which can be |
| 51 // guaranteed via static_assert, see TraceCategory ctor). |
| 52 static const TraceCategory* GetCategoryByStatePtr( |
| 53 const uint8_t* category_state); |
| 54 |
| 55 static bool IsBuiltinCategory(const TraceCategory*); |
| 56 |
| 57 private: |
| 58 friend class TraceCategoryTest; |
| 59 friend class TraceLog; |
| 60 |
| 61 // Only for debugging/testing purposes, is a no-op on release builds. |
| 62 static void Initialize(); |
| 63 |
| 64 // Resets the state of all categories, to clear up the state between tests. |
| 65 static void ResetForTesting(); |
| 66 |
| 67 // The output |category| argument is an undefinitely lived pointer to the |
| 68 // TraceCategory owned by the registry. TRACE_EVENTx macros will cache this |
| 69 // pointer and use it for checks in their fast-paths. |
| 70 // Returns false if the category was already present, true if the category |
| 71 // has just been added and hence requires initialization. |
| 72 static bool GetOrCreateCategoryByName(const char* category_name, |
| 73 TraceCategory** category); |
| 74 |
| 75 // Allows to iterate over the valid categories in a for-each loop. |
| 76 // This includes builtin categories such as __metadata. |
| 77 static Range GetAllCategories(); |
| 78 }; |
| 79 |
| 80 } // namespace trace_event |
| 81 } // namespace base |
| 82 |
| 83 #endif // BASE_TRACE_EVENT_CATEGORY_H_ |
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