1 // 2 // Copyright (c) 2013 The WebRTC project authors. All Rights Reserved. 3 // 4 // Use of this source code is governed by a BSD-style license 5 // that can be found in the LICENSE file in the root of the source 6 // tree. An additional intellectual property rights grant can be found 7 // in the file PATENTS. All contributing project authors may 8 // be found in the AUTHORS file in the root of the source tree. 9 // 10 // Borrowed from 11 // https://code.google.com/p/gperftools/source/browse/src/base/thread_annotations.h 12 // but adapted for clang attributes instead of the gcc. 13 // 14 // This header file contains the macro definitions for thread safety 15 // annotations that allow the developers to document the locking policies 16 // of their multi-threaded code. The annotations can also help program 17 // analysis tools to identify potential thread safety issues. 18 19 #ifndef RTC_BASE_THREAD_ANNOTATIONS_H_ 20 #define RTC_BASE_THREAD_ANNOTATIONS_H_ 21 22 #if defined(__clang__) && (!defined(SWIG)) 23 #define RTC_THREAD_ANNOTATION_ATTRIBUTE__(x) __attribute__((x)) 24 #else 25 #define RTC_THREAD_ANNOTATION_ATTRIBUTE__(x) // no-op 26 #endif 27 28 // Document if a shared variable/field needs to be protected by a lock. 29 // GUARDED_BY allows the user to specify a particular lock that should be 30 // held when accessing the annotated variable. 31 #define RTC_GUARDED_BY(x) RTC_THREAD_ANNOTATION_ATTRIBUTE__(guarded_by(x)) 32 33 // Document if the memory location pointed to by a pointer should be guarded 34 // by a lock when dereferencing the pointer. Note that a pointer variable to a 35 // shared memory location could itself be a shared variable. For example, if a 36 // shared global pointer q, which is guarded by mu1, points to a shared memory 37 // location that is guarded by mu2, q should be annotated as follows: 38 // int *q GUARDED_BY(mu1) PT_GUARDED_BY(mu2); 39 #define RTC_PT_GUARDED_BY(x) RTC_THREAD_ANNOTATION_ATTRIBUTE__(pt_guarded_by(x)) 40 41 // Document the acquisition order between locks that can be held 42 // simultaneously by a thread. For any two locks that need to be annotated 43 // to establish an acquisition order, only one of them needs the annotation. 44 // (i.e. You don't have to annotate both locks with both ACQUIRED_AFTER 45 // and ACQUIRED_BEFORE.) 46 #define RTC_ACQUIRED_AFTER(x) \ 47 RTC_THREAD_ANNOTATION_ATTRIBUTE__(acquired_after(x)) 48 #define RTC_ACQUIRED_BEFORE(x) \ 49 RTC_THREAD_ANNOTATION_ATTRIBUTE__(acquired_before(x)) 50 51 // The following three annotations document the lock requirements for 52 // functions/methods. 53 54 // Document if a function expects certain locks to be held before it is called 55 #define RTC_EXCLUSIVE_LOCKS_REQUIRED(...) \ 56 RTC_THREAD_ANNOTATION_ATTRIBUTE__(exclusive_locks_required(__VA_ARGS__)) 57 #define RTC_SHARED_LOCKS_REQUIRED(...) \ 58 RTC_THREAD_ANNOTATION_ATTRIBUTE__(shared_locks_required(__VA_ARGS__)) 59 60 // Document the locks acquired in the body of the function. These locks 61 // cannot be held when calling this function (as google3's Mutex locks are 62 // non-reentrant). 63 #define RTC_LOCKS_EXCLUDED(...) \ 64 RTC_THREAD_ANNOTATION_ATTRIBUTE__(locks_excluded(__VA_ARGS__)) 65 66 // Document the lock the annotated function returns without acquiring it. 67 #define RTC_LOCK_RETURNED(x) RTC_THREAD_ANNOTATION_ATTRIBUTE__(lock_returned(x)) 68 69 // Document if a class/type is a lockable type (such as the Mutex class). 70 #define RTC_LOCKABLE RTC_THREAD_ANNOTATION_ATTRIBUTE__(lockable) 71 72 // Document if a class is a scoped lockable type (such as the MutexLock class). 73 #define RTC_SCOPED_LOCKABLE RTC_THREAD_ANNOTATION_ATTRIBUTE__(scoped_lockable) 74 75 // The following annotations specify lock and unlock primitives. 76 #define RTC_EXCLUSIVE_LOCK_FUNCTION(...) \ 77 RTC_THREAD_ANNOTATION_ATTRIBUTE__(exclusive_lock_function(__VA_ARGS__)) 78 79 #define RTC_SHARED_LOCK_FUNCTION(...) \ 80 RTC_THREAD_ANNOTATION_ATTRIBUTE__(shared_lock_function(__VA_ARGS__)) 81 82 #define RTC_EXCLUSIVE_TRYLOCK_FUNCTION(...) \ 83 RTC_THREAD_ANNOTATION_ATTRIBUTE__(exclusive_trylock_function(__VA_ARGS__)) 84 85 #define RTC_SHARED_TRYLOCK_FUNCTION(...) \ 86 RTC_THREAD_ANNOTATION_ATTRIBUTE__(shared_trylock_function(__VA_ARGS__)) 87 88 #define RTC_UNLOCK_FUNCTION(...) \ 89 RTC_THREAD_ANNOTATION_ATTRIBUTE__(unlock_function(__VA_ARGS__)) 90 91 // An escape hatch for thread safety analysis to ignore the annotated function. 92 #define RTC_NO_THREAD_SAFETY_ANALYSIS \ 93 RTC_THREAD_ANNOTATION_ATTRIBUTE__(no_thread_safety_analysis) 94 95 #endif // RTC_BASE_THREAD_ANNOTATIONS_H_ 96