1 // Copyright 2012 The Chromium Authors 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_SEQUENCE_CHECKER_IMPL_H_ 6 #define BASE_SEQUENCE_CHECKER_IMPL_H_ 7 8 #include <cstdint> 9 #include <memory> 10 #include <vector> 11 12 #include "base/base_export.h" 13 #include "base/sequence_token.h" 14 #include "base/synchronization/lock.h" 15 #include "base/thread_annotations.h" 16 #include "base/threading/platform_thread_ref.h" 17 18 namespace base { 19 namespace debug { 20 class StackTrace; 21 } 22 23 // Real implementation of SequenceChecker. 24 // 25 // In most cases, SEQUENCE_CHECKER should be used instead of this, get the right 26 // implementation for the build configuration. It's possible to temporarily use 27 // this directly to get sequence checking in production builds, which can be 28 // handy to debug issues only seen in the field. However, when used in a 29 // non-DCHECK build, SequenceCheckerImpl::CalledOnValidSequence() will not 30 // consider locks as a valid way to guarantee mutual exclusion (returns false if 31 // not invoked from the bound sequence, even if all calls are made under the 32 // same lock). 33 34 // Marked with "context" capability to support thread_annotations.h. 35 class THREAD_ANNOTATION_ATTRIBUTE__(capability("context")) 36 BASE_EXPORT SequenceCheckerImpl { 37 public: 38 static void EnableStackLogging(); 39 40 SequenceCheckerImpl(); 41 42 // Allow move construct/assign. This must be called on |other|'s associated 43 // sequence and assignment can only be made into a SequenceCheckerImpl which 44 // is detached or already associated with the current sequence. This isn't 45 // thread-safe (|this| and |other| shouldn't be in use while this move is 46 // performed). If the assignment was legal, the resulting SequenceCheckerImpl 47 // will be bound to the current sequence and |other| will be detached. 48 SequenceCheckerImpl(SequenceCheckerImpl&& other); 49 SequenceCheckerImpl& operator=(SequenceCheckerImpl&& other); 50 SequenceCheckerImpl(const SequenceCheckerImpl&) = delete; 51 SequenceCheckerImpl& operator=(const SequenceCheckerImpl&) = delete; 52 ~SequenceCheckerImpl(); 53 54 // Returns true if called in sequence with previous calls to this method and 55 // the constructor. 56 // On returning false, if logging is enabled with EnableStackLogging() and 57 // `out_bound_at` is not null, this method allocates a StackTrace and returns 58 // it in the out-parameter, storing inside it the stack from where the failing 59 // SequenceChecker was bound to its sequence. Otherwise, out_bound_at is left 60 // untouched. 61 [[nodiscard]] bool CalledOnValidSequence( 62 std::unique_ptr<debug::StackTrace>* out_bound_at = nullptr) const; 63 64 // Unbinds the checker from the currently associated sequence. The checker 65 // will be re-bound on the next call to CalledOnValidSequence(). 66 void DetachFromSequence(); 67 68 private: 69 void EnsureAssigned() const EXCLUSIVE_LOCKS_REQUIRED(lock_); 70 71 // Members are mutable so that `CalledOnValidSequence()` can set them. 72 73 mutable Lock lock_; 74 75 // Stack from which this was bound (set if `EnableStackLogging()` was called). 76 mutable std::unique_ptr<debug::StackTrace> bound_at_ GUARDED_BY(lock_); 77 78 // Sequence to which this is bound. 79 mutable internal::SequenceToken sequence_token_ GUARDED_BY(lock_); 80 81 #if DCHECK_IS_ON() 82 // Locks to which this is bound. 83 mutable std::vector<uintptr_t> locks_ GUARDED_BY(lock_); 84 #endif // DCHECK_IS_ON() 85 86 // Thread to which this is bound. Only used to evaluate 87 // `CalledOnValidSequence()` after TLS destruction. 88 mutable PlatformThreadRef thread_ref_ GUARDED_BY(lock_); 89 }; 90 91 } // namespace base 92 93 #endif // BASE_SEQUENCE_CHECKER_IMPL_H_ 94