| /* |
| * Copyright (C) 2008 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 ART_RUNTIME_MONITOR_H_ |
| #define ART_RUNTIME_MONITOR_H_ |
| |
| #include <pthread.h> |
| #include <stdint.h> |
| #include <stdlib.h> |
| |
| #include <iosfwd> |
| #include <list> |
| #include <vector> |
| |
| #include "base/allocator.h" |
| #include "base/atomic.h" |
| #include "base/mutex.h" |
| #include "gc_root.h" |
| #include "lock_word.h" |
| #include "obj_ptr.h" |
| #include "read_barrier_option.h" |
| #include "runtime_callbacks.h" |
| #include "thread_state.h" |
| |
| namespace art { |
| |
| class ArtMethod; |
| class IsMarkedVisitor; |
| class LockWord; |
| template<class T> class Handle; |
| class StackVisitor; |
| class Thread; |
| typedef uint32_t MonitorId; |
| |
| namespace mirror { |
| class Object; |
| } // namespace mirror |
| |
| enum class LockReason { |
| kForWait, |
| kForLock, |
| }; |
| |
| class Monitor { |
| public: |
| // The default number of spins that are done before thread suspension is used to forcibly inflate |
| // a lock word. See Runtime::max_spins_before_thin_lock_inflation_. |
| constexpr static size_t kDefaultMaxSpinsBeforeThinLockInflation = 50; |
| |
| ~Monitor(); |
| |
| static void Init(uint32_t lock_profiling_threshold, uint32_t stack_dump_lock_profiling_threshold); |
| |
| // Return the thread id of the lock owner or 0 when there is no owner. |
| static uint32_t GetLockOwnerThreadId(ObjPtr<mirror::Object> obj) |
| NO_THREAD_SAFETY_ANALYSIS; // TODO: Reading lock owner without holding lock is racy. |
| |
| // NO_THREAD_SAFETY_ANALYSIS for mon->Lock. |
| static ObjPtr<mirror::Object> MonitorEnter(Thread* thread, |
| ObjPtr<mirror::Object> obj, |
| bool trylock) |
| EXCLUSIVE_LOCK_FUNCTION(obj.Ptr()) |
| NO_THREAD_SAFETY_ANALYSIS |
| REQUIRES(!Roles::uninterruptible_) |
| REQUIRES_SHARED(Locks::mutator_lock_); |
| |
| // NO_THREAD_SAFETY_ANALYSIS for mon->Unlock. |
| static bool MonitorExit(Thread* thread, ObjPtr<mirror::Object> obj) |
| NO_THREAD_SAFETY_ANALYSIS |
| REQUIRES(!Roles::uninterruptible_) |
| REQUIRES_SHARED(Locks::mutator_lock_) |
| UNLOCK_FUNCTION(obj.Ptr()); |
| |
| static void Notify(Thread* self, ObjPtr<mirror::Object> obj) |
| REQUIRES_SHARED(Locks::mutator_lock_) { |
| DoNotify(self, obj, false); |
| } |
| static void NotifyAll(Thread* self, ObjPtr<mirror::Object> obj) |
| REQUIRES_SHARED(Locks::mutator_lock_) { |
| DoNotify(self, obj, true); |
| } |
| |
| // Object.wait(). Also called for class init. |
| // NO_THREAD_SAFETY_ANALYSIS for mon->Wait. |
| static void Wait(Thread* self, |
| ObjPtr<mirror::Object> obj, |
| int64_t ms, |
| int32_t ns, |
| bool interruptShouldThrow, ThreadState why) |
| REQUIRES_SHARED(Locks::mutator_lock_) NO_THREAD_SAFETY_ANALYSIS; |
| |
| static ThreadState FetchState(const Thread* thread, |
| /* out */ ObjPtr<mirror::Object>* monitor_object, |
| /* out */ uint32_t* lock_owner_tid) |
| REQUIRES(!Locks::thread_suspend_count_lock_) |
| REQUIRES_SHARED(Locks::mutator_lock_); |
| |
| // Used to implement JDWP's ThreadReference.CurrentContendedMonitor. |
| static ObjPtr<mirror::Object> GetContendedMonitor(Thread* thread) |
| REQUIRES_SHARED(Locks::mutator_lock_); |
| |
| // Calls 'callback' once for each lock held in the single stack frame represented by |
| // the current state of 'stack_visitor'. |
| // The abort_on_failure flag allows to not die when the state of the runtime is unorderly. This |
| // is necessary when we have already aborted but want to dump the stack as much as we can. |
| static void VisitLocks(StackVisitor* stack_visitor, |
| void (*callback)(ObjPtr<mirror::Object>, void*), |
| void* callback_context, |
| bool abort_on_failure = true) |
| REQUIRES_SHARED(Locks::mutator_lock_); |
| |
| static bool IsValidLockWord(LockWord lock_word); |
| |
| template<ReadBarrierOption kReadBarrierOption = kWithReadBarrier> |
| ObjPtr<mirror::Object> GetObject() REQUIRES_SHARED(Locks::mutator_lock_); |
| |
| void SetObject(ObjPtr<mirror::Object> object); |
| |
| Thread* GetOwner() const NO_THREAD_SAFETY_ANALYSIS { |
| return owner_; |
| } |
| |
| int32_t GetHashCode(); |
| |
| bool IsLocked() REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!monitor_lock_); |
| |
| bool HasHashCode() const { |
| return hash_code_.load(std::memory_order_relaxed) != 0; |
| } |
| |
| MonitorId GetMonitorId() const { |
| return monitor_id_; |
| } |
| |
| // Inflate the lock on obj. May fail to inflate for spurious reasons, always re-check. |
| static void InflateThinLocked(Thread* self, Handle<mirror::Object> obj, LockWord lock_word, |
| uint32_t hash_code) REQUIRES_SHARED(Locks::mutator_lock_); |
| |
| // Not exclusive because ImageWriter calls this during a Heap::VisitObjects() that |
| // does not allow a thread suspension in the middle. TODO: maybe make this exclusive. |
| // NO_THREAD_SAFETY_ANALYSIS for monitor->monitor_lock_. |
| static bool Deflate(Thread* self, ObjPtr<mirror::Object> obj) |
| REQUIRES_SHARED(Locks::mutator_lock_) NO_THREAD_SAFETY_ANALYSIS; |
| |
| #ifndef __LP64__ |
| void* operator new(size_t size) { |
| // Align Monitor* as per the monitor ID field size in the lock word. |
| void* result; |
| int error = posix_memalign(&result, LockWord::kMonitorIdAlignment, size); |
| CHECK_EQ(error, 0) << strerror(error); |
| return result; |
| } |
| |
| void operator delete(void* ptr) { |
| free(ptr); |
| } |
| #endif |
| |
| private: |
| Monitor(Thread* self, Thread* owner, ObjPtr<mirror::Object> obj, int32_t hash_code) |
| REQUIRES_SHARED(Locks::mutator_lock_); |
| Monitor(Thread* self, Thread* owner, ObjPtr<mirror::Object> obj, int32_t hash_code, MonitorId id) |
| REQUIRES_SHARED(Locks::mutator_lock_); |
| |
| // Install the monitor into its object, may fail if another thread installs a different monitor |
| // first. |
| bool Install(Thread* self) |
| REQUIRES(!monitor_lock_) |
| REQUIRES_SHARED(Locks::mutator_lock_); |
| |
| // Links a thread into a monitor's wait set. The monitor lock must be held by the caller of this |
| // routine. |
| void AppendToWaitSet(Thread* thread) REQUIRES(monitor_lock_); |
| |
| // Unlinks a thread from a monitor's wait set. The monitor lock must be held by the caller of |
| // this routine. |
| void RemoveFromWaitSet(Thread* thread) REQUIRES(monitor_lock_); |
| |
| void SignalContendersAndReleaseMonitorLock(Thread* self) RELEASE(monitor_lock_); |
| |
| // Changes the shape of a monitor from thin to fat, preserving the internal lock state. The |
| // calling thread must own the lock or the owner must be suspended. There's a race with other |
| // threads inflating the lock, installing hash codes and spurious failures. The caller should |
| // re-read the lock word following the call. |
| static void Inflate(Thread* self, Thread* owner, ObjPtr<mirror::Object> obj, int32_t hash_code) |
| REQUIRES_SHARED(Locks::mutator_lock_) |
| NO_THREAD_SAFETY_ANALYSIS; // For m->Install(self) |
| |
| void LogContentionEvent(Thread* self, |
| uint32_t wait_ms, |
| uint32_t sample_percent, |
| ArtMethod* owner_method, |
| uint32_t owner_dex_pc) |
| REQUIRES_SHARED(Locks::mutator_lock_); |
| |
| static void FailedUnlock(ObjPtr<mirror::Object> obj, |
| uint32_t expected_owner_thread_id, |
| uint32_t found_owner_thread_id, |
| Monitor* mon) |
| REQUIRES(!Locks::thread_list_lock_, |
| !monitor_lock_) |
| REQUIRES_SHARED(Locks::mutator_lock_); |
| |
| // Try to lock without blocking, returns true if we acquired the lock. |
| bool TryLock(Thread* self) |
| REQUIRES(!monitor_lock_) |
| REQUIRES_SHARED(Locks::mutator_lock_); |
| // Variant for already holding the monitor lock. |
| bool TryLockLocked(Thread* self) |
| REQUIRES(monitor_lock_) |
| REQUIRES_SHARED(Locks::mutator_lock_); |
| |
| template<LockReason reason = LockReason::kForLock> |
| void Lock(Thread* self) |
| REQUIRES(!monitor_lock_) |
| REQUIRES_SHARED(Locks::mutator_lock_); |
| |
| bool Unlock(Thread* thread) |
| REQUIRES(!monitor_lock_) |
| REQUIRES_SHARED(Locks::mutator_lock_); |
| |
| static void DoNotify(Thread* self, ObjPtr<mirror::Object> obj, bool notify_all) |
| REQUIRES_SHARED(Locks::mutator_lock_) NO_THREAD_SAFETY_ANALYSIS; // For mon->Notify. |
| |
| void Notify(Thread* self) |
| REQUIRES(!monitor_lock_) |
| REQUIRES_SHARED(Locks::mutator_lock_); |
| |
| void NotifyAll(Thread* self) |
| REQUIRES(!monitor_lock_) |
| REQUIRES_SHARED(Locks::mutator_lock_); |
| |
| static std::string PrettyContentionInfo(const std::string& owner_name, |
| pid_t owner_tid, |
| ArtMethod* owners_method, |
| uint32_t owners_dex_pc, |
| size_t num_waiters) |
| REQUIRES_SHARED(Locks::mutator_lock_); |
| |
| // Wait on a monitor until timeout, interrupt, or notification. Used for Object.wait() and |
| // (somewhat indirectly) Thread.sleep() and Thread.join(). |
| // |
| // If another thread calls Thread.interrupt(), we throw InterruptedException and return |
| // immediately if one of the following are true: |
| // - blocked in wait(), wait(long), or wait(long, int) methods of Object |
| // - blocked in join(), join(long), or join(long, int) methods of Thread |
| // - blocked in sleep(long), or sleep(long, int) methods of Thread |
| // Otherwise, we set the "interrupted" flag. |
| // |
| // Checks to make sure that "ns" is in the range 0-999999 (i.e. fractions of a millisecond) and |
| // throws the appropriate exception if it isn't. |
| // |
| // The spec allows "spurious wakeups", and recommends that all code using Object.wait() do so in |
| // a loop. This appears to derive from concerns about pthread_cond_wait() on multiprocessor |
| // systems. Some commentary on the web casts doubt on whether these can/should occur. |
| // |
| // Since we're allowed to wake up "early", we clamp extremely long durations to return at the end |
| // of the 32-bit time epoch. |
| void Wait(Thread* self, int64_t msec, int32_t nsec, bool interruptShouldThrow, ThreadState why) |
| REQUIRES(!monitor_lock_) |
| REQUIRES_SHARED(Locks::mutator_lock_); |
| |
| // Translates the provided method and pc into its declaring class' source file and line number. |
| static void TranslateLocation(ArtMethod* method, uint32_t pc, |
| const char** source_file, |
| int32_t* line_number) |
| REQUIRES_SHARED(Locks::mutator_lock_); |
| |
| uint32_t GetOwnerThreadId() REQUIRES(!monitor_lock_); |
| |
| // Support for systrace output of monitor operations. |
| ALWAYS_INLINE static void AtraceMonitorLock(Thread* self, |
| ObjPtr<mirror::Object> obj, |
| bool is_wait) |
| REQUIRES_SHARED(Locks::mutator_lock_); |
| static void AtraceMonitorLockImpl(Thread* self, |
| ObjPtr<mirror::Object> obj, |
| bool is_wait) |
| REQUIRES_SHARED(Locks::mutator_lock_); |
| ALWAYS_INLINE static void AtraceMonitorUnlock(); |
| |
| static uint32_t lock_profiling_threshold_; |
| static uint32_t stack_dump_lock_profiling_threshold_; |
| |
| Mutex monitor_lock_ DEFAULT_MUTEX_ACQUIRED_AFTER; |
| |
| ConditionVariable monitor_contenders_ GUARDED_BY(monitor_lock_); |
| |
| // Number of people waiting on the condition. |
| size_t num_waiters_ GUARDED_BY(monitor_lock_); |
| |
| // Which thread currently owns the lock? |
| Thread* volatile owner_ GUARDED_BY(monitor_lock_); |
| |
| // Owner's recursive lock depth. |
| int lock_count_ GUARDED_BY(monitor_lock_); |
| |
| // What object are we part of. This is a weak root. Do not access |
| // this directly, use GetObject() to read it so it will be guarded |
| // by a read barrier. |
| GcRoot<mirror::Object> obj_; |
| |
| // Threads currently waiting on this monitor. |
| Thread* wait_set_ GUARDED_BY(monitor_lock_); |
| |
| // Threads that were waiting on this monitor, but are now contending on it. |
| Thread* wake_set_ GUARDED_BY(monitor_lock_); |
| |
| // Stored object hash code, generated lazily by GetHashCode. |
| AtomicInteger hash_code_; |
| |
| // Method and dex pc where the lock owner acquired the lock, used when lock |
| // sampling is enabled. locking_method_ may be null if the lock is currently |
| // unlocked, or if the lock is acquired by the system when the stack is empty. |
| ArtMethod* locking_method_ GUARDED_BY(monitor_lock_); |
| uint32_t locking_dex_pc_ GUARDED_BY(monitor_lock_); |
| |
| // The denser encoded version of this monitor as stored in the lock word. |
| MonitorId monitor_id_; |
| |
| #ifdef __LP64__ |
| // Free list for monitor pool. |
| Monitor* next_free_ GUARDED_BY(Locks::allocated_monitor_ids_lock_); |
| #endif |
| |
| friend class MonitorInfo; |
| friend class MonitorList; |
| friend class MonitorPool; |
| friend class mirror::Object; |
| DISALLOW_COPY_AND_ASSIGN(Monitor); |
| }; |
| |
| class MonitorList { |
| public: |
| MonitorList(); |
| ~MonitorList(); |
| |
| void Add(Monitor* m) REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!monitor_list_lock_); |
| |
| void SweepMonitorList(IsMarkedVisitor* visitor) |
| REQUIRES(!monitor_list_lock_) REQUIRES_SHARED(Locks::mutator_lock_); |
| void DisallowNewMonitors() REQUIRES(!monitor_list_lock_); |
| void AllowNewMonitors() REQUIRES(!monitor_list_lock_); |
| void BroadcastForNewMonitors() REQUIRES(!monitor_list_lock_); |
| // Returns how many monitors were deflated. |
| size_t DeflateMonitors() REQUIRES(!monitor_list_lock_) REQUIRES(Locks::mutator_lock_); |
| size_t Size() REQUIRES(!monitor_list_lock_); |
| |
| typedef std::list<Monitor*, TrackingAllocator<Monitor*, kAllocatorTagMonitorList>> Monitors; |
| |
| private: |
| // During sweeping we may free an object and on a separate thread have an object created using |
| // the newly freed memory. That object may then have its lock-word inflated and a monitor created. |
| // If we allow new monitor registration during sweeping this monitor may be incorrectly freed as |
| // the object wasn't marked when sweeping began. |
| bool allow_new_monitors_ GUARDED_BY(monitor_list_lock_); |
| Mutex monitor_list_lock_ DEFAULT_MUTEX_ACQUIRED_AFTER; |
| ConditionVariable monitor_add_condition_ GUARDED_BY(monitor_list_lock_); |
| Monitors list_ GUARDED_BY(monitor_list_lock_); |
| |
| friend class Monitor; |
| DISALLOW_COPY_AND_ASSIGN(MonitorList); |
| }; |
| |
| // Collects information about the current state of an object's monitor. |
| // This is very unsafe, and must only be called when all threads are suspended. |
| // For use only by the JDWP implementation. |
| class MonitorInfo { |
| public: |
| MonitorInfo() : owner_(nullptr), entry_count_(0) {} |
| MonitorInfo(const MonitorInfo&) = default; |
| MonitorInfo& operator=(const MonitorInfo&) = default; |
| explicit MonitorInfo(ObjPtr<mirror::Object> o) REQUIRES(Locks::mutator_lock_); |
| |
| Thread* owner_; |
| size_t entry_count_; |
| std::vector<Thread*> waiters_; |
| }; |
| |
| } // namespace art |
| |
| #endif // ART_RUNTIME_MONITOR_H_ |