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/*
* 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 <iosfwd>
#include <list>
#include <vector>
#include "atomic.h"
#include "base/mutex.h"
#include "object_callbacks.h"
#include "read_barrier.h"
#include "thread_state.h"
namespace art {
class LockWord;
template<class T> class Handle;
class Thread;
class StackVisitor;
typedef uint32_t MonitorId;
namespace mirror {
class ArtMethod;
class Object;
} // namespace mirror
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 bool IsSensitiveThread();
static void Init(uint32_t lock_profiling_threshold, bool (*is_sensitive_thread_hook)());
// Return the thread id of the lock owner or 0 when there is no owner.
static uint32_t GetLockOwnerThreadId(mirror::Object* obj)
NO_THREAD_SAFETY_ANALYSIS; // TODO: Reading lock owner without holding lock is racy.
static mirror::Object* MonitorEnter(Thread* thread, mirror::Object* obj)
EXCLUSIVE_LOCK_FUNCTION(obj)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
static bool MonitorExit(Thread* thread, mirror::Object* obj)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_)
UNLOCK_FUNCTION(obj);
static void Notify(Thread* self, mirror::Object* obj)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
DoNotify(self, obj, false);
}
static void NotifyAll(Thread* self, mirror::Object* obj)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
DoNotify(self, obj, true);
}
static void Wait(Thread* self, mirror::Object* obj, int64_t ms, int32_t ns,
bool interruptShouldThrow, ThreadState why)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
static void DescribeWait(std::ostream& os, const Thread* thread)
LOCKS_EXCLUDED(Locks::thread_suspend_count_lock_)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
// Used to implement JDWP's ThreadReference.CurrentContendedMonitor.
static mirror::Object* GetContendedMonitor(Thread* thread)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
// Calls 'callback' once for each lock held in the single stack frame represented by
// the current state of 'stack_visitor'.
static void VisitLocks(StackVisitor* stack_visitor, void (*callback)(mirror::Object*, void*),
void* callback_context)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
static bool IsValidLockWord(LockWord lock_word);
template<ReadBarrierOption kReadBarrierOption = kWithReadBarrier>
mirror::Object* GetObject() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
return ReadBarrier::BarrierForRoot<mirror::Object, kReadBarrierOption>(&obj_);
}
void SetObject(mirror::Object* object);
Thread* GetOwner() const NO_THREAD_SAFETY_ANALYSIS {
return owner_;
}
int32_t GetHashCode();
bool IsLocked() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
bool HasHashCode() const {
return hash_code_.LoadRelaxed() != 0;
}
MonitorId GetMonitorId() const {
return monitor_id_;
}
static void InflateThinLocked(Thread* self, Handle<mirror::Object> obj, LockWord lock_word,
uint32_t hash_code) NO_THREAD_SAFETY_ANALYSIS;
static bool Deflate(Thread* self, mirror::Object* obj)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
private:
explicit Monitor(Thread* self, Thread* owner, mirror::Object* obj, int32_t hash_code)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
explicit Monitor(Thread* self, Thread* owner, mirror::Object* obj, int32_t hash_code,
MonitorId id) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
// Install the monitor into its object, may fail if another thread installs a different monitor
// first.
bool Install(Thread* self)
LOCKS_EXCLUDED(monitor_lock_)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
void AppendToWaitSet(Thread* thread) EXCLUSIVE_LOCKS_REQUIRED(monitor_lock_);
void RemoveFromWaitSet(Thread* thread) EXCLUSIVE_LOCKS_REQUIRED(monitor_lock_);
static void Inflate(Thread* self, Thread* owner, mirror::Object* obj, int32_t hash_code)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
void LogContentionEvent(Thread* self, uint32_t wait_ms, uint32_t sample_percent,
const char* owner_filename, uint32_t owner_line_number)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
static void FailedUnlock(mirror::Object* obj, Thread* expected_owner, Thread* found_owner, Monitor* mon)
LOCKS_EXCLUDED(Locks::thread_list_lock_)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
void Lock(Thread* self)
LOCKS_EXCLUDED(monitor_lock_)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
bool Unlock(Thread* thread)
LOCKS_EXCLUDED(monitor_lock_)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
static void DoNotify(Thread* self, mirror::Object* obj, bool notify_all)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
void Notify(Thread* self)
LOCKS_EXCLUDED(monitor_lock_)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
void NotifyAll(Thread* self)
LOCKS_EXCLUDED(monitor_lock_)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
void Wait(Thread* self, int64_t msec, int32_t nsec, bool interruptShouldThrow, ThreadState why)
LOCKS_EXCLUDED(monitor_lock_)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
// Translates the provided method and pc into its declaring class' source file and line number.
void TranslateLocation(mirror::ArtMethod* method, uint32_t pc,
const char** source_file, uint32_t* line_number) const
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
uint32_t GetOwnerThreadId();
static bool (*is_sensitive_thread_hook_)();
static uint32_t 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.
mirror::Object* obj_;
// Threads currently waiting on this monitor.
Thread* wait_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.
mirror::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);
void SweepMonitorList(IsMarkedCallback* callback, void* arg)
LOCKS_EXCLUDED(monitor_list_lock_) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
void DisallowNewMonitors() LOCKS_EXCLUDED(monitor_list_lock_);
void AllowNewMonitors() LOCKS_EXCLUDED(monitor_list_lock_);
// Returns how many monitors were deflated.
size_t DeflateMonitors() LOCKS_EXCLUDED(monitor_list_lock_)
EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_);
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_);
std::list<Monitor*> 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:
explicit MonitorInfo(mirror::Object* o) EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_);
Thread* owner_;
size_t entry_count_;
std::vector<Thread*> waiters_;
private:
DISALLOW_COPY_AND_ASSIGN(MonitorInfo);
};
} // namespace art
#endif // ART_RUNTIME_MONITOR_H_