1/*
2 * Copyright (C) 2008 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef ART_RUNTIME_MONITOR_H_
18#define ART_RUNTIME_MONITOR_H_
19
20#include <pthread.h>
21#include <stdint.h>
22
23#include <iosfwd>
24#include <list>
25#include <vector>
26
27#include "base/mutex.h"
28#include "root_visitor.h"
29#include "thread_state.h"
30
31namespace art {
32
33/*
34 * Monitor shape field. Used to distinguish thin locks from fat locks.
35 */
36#define LW_SHAPE_THIN 0
37#define LW_SHAPE_FAT 1
38
39/*
40 * Hash state field.  Used to signify that an object has had its
41 * identity hash code exposed or relocated.
42 */
43#define LW_HASH_STATE_UNHASHED 0
44#define LW_HASH_STATE_HASHED 1
45#define LW_HASH_STATE_HASHED_AND_MOVED 3
46#define LW_HASH_STATE_MASK 0x3
47#define LW_HASH_STATE_SHIFT 1
48#define LW_HASH_STATE(x) (((x) >> LW_HASH_STATE_SHIFT) & LW_HASH_STATE_MASK)
49
50/*
51 * Lock owner field.  Contains the thread id of the thread currently
52 * holding the lock.
53 */
54#define LW_LOCK_OWNER_MASK 0xffff
55#define LW_LOCK_OWNER_SHIFT 3
56#define LW_LOCK_OWNER(x) (((x) >> LW_LOCK_OWNER_SHIFT) & LW_LOCK_OWNER_MASK)
57
58namespace mirror {
59  class ArtMethod;
60  class Object;
61}  // namespace mirror
62class Thread;
63class StackVisitor;
64
65class Monitor {
66 public:
67  ~Monitor();
68
69  static bool IsSensitiveThread();
70  static void Init(uint32_t lock_profiling_threshold, bool (*is_sensitive_thread_hook)());
71
72  static uint32_t GetThinLockId(uint32_t raw_lock_word)
73      NO_THREAD_SAFETY_ANALYSIS;  // Reading lock owner without holding lock is racy.
74
75  static void MonitorEnter(Thread* thread, mirror::Object* obj)
76      EXCLUSIVE_LOCK_FUNCTION(monitor_lock_)
77      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
78  static bool MonitorExit(Thread* thread, mirror::Object* obj)
79      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_)
80      UNLOCK_FUNCTION(monitor_lock_);
81
82  static void Notify(Thread* self, mirror::Object* obj)
83      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
84  static void NotifyAll(Thread* self, mirror::Object* obj)
85      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
86  static void Wait(Thread* self, mirror::Object* obj, int64_t ms, int32_t ns,
87                   bool interruptShouldThrow, ThreadState why)
88      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
89
90  static void DescribeWait(std::ostream& os, const Thread* thread)
91      LOCKS_EXCLUDED(Locks::thread_suspend_count_lock_)
92      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
93
94  // Used to implement JDWP's ThreadReference.CurrentContendedMonitor.
95  static mirror::Object* GetContendedMonitor(Thread* thread);
96
97  // Calls 'callback' once for each lock held in the single stack frame represented by
98  // the current state of 'stack_visitor'.
99  static void VisitLocks(StackVisitor* stack_visitor, void (*callback)(mirror::Object*, void*),
100                         void* callback_context)
101      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
102
103  static bool IsValidLockWord(int32_t lock_word);
104
105  mirror::Object* GetObject();
106
107 private:
108  explicit Monitor(Thread* owner, mirror::Object* obj)
109      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
110
111  void AppendToWaitSet(Thread* thread) EXCLUSIVE_LOCKS_REQUIRED(monitor_lock_);
112  void RemoveFromWaitSet(Thread* thread) EXCLUSIVE_LOCKS_REQUIRED(monitor_lock_);
113
114  static void Inflate(Thread* self, mirror::Object* obj)
115      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
116
117  void LogContentionEvent(Thread* self, uint32_t wait_ms, uint32_t sample_percent,
118                          const char* owner_filename, uint32_t owner_line_number)
119      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
120
121  static void FailedUnlock(mirror::Object* obj, Thread* expected_owner, Thread* found_owner, Monitor* mon)
122      LOCKS_EXCLUDED(Locks::thread_list_lock_)
123      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
124
125  void Lock(Thread* self) EXCLUSIVE_LOCK_FUNCTION(monitor_lock_);
126  bool Unlock(Thread* thread, bool for_wait) UNLOCK_FUNCTION(monitor_lock_);
127
128  void Notify(Thread* self) NO_THREAD_SAFETY_ANALYSIS;
129  void NotifyWithLock(Thread* self)
130      EXCLUSIVE_LOCKS_REQUIRED(monitor_lock_)
131      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
132
133  void NotifyAll(Thread* self) NO_THREAD_SAFETY_ANALYSIS;
134  void NotifyAllWithLock()
135      EXCLUSIVE_LOCKS_REQUIRED(monitor_lock_)
136      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
137
138
139  void Wait(Thread* self, int64_t msec, int32_t nsec, bool interruptShouldThrow, ThreadState why)
140      NO_THREAD_SAFETY_ANALYSIS;
141  void WaitWithLock(Thread* self, int64_t ms, int32_t ns, bool interruptShouldThrow, ThreadState why)
142      EXCLUSIVE_LOCKS_REQUIRED(monitor_lock_)
143      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
144
145  // Translates the provided method and pc into its declaring class' source file and line number.
146  void TranslateLocation(const mirror::ArtMethod* method, uint32_t pc,
147                         const char*& source_file, uint32_t& line_number) const
148      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
149
150  static bool (*is_sensitive_thread_hook_)();
151  static uint32_t lock_profiling_threshold_;
152
153  Mutex monitor_lock_ DEFAULT_MUTEX_ACQUIRED_AFTER;
154
155  // Which thread currently owns the lock?
156  Thread* volatile owner_;
157
158  // Owner's recursive lock depth.
159  int lock_count_ GUARDED_BY(monitor_lock_);
160
161  // What object are we part of (for debugging).
162  mirror::Object* const obj_;
163
164  // Threads currently waiting on this monitor.
165  Thread* wait_set_ GUARDED_BY(monitor_lock_);
166
167  // Method and dex pc where the lock owner acquired the lock, used when lock
168  // sampling is enabled. locking_method_ may be null if the lock is currently
169  // unlocked, or if the lock is acquired by the system when the stack is empty.
170  const mirror::ArtMethod* locking_method_ GUARDED_BY(monitor_lock_);
171  uint32_t locking_dex_pc_ GUARDED_BY(monitor_lock_);
172
173  friend class MonitorInfo;
174  friend class MonitorList;
175  friend class mirror::Object;
176  DISALLOW_COPY_AND_ASSIGN(Monitor);
177};
178
179class MonitorList {
180 public:
181  MonitorList();
182  ~MonitorList();
183
184  void Add(Monitor* m);
185  void SweepMonitorList(IsMarkedTester is_marked, void* arg)
186      SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_);
187  void DisallowNewMonitors();
188  void AllowNewMonitors();
189 private:
190  bool allow_new_monitors_ GUARDED_BY(monitor_list_lock_);
191  Mutex monitor_list_lock_ DEFAULT_MUTEX_ACQUIRED_AFTER;
192  ConditionVariable monitor_add_condition_ GUARDED_BY(monitor_list_lock_);
193  std::list<Monitor*> list_ GUARDED_BY(monitor_list_lock_);
194
195  friend class Monitor;
196  DISALLOW_COPY_AND_ASSIGN(MonitorList);
197};
198
199// Collects information about the current state of an object's monitor.
200// This is very unsafe, and must only be called when all threads are suspended.
201// For use only by the JDWP implementation.
202class MonitorInfo {
203 public:
204  explicit MonitorInfo(mirror::Object* o) EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_);
205
206  Thread* owner;
207  size_t entry_count;
208  std::vector<Thread*> waiters;
209
210 private:
211  DISALLOW_COPY_AND_ASSIGN(MonitorInfo);
212};
213
214}  // namespace art
215
216#endif  // ART_RUNTIME_MONITOR_H_
217