vmThread.hpp revision 11236:aa11081b8307 
1/*
2 * Copyright (c) 1998, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25#ifndef SHARE_VM_RUNTIME_VMTHREAD_HPP
26#define SHARE_VM_RUNTIME_VMTHREAD_HPP
27
28#include "runtime/perfData.hpp"
29#include "runtime/thread.hpp"
30#include "runtime/vm_operations.hpp"
31
32//
33// Prioritized queue of VM operations.
34//
35// Encapsulates both queue management and
36// and priority policy
37//
38class VMOperationQueue : public CHeapObj<mtInternal> {
39 private:
40  enum Priorities {
41     SafepointPriority, // Highest priority (operation executed at a safepoint)
42     MediumPriority,    // Medium priority
43     nof_priorities
44  };
45
46  // We maintain a doubled linked list, with explicit count.
47  int           _queue_length[nof_priorities];
48  int           _queue_counter;
49  VM_Operation* _queue       [nof_priorities];
50  // we also allow the vmThread to register the ops it has drained so we
51  // can scan them from oops_do
52  VM_Operation* _drain_list;
53
54  // Double-linked non-empty list insert.
55  void insert(VM_Operation* q,VM_Operation* n);
56  void unlink(VM_Operation* q);
57
58  // Basic queue manipulation
59  bool queue_empty                (int prio);
60  void queue_add_front            (int prio, VM_Operation *op);
61  void queue_add_back             (int prio, VM_Operation *op);
62  VM_Operation* queue_remove_front(int prio);
63  void queue_oops_do(int queue, OopClosure* f);
64  void drain_list_oops_do(OopClosure* f);
65  VM_Operation* queue_drain(int prio);
66  // lock-free query: may return the wrong answer but must not break
67  bool queue_peek(int prio) { return _queue_length[prio] > 0; }
68
69 public:
70  VMOperationQueue();
71
72  // Highlevel operations. Encapsulates policy
73  bool add(VM_Operation *op);
74  VM_Operation* remove_next();                        // Returns next or null
75  VM_Operation* remove_next_at_safepoint_priority()   { return queue_remove_front(SafepointPriority); }
76  VM_Operation* drain_at_safepoint_priority() { return queue_drain(SafepointPriority); }
77  void set_drain_list(VM_Operation* list) { _drain_list = list; }
78  bool peek_at_safepoint_priority() { return queue_peek(SafepointPriority); }
79
80  // GC support
81  void oops_do(OopClosure* f);
82
83  void verify_queue(int prio) PRODUCT_RETURN;
84};
85
86
87//
88// A single VMThread (the primordial thread) spawns all other threads
89// and is itself used by other threads to offload heavy vm operations
90// like scavenge, garbage_collect etc.
91//
92
93class VMThread: public NamedThread {
94 private:
95  static ThreadPriority _current_priority;
96
97  static bool _should_terminate;
98  static bool _terminated;
99  static Monitor * _terminate_lock;
100  static PerfCounter* _perf_accumulated_vm_operation_time;
101
102  void evaluate_operation(VM_Operation* op);
103 public:
104  // Constructor
105  VMThread();
106
107  // No destruction allowed
108  ~VMThread() {
109    guarantee(false, "VMThread deletion must fix the race with VM termination");
110  }
111
112
113  // Tester
114  bool is_VM_thread() const                      { return true; }
115  bool is_GC_thread() const                      { return true; }
116
117  // The ever running loop for the VMThread
118  void loop();
119
120  // Called to stop the VM thread
121  static void wait_for_vm_thread_exit();
122  static bool should_terminate()                  { return _should_terminate; }
123  static bool is_terminated()                     { return _terminated == true; }
124
125  // Execution of vm operation
126  static void execute(VM_Operation* op);
127
128  // Returns the current vm operation if any.
129  static VM_Operation* vm_operation()             { return _cur_vm_operation;   }
130
131  // Returns the single instance of VMThread.
132  static VMThread* vm_thread()                    { return _vm_thread; }
133
134  // GC support
135  void oops_do(OopClosure* f, CodeBlobClosure* cf);
136
137  void verify();
138
139  // Performance measurement
140  static PerfCounter* perf_accumulated_vm_operation_time()               { return _perf_accumulated_vm_operation_time; }
141
142  // Entry for starting vm thread
143  virtual void run();
144
145  // Creations/Destructions
146  static void create();
147  static void destroy();
148
149 private:
150  // VM_Operation support
151  static VM_Operation*     _cur_vm_operation;   // Current VM operation
152  static VMOperationQueue* _vm_queue;           // Queue (w/ policy) of VM operations
153
154  // Pointer to single-instance of VM thread
155  static VMThread*     _vm_thread;
156};
157
158#endif // SHARE_VM_RUNTIME_VMTHREAD_HPP
159