1 /*
2 * Copyright (c) 1998, 2010, 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/vm_operations.hpp"
30 #ifdef TARGET_OS_FAMILY_linux
31 # include "thread_linux.inline.hpp"
32 #endif
33 #ifdef TARGET_OS_FAMILY_solaris
34 # include "thread_solaris.inline.hpp"
35 #endif
36 #ifdef TARGET_OS_FAMILY_windows
37 # include "thread_windows.inline.hpp"
38 #endif
39
40 //
41 // Prioritized queue of VM operations.
42 //
43 // Encapsulates both queue management and
44 // and priority policy
45 //
46 class VMOperationQueue : public CHeapObj {
47 private:
48 enum Priorities {
49 SafepointPriority, // Highest priority (operation executed at a safepoint)
50 MediumPriority, // Medium priority
51 nof_priorities
52 };
53
54 // We maintain a doubled linked list, with explicit count.
55 int _queue_length[nof_priorities];
56 int _queue_counter;
57 VM_Operation* _queue [nof_priorities];
58 // we also allow the vmThread to register the ops it has drained so we
59 // can scan them from oops_do
60 VM_Operation* _drain_list;
61
62 // Double-linked non-empty list insert.
63 void insert(VM_Operation* q,VM_Operation* n);
64 void unlink(VM_Operation* q);
65
66 // Basic queue manipulation
67 bool queue_empty (int prio);
68 void queue_add_front (int prio, VM_Operation *op);
69 void queue_add_back (int prio, VM_Operation *op);
70 VM_Operation* queue_remove_front(int prio);
71 void queue_oops_do(int queue, OopClosure* f);
72 void drain_list_oops_do(OopClosure* f);
73 VM_Operation* queue_drain(int prio);
74 // lock-free query: may return the wrong answer but must not break
75 bool queue_peek(int prio) { return _queue_length[prio] > 0; }
76
77 public:
78 VMOperationQueue();
79
80 // Highlevel operations. Encapsulates policy
81 bool add(VM_Operation *op);
82 VM_Operation* remove_next(); // Returns next or null
83 VM_Operation* remove_next_at_safepoint_priority() { return queue_remove_front(SafepointPriority); }
84 VM_Operation* drain_at_safepoint_priority() { return queue_drain(SafepointPriority); }
85 void set_drain_list(VM_Operation* list) { _drain_list = list; }
86 bool peek_at_safepoint_priority() { return queue_peek(SafepointPriority); }
87
88 // GC support
89 void oops_do(OopClosure* f);
90
91 void verify_queue(int prio) PRODUCT_RETURN;
92 };
93
94
95 //
96 // A single VMThread (the primordial thread) spawns all other threads
97 // and is itself used by other threads to offload heavy vm operations
98 // like scavenge, garbage_collect etc.
99 //
100
101 class VMThread: public NamedThread {
102 private:
103 static ThreadPriority _current_priority;
104
105 static bool _should_terminate;
106 static bool _terminated;
107 static Monitor * _terminate_lock;
108 static PerfCounter* _perf_accumulated_vm_operation_time;
109
110 void evaluate_operation(VM_Operation* op);
111 public:
112 // Constructor
113 VMThread();
114
115 // Tester
116 bool is_VM_thread() const { return true; }
117 bool is_GC_thread() const { return true; }
118
119 // The ever running loop for the VMThread
120 void loop();
121
122 // Called to stop the VM thread
123 static void wait_for_vm_thread_exit();
124 static bool should_terminate() { return _should_terminate; }
125 static bool is_terminated() { return _terminated == true; }
126
127 // Execution of vm operation
128 static void execute(VM_Operation* op);
129
130 // Returns the current vm operation if any.
131 static VM_Operation* vm_operation() { return _cur_vm_operation; }
132
133 // Returns the single instance of VMThread.
134 static VMThread* vm_thread() { return _vm_thread; }
135
136 // GC support
137 void oops_do(OopClosure* f, CodeBlobClosure* cf);
138
139 // Debugging
140 void print_on(outputStream* st) const;
141 void print() const { print_on(tty); }
142 void verify();
143
144 // Performance measurement
145 static PerfCounter* perf_accumulated_vm_operation_time() { return _perf_accumulated_vm_operation_time; }
146
147 // Entry for starting vm thread
148 virtual void run();
149
150 // Creations/Destructions
151 static void create();
152 static void destroy();
153
154 private:
155 // VM_Operation support
156 static VM_Operation* _cur_vm_operation; // Current VM operation
157 static VMOperationQueue* _vm_queue; // Queue (w/ policy) of VM operations
158
159 // Pointer to single-instance of VM thread
160 static VMThread* _vm_thread;
161 };
162
163 #endif // SHARE_VM_RUNTIME_VMTHREAD_HPP