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comparison src/share/vm/utilities/yieldingWorkgroup.hpp @ 0:a61af66fc99e jdk7-b24

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author duke
date Sat, 01 Dec 2007 00:00:00 +0000
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1 /*
2 * Copyright 2005 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25
26 // Forward declarations
27 class YieldingFlexibleWorkGang;
28
29 // Status of tasks
30 enum Status {
31 INACTIVE,
32 ACTIVE,
33 YIELDING,
34 YIELDED,
35 ABORTING,
36 ABORTED,
37 COMPLETING,
38 COMPLETED
39 };
40
41 // Class YieldingFlexibleGangWorker:
42 // Several instances of this class run in parallel as workers for a gang.
43 class YieldingFlexibleGangWorker: public GangWorker {
44 public:
45 // Ctor
46 YieldingFlexibleGangWorker(AbstractWorkGang* gang, int id) :
47 GangWorker(gang, id) { }
48
49 public:
50 YieldingFlexibleWorkGang* yf_gang() const
51 { return (YieldingFlexibleWorkGang*)gang(); }
52
53 protected: // Override from parent class
54 virtual void loop();
55 };
56
57 // An abstract task to be worked on by a flexible work gang,
58 // and where the workers will periodically yield, usually
59 // in response to some condition that is signalled by means
60 // that are specific to the task at hand.
61 // You subclass this to supply your own work() method.
62 // A second feature of this kind of work gang is that
63 // it allows for the signalling of certain exceptional
64 // conditions that may be encountered during the performance
65 // of the task and that may require the task at hand to be
66 // `aborted' forthwith. Finally, these gangs are `flexible'
67 // in that they can operate at partial capacity with some
68 // gang workers waiting on the bench; in other words, the
69 // size of the active worker pool can flex (up to an apriori
70 // maximum) in response to task requests at certain points.
71 // The last part (the flexible part) has not yet been fully
72 // fleshed out and is a work in progress.
73 class YieldingFlexibleGangTask: public AbstractGangTask {
74 Status _status;
75 YieldingFlexibleWorkGang* _gang;
76 int _actual_size; // size of gang obtained
77
78 protected:
79 int _requested_size; // size of gang requested
80
81 // Constructor and desctructor: only construct subclasses.
82 YieldingFlexibleGangTask(const char* name): AbstractGangTask(name),
83 _status(INACTIVE),
84 _gang(NULL),
85 _requested_size(0) { }
86
87 virtual ~YieldingFlexibleGangTask() { }
88
89 friend class YieldingFlexibleWorkGang;
90 friend class YieldingFlexibleGangWorker;
91 NOT_PRODUCT(virtual bool is_YieldingFlexibleGang_task() const {
92 return true;
93 })
94
95 void set_status(Status s) {
96 _status = s;
97 }
98 YieldingFlexibleWorkGang* gang() {
99 return _gang;
100 }
101 void set_gang(YieldingFlexibleWorkGang* gang) {
102 assert(_gang == NULL || gang == NULL, "Clobber without intermediate reset?");
103 _gang = gang;
104 }
105
106 public:
107 // The abstract work method.
108 // The argument tells you which member of the gang you are.
109 virtual void work(int i) = 0;
110
111 // Subclasses should call the parent's yield() method
112 // after having done any work specific to the subclass.
113 virtual void yield();
114
115 // An abstract method supplied by
116 // a concrete sub-class which is used by the coordinator
117 // to do any "central yielding" work.
118 virtual void coordinator_yield() = 0;
119
120 // Subclasses should call the parent's abort() method
121 // after having done any work specific to the sunbclass.
122 virtual void abort();
123
124 Status status() const { return _status; }
125 bool yielded() const { return _status == YIELDED; }
126 bool completed() const { return _status == COMPLETED; }
127 bool aborted() const { return _status == ABORTED; }
128 bool active() const { return _status == ACTIVE; }
129
130 int requested_size() const { return _requested_size; }
131 int actual_size() const { return _actual_size; }
132
133 void set_requested_size(int sz) { _requested_size = sz; }
134 void set_actual_size(int sz) { _actual_size = sz; }
135 };
136
137 // Class YieldingWorkGang: A subclass of WorkGang.
138 // In particular, a YieldingWorkGang is made up of
139 // YieldingGangWorkers, and provides infrastructure
140 // supporting yielding to the "GangOverseer",
141 // being the thread that orchestrates the WorkGang via run_task().
142 class YieldingFlexibleWorkGang: public AbstractWorkGang {
143 // Here's the public interface to this class.
144 public:
145 // Constructor and destructor.
146 YieldingFlexibleWorkGang(const char* name, int workers, bool are_GC_threads);
147
148 YieldingFlexibleGangTask* yielding_task() const {
149 assert(task() == NULL || task()->is_YieldingFlexibleGang_task(),
150 "Incorrect cast");
151 return (YieldingFlexibleGangTask*)task();
152 }
153 // Run a task; returns when the task is done, or the workers yield,
154 // or the task is aborted, or the work gang is terminated via stop().
155 // A task that has been yielded can be continued via this same interface
156 // by using the same task repeatedly as the argument to the call.
157 // It is expected that the YieldingFlexibleGangTask carries the appropriate
158 // continuation information used by workers to continue the task
159 // from its last yield point. Thus, a completed task will return
160 // immediately with no actual work having been done by the workers.
161 void run_task(AbstractGangTask* task) {
162 guarantee(false, "Use start_task instead");
163 }
164 void start_task(YieldingFlexibleGangTask* new_task);
165 void continue_task(YieldingFlexibleGangTask* gang_task);
166
167 // Abort a currently running task, if any; returns when all the workers
168 // have stopped working on the current task and have returned to their
169 // waiting stations.
170 void abort_task();
171
172 // Yield: workers wait at their current working stations
173 // until signalled to proceed by the overseer.
174 void yield();
175
176 // Abort: workers are expected to return to their waiting
177 // stations, whence they are ready for the next task dispatched
178 // by the overseer.
179 void abort();
180
181 private:
182 // The currently active workers in this gang.
183 // This is a number that is dynamically adjusted by
184 // the run_task() method at each subsequent invocation,
185 // using data in the YieldingFlexibleGangTask.
186 int _active_workers;
187 int _yielded_workers;
188 void wait_for_gang();
189
190 public:
191 // Accessors for fields
192 int active_workers() const {
193 return _active_workers;
194 }
195
196 int yielded_workers() const {
197 return _yielded_workers;
198 }
199
200 private:
201 friend class YieldingFlexibleGangWorker;
202 void reset(); // NYI
203 };