1 /*
2 * Copyright (c) 2005, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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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.
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23 */
24
25 #ifndef SHARE_VM_GC_CMS_YIELDINGWORKGROUP_HPP
26 #define SHARE_VM_GC_CMS_YIELDINGWORKGROUP_HPP
27
28 #include "gc/shared/workgroup.hpp"
29 #include "utilities/macros.hpp"
30
31 // Forward declarations
32 class YieldingFlexibleWorkGang;
33
34 // Status of tasks
35 enum Status {
36 INACTIVE,
37 ACTIVE,
38 YIELDING,
39 YIELDED,
40 ABORTING,
41 ABORTED,
42 COMPLETING,
43 COMPLETED
44 };
45
46 // Class YieldingFlexibleGangWorker:
47 // Several instances of this class run in parallel as workers for a gang.
48 class YieldingFlexibleGangWorker: public GangWorker {
49 public:
50 // Ctor
51 YieldingFlexibleGangWorker(AbstractWorkGang* gang, int id) :
52 GangWorker(gang, id) { }
53
54 public:
55 YieldingFlexibleWorkGang* yf_gang() const
56 { return (YieldingFlexibleWorkGang*)gang(); }
57
58 protected: // Override from parent class
59 virtual void loop();
60 };
61
62 class FlexibleGangTask: public AbstractGangTask {
63 int _actual_size; // size of gang obtained
64 protected:
65 int _requested_size; // size of gang requested
66 public:
67 FlexibleGangTask(const char* name): AbstractGangTask(name),
68 _requested_size(0) {}
69
70 // The abstract work method.
71 // The argument tells you which member of the gang you are.
72 virtual void work(uint worker_id) = 0;
73
74 int requested_size() const { return _requested_size; }
75 int actual_size() const { return _actual_size; }
76
77 void set_requested_size(int sz) { _requested_size = sz; }
78 void set_actual_size(int sz) { _actual_size = sz; }
79 };
80
81 // An abstract task to be worked on by a flexible work gang,
82 // and where the workers will periodically yield, usually
83 // in response to some condition that is signalled by means
84 // that are specific to the task at hand.
85 // You subclass this to supply your own work() method.
86 // A second feature of this kind of work gang is that
87 // it allows for the signalling of certain exceptional
88 // conditions that may be encountered during the performance
89 // of the task and that may require the task at hand to be
90 // `aborted' forthwith. Finally, these gangs are `flexible'
91 // in that they can operate at partial capacity with some
92 // gang workers waiting on the bench; in other words, the
93 // size of the active worker pool can flex (up to an apriori
94 // maximum) in response to task requests at certain points.
95 // The last part (the flexible part) has not yet been fully
96 // fleshed out and is a work in progress.
97 class YieldingFlexibleGangTask: public FlexibleGangTask {
98 Status _status;
99 YieldingFlexibleWorkGang* _gang;
100
101 protected:
102 // Constructor and desctructor: only construct subclasses.
103 YieldingFlexibleGangTask(const char* name): FlexibleGangTask(name),
104 _status(INACTIVE),
105 _gang(NULL) { }
106
107 ~YieldingFlexibleGangTask() { }
108
109 friend class YieldingFlexibleWorkGang;
110 friend class YieldingFlexibleGangWorker;
111 NOT_PRODUCT(virtual bool is_YieldingFlexibleGang_task() const {
112 return true;
113 })
114
115 void set_status(Status s) {
116 _status = s;
117 }
118 YieldingFlexibleWorkGang* gang() {
119 return _gang;
120 }
121 void set_gang(YieldingFlexibleWorkGang* gang) {
122 assert(_gang == NULL || gang == NULL, "Clobber without intermediate reset?");
123 _gang = gang;
124 }
125
126 public:
127 // The abstract work method.
128 // The argument tells you which member of the gang you are.
129 virtual void work(uint worker_id) = 0;
130
131 // Subclasses should call the parent's yield() method
132 // after having done any work specific to the subclass.
133 virtual void yield();
134
135 // An abstract method supplied by
136 // a concrete sub-class which is used by the coordinator
137 // to do any "central yielding" work.
138 virtual void coordinator_yield() = 0;
139
140 // Subclasses should call the parent's abort() method
141 // after having done any work specific to the sunbclass.
142 virtual void abort();
143
144 Status status() const { return _status; }
145 bool yielding() const { return _status == YIELDING; }
146 bool yielded() const { return _status == YIELDED; }
147 bool completed() const { return _status == COMPLETED; }
148 bool aborted() const { return _status == ABORTED; }
149 bool active() const { return _status == ACTIVE; }
150
151 // This method configures the task for proper termination.
152 // Some tasks do not have any requirements on termination
153 // and may inherit this method that does nothing. Some
154 // tasks do some coordination on termination and override
155 // this method to implement that coordination.
156 virtual void set_for_termination(uint active_workers) {}
157 };
158 // Class YieldingWorkGang: A subclass of WorkGang.
159 // In particular, a YieldingWorkGang is made up of
160 // YieldingGangWorkers, and provides infrastructure
161 // supporting yielding to the "GangOverseer",
162 // being the thread that orchestrates the WorkGang via run_task().
163 class YieldingFlexibleWorkGang: public FlexibleWorkGang {
164 // Here's the public interface to this class.
165 public:
166 // Constructor and destructor.
167 YieldingFlexibleWorkGang(const char* name, uint workers,
168 bool are_GC_task_threads);
169
170 YieldingFlexibleGangTask* yielding_task() const {
171 assert(task() == NULL || task()->is_YieldingFlexibleGang_task(),
172 "Incorrect cast");
173 return (YieldingFlexibleGangTask*)task();
174 }
175 // Allocate a worker and return a pointer to it.
176 GangWorker* allocate_worker(uint which);
177
178 // Run a task; returns when the task is done, or the workers yield,
179 // or the task is aborted.
180 // A task that has been yielded can be continued via this same interface
181 // by using the same task repeatedly as the argument to the call.
182 // It is expected that the YieldingFlexibleGangTask carries the appropriate
183 // continuation information used by workers to continue the task
184 // from its last yield point. Thus, a completed task will return
185 // immediately with no actual work having been done by the workers.
186 void run_task(AbstractGangTask* task) {
187 guarantee(false, "Use start_task instead");
188 }
189 void start_task(YieldingFlexibleGangTask* new_task);
190 void continue_task(YieldingFlexibleGangTask* gang_task);
191
192 // Abort a currently running task, if any; returns when all the workers
193 // have stopped working on the current task and have returned to their
194 // waiting stations.
195 void abort_task();
196
197 // Yield: workers wait at their current working stations
198 // until signalled to proceed by the overseer.
199 void yield();
200
201 // Abort: workers are expected to return to their waiting
202 // stations, whence they are ready for the next task dispatched
203 // by the overseer.
204 void abort();
205
206 private:
207 uint _yielded_workers;
208 void wait_for_gang();
209
210 public:
211 // Accessors for fields
212 uint yielded_workers() const {
213 return _yielded_workers;
214 }
215
216 private:
217 friend class YieldingFlexibleGangWorker;
218 void reset(); // NYI
219 };
220
221 #endif // SHARE_VM_GC_CMS_YIELDINGWORKGROUP_HPP