| /* |
| * Copyright (c) 2005, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| * |
| */ |
| |
| |
| // Forward declarations |
| class YieldingFlexibleWorkGang; |
| |
| // Status of tasks |
| enum Status { |
| INACTIVE, |
| ACTIVE, |
| YIELDING, |
| YIELDED, |
| ABORTING, |
| ABORTED, |
| COMPLETING, |
| COMPLETED |
| }; |
| |
| // Class YieldingFlexibleGangWorker: |
| // Several instances of this class run in parallel as workers for a gang. |
| class YieldingFlexibleGangWorker: public GangWorker { |
| public: |
| // Ctor |
| YieldingFlexibleGangWorker(AbstractWorkGang* gang, int id) : |
| GangWorker(gang, id) { } |
| |
| public: |
| YieldingFlexibleWorkGang* yf_gang() const |
| { return (YieldingFlexibleWorkGang*)gang(); } |
| |
| protected: // Override from parent class |
| virtual void loop(); |
| }; |
| |
| // An abstract task to be worked on by a flexible work gang, |
| // and where the workers will periodically yield, usually |
| // in response to some condition that is signalled by means |
| // that are specific to the task at hand. |
| // You subclass this to supply your own work() method. |
| // A second feature of this kind of work gang is that |
| // it allows for the signalling of certain exceptional |
| // conditions that may be encountered during the performance |
| // of the task and that may require the task at hand to be |
| // `aborted' forthwith. Finally, these gangs are `flexible' |
| // in that they can operate at partial capacity with some |
| // gang workers waiting on the bench; in other words, the |
| // size of the active worker pool can flex (up to an apriori |
| // maximum) in response to task requests at certain points. |
| // The last part (the flexible part) has not yet been fully |
| // fleshed out and is a work in progress. |
| class YieldingFlexibleGangTask: public AbstractGangTask { |
| Status _status; |
| YieldingFlexibleWorkGang* _gang; |
| int _actual_size; // size of gang obtained |
| |
| protected: |
| int _requested_size; // size of gang requested |
| |
| // Constructor and desctructor: only construct subclasses. |
| YieldingFlexibleGangTask(const char* name): AbstractGangTask(name), |
| _status(INACTIVE), |
| _gang(NULL), |
| _requested_size(0) { } |
| |
| virtual ~YieldingFlexibleGangTask() { } |
| |
| friend class YieldingFlexibleWorkGang; |
| friend class YieldingFlexibleGangWorker; |
| NOT_PRODUCT(virtual bool is_YieldingFlexibleGang_task() const { |
| return true; |
| }) |
| |
| void set_status(Status s) { |
| _status = s; |
| } |
| YieldingFlexibleWorkGang* gang() { |
| return _gang; |
| } |
| void set_gang(YieldingFlexibleWorkGang* gang) { |
| assert(_gang == NULL || gang == NULL, "Clobber without intermediate reset?"); |
| _gang = gang; |
| } |
| |
| public: |
| // The abstract work method. |
| // The argument tells you which member of the gang you are. |
| virtual void work(int i) = 0; |
| |
| // Subclasses should call the parent's yield() method |
| // after having done any work specific to the subclass. |
| virtual void yield(); |
| |
| // An abstract method supplied by |
| // a concrete sub-class which is used by the coordinator |
| // to do any "central yielding" work. |
| virtual void coordinator_yield() = 0; |
| |
| // Subclasses should call the parent's abort() method |
| // after having done any work specific to the sunbclass. |
| virtual void abort(); |
| |
| Status status() const { return _status; } |
| bool yielded() const { return _status == YIELDED; } |
| bool completed() const { return _status == COMPLETED; } |
| bool aborted() const { return _status == ABORTED; } |
| bool active() const { return _status == ACTIVE; } |
| |
| int requested_size() const { return _requested_size; } |
| int actual_size() const { return _actual_size; } |
| |
| void set_requested_size(int sz) { _requested_size = sz; } |
| void set_actual_size(int sz) { _actual_size = sz; } |
| }; |
| |
| // Class YieldingWorkGang: A subclass of WorkGang. |
| // In particular, a YieldingWorkGang is made up of |
| // YieldingGangWorkers, and provides infrastructure |
| // supporting yielding to the "GangOverseer", |
| // being the thread that orchestrates the WorkGang via run_task(). |
| class YieldingFlexibleWorkGang: public AbstractWorkGang { |
| // Here's the public interface to this class. |
| public: |
| // Constructor and destructor. |
| YieldingFlexibleWorkGang(const char* name, int workers, |
| bool are_GC_task_threads); |
| |
| YieldingFlexibleGangTask* yielding_task() const { |
| assert(task() == NULL || task()->is_YieldingFlexibleGang_task(), |
| "Incorrect cast"); |
| return (YieldingFlexibleGangTask*)task(); |
| } |
| // Run a task; returns when the task is done, or the workers yield, |
| // or the task is aborted, or the work gang is terminated via stop(). |
| // A task that has been yielded can be continued via this same interface |
| // by using the same task repeatedly as the argument to the call. |
| // It is expected that the YieldingFlexibleGangTask carries the appropriate |
| // continuation information used by workers to continue the task |
| // from its last yield point. Thus, a completed task will return |
| // immediately with no actual work having been done by the workers. |
| void run_task(AbstractGangTask* task) { |
| guarantee(false, "Use start_task instead"); |
| } |
| void start_task(YieldingFlexibleGangTask* new_task); |
| void continue_task(YieldingFlexibleGangTask* gang_task); |
| |
| // Abort a currently running task, if any; returns when all the workers |
| // have stopped working on the current task and have returned to their |
| // waiting stations. |
| void abort_task(); |
| |
| // Yield: workers wait at their current working stations |
| // until signalled to proceed by the overseer. |
| void yield(); |
| |
| // Abort: workers are expected to return to their waiting |
| // stations, whence they are ready for the next task dispatched |
| // by the overseer. |
| void abort(); |
| |
| private: |
| // The currently active workers in this gang. |
| // This is a number that is dynamically adjusted by |
| // the run_task() method at each subsequent invocation, |
| // using data in the YieldingFlexibleGangTask. |
| int _active_workers; |
| int _yielded_workers; |
| void wait_for_gang(); |
| |
| public: |
| // Accessors for fields |
| int active_workers() const { |
| return _active_workers; |
| } |
| |
| int yielded_workers() const { |
| return _yielded_workers; |
| } |
| |
| private: |
| friend class YieldingFlexibleGangWorker; |
| void reset(); // NYI |
| }; |