aoqi@0: /*
aoqi@0:  * Copyright (c) 2005, 2013, Oracle and/or its affiliates. All rights reserved.
aoqi@0:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0:  *
aoqi@0:  * This code is free software; you can redistribute it and/or modify it
aoqi@0:  * under the terms of the GNU General Public License version 2 only, as
aoqi@0:  * published by the Free Software Foundation.
aoqi@0:  *
aoqi@0:  * This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
aoqi@0:  * version 2 for more details (a copy is included in the LICENSE file that
aoqi@0:  * accompanied this code).
aoqi@0:  *
aoqi@0:  * You should have received a copy of the GNU General Public License version
aoqi@0:  * 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0:  *
aoqi@0:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0:  * or visit www.oracle.com if you need additional information or have any
aoqi@0:  * questions.
aoqi@0:  *
aoqi@0:  */
aoqi@0: 
aoqi@0: #ifndef SHARE_VM_UTILITIES_YIELDINGWORKGROUP_HPP
aoqi@0: #define SHARE_VM_UTILITIES_YIELDINGWORKGROUP_HPP
aoqi@0: 
aoqi@0: #include "utilities/macros.hpp"
aoqi@0: #include "utilities/workgroup.hpp"
aoqi@0: 
aoqi@0: // Forward declarations
aoqi@0: class YieldingFlexibleWorkGang;
aoqi@0: 
aoqi@0: // Status of tasks
aoqi@0: enum Status {
aoqi@0:     INACTIVE,
aoqi@0:     ACTIVE,
aoqi@0:     YIELDING,
aoqi@0:     YIELDED,
aoqi@0:     ABORTING,
aoqi@0:     ABORTED,
aoqi@0:     COMPLETING,
aoqi@0:     COMPLETED
aoqi@0: };
aoqi@0: 
aoqi@0: // Class YieldingFlexibleGangWorker:
aoqi@0: //   Several instances of this class run in parallel as workers for a gang.
aoqi@0: class YieldingFlexibleGangWorker: public GangWorker {
aoqi@0: public:
aoqi@0:   // Ctor
aoqi@0:   YieldingFlexibleGangWorker(AbstractWorkGang* gang, int id) :
aoqi@0:     GangWorker(gang, id) { }
aoqi@0: 
aoqi@0: public:
aoqi@0:   YieldingFlexibleWorkGang* yf_gang() const
aoqi@0:     { return (YieldingFlexibleWorkGang*)gang(); }
aoqi@0: 
aoqi@0: protected: // Override from parent class
aoqi@0:   virtual void loop();
aoqi@0: };
aoqi@0: 
aoqi@0: class FlexibleGangTask: public AbstractGangTask {
aoqi@0:   int _actual_size;                      // size of gang obtained
aoqi@0: protected:
aoqi@0:   int _requested_size;                   // size of gang requested
aoqi@0: public:
aoqi@0:  FlexibleGangTask(const char* name): AbstractGangTask(name),
aoqi@0:     _requested_size(0) {}
aoqi@0: 
aoqi@0:   // The abstract work method.
aoqi@0:   // The argument tells you which member of the gang you are.
aoqi@0:   virtual void work(uint worker_id) = 0;
aoqi@0: 
aoqi@0:   int requested_size() const { return _requested_size; }
aoqi@0:   int actual_size()    const { return _actual_size; }
aoqi@0: 
aoqi@0:   void set_requested_size(int sz) { _requested_size = sz; }
aoqi@0:   void set_actual_size(int sz)    { _actual_size    = sz; }
aoqi@0: };
aoqi@0: 
aoqi@0: // An abstract task to be worked on by a flexible work gang,
aoqi@0: // and where the workers will periodically yield, usually
aoqi@0: // in response to some condition that is signalled by means
aoqi@0: // that are specific to the task at hand.
aoqi@0: // You subclass this to supply your own work() method.
aoqi@0: // A second feature of this kind of work gang is that
aoqi@0: // it allows for the signalling of certain exceptional
aoqi@0: // conditions that may be encountered during the performance
aoqi@0: // of the task and that may require the task at hand to be
aoqi@0: // `aborted' forthwith. Finally, these gangs are `flexible'
aoqi@0: // in that they can operate at partial capacity with some
aoqi@0: // gang workers waiting on the bench; in other words, the
aoqi@0: // size of the active worker pool can flex (up to an apriori
aoqi@0: // maximum) in response to task requests at certain points.
aoqi@0: // The last part (the flexible part) has not yet been fully
aoqi@0: // fleshed out and is a work in progress.
aoqi@0: class YieldingFlexibleGangTask: public FlexibleGangTask {
aoqi@0:   Status _status;
aoqi@0:   YieldingFlexibleWorkGang* _gang;
aoqi@0: 
aoqi@0: protected:
aoqi@0:   // Constructor and desctructor: only construct subclasses.
aoqi@0:   YieldingFlexibleGangTask(const char* name): FlexibleGangTask(name),
aoqi@0:     _status(INACTIVE),
aoqi@0:     _gang(NULL) { }
aoqi@0: 
aoqi@0:   ~YieldingFlexibleGangTask() { }
aoqi@0: 
aoqi@0:   friend class YieldingFlexibleWorkGang;
aoqi@0:   friend class YieldingFlexibleGangWorker;
aoqi@0:   NOT_PRODUCT(virtual bool is_YieldingFlexibleGang_task() const {
aoqi@0:     return true;
aoqi@0:   })
aoqi@0: 
aoqi@0:   void set_status(Status s) {
aoqi@0:     _status = s;
aoqi@0:   }
aoqi@0:   YieldingFlexibleWorkGang* gang() {
aoqi@0:     return _gang;
aoqi@0:   }
aoqi@0:   void set_gang(YieldingFlexibleWorkGang* gang) {
aoqi@0:     assert(_gang == NULL || gang == NULL, "Clobber without intermediate reset?");
aoqi@0:     _gang = gang;
aoqi@0:   }
aoqi@0: 
aoqi@0: public:
aoqi@0:   // The abstract work method.
aoqi@0:   // The argument tells you which member of the gang you are.
aoqi@0:   virtual void work(uint worker_id) = 0;
aoqi@0: 
aoqi@0:   // Subclasses should call the parent's yield() method
aoqi@0:   // after having done any work specific to the subclass.
aoqi@0:   virtual void yield();
aoqi@0: 
aoqi@0:   // An abstract method supplied by
aoqi@0:   // a concrete sub-class which is used by the coordinator
aoqi@0:   // to do any "central yielding" work.
aoqi@0:   virtual void coordinator_yield() = 0;
aoqi@0: 
aoqi@0:   // Subclasses should call the parent's abort() method
aoqi@0:   // after having done any work specific to the sunbclass.
aoqi@0:   virtual void abort();
aoqi@0: 
aoqi@0:   Status status()  const { return _status; }
aoqi@0:   bool yielding()  const { return _status == YIELDING; }
aoqi@0:   bool yielded()   const { return _status == YIELDED; }
aoqi@0:   bool completed() const { return _status == COMPLETED; }
aoqi@0:   bool aborted()   const { return _status == ABORTED; }
aoqi@0:   bool active()    const { return _status == ACTIVE; }
aoqi@0: };
aoqi@0: // Class YieldingWorkGang: A subclass of WorkGang.
aoqi@0: // In particular, a YieldingWorkGang is made up of
aoqi@0: // YieldingGangWorkers, and provides infrastructure
aoqi@0: // supporting yielding to the "GangOverseer",
aoqi@0: // being the thread that orchestrates the WorkGang via run_task().
aoqi@0: class YieldingFlexibleWorkGang: public FlexibleWorkGang {
aoqi@0:   // Here's the public interface to this class.
aoqi@0: public:
aoqi@0:   // Constructor and destructor.
aoqi@0:   YieldingFlexibleWorkGang(const char* name, uint workers,
aoqi@0:                            bool are_GC_task_threads);
aoqi@0: 
aoqi@0:   YieldingFlexibleGangTask* yielding_task() const {
aoqi@0:     assert(task() == NULL || task()->is_YieldingFlexibleGang_task(),
aoqi@0:            "Incorrect cast");
aoqi@0:     return (YieldingFlexibleGangTask*)task();
aoqi@0:   }
aoqi@0:   // Allocate a worker and return a pointer to it.
aoqi@0:   GangWorker* allocate_worker(uint which);
aoqi@0: 
aoqi@0:   // Run a task; returns when the task is done, or the workers yield,
aoqi@0:   // or the task is aborted, or the work gang is terminated via stop().
aoqi@0:   // A task that has been yielded can be continued via this same interface
aoqi@0:   // by using the same task repeatedly as the argument to the call.
aoqi@0:   // It is expected that the YieldingFlexibleGangTask carries the appropriate
aoqi@0:   // continuation information used by workers to continue the task
aoqi@0:   // from its last yield point. Thus, a completed task will return
aoqi@0:   // immediately with no actual work having been done by the workers.
aoqi@0:   void run_task(AbstractGangTask* task) {
aoqi@0:     guarantee(false, "Use start_task instead");
aoqi@0:   }
aoqi@0:   void start_task(YieldingFlexibleGangTask* new_task);
aoqi@0:   void continue_task(YieldingFlexibleGangTask* gang_task);
aoqi@0: 
aoqi@0:   // Abort a currently running task, if any; returns when all the workers
aoqi@0:   // have stopped working on the current task and have returned to their
aoqi@0:   // waiting stations.
aoqi@0:   void abort_task();
aoqi@0: 
aoqi@0:   // Yield: workers wait at their current working stations
aoqi@0:   // until signalled to proceed by the overseer.
aoqi@0:   void yield();
aoqi@0: 
aoqi@0:   // Abort: workers are expected to return to their waiting
aoqi@0:   // stations, whence they are ready for the next task dispatched
aoqi@0:   // by the overseer.
aoqi@0:   void abort();
aoqi@0: 
aoqi@0: private:
aoqi@0:   uint _yielded_workers;
aoqi@0:   void wait_for_gang();
aoqi@0: 
aoqi@0: public:
aoqi@0:   // Accessors for fields
aoqi@0:   uint yielded_workers() const {
aoqi@0:     return _yielded_workers;
aoqi@0:   }
aoqi@0: 
aoqi@0: private:
aoqi@0:   friend class YieldingFlexibleGangWorker;
aoqi@0:   void reset(); // NYI
aoqi@0: };
aoqi@0: 
aoqi@0: #endif // SHARE_VM_UTILITIES_YIELDINGWORKGROUP_HPP