duke@435: /*
ysr@2192:  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
duke@435:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435:  *
duke@435:  * This code is free software; you can redistribute it and/or modify it
duke@435:  * under the terms of the GNU General Public License version 2 only, as
duke@435:  * published by the Free Software Foundation.
duke@435:  *
duke@435:  * This code is distributed in the hope that it will be useful, but WITHOUT
duke@435:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
duke@435:  * version 2 for more details (a copy is included in the LICENSE file that
duke@435:  * accompanied this code).
duke@435:  *
duke@435:  * You should have received a copy of the GNU General Public License version
duke@435:  * 2 along with this work; if not, write to the Free Software Foundation,
duke@435:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435:  *
trims@1907:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
trims@1907:  * or visit www.oracle.com if you need additional information or have any
trims@1907:  * questions.
duke@435:  *
duke@435:  */
duke@435: 
stefank@2314: #ifndef SHARE_VM_UTILITIES_YIELDINGWORKGROUP_HPP
stefank@2314: #define SHARE_VM_UTILITIES_YIELDINGWORKGROUP_HPP
stefank@2314: 
stefank@2314: #ifndef SERIALGC
stefank@2314: #include "utilities/workgroup.hpp"
stefank@2314: #endif
stefank@2314: 
duke@435: 
duke@435: // Forward declarations
duke@435: class YieldingFlexibleWorkGang;
duke@435: 
duke@435: // Status of tasks
duke@435: enum Status {
duke@435:     INACTIVE,
duke@435:     ACTIVE,
duke@435:     YIELDING,
duke@435:     YIELDED,
duke@435:     ABORTING,
duke@435:     ABORTED,
duke@435:     COMPLETING,
duke@435:     COMPLETED
duke@435: };
duke@435: 
duke@435: // Class YieldingFlexibleGangWorker:
duke@435: //   Several instances of this class run in parallel as workers for a gang.
duke@435: class YieldingFlexibleGangWorker: public GangWorker {
duke@435: public:
duke@435:   // Ctor
duke@435:   YieldingFlexibleGangWorker(AbstractWorkGang* gang, int id) :
duke@435:     GangWorker(gang, id) { }
duke@435: 
duke@435: public:
duke@435:   YieldingFlexibleWorkGang* yf_gang() const
duke@435:     { return (YieldingFlexibleWorkGang*)gang(); }
duke@435: 
duke@435: protected: // Override from parent class
duke@435:   virtual void loop();
duke@435: };
duke@435: 
jmasa@2188: class FlexibleGangTask: public AbstractGangTask {
jmasa@2188:   int _actual_size;                      // size of gang obtained
jmasa@2188: protected:
jmasa@2188:   int _requested_size;                   // size of gang requested
jmasa@2188: public:
jmasa@2188:  FlexibleGangTask(const char* name): AbstractGangTask(name),
jmasa@2188:     _requested_size(0) {}
jmasa@2188: 
jmasa@2188:   // The abstract work method.
jmasa@2188:   // The argument tells you which member of the gang you are.
jmasa@2188:   virtual void work(int i) = 0;
jmasa@2188: 
jmasa@2188:   int requested_size() const { return _requested_size; }
jmasa@2188:   int actual_size()    const { return _actual_size; }
jmasa@2188: 
jmasa@2188:   void set_requested_size(int sz) { _requested_size = sz; }
jmasa@2188:   void set_actual_size(int sz)    { _actual_size    = sz; }
jmasa@2188: };
jmasa@2188: 
duke@435: // An abstract task to be worked on by a flexible work gang,
duke@435: // and where the workers will periodically yield, usually
duke@435: // in response to some condition that is signalled by means
duke@435: // that are specific to the task at hand.
duke@435: // You subclass this to supply your own work() method.
duke@435: // A second feature of this kind of work gang is that
duke@435: // it allows for the signalling of certain exceptional
duke@435: // conditions that may be encountered during the performance
duke@435: // of the task and that may require the task at hand to be
duke@435: // `aborted' forthwith. Finally, these gangs are `flexible'
duke@435: // in that they can operate at partial capacity with some
duke@435: // gang workers waiting on the bench; in other words, the
duke@435: // size of the active worker pool can flex (up to an apriori
duke@435: // maximum) in response to task requests at certain points.
duke@435: // The last part (the flexible part) has not yet been fully
duke@435: // fleshed out and is a work in progress.
jmasa@2188: class YieldingFlexibleGangTask: public FlexibleGangTask {
duke@435:   Status _status;
duke@435:   YieldingFlexibleWorkGang* _gang;
duke@435: 
duke@435: protected:
duke@435:   // Constructor and desctructor: only construct subclasses.
jmasa@2188:   YieldingFlexibleGangTask(const char* name): FlexibleGangTask(name),
duke@435:     _status(INACTIVE),
jmasa@2188:     _gang(NULL) { }
duke@435: 
duke@435:   virtual ~YieldingFlexibleGangTask() { }
duke@435: 
duke@435:   friend class YieldingFlexibleWorkGang;
duke@435:   friend class YieldingFlexibleGangWorker;
duke@435:   NOT_PRODUCT(virtual bool is_YieldingFlexibleGang_task() const {
duke@435:     return true;
duke@435:   })
duke@435: 
duke@435:   void set_status(Status s) {
duke@435:     _status = s;
duke@435:   }
duke@435:   YieldingFlexibleWorkGang* gang() {
duke@435:     return _gang;
duke@435:   }
duke@435:   void set_gang(YieldingFlexibleWorkGang* gang) {
duke@435:     assert(_gang == NULL || gang == NULL, "Clobber without intermediate reset?");
duke@435:     _gang = gang;
duke@435:   }
duke@435: 
duke@435: public:
duke@435:   // The abstract work method.
duke@435:   // The argument tells you which member of the gang you are.
duke@435:   virtual void work(int i) = 0;
duke@435: 
duke@435:   // Subclasses should call the parent's yield() method
duke@435:   // after having done any work specific to the subclass.
duke@435:   virtual void yield();
duke@435: 
duke@435:   // An abstract method supplied by
duke@435:   // a concrete sub-class which is used by the coordinator
duke@435:   // to do any "central yielding" work.
duke@435:   virtual void coordinator_yield() = 0;
duke@435: 
duke@435:   // Subclasses should call the parent's abort() method
duke@435:   // after having done any work specific to the sunbclass.
duke@435:   virtual void abort();
duke@435: 
duke@435:   Status status()  const { return _status; }
ysr@2192:   bool yielding()  const { return _status == YIELDING; }
duke@435:   bool yielded()   const { return _status == YIELDED; }
duke@435:   bool completed() const { return _status == COMPLETED; }
duke@435:   bool aborted()   const { return _status == ABORTED; }
duke@435:   bool active()    const { return _status == ACTIVE; }
duke@435: };
duke@435: // Class YieldingWorkGang: A subclass of WorkGang.
duke@435: // In particular, a YieldingWorkGang is made up of
duke@435: // YieldingGangWorkers, and provides infrastructure
duke@435: // supporting yielding to the "GangOverseer",
duke@435: // being the thread that orchestrates the WorkGang via run_task().
jmasa@2188: class YieldingFlexibleWorkGang: public FlexibleWorkGang {
duke@435:   // Here's the public interface to this class.
duke@435: public:
duke@435:   // Constructor and destructor.
ysr@777:   YieldingFlexibleWorkGang(const char* name, int workers,
ysr@777:                            bool are_GC_task_threads);
duke@435: 
duke@435:   YieldingFlexibleGangTask* yielding_task() const {
duke@435:     assert(task() == NULL || task()->is_YieldingFlexibleGang_task(),
duke@435:            "Incorrect cast");
duke@435:     return (YieldingFlexibleGangTask*)task();
duke@435:   }
jmasa@2188:   // Allocate a worker and return a pointer to it.
jmasa@2188:   GangWorker* allocate_worker(int which);
jmasa@2188: 
duke@435:   // Run a task; returns when the task is done, or the workers yield,
duke@435:   // or the task is aborted, or the work gang is terminated via stop().
duke@435:   // A task that has been yielded can be continued via this same interface
duke@435:   // by using the same task repeatedly as the argument to the call.
duke@435:   // It is expected that the YieldingFlexibleGangTask carries the appropriate
duke@435:   // continuation information used by workers to continue the task
duke@435:   // from its last yield point. Thus, a completed task will return
duke@435:   // immediately with no actual work having been done by the workers.
duke@435:   void run_task(AbstractGangTask* task) {
duke@435:     guarantee(false, "Use start_task instead");
duke@435:   }
duke@435:   void start_task(YieldingFlexibleGangTask* new_task);
duke@435:   void continue_task(YieldingFlexibleGangTask* gang_task);
duke@435: 
duke@435:   // Abort a currently running task, if any; returns when all the workers
duke@435:   // have stopped working on the current task and have returned to their
duke@435:   // waiting stations.
duke@435:   void abort_task();
duke@435: 
duke@435:   // Yield: workers wait at their current working stations
duke@435:   // until signalled to proceed by the overseer.
duke@435:   void yield();
duke@435: 
duke@435:   // Abort: workers are expected to return to their waiting
duke@435:   // stations, whence they are ready for the next task dispatched
duke@435:   // by the overseer.
duke@435:   void abort();
duke@435: 
duke@435: private:
duke@435:   int _active_workers;
duke@435:   int _yielded_workers;
duke@435:   void wait_for_gang();
duke@435: 
duke@435: public:
duke@435:   // Accessors for fields
duke@435:   int active_workers() const {
duke@435:     return _active_workers;
duke@435:   }
duke@435: 
jmasa@2188:   // Accessors for fields
duke@435:   int yielded_workers() const {
duke@435:     return _yielded_workers;
duke@435:   }
duke@435: 
duke@435: private:
duke@435:   friend class YieldingFlexibleGangWorker;
duke@435:   void reset(); // NYI
duke@435: };
stefank@2314: 
stefank@2314: #endif // SHARE_VM_UTILITIES_YIELDINGWORKGROUP_HPP