--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/utilities/yieldingWorkgroup.hpp Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,203 @@
+/*
+ * Copyright 2005 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.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_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
+};