--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/gc/shared/workgroup.hpp Wed May 13 15:16:06 2015 +0200
@@ -0,0 +1,531 @@
+/*
+ * Copyright (c) 2002, 2015, 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.
+ *
+ */
+
+#ifndef SHARE_VM_GC_SHARED_WORKGROUP_HPP
+#define SHARE_VM_GC_SHARED_WORKGROUP_HPP
+
+#include "gc/shared/taskqueue.hpp"
+#include "runtime/thread.inline.hpp"
+
+// Task class hierarchy:
+// AbstractGangTask
+// AbstractGangTaskWOopQueues
+//
+// Gang/Group class hierarchy:
+// AbstractWorkGang
+// WorkGang
+// FlexibleWorkGang
+// YieldingFlexibleWorkGang (defined in another file)
+//
+// Worker class hierarchy:
+// GangWorker (subclass of WorkerThread)
+// YieldingFlexibleGangWorker (defined in another file)
+
+// Forward declarations of classes defined here
+
+class WorkGang;
+class GangWorker;
+class YieldingFlexibleGangWorker;
+class YieldingFlexibleGangTask;
+class WorkData;
+class AbstractWorkGang;
+
+// An abstract task to be worked on by a gang.
+// You subclass this to supply your own work() method
+class AbstractGangTask VALUE_OBJ_CLASS_SPEC {
+public:
+ // The abstract work method.
+ // The argument tells you which member of the gang you are.
+ virtual void work(uint worker_id) = 0;
+
+ // This method configures the task for proper termination.
+ // Some tasks do not have any requirements on termination
+ // and may inherit this method that does nothing. Some
+ // tasks do some coordination on termination and override
+ // this method to implement that coordination.
+ virtual void set_for_termination(uint active_workers) {};
+
+ // Debugging accessor for the name.
+ const char* name() const PRODUCT_RETURN_(return NULL;);
+ int counter() { return _counter; }
+ void set_counter(int value) { _counter = value; }
+ int *address_of_counter() { return &_counter; }
+
+ // RTTI
+ NOT_PRODUCT(virtual bool is_YieldingFlexibleGang_task() const {
+ return false;
+ })
+
+private:
+ NOT_PRODUCT(const char* _name;)
+ // ??? Should a task have a priority associated with it?
+ // ??? Or can the run method adjust priority as needed?
+ int _counter;
+
+protected:
+ // Constructor and desctructor: only construct subclasses.
+ AbstractGangTask(const char* name)
+ {
+ NOT_PRODUCT(_name = name);
+ _counter = 0;
+ }
+ ~AbstractGangTask() { }
+
+public:
+};
+
+class AbstractGangTaskWOopQueues : public AbstractGangTask {
+ OopTaskQueueSet* _queues;
+ ParallelTaskTerminator _terminator;
+ public:
+ AbstractGangTaskWOopQueues(const char* name, OopTaskQueueSet* queues) :
+ AbstractGangTask(name), _queues(queues), _terminator(0, _queues) {}
+ ParallelTaskTerminator* terminator() { return &_terminator; }
+ virtual void set_for_termination(uint active_workers) {
+ terminator()->reset_for_reuse(active_workers);
+ }
+ OopTaskQueueSet* queues() { return _queues; }
+};
+
+
+// Class AbstractWorkGang:
+// An abstract class representing a gang of workers.
+// You subclass this to supply an implementation of run_task().
+class AbstractWorkGang: public CHeapObj<mtInternal> {
+ // Here's the public interface to this class.
+public:
+ // Constructor and destructor.
+ AbstractWorkGang(const char* name, bool are_GC_task_threads,
+ bool are_ConcurrentGC_threads);
+ ~AbstractWorkGang();
+ // Run a task, returns when the task is done (or terminated).
+ virtual void run_task(AbstractGangTask* task) = 0;
+ // Stop and terminate all workers.
+ virtual void stop();
+ // Return true if more workers should be applied to the task.
+ virtual bool needs_more_workers() const { return true; }
+public:
+ // Debugging.
+ const char* name() const;
+protected:
+ // Initialize only instance data.
+ const bool _are_GC_task_threads;
+ const bool _are_ConcurrentGC_threads;
+ // Printing support.
+ const char* _name;
+ // The monitor which protects these data,
+ // and notifies of changes in it.
+ Monitor* _monitor;
+ // The count of the number of workers in the gang.
+ uint _total_workers;
+ // Whether the workers should terminate.
+ bool _terminate;
+ // The array of worker threads for this gang.
+ // This is only needed for cleaning up.
+ GangWorker** _gang_workers;
+ // The task for this gang.
+ AbstractGangTask* _task;
+ // A sequence number for the current task.
+ int _sequence_number;
+ // The number of started workers.
+ uint _started_workers;
+ // The number of finished workers.
+ uint _finished_workers;
+public:
+ // Accessors for fields
+ Monitor* monitor() const {
+ return _monitor;
+ }
+ uint total_workers() const {
+ return _total_workers;
+ }
+ virtual uint active_workers() const {
+ return _total_workers;
+ }
+ bool terminate() const {
+ return _terminate;
+ }
+ GangWorker** gang_workers() const {
+ return _gang_workers;
+ }
+ AbstractGangTask* task() const {
+ return _task;
+ }
+ int sequence_number() const {
+ return _sequence_number;
+ }
+ uint started_workers() const {
+ return _started_workers;
+ }
+ uint finished_workers() const {
+ return _finished_workers;
+ }
+ bool are_GC_task_threads() const {
+ return _are_GC_task_threads;
+ }
+ bool are_ConcurrentGC_threads() const {
+ return _are_ConcurrentGC_threads;
+ }
+ // Predicates.
+ bool is_idle() const {
+ return (task() == NULL);
+ }
+ // Return the Ith gang worker.
+ GangWorker* gang_worker(uint i) const;
+
+ void threads_do(ThreadClosure* tc) const;
+
+ // Printing
+ void print_worker_threads_on(outputStream *st) const;
+ void print_worker_threads() const {
+ print_worker_threads_on(tty);
+ }
+
+protected:
+ friend class GangWorker;
+ friend class YieldingFlexibleGangWorker;
+ // Note activation and deactivation of workers.
+ // These methods should only be called with the mutex held.
+ void internal_worker_poll(WorkData* data) const;
+ void internal_note_start();
+ void internal_note_finish();
+};
+
+class WorkData: public StackObj {
+ // This would be a struct, but I want accessor methods.
+private:
+ bool _terminate;
+ AbstractGangTask* _task;
+ int _sequence_number;
+public:
+ // Constructor and destructor
+ WorkData() {
+ _terminate = false;
+ _task = NULL;
+ _sequence_number = 0;
+ }
+ ~WorkData() {
+ }
+ // Accessors and modifiers
+ bool terminate() const { return _terminate; }
+ void set_terminate(bool value) { _terminate = value; }
+ AbstractGangTask* task() const { return _task; }
+ void set_task(AbstractGangTask* value) { _task = value; }
+ int sequence_number() const { return _sequence_number; }
+ void set_sequence_number(int value) { _sequence_number = value; }
+
+ YieldingFlexibleGangTask* yf_task() const {
+ return (YieldingFlexibleGangTask*)_task;
+ }
+};
+
+// Class WorkGang:
+class WorkGang: public AbstractWorkGang {
+public:
+ // Constructor
+ WorkGang(const char* name, uint workers,
+ bool are_GC_task_threads, bool are_ConcurrentGC_threads);
+ // Run a task, returns when the task is done (or terminated).
+ virtual void run_task(AbstractGangTask* task);
+ void run_task(AbstractGangTask* task, uint no_of_parallel_workers);
+ // Allocate a worker and return a pointer to it.
+ virtual GangWorker* allocate_worker(uint which);
+ // Initialize workers in the gang. Return true if initialization
+ // succeeded. The type of the worker can be overridden in a derived
+ // class with the appropriate implementation of allocate_worker().
+ bool initialize_workers();
+};
+
+// Class GangWorker:
+// Several instances of this class run in parallel as workers for a gang.
+class GangWorker: public WorkerThread {
+public:
+ // Constructors and destructor.
+ GangWorker(AbstractWorkGang* gang, uint id);
+
+ // The only real method: run a task for the gang.
+ virtual void run();
+ // Predicate for Thread
+ virtual bool is_GC_task_thread() const;
+ virtual bool is_ConcurrentGC_thread() const;
+ // Printing
+ void print_on(outputStream* st) const;
+ virtual void print() const { print_on(tty); }
+protected:
+ AbstractWorkGang* _gang;
+
+ virtual void initialize();
+ virtual void loop();
+
+public:
+ AbstractWorkGang* gang() const { return _gang; }
+};
+
+// Dynamic number of worker threads
+//
+// This type of work gang is used to run different numbers of
+// worker threads at different times. The
+// number of workers run for a task is "_active_workers"
+// instead of "_total_workers" in a WorkGang. The method
+// "needs_more_workers()" returns true until "_active_workers"
+// have been started and returns false afterwards. The
+// implementation of "needs_more_workers()" in WorkGang always
+// returns true so that all workers are started. The method
+// "loop()" in GangWorker was modified to ask "needs_more_workers()"
+// in its loop to decide if it should start working on a task.
+// A worker in "loop()" waits for notification on the WorkGang
+// monitor and execution of each worker as it checks for work
+// is serialized via the same monitor. The "needs_more_workers()"
+// call is serialized and additionally the calculation for the
+// "part" (effectively the worker id for executing the task) is
+// serialized to give each worker a unique "part". Workers that
+// are not needed for this tasks (i.e., "_active_workers" have
+// been started before it, continue to wait for work.
+
+class FlexibleWorkGang: public WorkGang {
+ // The currently active workers in this gang.
+ // This is a number that is dynamically adjusted
+ // and checked in the run_task() method at each invocation.
+ // As described above _active_workers determines the number
+ // of threads started on a task. It must also be used to
+ // determine completion.
+
+ protected:
+ uint _active_workers;
+ public:
+ // Constructor and destructor.
+ // Initialize active_workers to a minimum value. Setting it to
+ // the parameter "workers" will initialize it to a maximum
+ // value which is not desirable.
+ FlexibleWorkGang(const char* name, uint workers,
+ bool are_GC_task_threads,
+ bool are_ConcurrentGC_threads) :
+ WorkGang(name, workers, are_GC_task_threads, are_ConcurrentGC_threads),
+ _active_workers(UseDynamicNumberOfGCThreads ? 1U : ParallelGCThreads) {}
+ // Accessors for fields
+ virtual uint active_workers() const { return _active_workers; }
+ void set_active_workers(uint v) {
+ assert(v <= _total_workers,
+ "Trying to set more workers active than there are");
+ _active_workers = MIN2(v, _total_workers);
+ assert(v != 0, "Trying to set active workers to 0");
+ _active_workers = MAX2(1U, _active_workers);
+ assert(UseDynamicNumberOfGCThreads || _active_workers == _total_workers,
+ "Unless dynamic should use total workers");
+ }
+ virtual void run_task(AbstractGangTask* task);
+ virtual bool needs_more_workers() const {
+ return _started_workers < _active_workers;
+ }
+};
+
+// A class that acts as a synchronisation barrier. Workers enter
+// the barrier and must wait until all other workers have entered
+// before any of them may leave.
+
+class WorkGangBarrierSync : public StackObj {
+protected:
+ Monitor _monitor;
+ uint _n_workers;
+ uint _n_completed;
+ bool _should_reset;
+ bool _aborted;
+
+ Monitor* monitor() { return &_monitor; }
+ uint n_workers() { return _n_workers; }
+ uint n_completed() { return _n_completed; }
+ bool should_reset() { return _should_reset; }
+ bool aborted() { return _aborted; }
+
+ void zero_completed() { _n_completed = 0; }
+ void inc_completed() { _n_completed++; }
+ void set_aborted() { _aborted = true; }
+ void set_should_reset(bool v) { _should_reset = v; }
+
+public:
+ WorkGangBarrierSync();
+ WorkGangBarrierSync(uint n_workers, const char* name);
+
+ // Set the number of workers that will use the barrier.
+ // Must be called before any of the workers start running.
+ void set_n_workers(uint n_workers);
+
+ // Enter the barrier. A worker that enters the barrier will
+ // not be allowed to leave until all other threads have
+ // also entered the barrier or the barrier is aborted.
+ // Returns false if the barrier was aborted.
+ bool enter();
+
+ // Aborts the barrier and wakes up any threads waiting for
+ // the barrier to complete. The barrier will remain in the
+ // aborted state until the next call to set_n_workers().
+ void abort();
+};
+
+// A class to manage claiming of subtasks within a group of tasks. The
+// subtasks will be identified by integer indices, usually elements of an
+// enumeration type.
+
+class SubTasksDone: public CHeapObj<mtInternal> {
+ uint* _tasks;
+ uint _n_tasks;
+ // _n_threads is used to determine when a sub task is done.
+ // It does not control how many threads will execute the subtask
+ // but must be initialized to the number that do execute the task
+ // in order to correctly decide when the subtask is done (all the
+ // threads working on the task have finished).
+ uint _n_threads;
+ uint _threads_completed;
+#ifdef ASSERT
+ volatile uint _claimed;
+#endif
+
+ // Set all tasks to unclaimed.
+ void clear();
+
+public:
+ // Initializes "this" to a state in which there are "n" tasks to be
+ // processed, none of the which are originally claimed. The number of
+ // threads doing the tasks is initialized 1.
+ SubTasksDone(uint n);
+
+ // True iff the object is in a valid state.
+ bool valid();
+
+ // Get/set the number of parallel threads doing the tasks to "t". Can only
+ // be called before tasks start or after they are complete.
+ uint n_threads() { return _n_threads; }
+ void set_n_threads(uint t);
+
+ // Returns "false" if the task "t" is unclaimed, and ensures that task is
+ // claimed. The task "t" is required to be within the range of "this".
+ bool is_task_claimed(uint t);
+
+ // The calling thread asserts that it has attempted to claim all the
+ // tasks that it will try to claim. Every thread in the parallel task
+ // must execute this. (When the last thread does so, the task array is
+ // cleared.)
+ void all_tasks_completed();
+
+ // Destructor.
+ ~SubTasksDone();
+};
+
+// As above, but for sequential tasks, i.e. instead of claiming
+// sub-tasks from a set (possibly an enumeration), claim sub-tasks
+// in sequential order. This is ideal for claiming dynamically
+// partitioned tasks (like striding in the parallel remembered
+// set scanning). Note that unlike the above class this is
+// a stack object - is there any reason for it not to be?
+
+class SequentialSubTasksDone : public StackObj {
+protected:
+ uint _n_tasks; // Total number of tasks available.
+ uint _n_claimed; // Number of tasks claimed.
+ // _n_threads is used to determine when a sub task is done.
+ // See comments on SubTasksDone::_n_threads
+ uint _n_threads; // Total number of parallel threads.
+ uint _n_completed; // Number of completed threads.
+
+ void clear();
+
+public:
+ SequentialSubTasksDone() {
+ clear();
+ }
+ ~SequentialSubTasksDone() {}
+
+ // True iff the object is in a valid state.
+ bool valid();
+
+ // number of tasks
+ uint n_tasks() const { return _n_tasks; }
+
+ // Get/set the number of parallel threads doing the tasks to t.
+ // Should be called before the task starts but it is safe
+ // to call this once a task is running provided that all
+ // threads agree on the number of threads.
+ uint n_threads() { return _n_threads; }
+ void set_n_threads(uint t) { _n_threads = t; }
+
+ // Set the number of tasks to be claimed to t. As above,
+ // should be called before the tasks start but it is safe
+ // to call this once a task is running provided all threads
+ // agree on the number of tasks.
+ void set_n_tasks(uint t) { _n_tasks = t; }
+
+ // Returns false if the next task in the sequence is unclaimed,
+ // and ensures that it is claimed. Will set t to be the index
+ // of the claimed task in the sequence. Will return true if
+ // the task cannot be claimed and there are none left to claim.
+ bool is_task_claimed(uint& t);
+
+ // The calling thread asserts that it has attempted to claim
+ // all the tasks it possibly can in the sequence. Every thread
+ // claiming tasks must promise call this. Returns true if this
+ // is the last thread to complete so that the thread can perform
+ // cleanup if necessary.
+ bool all_tasks_completed();
+};
+
+// Represents a set of free small integer ids.
+class FreeIdSet : public CHeapObj<mtInternal> {
+ enum {
+ end_of_list = -1,
+ claimed = -2
+ };
+
+ int _sz;
+ Monitor* _mon;
+
+ int* _ids;
+ int _hd;
+ int _waiters;
+ int _claimed;
+
+ static bool _safepoint;
+ typedef FreeIdSet* FreeIdSetPtr;
+ static const int NSets = 10;
+ static FreeIdSetPtr _sets[NSets];
+ static bool _stat_init;
+ int _index;
+
+public:
+ FreeIdSet(int sz, Monitor* mon);
+ ~FreeIdSet();
+
+ static void set_safepoint(bool b);
+
+ // Attempt to claim the given id permanently. Returns "true" iff
+ // successful.
+ bool claim_perm_id(int i);
+
+ // Returns an unclaimed parallel id (waiting for one to be released if
+ // necessary). Returns "-1" if a GC wakes up a wait for an id.
+ int claim_par_id();
+
+ void release_par_id(int id);
+};
+
+#endif // SHARE_VM_GC_SHARED_WORKGROUP_HPP