--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/shared/workgroup.hpp Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,413 @@
+/*
+ * Copyright (c) 2002, 2016, 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 "memory/allocation.hpp"
+#include "runtime/globals.hpp"
+#include "runtime/thread.hpp"
+#include "gc/shared/gcId.hpp"
+#include "logging/log.hpp"
+#include "utilities/debug.hpp"
+#include "utilities/globalDefinitions.hpp"
+
+// Task class hierarchy:
+// AbstractGangTask
+//
+// Gang/Group class hierarchy:
+// AbstractWorkGang
+// WorkGang
+// YieldingFlexibleWorkGang (defined in another file)
+//
+// Worker class hierarchy:
+// AbstractGangWorker (subclass of WorkerThread)
+// GangWorker
+// YieldingFlexibleGangWorker (defined in another file)
+
+// Forward declarations of classes defined here
+
+class AbstractGangWorker;
+class Semaphore;
+class WorkGang;
+
+// 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 {
+ const char* _name;
+ const uint _gc_id;
+
+ public:
+ AbstractGangTask(const char* name) :
+ _name(name),
+ _gc_id(GCId::current_raw())
+ {}
+
+ AbstractGangTask(const char* name, const uint gc_id) :
+ _name(name),
+ _gc_id(gc_id)
+ {}
+
+ // The abstract work method.
+ // The argument tells you which member of the gang you are.
+ virtual void work(uint worker_id) = 0;
+
+ // Debugging accessor for the name.
+ const char* name() const { return _name; }
+ const uint gc_id() const { return _gc_id; }
+};
+
+struct WorkData {
+ AbstractGangTask* _task;
+ uint _worker_id;
+ WorkData(AbstractGangTask* task, uint worker_id) : _task(task), _worker_id(worker_id) {}
+};
+
+// Interface to handle the synchronization between the coordinator thread and the worker threads,
+// when a task is dispatched out to the worker threads.
+class GangTaskDispatcher : public CHeapObj<mtGC> {
+ public:
+ virtual ~GangTaskDispatcher() {}
+
+ // Coordinator API.
+
+ // Distributes the task out to num_workers workers.
+ // Returns when the task has been completed by all workers.
+ virtual void coordinator_execute_on_workers(AbstractGangTask* task, uint num_workers) = 0;
+
+ // Worker API.
+
+ // Waits for a task to become available to the worker.
+ // Returns when the worker has been assigned a task.
+ virtual WorkData worker_wait_for_task() = 0;
+
+ // Signal to the coordinator that the worker is done with the assigned task.
+ virtual void worker_done_with_task() = 0;
+};
+
+// The work gang is the collection of workers to execute tasks.
+// The number of workers run for a task is "_active_workers"
+// while "_total_workers" is the number of available of workers.
+class AbstractWorkGang : public CHeapObj<mtInternal> {
+ protected:
+ // The array of worker threads for this gang.
+ AbstractGangWorker** _workers;
+ // The count of the number of workers in the gang.
+ uint _total_workers;
+ // The currently active workers in this gang.
+ uint _active_workers;
+ // The count of created workers in the gang.
+ uint _created_workers;
+ // Printing support.
+ const char* _name;
+
+ private:
+ // Initialize only instance data.
+ const bool _are_GC_task_threads;
+ const bool _are_ConcurrentGC_threads;
+
+ void set_thread(uint worker_id, AbstractGangWorker* worker) {
+ _workers[worker_id] = worker;
+ }
+
+ public:
+ AbstractWorkGang(const char* name, uint workers, bool are_GC_task_threads, bool are_ConcurrentGC_threads) :
+ _name(name),
+ _total_workers(workers),
+ _active_workers(UseDynamicNumberOfGCThreads ? 1U : workers),
+ _created_workers(0),
+ _are_GC_task_threads(are_GC_task_threads),
+ _are_ConcurrentGC_threads(are_ConcurrentGC_threads)
+ { }
+
+ // Initialize workers in the gang. Return true if initialization succeeded.
+ void initialize_workers();
+
+ bool are_GC_task_threads() const { return _are_GC_task_threads; }
+ bool are_ConcurrentGC_threads() const { return _are_ConcurrentGC_threads; }
+
+ uint total_workers() const { return _total_workers; }
+
+ uint created_workers() const {
+ return _created_workers;
+ }
+
+ virtual uint active_workers() const {
+ assert(_active_workers <= _total_workers,
+ "_active_workers: %u > _total_workers: %u", _active_workers, _total_workers);
+ assert(UseDynamicNumberOfGCThreads || _active_workers == _total_workers,
+ "Unless dynamic should use total workers");
+ return _active_workers;
+ }
+
+ uint update_active_workers(uint v) {
+ assert(v <= _total_workers,
+ "Trying to set more workers active than there are");
+ _active_workers = MIN2(v, _total_workers);
+ add_workers(false /* exit_on_failure */);
+ assert(v != 0, "Trying to set active workers to 0");
+ log_trace(gc, task)("%s: using %d out of %d workers", name(), _active_workers, _total_workers);
+ return _active_workers;
+ }
+
+ // Add GC workers as needed.
+ void add_workers(bool initializing);
+
+ // Add GC workers as needed to reach the specified number of workers.
+ void add_workers(uint active_workers, bool initializing);
+
+ // Return the Ith worker.
+ AbstractGangWorker* worker(uint i) const;
+
+ // Base name (without worker id #) of threads.
+ const char* group_name() { return name(); }
+
+ void threads_do(ThreadClosure* tc) const;
+
+ // Create a GC worker and install it into the work gang.
+ virtual AbstractGangWorker* install_worker(uint which);
+
+ // Debugging.
+ const char* name() const { return _name; }
+
+ // Printing
+ void print_worker_threads_on(outputStream *st) const;
+ void print_worker_threads() const {
+ print_worker_threads_on(tty);
+ }
+
+ protected:
+ virtual AbstractGangWorker* allocate_worker(uint which) = 0;
+};
+
+// An class representing a gang of workers.
+class WorkGang: public AbstractWorkGang {
+ // To get access to the GangTaskDispatcher instance.
+ friend class GangWorker;
+
+ // Never deleted.
+ ~WorkGang();
+
+ GangTaskDispatcher* const _dispatcher;
+ GangTaskDispatcher* dispatcher() const {
+ return _dispatcher;
+ }
+
+public:
+ WorkGang(const char* name,
+ uint workers,
+ bool are_GC_task_threads,
+ bool are_ConcurrentGC_threads);
+
+ // Run a task using the current active number of workers, returns when the task is done.
+ virtual void run_task(AbstractGangTask* task);
+ // Run a task with the given number of workers, returns
+ // when the task is done. The number of workers must be at most the number of
+ // active workers. Additional workers may be created if an insufficient
+ // number currently exists.
+ void run_task(AbstractGangTask* task, uint num_workers);
+
+protected:
+ virtual AbstractGangWorker* allocate_worker(uint which);
+};
+
+// Several instances of this class run in parallel as workers for a gang.
+class AbstractGangWorker: public WorkerThread {
+public:
+ AbstractGangWorker(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() = 0;
+
+ AbstractWorkGang* gang() const { return _gang; }
+};
+
+class GangWorker: public AbstractGangWorker {
+public:
+ GangWorker(WorkGang* gang, uint id) : AbstractGangWorker(gang, id) {}
+
+protected:
+ virtual void loop();
+
+private:
+ WorkData wait_for_task();
+ void run_task(WorkData work);
+ void signal_task_done();
+
+ WorkGang* gang() const { return (WorkGang*)_gang; }
+};
+
+// 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> {
+ volatile uint* _tasks;
+ uint _n_tasks;
+ volatile 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();
+
+ // 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.)
+ //
+ // n_threads - Number of threads executing the sub-tasks.
+ void all_tasks_completed(uint n_threads);
+
+ // 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.
+ volatile 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.
+ volatile 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();
+};
+
+#endif // SHARE_VM_GC_SHARED_WORKGROUP_HPP