duke@435: /*
ysr@2651:  * Copyright (c) 2001, 2011, 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: #include "precompiled.hpp"
stefank@2314: #include "memory/allocation.hpp"
stefank@2314: #include "memory/allocation.inline.hpp"
stefank@2314: #include "runtime/os.hpp"
stefank@2314: #include "utilities/workgroup.hpp"
duke@435: 
duke@435: // Definitions of WorkGang methods.
duke@435: 
duke@435: AbstractWorkGang::AbstractWorkGang(const char* name,
ysr@777:                                    bool  are_GC_task_threads,
ysr@777:                                    bool  are_ConcurrentGC_threads) :
duke@435:   _name(name),
ysr@777:   _are_GC_task_threads(are_GC_task_threads),
ysr@777:   _are_ConcurrentGC_threads(are_ConcurrentGC_threads) {
ysr@777: 
ysr@777:   assert(!(are_GC_task_threads && are_ConcurrentGC_threads),
ysr@777:          "They cannot both be STW GC and Concurrent threads" );
ysr@777: 
duke@435:   // Other initialization.
duke@435:   _monitor = new Monitor(/* priority */       Mutex::leaf,
duke@435:                          /* name */           "WorkGroup monitor",
ysr@777:                          /* allow_vm_block */ are_GC_task_threads);
duke@435:   assert(monitor() != NULL, "Failed to allocate monitor");
duke@435:   _terminate = false;
duke@435:   _task = NULL;
duke@435:   _sequence_number = 0;
duke@435:   _started_workers = 0;
duke@435:   _finished_workers = 0;
duke@435: }
duke@435: 
duke@435: WorkGang::WorkGang(const char* name,
jmasa@3357:                    uint        workers,
ysr@777:                    bool        are_GC_task_threads,
ysr@777:                    bool        are_ConcurrentGC_threads) :
jmasa@2188:   AbstractWorkGang(name, are_GC_task_threads, are_ConcurrentGC_threads) {
duke@435:   _total_workers = workers;
jmasa@2188: }
jmasa@2188: 
jmasa@3357: GangWorker* WorkGang::allocate_worker(uint which) {
jmasa@2188:   GangWorker* new_worker = new GangWorker(this, which);
jmasa@2188:   return new_worker;
jmasa@2188: }
jmasa@2188: 
jmasa@2188: // The current implementation will exit if the allocation
jmasa@2188: // of any worker fails.  Still, return a boolean so that
jmasa@2188: // a future implementation can possibly do a partial
jmasa@2188: // initialization of the workers and report such to the
jmasa@2188: // caller.
jmasa@2188: bool WorkGang::initialize_workers() {
ysr@777: 
duke@435:   if (TraceWorkGang) {
jmasa@2188:     tty->print_cr("Constructing work gang %s with %d threads",
jmasa@2188:                   name(),
jmasa@2188:                   total_workers());
duke@435:   }
jmasa@2188:   _gang_workers = NEW_C_HEAP_ARRAY(GangWorker*, total_workers());
ysr@777:   if (gang_workers() == NULL) {
ysr@777:     vm_exit_out_of_memory(0, "Cannot create GangWorker array.");
jmasa@2188:     return false;
jmasa@2188:   }
jmasa@2188:   os::ThreadType worker_type;
jmasa@2188:   if (are_ConcurrentGC_threads()) {
jmasa@2188:     worker_type = os::cgc_thread;
jmasa@2188:   } else {
jmasa@2188:     worker_type = os::pgc_thread;
ysr@777:   }
jmasa@3357:   for (uint worker = 0; worker < total_workers(); worker += 1) {
jmasa@2188:     GangWorker* new_worker = allocate_worker(worker);
duke@435:     assert(new_worker != NULL, "Failed to allocate GangWorker");
duke@435:     _gang_workers[worker] = new_worker;
jmasa@2188:     if (new_worker == NULL || !os::create_thread(new_worker, worker_type)) {
duke@435:       vm_exit_out_of_memory(0, "Cannot create worker GC thread. Out of system resources.");
jmasa@2188:       return false;
jmasa@2188:     }
duke@435:     if (!DisableStartThread) {
duke@435:       os::start_thread(new_worker);
duke@435:     }
duke@435:   }
jmasa@2188:   return true;
duke@435: }
duke@435: 
duke@435: AbstractWorkGang::~AbstractWorkGang() {
duke@435:   if (TraceWorkGang) {
duke@435:     tty->print_cr("Destructing work gang %s", name());
duke@435:   }
duke@435:   stop();   // stop all the workers
jmasa@3357:   for (uint worker = 0; worker < total_workers(); worker += 1) {
duke@435:     delete gang_worker(worker);
duke@435:   }
duke@435:   delete gang_workers();
duke@435:   delete monitor();
duke@435: }
duke@435: 
jmasa@3357: GangWorker* AbstractWorkGang::gang_worker(uint i) const {
duke@435:   // Array index bounds checking.
duke@435:   GangWorker* result = NULL;
duke@435:   assert(gang_workers() != NULL, "No workers for indexing");
duke@435:   assert(((i >= 0) && (i < total_workers())), "Worker index out of bounds");
duke@435:   result = _gang_workers[i];
duke@435:   assert(result != NULL, "Indexing to null worker");
duke@435:   return result;
duke@435: }
duke@435: 
duke@435: void WorkGang::run_task(AbstractGangTask* task) {
jmasa@3294:   run_task(task, total_workers());
jmasa@3294: }
jmasa@3294: 
jmasa@3294: void WorkGang::run_task(AbstractGangTask* task, uint no_of_parallel_workers) {
jmasa@3294:   task->set_for_termination(no_of_parallel_workers);
jmasa@3294: 
duke@435:   // This thread is executed by the VM thread which does not block
duke@435:   // on ordinary MutexLocker's.
duke@435:   MutexLockerEx ml(monitor(), Mutex::_no_safepoint_check_flag);
duke@435:   if (TraceWorkGang) {
duke@435:     tty->print_cr("Running work gang %s task %s", name(), task->name());
duke@435:   }
duke@435:   // Tell all the workers to run a task.
duke@435:   assert(task != NULL, "Running a null task");
duke@435:   // Initialize.
duke@435:   _task = task;
duke@435:   _sequence_number += 1;
duke@435:   _started_workers = 0;
duke@435:   _finished_workers = 0;
duke@435:   // Tell the workers to get to work.
duke@435:   monitor()->notify_all();
duke@435:   // Wait for them to be finished
jmasa@3357:   while (finished_workers() < no_of_parallel_workers) {
duke@435:     if (TraceWorkGang) {
duke@435:       tty->print_cr("Waiting in work gang %s: %d/%d finished sequence %d",
jmasa@3294:                     name(), finished_workers(), no_of_parallel_workers,
duke@435:                     _sequence_number);
duke@435:     }
duke@435:     monitor()->wait(/* no_safepoint_check */ true);
duke@435:   }
duke@435:   _task = NULL;
duke@435:   if (TraceWorkGang) {
jmasa@3294:     tty->print_cr("\nFinished work gang %s: %d/%d sequence %d",
jmasa@3294:                   name(), finished_workers(), no_of_parallel_workers,
duke@435:                   _sequence_number);
jmasa@3294:     Thread* me = Thread::current();
jmasa@3294:     tty->print_cr("  T: 0x%x  VM_thread: %d", me, me->is_VM_thread());
ysr@2651:   }
duke@435: }
duke@435: 
jmasa@3294: void FlexibleWorkGang::run_task(AbstractGangTask* task) {
jmasa@3294:   // If active_workers() is passed, _finished_workers
jmasa@3294:   // must only be incremented for workers that find non_null
jmasa@3294:   // work (as opposed to all those that just check that the
jmasa@3294:   // task is not null).
jmasa@3294:   WorkGang::run_task(task, (uint) active_workers());
jmasa@3294: }
jmasa@3294: 
duke@435: void AbstractWorkGang::stop() {
duke@435:   // Tell all workers to terminate, then wait for them to become inactive.
duke@435:   MutexLockerEx ml(monitor(), Mutex::_no_safepoint_check_flag);
duke@435:   if (TraceWorkGang) {
duke@435:     tty->print_cr("Stopping work gang %s task %s", name(), task()->name());
duke@435:   }
duke@435:   _task = NULL;
duke@435:   _terminate = true;
duke@435:   monitor()->notify_all();
jmasa@3294:   while (finished_workers() < active_workers()) {
duke@435:     if (TraceWorkGang) {
duke@435:       tty->print_cr("Waiting in work gang %s: %d/%d finished",
jmasa@3294:                     name(), finished_workers(), active_workers());
duke@435:     }
duke@435:     monitor()->wait(/* no_safepoint_check */ true);
duke@435:   }
duke@435: }
duke@435: 
duke@435: void AbstractWorkGang::internal_worker_poll(WorkData* data) const {
duke@435:   assert(monitor()->owned_by_self(), "worker_poll is an internal method");
duke@435:   assert(data != NULL, "worker data is null");
duke@435:   data->set_terminate(terminate());
duke@435:   data->set_task(task());
duke@435:   data->set_sequence_number(sequence_number());
duke@435: }
duke@435: 
duke@435: void AbstractWorkGang::internal_note_start() {
duke@435:   assert(monitor()->owned_by_self(), "note_finish is an internal method");
duke@435:   _started_workers += 1;
duke@435: }
duke@435: 
duke@435: void AbstractWorkGang::internal_note_finish() {
duke@435:   assert(monitor()->owned_by_self(), "note_finish is an internal method");
duke@435:   _finished_workers += 1;
duke@435: }
duke@435: 
duke@435: void AbstractWorkGang::print_worker_threads_on(outputStream* st) const {
duke@435:   uint    num_thr = total_workers();
duke@435:   for (uint i = 0; i < num_thr; i++) {
duke@435:     gang_worker(i)->print_on(st);
duke@435:     st->cr();
duke@435:   }
duke@435: }
duke@435: 
duke@435: void AbstractWorkGang::threads_do(ThreadClosure* tc) const {
duke@435:   assert(tc != NULL, "Null ThreadClosure");
duke@435:   uint num_thr = total_workers();
duke@435:   for (uint i = 0; i < num_thr; i++) {
duke@435:     tc->do_thread(gang_worker(i));
duke@435:   }
duke@435: }
duke@435: 
duke@435: // GangWorker methods.
duke@435: 
duke@435: GangWorker::GangWorker(AbstractWorkGang* gang, uint id) {
duke@435:   _gang = gang;
duke@435:   set_id(id);
duke@435:   set_name("Gang worker#%d (%s)", id, gang->name());
duke@435: }
duke@435: 
duke@435: void GangWorker::run() {
duke@435:   initialize();
duke@435:   loop();
duke@435: }
duke@435: 
duke@435: void GangWorker::initialize() {
duke@435:   this->initialize_thread_local_storage();
duke@435:   assert(_gang != NULL, "No gang to run in");
duke@435:   os::set_priority(this, NearMaxPriority);
duke@435:   if (TraceWorkGang) {
duke@435:     tty->print_cr("Running gang worker for gang %s id %d",
duke@435:                   gang()->name(), id());
duke@435:   }
duke@435:   // The VM thread should not execute here because MutexLocker's are used
duke@435:   // as (opposed to MutexLockerEx's).
duke@435:   assert(!Thread::current()->is_VM_thread(), "VM thread should not be part"
duke@435:          " of a work gang");
duke@435: }
duke@435: 
duke@435: void GangWorker::loop() {
duke@435:   int previous_sequence_number = 0;
duke@435:   Monitor* gang_monitor = gang()->monitor();
duke@435:   for ( ; /* !terminate() */; ) {
duke@435:     WorkData data;
duke@435:     int part;  // Initialized below.
duke@435:     {
duke@435:       // Grab the gang mutex.
duke@435:       MutexLocker ml(gang_monitor);
duke@435:       // Wait for something to do.
duke@435:       // Polling outside the while { wait } avoids missed notifies
duke@435:       // in the outer loop.
duke@435:       gang()->internal_worker_poll(&data);
duke@435:       if (TraceWorkGang) {
duke@435:         tty->print("Polled outside for work in gang %s worker %d",
duke@435:                    gang()->name(), id());
duke@435:         tty->print("  terminate: %s",
duke@435:                    data.terminate() ? "true" : "false");
duke@435:         tty->print("  sequence: %d (prev: %d)",
duke@435:                    data.sequence_number(), previous_sequence_number);
duke@435:         if (data.task() != NULL) {
duke@435:           tty->print("  task: %s", data.task()->name());
duke@435:         } else {
duke@435:           tty->print("  task: NULL");
duke@435:         }
duke@435:         tty->cr();
duke@435:       }
duke@435:       for ( ; /* break or return */; ) {
duke@435:         // Terminate if requested.
duke@435:         if (data.terminate()) {
duke@435:           gang()->internal_note_finish();
duke@435:           gang_monitor->notify_all();
duke@435:           return;
duke@435:         }
duke@435:         // Check for new work.
duke@435:         if ((data.task() != NULL) &&
duke@435:             (data.sequence_number() != previous_sequence_number)) {
jmasa@3294:           if (gang()->needs_more_workers()) {
jmasa@3294:             gang()->internal_note_start();
jmasa@3294:             gang_monitor->notify_all();
jmasa@3294:             part = gang()->started_workers() - 1;
jmasa@3294:             break;
jmasa@3294:           }
duke@435:         }
duke@435:         // Nothing to do.
duke@435:         gang_monitor->wait(/* no_safepoint_check */ true);
duke@435:         gang()->internal_worker_poll(&data);
duke@435:         if (TraceWorkGang) {
duke@435:           tty->print("Polled inside for work in gang %s worker %d",
duke@435:                      gang()->name(), id());
duke@435:           tty->print("  terminate: %s",
duke@435:                      data.terminate() ? "true" : "false");
duke@435:           tty->print("  sequence: %d (prev: %d)",
duke@435:                      data.sequence_number(), previous_sequence_number);
duke@435:           if (data.task() != NULL) {
duke@435:             tty->print("  task: %s", data.task()->name());
duke@435:           } else {
duke@435:             tty->print("  task: NULL");
duke@435:           }
duke@435:           tty->cr();
duke@435:         }
duke@435:       }
duke@435:       // Drop gang mutex.
duke@435:     }
duke@435:     if (TraceWorkGang) {
duke@435:       tty->print("Work for work gang %s id %d task %s part %d",
duke@435:                  gang()->name(), id(), data.task()->name(), part);
duke@435:     }
duke@435:     assert(data.task() != NULL, "Got null task");
duke@435:     data.task()->work(part);
duke@435:     {
duke@435:       if (TraceWorkGang) {
duke@435:         tty->print("Finish for work gang %s id %d task %s part %d",
duke@435:                    gang()->name(), id(), data.task()->name(), part);
duke@435:       }
duke@435:       // Grab the gang mutex.
duke@435:       MutexLocker ml(gang_monitor);
duke@435:       gang()->internal_note_finish();
duke@435:       // Tell the gang you are done.
duke@435:       gang_monitor->notify_all();
duke@435:       // Drop the gang mutex.
duke@435:     }
duke@435:     previous_sequence_number = data.sequence_number();
duke@435:   }
duke@435: }
duke@435: 
duke@435: bool GangWorker::is_GC_task_thread() const {
ysr@777:   return gang()->are_GC_task_threads();
ysr@777: }
ysr@777: 
ysr@777: bool GangWorker::is_ConcurrentGC_thread() const {
ysr@777:   return gang()->are_ConcurrentGC_threads();
duke@435: }
duke@435: 
duke@435: void GangWorker::print_on(outputStream* st) const {
duke@435:   st->print("\"%s\" ", name());
duke@435:   Thread::print_on(st);
duke@435:   st->cr();
duke@435: }
duke@435: 
duke@435: // Printing methods
duke@435: 
duke@435: const char* AbstractWorkGang::name() const {
duke@435:   return _name;
duke@435: }
duke@435: 
duke@435: #ifndef PRODUCT
duke@435: 
duke@435: const char* AbstractGangTask::name() const {
duke@435:   return _name;
duke@435: }
duke@435: 
duke@435: #endif /* PRODUCT */
duke@435: 
jmasa@3294: // FlexibleWorkGang
jmasa@3294: 
jmasa@3294: 
duke@435: // *** WorkGangBarrierSync
duke@435: 
duke@435: WorkGangBarrierSync::WorkGangBarrierSync()
duke@435:   : _monitor(Mutex::safepoint, "work gang barrier sync", true),
ysr@777:     _n_workers(0), _n_completed(0), _should_reset(false) {
duke@435: }
duke@435: 
jmasa@3357: WorkGangBarrierSync::WorkGangBarrierSync(uint n_workers, const char* name)
duke@435:   : _monitor(Mutex::safepoint, name, true),
ysr@777:     _n_workers(n_workers), _n_completed(0), _should_reset(false) {
duke@435: }
duke@435: 
jmasa@3357: void WorkGangBarrierSync::set_n_workers(uint n_workers) {
duke@435:   _n_workers   = n_workers;
duke@435:   _n_completed = 0;
ysr@777:   _should_reset = false;
duke@435: }
duke@435: 
duke@435: void WorkGangBarrierSync::enter() {
duke@435:   MutexLockerEx x(monitor(), Mutex::_no_safepoint_check_flag);
ysr@777:   if (should_reset()) {
ysr@777:     // The should_reset() was set and we are the first worker to enter
ysr@777:     // the sync barrier. We will zero the n_completed() count which
ysr@777:     // effectively resets the barrier.
ysr@777:     zero_completed();
ysr@777:     set_should_reset(false);
ysr@777:   }
duke@435:   inc_completed();
duke@435:   if (n_completed() == n_workers()) {
ysr@777:     // At this point we would like to reset the barrier to be ready in
ysr@777:     // case it is used again. However, we cannot set n_completed() to
ysr@777:     // 0, even after the notify_all(), given that some other workers
ysr@777:     // might still be waiting for n_completed() to become ==
ysr@777:     // n_workers(). So, if we set n_completed() to 0, those workers
ysr@777:     // will get stuck (as they will wake up, see that n_completed() !=
ysr@777:     // n_workers() and go back to sleep). Instead, we raise the
ysr@777:     // should_reset() flag and the barrier will be reset the first
ysr@777:     // time a worker enters it again.
ysr@777:     set_should_reset(true);
duke@435:     monitor()->notify_all();
ysr@777:   } else {
duke@435:     while (n_completed() != n_workers()) {
duke@435:       monitor()->wait(/* no_safepoint_check */ true);
duke@435:     }
duke@435:   }
duke@435: }
duke@435: 
duke@435: // SubTasksDone functions.
duke@435: 
jmasa@3357: SubTasksDone::SubTasksDone(uint n) :
duke@435:   _n_tasks(n), _n_threads(1), _tasks(NULL) {
jmasa@3357:   _tasks = NEW_C_HEAP_ARRAY(uint, n);
duke@435:   guarantee(_tasks != NULL, "alloc failure");
duke@435:   clear();
duke@435: }
duke@435: 
duke@435: bool SubTasksDone::valid() {
duke@435:   return _tasks != NULL;
duke@435: }
duke@435: 
jmasa@3357: void SubTasksDone::set_n_threads(uint t) {
duke@435:   assert(_claimed == 0 || _threads_completed == _n_threads,
duke@435:          "should not be called while tasks are being processed!");
duke@435:   _n_threads = (t == 0 ? 1 : t);
duke@435: }
duke@435: 
duke@435: void SubTasksDone::clear() {
jmasa@3357:   for (uint i = 0; i < _n_tasks; i++) {
duke@435:     _tasks[i] = 0;
duke@435:   }
duke@435:   _threads_completed = 0;
duke@435: #ifdef ASSERT
duke@435:   _claimed = 0;
duke@435: #endif
duke@435: }
duke@435: 
jmasa@3357: bool SubTasksDone::is_task_claimed(uint t) {
duke@435:   assert(0 <= t && t < _n_tasks, "bad task id.");
jmasa@3357:   uint old = _tasks[t];
duke@435:   if (old == 0) {
duke@435:     old = Atomic::cmpxchg(1, &_tasks[t], 0);
duke@435:   }
duke@435:   assert(_tasks[t] == 1, "What else?");
duke@435:   bool res = old != 0;
duke@435: #ifdef ASSERT
duke@435:   if (!res) {
duke@435:     assert(_claimed < _n_tasks, "Too many tasks claimed; missing clear?");
jmasa@3357:     Atomic::inc((volatile jint*) &_claimed);
duke@435:   }
duke@435: #endif
duke@435:   return res;
duke@435: }
duke@435: 
duke@435: void SubTasksDone::all_tasks_completed() {
duke@435:   jint observed = _threads_completed;
duke@435:   jint old;
duke@435:   do {
duke@435:     old = observed;
duke@435:     observed = Atomic::cmpxchg(old+1, &_threads_completed, old);
duke@435:   } while (observed != old);
duke@435:   // If this was the last thread checking in, clear the tasks.
jmasa@3357:   if (observed+1 == (jint)_n_threads) clear();
duke@435: }
duke@435: 
duke@435: 
duke@435: SubTasksDone::~SubTasksDone() {
duke@435:   if (_tasks != NULL) FREE_C_HEAP_ARRAY(jint, _tasks);
duke@435: }
duke@435: 
duke@435: // *** SequentialSubTasksDone
duke@435: 
duke@435: void SequentialSubTasksDone::clear() {
duke@435:   _n_tasks   = _n_claimed   = 0;
duke@435:   _n_threads = _n_completed = 0;
duke@435: }
duke@435: 
duke@435: bool SequentialSubTasksDone::valid() {
duke@435:   return _n_threads > 0;
duke@435: }
duke@435: 
jmasa@3357: bool SequentialSubTasksDone::is_task_claimed(uint& t) {
jmasa@3357:   uint* n_claimed_ptr = &_n_claimed;
duke@435:   t = *n_claimed_ptr;
duke@435:   while (t < _n_tasks) {
duke@435:     jint res = Atomic::cmpxchg(t+1, n_claimed_ptr, t);
jmasa@3357:     if (res == (jint)t) {
duke@435:       return false;
duke@435:     }
duke@435:     t = *n_claimed_ptr;
duke@435:   }
duke@435:   return true;
duke@435: }
duke@435: 
duke@435: bool SequentialSubTasksDone::all_tasks_completed() {
jmasa@3357:   uint* n_completed_ptr = &_n_completed;
jmasa@3357:   uint  complete        = *n_completed_ptr;
duke@435:   while (true) {
jmasa@3357:     uint res = Atomic::cmpxchg(complete+1, n_completed_ptr, complete);
duke@435:     if (res == complete) {
duke@435:       break;
duke@435:     }
duke@435:     complete = res;
duke@435:   }
duke@435:   if (complete+1 == _n_threads) {
duke@435:     clear();
duke@435:     return true;
duke@435:   }
duke@435:   return false;
duke@435: }
ysr@777: 
ysr@777: bool FreeIdSet::_stat_init = false;
ysr@777: FreeIdSet* FreeIdSet::_sets[NSets];
ysr@777: bool FreeIdSet::_safepoint;
ysr@777: 
ysr@777: FreeIdSet::FreeIdSet(int sz, Monitor* mon) :
ysr@777:   _sz(sz), _mon(mon), _hd(0), _waiters(0), _index(-1), _claimed(0)
ysr@777: {
ysr@777:   _ids = new int[sz];
ysr@777:   for (int i = 0; i < sz; i++) _ids[i] = i+1;
ysr@777:   _ids[sz-1] = end_of_list; // end of list.
ysr@777:   if (_stat_init) {
ysr@777:     for (int j = 0; j < NSets; j++) _sets[j] = NULL;
ysr@777:     _stat_init = true;
ysr@777:   }
ysr@777:   // Add to sets.  (This should happen while the system is still single-threaded.)
ysr@777:   for (int j = 0; j < NSets; j++) {
ysr@777:     if (_sets[j] == NULL) {
ysr@777:       _sets[j] = this;
ysr@777:       _index = j;
ysr@777:       break;
ysr@777:     }
ysr@777:   }
ysr@777:   guarantee(_index != -1, "Too many FreeIdSets in use!");
ysr@777: }
ysr@777: 
ysr@777: FreeIdSet::~FreeIdSet() {
ysr@777:   _sets[_index] = NULL;
ysr@777: }
ysr@777: 
ysr@777: void FreeIdSet::set_safepoint(bool b) {
ysr@777:   _safepoint = b;
ysr@777:   if (b) {
ysr@777:     for (int j = 0; j < NSets; j++) {
ysr@777:       if (_sets[j] != NULL && _sets[j]->_waiters > 0) {
ysr@777:         Monitor* mon = _sets[j]->_mon;
ysr@777:         mon->lock_without_safepoint_check();
ysr@777:         mon->notify_all();
ysr@777:         mon->unlock();
ysr@777:       }
ysr@777:     }
ysr@777:   }
ysr@777: }
ysr@777: 
ysr@777: #define FID_STATS 0
ysr@777: 
ysr@777: int FreeIdSet::claim_par_id() {
ysr@777: #if FID_STATS
ysr@777:   thread_t tslf = thr_self();
ysr@777:   tty->print("claim_par_id[%d]: sz = %d, claimed = %d\n", tslf, _sz, _claimed);
ysr@777: #endif
ysr@777:   MutexLockerEx x(_mon, Mutex::_no_safepoint_check_flag);
ysr@777:   while (!_safepoint && _hd == end_of_list) {
ysr@777:     _waiters++;
ysr@777: #if FID_STATS
ysr@777:     if (_waiters > 5) {
ysr@777:       tty->print("claim_par_id waiting[%d]: %d waiters, %d claimed.\n",
ysr@777:                  tslf, _waiters, _claimed);
ysr@777:     }
ysr@777: #endif
ysr@777:     _mon->wait(Mutex::_no_safepoint_check_flag);
ysr@777:     _waiters--;
ysr@777:   }
ysr@777:   if (_hd == end_of_list) {
ysr@777: #if FID_STATS
ysr@777:     tty->print("claim_par_id[%d]: returning EOL.\n", tslf);
ysr@777: #endif
ysr@777:     return -1;
ysr@777:   } else {
ysr@777:     int res = _hd;
ysr@777:     _hd = _ids[res];
ysr@777:     _ids[res] = claimed;  // For debugging.
ysr@777:     _claimed++;
ysr@777: #if FID_STATS
ysr@777:     tty->print("claim_par_id[%d]: returning %d, claimed = %d.\n",
ysr@777:                tslf, res, _claimed);
ysr@777: #endif
ysr@777:     return res;
ysr@777:   }
ysr@777: }
ysr@777: 
ysr@777: bool FreeIdSet::claim_perm_id(int i) {
ysr@777:   assert(0 <= i && i < _sz, "Out of range.");
ysr@777:   MutexLockerEx x(_mon, Mutex::_no_safepoint_check_flag);
ysr@777:   int prev = end_of_list;
ysr@777:   int cur = _hd;
ysr@777:   while (cur != end_of_list) {
ysr@777:     if (cur == i) {
ysr@777:       if (prev == end_of_list) {
ysr@777:         _hd = _ids[cur];
ysr@777:       } else {
ysr@777:         _ids[prev] = _ids[cur];
ysr@777:       }
ysr@777:       _ids[cur] = claimed;
ysr@777:       _claimed++;
ysr@777:       return true;
ysr@777:     } else {
ysr@777:       prev = cur;
ysr@777:       cur = _ids[cur];
ysr@777:     }
ysr@777:   }
ysr@777:   return false;
ysr@777: 
ysr@777: }
ysr@777: 
ysr@777: void FreeIdSet::release_par_id(int id) {
ysr@777:   MutexLockerEx x(_mon, Mutex::_no_safepoint_check_flag);
ysr@777:   assert(_ids[id] == claimed, "Precondition.");
ysr@777:   _ids[id] = _hd;
ysr@777:   _hd = id;
ysr@777:   _claimed--;
ysr@777: #if FID_STATS
ysr@777:   tty->print("[%d] release_par_id(%d), waiters =%d,  claimed = %d.\n",
ysr@777:              thr_self(), id, _waiters, _claimed);
ysr@777: #endif
ysr@777:   if (_waiters > 0)
ysr@777:     // Notify all would be safer, but this is OK, right?
ysr@777:     _mon->notify_all();
ysr@777: }