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hotspot/src/share/vm/utilities/taskqueue.cpp

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+/*
+ * Copyright 2001-2006 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.
+ *
+ */
+
+# include "incls/_precompiled.incl"
+# include "incls/_taskqueue.cpp.incl"
+
+bool TaskQueueSuper::peek() {
+  return _bottom != _age.top();
+}
+
+int TaskQueueSetSuper::randomParkAndMiller(int *seed0) {
+  const int a =      16807;
+  const int m = 2147483647;
+  const int q =     127773;  /* m div a */
+  const int r =       2836;  /* m mod a */
+  assert(sizeof(int) == 4, "I think this relies on that");
+  int seed = *seed0;
+  int hi   = seed / q;
+  int lo   = seed % q;
+  int test = a * lo - r * hi;
+  if (test > 0)
+    seed = test;
+  else
+    seed = test + m;
+  *seed0 = seed;
+  return seed;
+}
+
+ParallelTaskTerminator::
+ParallelTaskTerminator(int n_threads, TaskQueueSetSuper* queue_set) :
+  _n_threads(n_threads),
+  _queue_set(queue_set),
+  _offered_termination(0) {}
+
+bool ParallelTaskTerminator::peek_in_queue_set() {
+  return _queue_set->peek();
+}
+
+void ParallelTaskTerminator::yield() {
+  os::yield();
+}
+
+void ParallelTaskTerminator::sleep(uint millis) {
+  os::sleep(Thread::current(), millis, false);
+}
+
+bool ParallelTaskTerminator::offer_termination() {
+  Atomic::inc(&_offered_termination);
+
+  juint yield_count = 0;
+  while (true) {
+    if (_offered_termination == _n_threads) {
+      //inner_termination_loop();
+      return true;
+    } else {
+      if (yield_count <= WorkStealingYieldsBeforeSleep) {
+        yield_count++;
+        yield();
+      } else {
+        if (PrintGCDetails && Verbose) {
+         gclog_or_tty->print_cr("ParallelTaskTerminator::offer_termination() "
+           "thread %d sleeps after %d yields",
+           Thread::current(), yield_count);
+        }
+        yield_count = 0;
+        // A sleep will cause this processor to seek work on another processor's
+        // runqueue, if it has nothing else to run (as opposed to the yield
+        // which may only move the thread to the end of the this processor's
+        // runqueue).
+        sleep(WorkStealingSleepMillis);
+      }
+
+      if (peek_in_queue_set()) {
+        Atomic::dec(&_offered_termination);
+        return false;
+      }
+    }
+  }
+}
+
+void ParallelTaskTerminator::reset_for_reuse() {
+  if (_offered_termination != 0) {
+    assert(_offered_termination == _n_threads,
+           "Terminator may still be in use");
+    _offered_termination = 0;
+  }
+}
+
+bool ChunkTaskQueueWithOverflow::is_empty() {
+  return (_chunk_queue.size() == 0) &&
+         (_overflow_stack->length() == 0);
+}
+
+bool ChunkTaskQueueWithOverflow::stealable_is_empty() {
+  return _chunk_queue.size() == 0;
+}
+
+bool ChunkTaskQueueWithOverflow::overflow_is_empty() {
+  return _overflow_stack->length() == 0;
+}
+
+void ChunkTaskQueueWithOverflow::initialize() {
+  _chunk_queue.initialize();
+  assert(_overflow_stack == 0, "Creating memory leak");
+  _overflow_stack =
+    new (ResourceObj::C_HEAP) GrowableArray<ChunkTask>(10, true);
+}
+
+void ChunkTaskQueueWithOverflow::save(ChunkTask t) {
+  if (TraceChunkTasksQueuing && Verbose) {
+    gclog_or_tty->print_cr("CTQ: save " PTR_FORMAT, t);
+  }
+  if(!_chunk_queue.push(t)) {
+    _overflow_stack->push(t);
+  }
+}
+
+// Note that using this method will retrieve all chunks
+// that have been saved but that it will always check
+// the overflow stack.  It may be more efficient to
+// check the stealable queue and the overflow stack
+// separately.
+bool ChunkTaskQueueWithOverflow::retrieve(ChunkTask& chunk_task) {
+  bool result = retrieve_from_overflow(chunk_task);
+  if (!result) {
+    result = retrieve_from_stealable_queue(chunk_task);
+  }
+  if (TraceChunkTasksQueuing && Verbose && result) {
+    gclog_or_tty->print_cr("  CTQ: retrieve " PTR_FORMAT, result);
+  }
+  return result;
+}
+
+bool ChunkTaskQueueWithOverflow::retrieve_from_stealable_queue(
+                                   ChunkTask& chunk_task) {
+  bool result = _chunk_queue.pop_local(chunk_task);
+  if (TraceChunkTasksQueuing && Verbose) {
+    gclog_or_tty->print_cr("CTQ: retrieve_stealable " PTR_FORMAT, chunk_task);
+  }
+  return result;
+}
+
+bool ChunkTaskQueueWithOverflow::retrieve_from_overflow(
+                                        ChunkTask& chunk_task) {
+  bool result;
+  if (!_overflow_stack->is_empty()) {
+    chunk_task = _overflow_stack->pop();
+    result = true;
+  } else {
+    chunk_task = (ChunkTask) NULL;
+    result = false;
+  }
+  if (TraceChunkTasksQueuing && Verbose) {
+    gclog_or_tty->print_cr("CTQ: retrieve_stealable " PTR_FORMAT, chunk_task);
+  }
+  return result;
+}