6711316: Open source the Garbage-First garbage collector

First mercurial integration of the code for the Garbage-First garbage collector.

Reviewed-by: apetrusenko, iveresov, jmasa, sgoldman, tonyp, ysr

hotspot/src/share/vm/gc_implementation/g1/bufferingOopClosure.hpp

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+/*
+ * Copyright 2001-2007 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.
+ *
+ */
+
+// A BufferingOops closure tries to separate out the cost of finding roots
+// from the cost of applying closures to them.  It maintains an array of
+// ref-containing locations.  Until the array is full, applying the closure
+// to an oop* merely records that location in the array.  Since this
+// closure app cost is small, an elapsed timer can approximately attribute
+// all of this cost to the cost of finding the roots.  When the array fills
+// up, the wrapped closure is applied to all elements, keeping track of
+// this elapsed time of this process, and leaving the array empty.
+// The caller must be sure to call "done" to process any unprocessed
+// buffered entriess.
+
+class Generation;
+class HeapRegion;
+
+class BufferingOopClosure: public OopClosure {
+protected:
+  enum PrivateConstants {
+    BufferLength = 1024
+  };
+
+  oop          *_buffer[BufferLength];
+  oop         **_buffer_top;
+  oop         **_buffer_curr;
+
+  OopClosure  *_oc;
+  double       _closure_app_seconds;
+
+  void process_buffer () {
+
+    double start = os::elapsedTime();
+    for (oop **curr = _buffer; curr < _buffer_curr; ++curr) {
+      _oc->do_oop(*curr);
+    }
+    _buffer_curr = _buffer;
+    _closure_app_seconds += (os::elapsedTime() - start);
+  }
+
+public:
+  virtual void do_oop(narrowOop* p) {
+    guarantee(false, "NYI");
+  }
+  virtual void do_oop(oop *p) {
+    if (_buffer_curr == _buffer_top) {
+      process_buffer();
+    }
+
+    *_buffer_curr = p;
+    ++_buffer_curr;
+  }
+  void done () {
+    if (_buffer_curr > _buffer) {
+      process_buffer();
+    }
+  }
+  double closure_app_seconds () {
+    return _closure_app_seconds;
+  }
+  BufferingOopClosure (OopClosure *oc) :
+    _oc(oc),
+    _buffer_curr(_buffer), _buffer_top(_buffer + BufferLength),
+    _closure_app_seconds(0.0) { }
+};
+
+class BufferingOopsInGenClosure: public OopsInGenClosure {
+  BufferingOopClosure _boc;
+  OopsInGenClosure* _oc;
+public:
+  BufferingOopsInGenClosure(OopsInGenClosure *oc) :
+    _boc(oc), _oc(oc) {}
+
+  virtual void do_oop(narrowOop* p) {
+    guarantee(false, "NYI");
+  }
+
+  virtual void do_oop(oop* p) {
+    assert(generation()->is_in_reserved(p), "Must be in!");
+    _boc.do_oop(p);
+  }
+
+  void done() {
+    _boc.done();
+  }
+
+  double closure_app_seconds () {
+    return _boc.closure_app_seconds();
+  }
+
+  void set_generation(Generation* gen) {
+    OopsInGenClosure::set_generation(gen);
+    _oc->set_generation(gen);
+  }
+
+  void reset_generation() {
+    // Make sure we finish the current work with the current generation.
+    _boc.done();
+    OopsInGenClosure::reset_generation();
+    _oc->reset_generation();
+  }
+
+};
+
+
+class BufferingOopsInHeapRegionClosure: public OopsInHeapRegionClosure {
+private:
+  enum PrivateConstants {
+    BufferLength = 1024
+  };
+
+  oop                      *_buffer[BufferLength];
+  oop                     **_buffer_top;
+  oop                     **_buffer_curr;
+
+  HeapRegion               *_hr_buffer[BufferLength];
+  HeapRegion              **_hr_curr;
+
+  OopsInHeapRegionClosure  *_oc;
+  double                    _closure_app_seconds;
+
+  void process_buffer () {
+
+    assert((_hr_curr - _hr_buffer) == (_buffer_curr - _buffer),
+           "the two lengths should be the same");
+
+    double start = os::elapsedTime();
+    HeapRegion **hr_curr = _hr_buffer;
+    HeapRegion *hr_prev = NULL;
+    for (oop **curr = _buffer; curr < _buffer_curr; ++curr) {
+      HeapRegion *region = *hr_curr;
+      if (region != hr_prev) {
+        _oc->set_region(region);
+        hr_prev = region;
+      }
+      _oc->do_oop(*curr);
+      ++hr_curr;
+    }
+    _buffer_curr = _buffer;
+    _hr_curr = _hr_buffer;
+    _closure_app_seconds += (os::elapsedTime() - start);
+  }
+
+public:
+  virtual void do_oop(narrowOop *p) {
+    guarantee(false, "NYI");
+  }
+
+  virtual void do_oop(oop *p) {
+    if (_buffer_curr == _buffer_top) {
+      assert(_hr_curr > _hr_buffer, "_hr_curr should be consistent with _buffer_curr");
+      process_buffer();
+    }
+
+    *_buffer_curr = p;
+    ++_buffer_curr;
+    *_hr_curr = _from;
+    ++_hr_curr;
+  }
+  void done () {
+    if (_buffer_curr > _buffer) {
+      assert(_hr_curr > _hr_buffer, "_hr_curr should be consistent with _buffer_curr");
+      process_buffer();
+    }
+  }
+  double closure_app_seconds () {
+    return _closure_app_seconds;
+  }
+  BufferingOopsInHeapRegionClosure (OopsInHeapRegionClosure *oc) :
+    _oc(oc),
+    _buffer_curr(_buffer), _buffer_top(_buffer + BufferLength),
+    _hr_curr(_hr_buffer),
+    _closure_app_seconds(0.0) { }
+};