/*

 * Copyright (c) 2005, 2010, 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.

 *

 */

// The following class hierarchy represents

// a set of operations (VM_Operation) related to GC.

//

//  VM_Operation

//      VM_GC_Operation

//          VM_GC_HeapInspection

//          VM_GenCollectForAllocation

//          VM_GenCollectFull

//          VM_GenCollectFullConcurrent

//          VM_ParallelGCFailedAllocation

//          VM_ParallelGCFailedPermanentAllocation

//          VM_ParallelGCSystemGC

//  VM_GC_Operation

//   - implements methods common to all classes in the hierarchy:

//     prevents multiple gc requests and manages lock on heap;

//

//  VM_GC_HeapInspection

//   - prints class histogram on SIGBREAK if PrintClassHistogram

//     is specified; and also the attach "inspectheap" operation

//

//  VM_GenCollectForAllocation

//  VM_GenCollectForPermanentAllocation

//  VM_ParallelGCFailedAllocation

//  VM_ParallelGCFailedPermanentAllocation

//   - this operation is invoked when allocation is failed;

//     operation performs garbage collection and tries to

//     allocate afterwards;

//

//  VM_GenCollectFull

//  VM_GenCollectFullConcurrent

//  VM_ParallelGCSystemGC

//   - these operations preform full collection of heaps of

//     different kind

//

class VM_GC_Operation: public VM_Operation {

 protected:

  BasicLock     _pending_list_basic_lock; // for refs pending list notification (PLL)

  unsigned int  _gc_count_before;         // gc count before acquiring PLL

  unsigned int  _full_gc_count_before;    // full gc count before acquiring PLL

  bool          _full;                    // whether a "full" collection

  bool          _prologue_succeeded;      // whether doit_prologue succeeded

  GCCause::Cause _gc_cause;                // the putative cause for this gc op

  bool          _gc_locked;               // will be set if gc was locked

  virtual bool skip_operation() const;

  // java.lang.ref.Reference support

  void acquire_pending_list_lock();

  void release_and_notify_pending_list_lock();

 public:

  VM_GC_Operation(unsigned int gc_count_before,

                  unsigned int full_gc_count_before = 0,

                  bool full = false) {

    _full = full;

    _prologue_succeeded = false;

    _gc_count_before    = gc_count_before;

    // A subclass constructor will likely overwrite the following

    _gc_cause           = GCCause::_no_cause_specified;

    _gc_locked = false;

    // In ParallelScavengeHeap::mem_allocate() collections can be

    // executed within a loop and _all_soft_refs_clear can be set

    // true after they have been cleared by a collection and another

    // collection started so that _all_soft_refs_clear can be true

    // when this collection is started.  Don't assert that

    // _all_soft_refs_clear have to be false here even though

    // mutators have run.  Soft refs will be cleared again in this

    // collection.

  }

  ~VM_GC_Operation() {

    CollectedHeap* ch = Universe::heap();

    ch->collector_policy()->set_all_soft_refs_clear(false);

  }

  // Acquire the reference synchronization lock

  virtual bool doit_prologue();

  // Do notifyAll (if needed) and release held lock

  virtual void doit_epilogue();

  virtual bool allow_nested_vm_operations() const  { return true; }

  bool prologue_succeeded() const { return _prologue_succeeded; }

  void set_gc_locked() { _gc_locked = true; }

  bool gc_locked() const  { return _gc_locked; }

  static void notify_gc_begin(bool full = false);

  static void notify_gc_end();

};

class VM_GC_HeapInspection: public VM_GC_Operation {

 private:

  outputStream* _out;

  bool _full_gc;

  bool _need_prologue;

 public:

  VM_GC_HeapInspection(outputStream* out, bool request_full_gc,

                       bool need_prologue) :

    VM_GC_Operation(0 /* total collections,      dummy, ignored */,

                    0 /* total full collections, dummy, ignored */,

                    request_full_gc) {

    _out = out;

    _full_gc = request_full_gc;

    _need_prologue = need_prologue;

  }

  ~VM_GC_HeapInspection() {}

  virtual VMOp_Type type() const { return VMOp_GC_HeapInspection; }

  virtual bool skip_operation() const;

  virtual bool doit_prologue();

  virtual void doit();

};

class VM_GenCollectForAllocation: public VM_GC_Operation {

 private:

  HeapWord*   _res;

  size_t      _size;                       // size of object to be allocated.

  bool        _tlab;                       // alloc is of a tlab.

 public:

  VM_GenCollectForAllocation(size_t size,

                             bool tlab,

                             unsigned int gc_count_before)

    : VM_GC_Operation(gc_count_before),

      _size(size),

      _tlab(tlab) {

    _res = NULL;

  }

  ~VM_GenCollectForAllocation()  {}

  virtual VMOp_Type type() const { return VMOp_GenCollectForAllocation; }

  virtual void doit();

  HeapWord* result() const       { return _res; }

};

// VM operation to invoke a collection of the heap as a

// GenCollectedHeap heap.

class VM_GenCollectFull: public VM_GC_Operation {

 private:

  int _max_level;

 public:

  VM_GenCollectFull(unsigned int gc_count_before,

                    unsigned int full_gc_count_before,

                    GCCause::Cause gc_cause,

                      int max_level)

    : VM_GC_Operation(gc_count_before, full_gc_count_before, true /* full */),

      _max_level(max_level)

  { _gc_cause = gc_cause; }

  ~VM_GenCollectFull() {}

  virtual VMOp_Type type() const { return VMOp_GenCollectFull; }

  virtual void doit();

};

class VM_GenCollectForPermanentAllocation: public VM_GC_Operation {

 private:

  HeapWord*   _res;

  size_t      _size;                       // size of object to be allocated

 public:

  VM_GenCollectForPermanentAllocation(size_t size,

                                      unsigned int gc_count_before,

                                      unsigned int full_gc_count_before,

                                      GCCause::Cause gc_cause)

    : VM_GC_Operation(gc_count_before, full_gc_count_before, true),

      _size(size) {

    _res = NULL;

    _gc_cause = gc_cause;

  }

  ~VM_GenCollectForPermanentAllocation()  {}

  virtual VMOp_Type type() const { return VMOp_GenCollectForPermanentAllocation; }

  virtual void doit();

  HeapWord* result() const       { return _res; }

};