src/share/vm/gc_implementation/g1/g1AllocRegion.hpp - platform/external/jetbrains/jdk8u_hotspot - Git at Google

 /*
  * Copyright (c) 2011, 2014, 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_IMPLEMENTATION_G1_G1ALLOCREGION_HPP
 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1ALLOCREGION_HPP

 #include "gc_implementation/g1/heapRegion.hpp"

 class G1CollectedHeap;

 // 0 -> no tracing, 1 -> basic tracing, 2 -> basic + allocation tracing
 #define G1_ALLOC_REGION_TRACING 0

 class ar_ext_msg;

 // A class that holds a region that is active in satisfying allocation
 // requests, potentially issued in parallel. When the active region is
 // full it will be retired and replaced with a new one. The
 // implementation assumes that fast-path allocations will be lock-free
 // and a lock will need to be taken when the active region needs to be
 // replaced.

 class G1AllocRegion VALUE_OBJ_CLASS_SPEC {
   friend class ar_ext_msg;

 private:
   // The active allocating region we are currently allocating out
   // of. The invariant is that if this object is initialized (i.e.,
   // init() has been called and release() has not) then _alloc_region
   // is either an active allocating region or the dummy region (i.e.,
   // it can never be NULL) and this object can be used to satisfy
   // allocation requests. If this object is not initialized
   // (i.e. init() has not been called or release() has been called)
   // then _alloc_region is NULL and this object should not be used to
   // satisfy allocation requests (it was done this way to force the
   // correct use of init() and release()).
   HeapRegion* volatile _alloc_region;

   // Allocation context associated with this alloc region.
   AllocationContext_t _allocation_context;

   // It keeps track of the distinct number of regions that are used
   // for allocation in the active interval of this object, i.e.,
   // between a call to init() and a call to release(). The count
   // mostly includes regions that are freshly allocated, as well as
   // the region that is re-used using the set() method. This count can
   // be used in any heuristics that might want to bound how many
   // distinct regions this object can used during an active interval.
   uint _count;

   // When we set up a new active region we save its used bytes in this
   // field so that, when we retire it, we can calculate how much space
   // we allocated in it.
   size_t _used_bytes_before;

   // When true, indicates that allocate calls should do BOT updates.
   const bool _bot_updates;

   // Useful for debugging and tracing.
   const char* _name;

   // A dummy region (i.e., it's been allocated specially for this
   // purpose and it is not part of the heap) that is full (i.e., top()
   // == end()). When we don't have a valid active region we make
   // _alloc_region point to this. This allows us to skip checking
   // whether the _alloc_region is NULL or not.
   static HeapRegion* _dummy_region;

   // Some of the methods below take a bot_updates parameter. Its value
   // should be the same as the _bot_updates field. The idea is that
   // the parameter will be a constant for a particular alloc region
   // and, given that these methods will be hopefully inlined, the
   // compiler should compile out the test.

   // Perform a non-MT-safe allocation out of the given region.
   static inline HeapWord* allocate(HeapRegion* alloc_region,
                                    size_t word_size,
                                    bool bot_updates);

   // Perform a MT-safe allocation out of the given region.
   static inline HeapWord* par_allocate(HeapRegion* alloc_region,
                                        size_t word_size,
                                        bool bot_updates);

   // Ensure that the region passed as a parameter has been filled up
   // so that noone else can allocate out of it any more.
   static void fill_up_remaining_space(HeapRegion* alloc_region,
                                       bool bot_updates);

   // Retire the active allocating region. If fill_up is true then make
   // sure that the region is full before we retire it so that noone
   // else can allocate out of it.
   void retire(bool fill_up);

   // After a region is allocated by alloc_new_region, this
   // method is used to set it as the active alloc_region
   void update_alloc_region(HeapRegion* alloc_region);

   // Allocate a new active region and use it to perform a word_size
   // allocation. The force parameter will be passed on to
   // G1CollectedHeap::allocate_new_alloc_region() and tells it to try
   // to allocate a new region even if the max has been reached.
   HeapWord* new_alloc_region_and_allocate(size_t word_size, bool force);

   void fill_in_ext_msg(ar_ext_msg* msg, const char* message);

 protected:
   // For convenience as subclasses use it.
   static G1CollectedHeap* _g1h;

   virtual HeapRegion* allocate_new_region(size_t word_size, bool force) = 0;
   virtual void retire_region(HeapRegion* alloc_region,
                              size_t allocated_bytes) = 0;

   G1AllocRegion(const char* name, bool bot_updates);

 public:
   static void setup(G1CollectedHeap* g1h, HeapRegion* dummy_region);

   HeapRegion* get() const {
     HeapRegion * hr = _alloc_region;
     // Make sure that the dummy region does not escape this class.
     return (hr == _dummy_region) ? NULL : hr;
   }

   void set_allocation_context(AllocationContext_t context) { _allocation_context = context; }
   AllocationContext_t  allocation_context() { return _allocation_context; }

   uint count() { return _count; }

   // The following two are the building blocks for the allocation method.

   // First-level allocation: Should be called without holding a
   // lock. It will try to allocate lock-free out of the active region,
   // or return NULL if it was unable to.
   inline HeapWord* attempt_allocation(size_t word_size, bool bot_updates);

   // Second-level allocation: Should be called while holding a
   // lock. It will try to first allocate lock-free out of the active
   // region or, if it's unable to, it will try to replace the active
   // alloc region with a new one. We require that the caller takes the
   // appropriate lock before calling this so that it is easier to make
   // it conform to its locking protocol.
   inline HeapWord* attempt_allocation_locked(size_t word_size,
                                              bool bot_updates);

   // Should be called to allocate a new region even if the max of this
   // type of regions has been reached. Should only be called if other
   // allocation attempts have failed and we are not holding a valid
   // active region.
   inline HeapWord* attempt_allocation_force(size_t word_size,
                                             bool bot_updates);

   // Should be called before we start using this object.
   void init();

   // This can be used to set the active region to a specific
   // region. (Use Example: we try to retain the last old GC alloc
   // region that we've used during a GC and we can use set() to
   // re-instate it at the beginning of the next GC.)
   void set(HeapRegion* alloc_region);

   // Should be called when we want to release the active region which
   // is returned after it's been retired.
   virtual HeapRegion* release();

 #if G1_ALLOC_REGION_TRACING
   void trace(const char* str, size_t word_size = 0, HeapWord* result = NULL);
 #else // G1_ALLOC_REGION_TRACING
   void trace(const char* str, size_t word_size = 0, HeapWord* result = NULL) { }
 #endif // G1_ALLOC_REGION_TRACING
 };

 class MutatorAllocRegion : public G1AllocRegion {
 protected:
   virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
   virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
 public:
   MutatorAllocRegion()
     : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { }
 };

 class SurvivorGCAllocRegion : public G1AllocRegion {
 protected:
   virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
   virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
 public:
   SurvivorGCAllocRegion()
   : G1AllocRegion("Survivor GC Alloc Region", false /* bot_updates */) { }
 };

 class OldGCAllocRegion : public G1AllocRegion {
 protected:
   virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
   virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
 public:
   OldGCAllocRegion()
   : G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { }

   // This specialization of release() makes sure that the last card that has
   // been allocated into has been completely filled by a dummy object.  This
   // avoids races when remembered set scanning wants to update the BOT of the
   // last card in the retained old gc alloc region, and allocation threads
   // allocating into that card at the same time.
   virtual HeapRegion* release();
 };

 class ar_ext_msg : public err_msg {
 public:
   ar_ext_msg(G1AllocRegion* alloc_region, const char *message) : err_msg("%s", "") {
     alloc_region->fill_in_ext_msg(this, message);
   }
 };

 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1ALLOCREGION_HPP
	/*
	* Copyright (c) 2011, 2014, 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_IMPLEMENTATION_G1_G1ALLOCREGION_HPP
	#define SHARE_VM_GC_IMPLEMENTATION_G1_G1ALLOCREGION_HPP

	#include "gc_implementation/g1/heapRegion.hpp"

	class G1CollectedHeap;

	// 0 -> no tracing, 1 -> basic tracing, 2 -> basic + allocation tracing
	#define G1_ALLOC_REGION_TRACING 0

	class ar_ext_msg;

	// A class that holds a region that is active in satisfying allocation
	// requests, potentially issued in parallel. When the active region is
	// full it will be retired and replaced with a new one. The
	// implementation assumes that fast-path allocations will be lock-free
	// and a lock will need to be taken when the active region needs to be
	// replaced.

	class G1AllocRegion VALUE_OBJ_CLASS_SPEC {
	friend class ar_ext_msg;

	private:
	// The active allocating region we are currently allocating out
	// of. The invariant is that if this object is initialized (i.e.,
	// init() has been called and release() has not) then _alloc_region
	// is either an active allocating region or the dummy region (i.e.,
	// it can never be NULL) and this object can be used to satisfy
	// allocation requests. If this object is not initialized
	// (i.e. init() has not been called or release() has been called)
	// then _alloc_region is NULL and this object should not be used to
	// satisfy allocation requests (it was done this way to force the
	// correct use of init() and release()).
	HeapRegion* volatile _alloc_region;

	// Allocation context associated with this alloc region.
	AllocationContext_t _allocation_context;

	// It keeps track of the distinct number of regions that are used
	// for allocation in the active interval of this object, i.e.,
	// between a call to init() and a call to release(). The count
	// mostly includes regions that are freshly allocated, as well as
	// the region that is re-used using the set() method. This count can
	// be used in any heuristics that might want to bound how many
	// distinct regions this object can used during an active interval.
	uint _count;

	// When we set up a new active region we save its used bytes in this
	// field so that, when we retire it, we can calculate how much space
	// we allocated in it.
	size_t _used_bytes_before;

	// When true, indicates that allocate calls should do BOT updates.
	const bool _bot_updates;

	// Useful for debugging and tracing.
	const char* _name;

	// A dummy region (i.e., it's been allocated specially for this
	// purpose and it is not part of the heap) that is full (i.e., top()
	// == end()). When we don't have a valid active region we make
	// _alloc_region point to this. This allows us to skip checking
	// whether the _alloc_region is NULL or not.
	static HeapRegion* _dummy_region;

	// Some of the methods below take a bot_updates parameter. Its value
	// should be the same as the _bot_updates field. The idea is that
	// the parameter will be a constant for a particular alloc region
	// and, given that these methods will be hopefully inlined, the
	// compiler should compile out the test.

	// Perform a non-MT-safe allocation out of the given region.
	static inline HeapWord* allocate(HeapRegion* alloc_region,
	size_t word_size,
	bool bot_updates);

	// Perform a MT-safe allocation out of the given region.
	static inline HeapWord* par_allocate(HeapRegion* alloc_region,
	size_t word_size,
	bool bot_updates);

	// Ensure that the region passed as a parameter has been filled up
	// so that noone else can allocate out of it any more.
	static void fill_up_remaining_space(HeapRegion* alloc_region,
	bool bot_updates);

	// Retire the active allocating region. If fill_up is true then make
	// sure that the region is full before we retire it so that noone
	// else can allocate out of it.
	void retire(bool fill_up);

	// After a region is allocated by alloc_new_region, this
	// method is used to set it as the active alloc_region
	void update_alloc_region(HeapRegion* alloc_region);

	// Allocate a new active region and use it to perform a word_size
	// allocation. The force parameter will be passed on to
	// G1CollectedHeap::allocate_new_alloc_region() and tells it to try
	// to allocate a new region even if the max has been reached.
	HeapWord* new_alloc_region_and_allocate(size_t word_size, bool force);

	void fill_in_ext_msg(ar_ext_msg* msg, const char* message);

	protected:
	// For convenience as subclasses use it.
	static G1CollectedHeap* _g1h;

	virtual HeapRegion* allocate_new_region(size_t word_size, bool force) = 0;
	virtual void retire_region(HeapRegion* alloc_region,
	size_t allocated_bytes) = 0;

	G1AllocRegion(const char* name, bool bot_updates);

	public:
	static void setup(G1CollectedHeap* g1h, HeapRegion* dummy_region);

	HeapRegion* get() const {
	HeapRegion * hr = _alloc_region;
	// Make sure that the dummy region does not escape this class.
	return (hr == _dummy_region) ? NULL : hr;
	}

	void set_allocation_context(AllocationContext_t context) { _allocation_context = context; }
	AllocationContext_t allocation_context() { return _allocation_context; }

	uint count() { return _count; }

	// The following two are the building blocks for the allocation method.

	// First-level allocation: Should be called without holding a
	// lock. It will try to allocate lock-free out of the active region,
	// or return NULL if it was unable to.
	inline HeapWord* attempt_allocation(size_t word_size, bool bot_updates);

	// Second-level allocation: Should be called while holding a
	// lock. It will try to first allocate lock-free out of the active
	// region or, if it's unable to, it will try to replace the active
	// alloc region with a new one. We require that the caller takes the
	// appropriate lock before calling this so that it is easier to make
	// it conform to its locking protocol.
	inline HeapWord* attempt_allocation_locked(size_t word_size,
	bool bot_updates);

	// Should be called to allocate a new region even if the max of this
	// type of regions has been reached. Should only be called if other
	// allocation attempts have failed and we are not holding a valid
	// active region.
	inline HeapWord* attempt_allocation_force(size_t word_size,
	bool bot_updates);

	// Should be called before we start using this object.
	void init();

	// This can be used to set the active region to a specific
	// region. (Use Example: we try to retain the last old GC alloc
	// region that we've used during a GC and we can use set() to
	// re-instate it at the beginning of the next GC.)
	void set(HeapRegion* alloc_region);

	// Should be called when we want to release the active region which
	// is returned after it's been retired.
	virtual HeapRegion* release();

	#if G1_ALLOC_REGION_TRACING
	void trace(const char* str, size_t word_size = 0, HeapWord* result = NULL);
	#else // G1_ALLOC_REGION_TRACING
	void trace(const char* str, size_t word_size = 0, HeapWord* result = NULL) { }
	#endif // G1_ALLOC_REGION_TRACING
	};

	class MutatorAllocRegion : public G1AllocRegion {
	protected:
	virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
	virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
	public:
	MutatorAllocRegion()
	: G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { }
	};

	class SurvivorGCAllocRegion : public G1AllocRegion {
	protected:
	virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
	virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
	public:
	SurvivorGCAllocRegion()
	: G1AllocRegion("Survivor GC Alloc Region", false /* bot_updates */) { }
	};

	class OldGCAllocRegion : public G1AllocRegion {
	protected:
	virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
	virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
	public:
	OldGCAllocRegion()
	: G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { }

	// This specialization of release() makes sure that the last card that has
	// been allocated into has been completely filled by a dummy object. This
	// avoids races when remembered set scanning wants to update the BOT of the
	// last card in the retained old gc alloc region, and allocation threads
	// allocating into that card at the same time.
	virtual HeapRegion* release();
	};

	class ar_ext_msg : public err_msg {
	public:
	ar_ext_msg(G1AllocRegion* alloc_region, const char *message) : err_msg("%s", "") {
	alloc_region->fill_in_ext_msg(this, message);
	}
	};

	#endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1ALLOCREGION_HPP