src/hotspot/share/gc/g1/g1AllocRegion.hpp - platform/libcore - Git at Google

 /*
  * Copyright (c) 2011, 2018, 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_G1_G1ALLOCREGION_HPP
 #define SHARE_VM_GC_G1_G1ALLOCREGION_HPP

 #include "gc/g1/heapRegion.hpp"
 #include "gc/g1/g1EvacStats.hpp"
 #include "gc/g1/g1InCSetState.hpp"

 class G1CollectedHeap;

 // 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 {

 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;

   // 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;

   // 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);

 protected:
   // Reset the alloc region to point a the dummy region.
   void reset_alloc_region();

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

   // Perform a MT-safe allocation out of the given region.
   inline HeapWord* par_allocate(HeapRegion* alloc_region,
                                 size_t word_size);
   // Perform a MT-safe allocation out of the given region, with the given
   // minimum and desired size. Returns the actual size allocated (between
   // minimum and desired size) in actual_word_size if the allocation has been
   // successful.
   inline HeapWord* par_allocate(HeapRegion* alloc_region,
                                 size_t min_word_size,
                                 size_t desired_word_size,
                                 size_t* actual_word_size);

   // Ensure that the region passed as a parameter has been filled up
   // so that noone else can allocate out of it any more.
   // Returns the number of bytes that have been wasted by filled up
   // the space.
   size_t fill_up_remaining_space(HeapRegion* alloc_region);

   // Retire the active allocating region. If fill_up is true then make
   // sure that the region is full before we retire it so that no one
   // else can allocate out of it.
   // Returns the number of bytes that have been filled up during retire.
   virtual size_t retire(bool fill_up);

   size_t retire_internal(HeapRegion* alloc_region, bool fill_up);

   // 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;
   }

   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);
   // Perform an allocation out of the current allocation region, with the given
   // minimum and desired size. Returns the actual size allocated (between
   // minimum and desired size) in actual_word_size if the allocation has been
   // successful.
   // 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 min_word_size,
                                       size_t desired_word_size,
                                       size_t* actual_word_size);

   // 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);
   // Same as attempt_allocation_locked(size_t, bool), but allowing specification
   // of minimum word size of the block in min_word_size, and the maximum word
   // size of the allocation in desired_word_size. The actual size of the block is
   // returned in actual_word_size.
   inline HeapWord* attempt_allocation_locked(size_t min_word_size,
                                              size_t desired_word_size,
                                              size_t* actual_word_size);

   // 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);

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

   void trace(const char* str,
              size_t min_word_size = 0,
              size_t desired_word_size = 0,
              size_t actual_word_size = 0,
              HeapWord* result = NULL) PRODUCT_RETURN;
 };

 class MutatorAllocRegion : public G1AllocRegion {
 private:
   // Keeps track of the total waste generated during the current
   // mutator phase.
   size_t _wasted_bytes;

   // Retained allocation region. Used to lower the waste generated
   // during mutation by having two active regions if the free space
   // in a region about to be retired still could fit a TLAB.
   HeapRegion* volatile _retained_alloc_region;

   // Decide if the region should be retained, based on the free size
   // in it and the free size in the currently retained region, if any.
   bool should_retain(HeapRegion* region);
 protected:
   virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
   virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
   virtual size_t retire(bool fill_up);
 public:
   MutatorAllocRegion()
     : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */),
       _wasted_bytes(0),
       _retained_alloc_region(NULL) { }

   // Returns the combined used memory in the current alloc region and
   // the retained alloc region.
   size_t used_in_alloc_regions();

   // Perform an allocation out of the retained allocation region, with the given
   // minimum and desired size. Returns the actual size allocated (between
   // minimum and desired size) in actual_word_size if the allocation has been
   // successful.
   // Should be called without holding a lock. It will try to allocate lock-free
   // out of the retained region, or return NULL if it was unable to.
   inline HeapWord* attempt_retained_allocation(size_t min_word_size,
                                                size_t desired_word_size,
                                                size_t* actual_word_size);

   // This specialization of release() makes sure that the retained alloc
   // region is retired and set to NULL.
   virtual HeapRegion* release();

   virtual void init();
 };
 // Common base class for allocation regions used during GC.
 class G1GCAllocRegion : public G1AllocRegion {
 protected:
   G1EvacStats* _stats;
   InCSetState::in_cset_state_t _purpose;

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

   virtual size_t retire(bool fill_up);

   G1GCAllocRegion(const char* name, bool bot_updates, G1EvacStats* stats, InCSetState::in_cset_state_t purpose)
   : G1AllocRegion(name, bot_updates), _stats(stats), _purpose(purpose) {
     assert(stats != NULL, "Must pass non-NULL PLAB statistics");
   }
 };

 class SurvivorGCAllocRegion : public G1GCAllocRegion {
 public:
   SurvivorGCAllocRegion(G1EvacStats* stats)
   : G1GCAllocRegion("Survivor GC Alloc Region", false /* bot_updates */, stats, InCSetState::Young) { }
 };

 class OldGCAllocRegion : public G1GCAllocRegion {
 public:
   OldGCAllocRegion(G1EvacStats* stats)
   : G1GCAllocRegion("Old GC Alloc Region", true /* bot_updates */, stats, InCSetState::Old) { }

   // 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();
 };

 #endif // SHARE_VM_GC_G1_G1ALLOCREGION_HPP
	/*
	* Copyright (c) 2011, 2018, 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_G1_G1ALLOCREGION_HPP
	#define SHARE_VM_GC_G1_G1ALLOCREGION_HPP

	#include "gc/g1/heapRegion.hpp"
	#include "gc/g1/g1EvacStats.hpp"
	#include "gc/g1/g1InCSetState.hpp"

	class G1CollectedHeap;

	// 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 {

	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;

	// 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;

	// 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);

	protected:
	// Reset the alloc region to point a the dummy region.
	void reset_alloc_region();

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

	// Perform a MT-safe allocation out of the given region.
	inline HeapWord* par_allocate(HeapRegion* alloc_region,
	size_t word_size);
	// Perform a MT-safe allocation out of the given region, with the given
	// minimum and desired size. Returns the actual size allocated (between
	// minimum and desired size) in actual_word_size if the allocation has been
	// successful.
	inline HeapWord* par_allocate(HeapRegion* alloc_region,
	size_t min_word_size,
	size_t desired_word_size,
	size_t* actual_word_size);

	// Ensure that the region passed as a parameter has been filled up
	// so that noone else can allocate out of it any more.
	// Returns the number of bytes that have been wasted by filled up
	// the space.
	size_t fill_up_remaining_space(HeapRegion* alloc_region);

	// Retire the active allocating region. If fill_up is true then make
	// sure that the region is full before we retire it so that no one
	// else can allocate out of it.
	// Returns the number of bytes that have been filled up during retire.
	virtual size_t retire(bool fill_up);

	size_t retire_internal(HeapRegion* alloc_region, bool fill_up);

	// 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;
	}

	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);
	// Perform an allocation out of the current allocation region, with the given
	// minimum and desired size. Returns the actual size allocated (between
	// minimum and desired size) in actual_word_size if the allocation has been
	// successful.
	// 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 min_word_size,
	size_t desired_word_size,
	size_t* actual_word_size);

	// 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);
	// Same as attempt_allocation_locked(size_t, bool), but allowing specification
	// of minimum word size of the block in min_word_size, and the maximum word
	// size of the allocation in desired_word_size. The actual size of the block is
	// returned in actual_word_size.
	inline HeapWord* attempt_allocation_locked(size_t min_word_size,
	size_t desired_word_size,
	size_t* actual_word_size);

	// 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);

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

	void trace(const char* str,
	size_t min_word_size = 0,
	size_t desired_word_size = 0,
	size_t actual_word_size = 0,
	HeapWord* result = NULL) PRODUCT_RETURN;
	};

	class MutatorAllocRegion : public G1AllocRegion {
	private:
	// Keeps track of the total waste generated during the current
	// mutator phase.
	size_t _wasted_bytes;

	// Retained allocation region. Used to lower the waste generated
	// during mutation by having two active regions if the free space
	// in a region about to be retired still could fit a TLAB.
	HeapRegion* volatile _retained_alloc_region;

	// Decide if the region should be retained, based on the free size
	// in it and the free size in the currently retained region, if any.
	bool should_retain(HeapRegion* region);
	protected:
	virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
	virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
	virtual size_t retire(bool fill_up);
	public:
	MutatorAllocRegion()
	: G1AllocRegion("Mutator Alloc Region", false /* bot_updates */),
	_wasted_bytes(0),
	_retained_alloc_region(NULL) { }

	// Returns the combined used memory in the current alloc region and
	// the retained alloc region.
	size_t used_in_alloc_regions();

	// Perform an allocation out of the retained allocation region, with the given
	// minimum and desired size. Returns the actual size allocated (between
	// minimum and desired size) in actual_word_size if the allocation has been
	// successful.
	// Should be called without holding a lock. It will try to allocate lock-free
	// out of the retained region, or return NULL if it was unable to.
	inline HeapWord* attempt_retained_allocation(size_t min_word_size,
	size_t desired_word_size,
	size_t* actual_word_size);

	// This specialization of release() makes sure that the retained alloc
	// region is retired and set to NULL.
	virtual HeapRegion* release();

	virtual void init();
	};
	// Common base class for allocation regions used during GC.
	class G1GCAllocRegion : public G1AllocRegion {
	protected:
	G1EvacStats* _stats;
	InCSetState::in_cset_state_t _purpose;

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

	virtual size_t retire(bool fill_up);

	G1GCAllocRegion(const char* name, bool bot_updates, G1EvacStats* stats, InCSetState::in_cset_state_t purpose)
	: G1AllocRegion(name, bot_updates), _stats(stats), _purpose(purpose) {
	assert(stats != NULL, "Must pass non-NULL PLAB statistics");
	}
	};

	class SurvivorGCAllocRegion : public G1GCAllocRegion {
	public:
	SurvivorGCAllocRegion(G1EvacStats* stats)
	: G1GCAllocRegion("Survivor GC Alloc Region", false /* bot_updates */, stats, InCSetState::Young) { }
	};

	class OldGCAllocRegion : public G1GCAllocRegion {
	public:
	OldGCAllocRegion(G1EvacStats* stats)
	: G1GCAllocRegion("Old GC Alloc Region", true /* bot_updates */, stats, InCSetState::Old) { }

	// 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();
	};

	#endif // SHARE_VM_GC_G1_G1ALLOCREGION_HPP