tonyp@2715: /*
tonyp@3713:  * Copyright (c) 2011, 2012, Oracle and/or its affiliates. All rights reserved.
tonyp@2715:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
tonyp@2715:  *
tonyp@2715:  * This code is free software; you can redistribute it and/or modify it
tonyp@2715:  * under the terms of the GNU General Public License version 2 only, as
tonyp@2715:  * published by the Free Software Foundation.
tonyp@2715:  *
tonyp@2715:  * This code is distributed in the hope that it will be useful, but WITHOUT
tonyp@2715:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
tonyp@2715:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
tonyp@2715:  * version 2 for more details (a copy is included in the LICENSE file that
tonyp@2715:  * accompanied this code).
tonyp@2715:  *
tonyp@2715:  * You should have received a copy of the GNU General Public License version
tonyp@2715:  * 2 along with this work; if not, write to the Free Software Foundation,
tonyp@2715:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
tonyp@2715:  *
tonyp@2715:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
tonyp@2715:  * or visit www.oracle.com if you need additional information or have any
tonyp@2715:  * questions.
tonyp@2715:  *
tonyp@2715:  */
tonyp@2715: 
tonyp@2715: #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1ALLOCREGION_HPP
tonyp@2715: #define SHARE_VM_GC_IMPLEMENTATION_G1_G1ALLOCREGION_HPP
tonyp@2715: 
tonyp@2715: #include "gc_implementation/g1/heapRegion.hpp"
tonyp@2715: 
tonyp@2715: class G1CollectedHeap;
tonyp@2715: 
tonyp@2715: // 0 -> no tracing, 1 -> basic tracing, 2 -> basic + allocation tracing
tonyp@2715: #define G1_ALLOC_REGION_TRACING 0
tonyp@2715: 
tonyp@2715: class ar_ext_msg;
tonyp@2715: 
tonyp@2715: // A class that holds a region that is active in satisfying allocation
tonyp@2715: // requests, potentially issued in parallel. When the active region is
tonyp@3028: // full it will be retired and replaced with a new one. The
tonyp@2715: // implementation assumes that fast-path allocations will be lock-free
tonyp@2715: // and a lock will need to be taken when the active region needs to be
tonyp@2715: // replaced.
tonyp@2715: 
tonyp@2715: class G1AllocRegion VALUE_OBJ_CLASS_SPEC {
tonyp@2715:   friend class ar_ext_msg;
tonyp@2715: 
tonyp@2715: private:
tonyp@2715:   // The active allocating region we are currently allocating out
tonyp@2715:   // of. The invariant is that if this object is initialized (i.e.,
tonyp@2715:   // init() has been called and release() has not) then _alloc_region
tonyp@2715:   // is either an active allocating region or the dummy region (i.e.,
tonyp@2715:   // it can never be NULL) and this object can be used to satisfy
tonyp@2715:   // allocation requests. If this object is not initialized
tonyp@2715:   // (i.e. init() has not been called or release() has been called)
tonyp@2715:   // then _alloc_region is NULL and this object should not be used to
tonyp@2715:   // satisfy allocation requests (it was done this way to force the
tonyp@2715:   // correct use of init() and release()).
tonyp@2715:   HeapRegion* _alloc_region;
tonyp@2715: 
tonyp@3028:   // It keeps track of the distinct number of regions that are used
tonyp@3028:   // for allocation in the active interval of this object, i.e.,
tonyp@3028:   // between a call to init() and a call to release(). The count
tonyp@3028:   // mostly includes regions that are freshly allocated, as well as
tonyp@3028:   // the region that is re-used using the set() method. This count can
tonyp@3028:   // be used in any heuristics that might want to bound how many
tonyp@3028:   // distinct regions this object can used during an active interval.
tonyp@3713:   uint _count;
tonyp@3028: 
tonyp@2715:   // When we set up a new active region we save its used bytes in this
tonyp@2715:   // field so that, when we retire it, we can calculate how much space
tonyp@2715:   // we allocated in it.
tonyp@2715:   size_t _used_bytes_before;
tonyp@2715: 
tonyp@3028:   // When true, indicates that allocate calls should do BOT updates.
tonyp@3028:   const bool _bot_updates;
tonyp@2715: 
tonyp@2715:   // Useful for debugging and tracing.
tonyp@2715:   const char* _name;
tonyp@2715: 
tonyp@2715:   // A dummy region (i.e., it's been allocated specially for this
tonyp@2715:   // purpose and it is not part of the heap) that is full (i.e., top()
tonyp@2715:   // == end()). When we don't have a valid active region we make
tonyp@2715:   // _alloc_region point to this. This allows us to skip checking
tonyp@2715:   // whether the _alloc_region is NULL or not.
tonyp@2715:   static HeapRegion* _dummy_region;
tonyp@2715: 
tonyp@2715:   // Some of the methods below take a bot_updates parameter. Its value
tonyp@2715:   // should be the same as the _bot_updates field. The idea is that
tonyp@2715:   // the parameter will be a constant for a particular alloc region
tonyp@2715:   // and, given that these methods will be hopefully inlined, the
tonyp@2715:   // compiler should compile out the test.
tonyp@2715: 
tonyp@2715:   // Perform a non-MT-safe allocation out of the given region.
tonyp@2715:   static inline HeapWord* allocate(HeapRegion* alloc_region,
tonyp@2715:                                    size_t word_size,
tonyp@2715:                                    bool bot_updates);
tonyp@2715: 
tonyp@2715:   // Perform a MT-safe allocation out of the given region.
tonyp@2715:   static inline HeapWord* par_allocate(HeapRegion* alloc_region,
tonyp@2715:                                        size_t word_size,
tonyp@2715:                                        bool bot_updates);
tonyp@2715: 
tonyp@2715:   // Ensure that the region passed as a parameter has been filled up
tonyp@2715:   // so that noone else can allocate out of it any more.
tonyp@2715:   static void fill_up_remaining_space(HeapRegion* alloc_region,
tonyp@2715:                                       bool bot_updates);
tonyp@2715: 
tonyp@2715:   // Retire the active allocating region. If fill_up is true then make
tonyp@2715:   // sure that the region is full before we retire it so that noone
tonyp@2715:   // else can allocate out of it.
tonyp@2715:   void retire(bool fill_up);
tonyp@2715: 
tonyp@2715:   // Allocate a new active region and use it to perform a word_size
tonyp@2715:   // allocation. The force parameter will be passed on to
tonyp@2715:   // G1CollectedHeap::allocate_new_alloc_region() and tells it to try
tonyp@2715:   // to allocate a new region even if the max has been reached.
tonyp@2715:   HeapWord* new_alloc_region_and_allocate(size_t word_size, bool force);
tonyp@2715: 
tonyp@2715:   void fill_in_ext_msg(ar_ext_msg* msg, const char* message);
tonyp@2715: 
tonyp@2715: protected:
tonyp@2715:   // For convenience as subclasses use it.
tonyp@2715:   static G1CollectedHeap* _g1h;
tonyp@2715: 
tonyp@2715:   virtual HeapRegion* allocate_new_region(size_t word_size, bool force) = 0;
tonyp@2715:   virtual void retire_region(HeapRegion* alloc_region,
tonyp@2715:                              size_t allocated_bytes) = 0;
tonyp@2715: 
tonyp@2715:   G1AllocRegion(const char* name, bool bot_updates);
tonyp@2715: 
tonyp@2715: public:
tonyp@2715:   static void setup(G1CollectedHeap* g1h, HeapRegion* dummy_region);
tonyp@2715: 
tonyp@2715:   HeapRegion* get() const {
tonyp@2715:     // Make sure that the dummy region does not escape this class.
tonyp@2715:     return (_alloc_region == _dummy_region) ? NULL : _alloc_region;
tonyp@2715:   }
tonyp@2715: 
tonyp@3713:   uint count() { return _count; }
tonyp@3028: 
tonyp@2715:   // The following two are the building blocks for the allocation method.
tonyp@2715: 
tonyp@2715:   // First-level allocation: Should be called without holding a
tonyp@2715:   // lock. It will try to allocate lock-free out of the active region,
tonyp@2715:   // or return NULL if it was unable to.
tonyp@2715:   inline HeapWord* attempt_allocation(size_t word_size, bool bot_updates);
tonyp@2715: 
tonyp@2715:   // Second-level allocation: Should be called while holding a
tonyp@2715:   // lock. It will try to first allocate lock-free out of the active
tonyp@2715:   // region or, if it's unable to, it will try to replace the active
tonyp@2715:   // alloc region with a new one. We require that the caller takes the
tonyp@2715:   // appropriate lock before calling this so that it is easier to make
tonyp@2715:   // it conform to its locking protocol.
tonyp@2715:   inline HeapWord* attempt_allocation_locked(size_t word_size,
tonyp@2715:                                              bool bot_updates);
tonyp@2715: 
tonyp@2715:   // Should be called to allocate a new region even if the max of this
tonyp@2715:   // type of regions has been reached. Should only be called if other
tonyp@2715:   // allocation attempts have failed and we are not holding a valid
tonyp@2715:   // active region.
tonyp@2715:   inline HeapWord* attempt_allocation_force(size_t word_size,
tonyp@2715:                                             bool bot_updates);
tonyp@2715: 
tonyp@2715:   // Should be called before we start using this object.
tonyp@2715:   void init();
tonyp@2715: 
tonyp@3028:   // This can be used to set the active region to a specific
tonyp@3028:   // region. (Use Example: we try to retain the last old GC alloc
tonyp@3028:   // region that we've used during a GC and we can use set() to
tonyp@3028:   // re-instate it at the beginning of the next GC.)
tonyp@3028:   void set(HeapRegion* alloc_region);
tonyp@3028: 
tonyp@2715:   // Should be called when we want to release the active region which
tonyp@2715:   // is returned after it's been retired.
tonyp@2715:   HeapRegion* release();
tonyp@2715: 
tonyp@2715: #if G1_ALLOC_REGION_TRACING
tonyp@2715:   void trace(const char* str, size_t word_size = 0, HeapWord* result = NULL);
tonyp@2715: #else // G1_ALLOC_REGION_TRACING
tonyp@2715:   void trace(const char* str, size_t word_size = 0, HeapWord* result = NULL) { }
tonyp@2715: #endif // G1_ALLOC_REGION_TRACING
tonyp@2715: };
tonyp@2715: 
tonyp@2715: class ar_ext_msg : public err_msg {
tonyp@2715: public:
tonyp@2715:   ar_ext_msg(G1AllocRegion* alloc_region, const char *message) : err_msg("") {
tonyp@2715:     alloc_region->fill_in_ext_msg(this, message);
tonyp@2715:   }
tonyp@2715: };
tonyp@2715: 
tonyp@2715: #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1ALLOCREGION_HPP