aoqi@0: /*
aoqi@0:  * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
aoqi@0:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0:  *
aoqi@0:  * This code is free software; you can redistribute it and/or modify it
aoqi@0:  * under the terms of the GNU General Public License version 2 only, as
aoqi@0:  * published by the Free Software Foundation.
aoqi@0:  *
aoqi@0:  * This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
aoqi@0:  * version 2 for more details (a copy is included in the LICENSE file that
aoqi@0:  * accompanied this code).
aoqi@0:  *
aoqi@0:  * You should have received a copy of the GNU General Public License version
aoqi@0:  * 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0:  *
aoqi@0:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0:  * or visit www.oracle.com if you need additional information or have any
aoqi@0:  * questions.
aoqi@0:  *
aoqi@0:  */
aoqi@0: 
aoqi@0: #ifndef SHARE_VM_MEMORY_GENERATION_HPP
aoqi@0: #define SHARE_VM_MEMORY_GENERATION_HPP
aoqi@0: 
aoqi@0: #include "gc_implementation/shared/collectorCounters.hpp"
aoqi@0: #include "memory/allocation.hpp"
aoqi@0: #include "memory/memRegion.hpp"
aoqi@0: #include "memory/referenceProcessor.hpp"
aoqi@0: #include "memory/universe.hpp"
aoqi@0: #include "memory/watermark.hpp"
aoqi@0: #include "runtime/mutex.hpp"
aoqi@0: #include "runtime/perfData.hpp"
aoqi@0: #include "runtime/virtualspace.hpp"
aoqi@0: 
aoqi@0: // A Generation models a heap area for similarly-aged objects.
aoqi@0: // It will contain one ore more spaces holding the actual objects.
aoqi@0: //
aoqi@0: // The Generation class hierarchy:
aoqi@0: //
aoqi@0: // Generation                      - abstract base class
aoqi@0: // - DefNewGeneration              - allocation area (copy collected)
aoqi@0: //   - ParNewGeneration            - a DefNewGeneration that is collected by
aoqi@0: //                                   several threads
aoqi@0: // - CardGeneration                 - abstract class adding offset array behavior
aoqi@0: //   - OneContigSpaceCardGeneration - abstract class holding a single
aoqi@0: //                                    contiguous space with card marking
aoqi@0: //     - TenuredGeneration         - tenured (old object) space (markSweepCompact)
aoqi@0: //   - ConcurrentMarkSweepGeneration - Mostly Concurrent Mark Sweep Generation
aoqi@0: //                                       (Detlefs-Printezis refinement of
aoqi@0: //                                       Boehm-Demers-Schenker)
aoqi@0: //
aoqi@0: // The system configurations currently allowed are:
aoqi@0: //
aoqi@0: //   DefNewGeneration + TenuredGeneration
aoqi@0: //   DefNewGeneration + ConcurrentMarkSweepGeneration
aoqi@0: //
aoqi@0: //   ParNewGeneration + TenuredGeneration
aoqi@0: //   ParNewGeneration + ConcurrentMarkSweepGeneration
aoqi@0: //
aoqi@0: 
aoqi@0: class DefNewGeneration;
aoqi@0: class GenerationSpec;
aoqi@0: class CompactibleSpace;
aoqi@0: class ContiguousSpace;
aoqi@0: class CompactPoint;
aoqi@0: class OopsInGenClosure;
aoqi@0: class OopClosure;
aoqi@0: class ScanClosure;
aoqi@0: class FastScanClosure;
aoqi@0: class GenCollectedHeap;
aoqi@0: class GenRemSet;
aoqi@0: class GCStats;
aoqi@0: 
aoqi@0: // A "ScratchBlock" represents a block of memory in one generation usable by
aoqi@0: // another.  It represents "num_words" free words, starting at and including
aoqi@0: // the address of "this".
aoqi@0: struct ScratchBlock {
aoqi@0:   ScratchBlock* next;
aoqi@0:   size_t num_words;
aoqi@0:   HeapWord scratch_space[1];  // Actually, of size "num_words-2" (assuming
aoqi@0:                               // first two fields are word-sized.)
aoqi@0: };
aoqi@0: 
aoqi@0: 
aoqi@0: class Generation: public CHeapObj<mtGC> {
aoqi@0:   friend class VMStructs;
aoqi@0:  private:
aoqi@0:   jlong _time_of_last_gc; // time when last gc on this generation happened (ms)
aoqi@0:   MemRegion _prev_used_region; // for collectors that want to "remember" a value for
aoqi@0:                                // used region at some specific point during collection.
aoqi@0: 
aoqi@0:  protected:
aoqi@0:   // Minimum and maximum addresses for memory reserved (not necessarily
aoqi@0:   // committed) for generation.
aoqi@0:   // Used by card marking code. Must not overlap with address ranges of
aoqi@0:   // other generations.
aoqi@0:   MemRegion _reserved;
aoqi@0: 
aoqi@0:   // Memory area reserved for generation
aoqi@0:   VirtualSpace _virtual_space;
aoqi@0: 
aoqi@0:   // Level in the generation hierarchy.
aoqi@0:   int _level;
aoqi@0: 
aoqi@0:   // ("Weak") Reference processing support
aoqi@0:   ReferenceProcessor* _ref_processor;
aoqi@0: 
aoqi@0:   // Performance Counters
aoqi@0:   CollectorCounters* _gc_counters;
aoqi@0: 
aoqi@0:   // Statistics for garbage collection
aoqi@0:   GCStats* _gc_stats;
aoqi@0: 
aoqi@0:   // Returns the next generation in the configuration, or else NULL if this
aoqi@0:   // is the highest generation.
aoqi@0:   Generation* next_gen() const;
aoqi@0: 
aoqi@0:   // Initialize the generation.
aoqi@0:   Generation(ReservedSpace rs, size_t initial_byte_size, int level);
aoqi@0: 
aoqi@0:   // Apply "cl->do_oop" to (the address of) (exactly) all the ref fields in
aoqi@0:   // "sp" that point into younger generations.
aoqi@0:   // The iteration is only over objects allocated at the start of the
aoqi@0:   // iterations; objects allocated as a result of applying the closure are
aoqi@0:   // not included.
aoqi@0:   void younger_refs_in_space_iterate(Space* sp, OopsInGenClosure* cl);
aoqi@0: 
aoqi@0:  public:
aoqi@0:   // The set of possible generation kinds.
aoqi@0:   enum Name {
aoqi@0:     ASParNew,
aoqi@0:     ASConcurrentMarkSweep,
aoqi@0:     DefNew,
aoqi@0:     ParNew,
aoqi@0:     MarkSweepCompact,
aoqi@0:     ConcurrentMarkSweep,
aoqi@0:     Other
aoqi@0:   };
aoqi@0: 
aoqi@0:   enum SomePublicConstants {
aoqi@0:     // Generations are GenGrain-aligned and have size that are multiples of
aoqi@0:     // GenGrain.
aoqi@0:     // Note: on ARM we add 1 bit for card_table_base to be properly aligned
aoqi@0:     // (we expect its low byte to be zero - see implementation of post_barrier)
aoqi@0:     LogOfGenGrain = 16 ARM_ONLY(+1),
aoqi@0:     GenGrain = 1 << LogOfGenGrain
aoqi@0:   };
aoqi@0: 
aoqi@0:   // allocate and initialize ("weak") refs processing support
aoqi@0:   virtual void ref_processor_init();
aoqi@0:   void set_ref_processor(ReferenceProcessor* rp) {
aoqi@0:     assert(_ref_processor == NULL, "clobbering existing _ref_processor");
aoqi@0:     _ref_processor = rp;
aoqi@0:   }
aoqi@0: 
aoqi@0:   virtual Generation::Name kind() { return Generation::Other; }
aoqi@0:   GenerationSpec* spec();
aoqi@0: 
aoqi@0:   // This properly belongs in the collector, but for now this
aoqi@0:   // will do.
aoqi@0:   virtual bool refs_discovery_is_atomic() const { return true;  }
aoqi@0:   virtual bool refs_discovery_is_mt()     const { return false; }
aoqi@0: 
aoqi@0:   // Space enquiries (results in bytes)
aoqi@0:   virtual size_t capacity() const = 0;  // The maximum number of object bytes the
aoqi@0:                                         // generation can currently hold.
aoqi@0:   virtual size_t used() const = 0;      // The number of used bytes in the gen.
aoqi@0:   virtual size_t free() const = 0;      // The number of free bytes in the gen.
aoqi@0: 
aoqi@0:   // Support for java.lang.Runtime.maxMemory(); see CollectedHeap.
aoqi@0:   // Returns the total number of bytes  available in a generation
aoqi@0:   // for the allocation of objects.
aoqi@0:   virtual size_t max_capacity() const;
aoqi@0: 
aoqi@0:   // If this is a young generation, the maximum number of bytes that can be
aoqi@0:   // allocated in this generation before a GC is triggered.
aoqi@0:   virtual size_t capacity_before_gc() const { return 0; }
aoqi@0: 
aoqi@0:   // The largest number of contiguous free bytes in the generation,
aoqi@0:   // including expansion  (Assumes called at a safepoint.)
aoqi@0:   virtual size_t contiguous_available() const = 0;
aoqi@0:   // The largest number of contiguous free bytes in this or any higher generation.
aoqi@0:   virtual size_t max_contiguous_available() const;
aoqi@0: 
aoqi@0:   // Returns true if promotions of the specified amount are
aoqi@0:   // likely to succeed without a promotion failure.
aoqi@0:   // Promotion of the full amount is not guaranteed but
aoqi@0:   // might be attempted in the worst case.
aoqi@0:   virtual bool promotion_attempt_is_safe(size_t max_promotion_in_bytes) const;
aoqi@0: 
aoqi@0:   // For a non-young generation, this interface can be used to inform a
aoqi@0:   // generation that a promotion attempt into that generation failed.
aoqi@0:   // Typically used to enable diagnostic output for post-mortem analysis,
aoqi@0:   // but other uses of the interface are not ruled out.
aoqi@0:   virtual void promotion_failure_occurred() { /* does nothing */ }
aoqi@0: 
aoqi@0:   // Return an estimate of the maximum allocation that could be performed
aoqi@0:   // in the generation without triggering any collection or expansion
aoqi@0:   // activity.  It is "unsafe" because no locks are taken; the result
aoqi@0:   // should be treated as an approximation, not a guarantee, for use in
aoqi@0:   // heuristic resizing decisions.
aoqi@0:   virtual size_t unsafe_max_alloc_nogc() const = 0;
aoqi@0: 
aoqi@0:   // Returns true if this generation cannot be expanded further
aoqi@0:   // without a GC. Override as appropriate.
aoqi@0:   virtual bool is_maximal_no_gc() const {
aoqi@0:     return _virtual_space.uncommitted_size() == 0;
aoqi@0:   }
aoqi@0: 
aoqi@0:   MemRegion reserved() const { return _reserved; }
aoqi@0: 
aoqi@0:   // Returns a region guaranteed to contain all the objects in the
aoqi@0:   // generation.
aoqi@0:   virtual MemRegion used_region() const { return _reserved; }
aoqi@0: 
aoqi@0:   MemRegion prev_used_region() const { return _prev_used_region; }
aoqi@0:   virtual void  save_used_region()   { _prev_used_region = used_region(); }
aoqi@0: 
aoqi@0:   // Returns "TRUE" iff "p" points into the committed areas in the generation.
aoqi@0:   // For some kinds of generations, this may be an expensive operation.
aoqi@0:   // To avoid performance problems stemming from its inadvertent use in
aoqi@0:   // product jvm's, we restrict its use to assertion checking or
aoqi@0:   // verification only.
aoqi@0:   virtual bool is_in(const void* p) const;
aoqi@0: 
aoqi@0:   /* Returns "TRUE" iff "p" points into the reserved area of the generation. */
aoqi@0:   bool is_in_reserved(const void* p) const {
aoqi@0:     return _reserved.contains(p);
aoqi@0:   }
aoqi@0: 
aoqi@0:   // Check that the generation kind is DefNewGeneration or a sub
aoqi@0:   // class of DefNewGeneration and return a DefNewGeneration*
aoqi@0:   DefNewGeneration*  as_DefNewGeneration();
aoqi@0: 
aoqi@0:   // If some space in the generation contains the given "addr", return a
aoqi@0:   // pointer to that space, else return "NULL".
aoqi@0:   virtual Space* space_containing(const void* addr) const;
aoqi@0: 
aoqi@0:   // Iteration - do not use for time critical operations
aoqi@0:   virtual void space_iterate(SpaceClosure* blk, bool usedOnly = false) = 0;
aoqi@0: 
aoqi@0:   // Returns the first space, if any, in the generation that can participate
aoqi@0:   // in compaction, or else "NULL".
aoqi@0:   virtual CompactibleSpace* first_compaction_space() const = 0;
aoqi@0: 
aoqi@0:   // Returns "true" iff this generation should be used to allocate an
aoqi@0:   // object of the given size.  Young generations might
aoqi@0:   // wish to exclude very large objects, for example, since, if allocated
aoqi@0:   // often, they would greatly increase the frequency of young-gen
aoqi@0:   // collection.
aoqi@0:   virtual bool should_allocate(size_t word_size, bool is_tlab) {
aoqi@0:     bool result = false;
aoqi@0:     size_t overflow_limit = (size_t)1 << (BitsPerSize_t - LogHeapWordSize);
aoqi@0:     if (!is_tlab || supports_tlab_allocation()) {
aoqi@0:       result = (word_size > 0) && (word_size < overflow_limit);
aoqi@0:     }
aoqi@0:     return result;
aoqi@0:   }
aoqi@0: 
aoqi@0:   // Allocate and returns a block of the requested size, or returns "NULL".
aoqi@0:   // Assumes the caller has done any necessary locking.
aoqi@0:   virtual HeapWord* allocate(size_t word_size, bool is_tlab) = 0;
aoqi@0: 
aoqi@0:   // Like "allocate", but performs any necessary locking internally.
aoqi@0:   virtual HeapWord* par_allocate(size_t word_size, bool is_tlab) = 0;
aoqi@0: 
aoqi@0:   // A 'younger' gen has reached an allocation limit, and uses this to notify
aoqi@0:   // the next older gen.  The return value is a new limit, or NULL if none.  The
aoqi@0:   // caller must do the necessary locking.
aoqi@0:   virtual HeapWord* allocation_limit_reached(Space* space, HeapWord* top,
aoqi@0:                                              size_t word_size) {
aoqi@0:     return NULL;
aoqi@0:   }
aoqi@0: 
aoqi@0:   // Some generation may offer a region for shared, contiguous allocation,
aoqi@0:   // via inlined code (by exporting the address of the top and end fields
aoqi@0:   // defining the extent of the contiguous allocation region.)
aoqi@0: 
aoqi@0:   // This function returns "true" iff the heap supports this kind of
aoqi@0:   // allocation.  (More precisely, this means the style of allocation that
aoqi@0:   // increments *top_addr()" with a CAS.) (Default is "no".)
aoqi@0:   // A generation that supports this allocation style must use lock-free
aoqi@0:   // allocation for *all* allocation, since there are times when lock free
aoqi@0:   // allocation will be concurrent with plain "allocate" calls.
aoqi@0:   virtual bool supports_inline_contig_alloc() const { return false; }
aoqi@0: 
aoqi@0:   // These functions return the addresses of the fields that define the
aoqi@0:   // boundaries of the contiguous allocation area.  (These fields should be
aoqi@0:   // physicall near to one another.)
aoqi@0:   virtual HeapWord** top_addr() const { return NULL; }
aoqi@0:   virtual HeapWord** end_addr() const { return NULL; }
aoqi@0: 
aoqi@0:   // Thread-local allocation buffers
aoqi@0:   virtual bool supports_tlab_allocation() const { return false; }
aoqi@0:   virtual size_t tlab_capacity() const {
aoqi@0:     guarantee(false, "Generation doesn't support thread local allocation buffers");
aoqi@0:     return 0;
aoqi@0:   }
aoqi@0:   virtual size_t tlab_used() const {
aoqi@0:     guarantee(false, "Generation doesn't support thread local allocation buffers");
aoqi@0:     return 0;
aoqi@0:   }
aoqi@0:   virtual size_t unsafe_max_tlab_alloc() const {
aoqi@0:     guarantee(false, "Generation doesn't support thread local allocation buffers");
aoqi@0:     return 0;
aoqi@0:   }
aoqi@0: 
aoqi@0:   // "obj" is the address of an object in a younger generation.  Allocate space
aoqi@0:   // for "obj" in the current (or some higher) generation, and copy "obj" into
aoqi@0:   // the newly allocated space, if possible, returning the result (or NULL if
aoqi@0:   // the allocation failed).
aoqi@0:   //
aoqi@0:   // The "obj_size" argument is just obj->size(), passed along so the caller can
aoqi@0:   // avoid repeating the virtual call to retrieve it.
aoqi@0:   virtual oop promote(oop obj, size_t obj_size);
aoqi@0: 
aoqi@0:   // Thread "thread_num" (0 <= i < ParalleGCThreads) wants to promote
aoqi@0:   // object "obj", whose original mark word was "m", and whose size is
aoqi@0:   // "word_sz".  If possible, allocate space for "obj", copy obj into it
aoqi@0:   // (taking care to copy "m" into the mark word when done, since the mark
aoqi@0:   // word of "obj" may have been overwritten with a forwarding pointer, and
aoqi@0:   // also taking care to copy the klass pointer *last*.  Returns the new
aoqi@0:   // object if successful, or else NULL.
aoqi@0:   virtual oop par_promote(int thread_num,
aoqi@0:                           oop obj, markOop m, size_t word_sz);
aoqi@0: 
aoqi@0:   // Undo, if possible, the most recent par_promote_alloc allocation by
aoqi@0:   // "thread_num" ("obj", of "word_sz").
aoqi@0:   virtual void par_promote_alloc_undo(int thread_num,
aoqi@0:                                       HeapWord* obj, size_t word_sz);
aoqi@0: 
aoqi@0:   // Informs the current generation that all par_promote_alloc's in the
aoqi@0:   // collection have been completed; any supporting data structures can be
aoqi@0:   // reset.  Default is to do nothing.
aoqi@0:   virtual void par_promote_alloc_done(int thread_num) {}
aoqi@0: 
aoqi@0:   // Informs the current generation that all oop_since_save_marks_iterates
aoqi@0:   // performed by "thread_num" in the current collection, if any, have been
aoqi@0:   // completed; any supporting data structures can be reset.  Default is to
aoqi@0:   // do nothing.
aoqi@0:   virtual void par_oop_since_save_marks_iterate_done(int thread_num) {}
aoqi@0: 
aoqi@0:   // This generation will collect all younger generations
aoqi@0:   // during a full collection.
aoqi@0:   virtual bool full_collects_younger_generations() const { return false; }
aoqi@0: 
aoqi@0:   // This generation does in-place marking, meaning that mark words
aoqi@0:   // are mutated during the marking phase and presumably reinitialized
aoqi@0:   // to a canonical value after the GC. This is currently used by the
aoqi@0:   // biased locking implementation to determine whether additional
aoqi@0:   // work is required during the GC prologue and epilogue.
aoqi@0:   virtual bool performs_in_place_marking() const { return true; }
aoqi@0: 
aoqi@0:   // Returns "true" iff collect() should subsequently be called on this
aoqi@0:   // this generation. See comment below.
aoqi@0:   // This is a generic implementation which can be overridden.
aoqi@0:   //
aoqi@0:   // Note: in the current (1.4) implementation, when genCollectedHeap's
aoqi@0:   // incremental_collection_will_fail flag is set, all allocations are
aoqi@0:   // slow path (the only fast-path place to allocate is DefNew, which
aoqi@0:   // will be full if the flag is set).
aoqi@0:   // Thus, older generations which collect younger generations should
aoqi@0:   // test this flag and collect if it is set.
aoqi@0:   virtual bool should_collect(bool   full,
aoqi@0:                               size_t word_size,
aoqi@0:                               bool   is_tlab) {
aoqi@0:     return (full || should_allocate(word_size, is_tlab));
aoqi@0:   }
aoqi@0: 
aoqi@0:   // Returns true if the collection is likely to be safely
aoqi@0:   // completed. Even if this method returns true, a collection
aoqi@0:   // may not be guaranteed to succeed, and the system should be
aoqi@0:   // able to safely unwind and recover from that failure, albeit
aoqi@0:   // at some additional cost.
aoqi@0:   virtual bool collection_attempt_is_safe() {
aoqi@0:     guarantee(false, "Are you sure you want to call this method?");
aoqi@0:     return true;
aoqi@0:   }
aoqi@0: 
aoqi@0:   // Perform a garbage collection.
aoqi@0:   // If full is true attempt a full garbage collection of this generation.
aoqi@0:   // Otherwise, attempting to (at least) free enough space to support an
aoqi@0:   // allocation of the given "word_size".
aoqi@0:   virtual void collect(bool   full,
aoqi@0:                        bool   clear_all_soft_refs,
aoqi@0:                        size_t word_size,
aoqi@0:                        bool   is_tlab) = 0;
aoqi@0: 
aoqi@0:   // Perform a heap collection, attempting to create (at least) enough
aoqi@0:   // space to support an allocation of the given "word_size".  If
aoqi@0:   // successful, perform the allocation and return the resulting
aoqi@0:   // "oop" (initializing the allocated block). If the allocation is
aoqi@0:   // still unsuccessful, return "NULL".
aoqi@0:   virtual HeapWord* expand_and_allocate(size_t word_size,
aoqi@0:                                         bool is_tlab,
aoqi@0:                                         bool parallel = false) = 0;
aoqi@0: 
aoqi@0:   // Some generations may require some cleanup or preparation actions before
aoqi@0:   // allowing a collection.  The default is to do nothing.
aoqi@0:   virtual void gc_prologue(bool full) {};
aoqi@0: 
aoqi@0:   // Some generations may require some cleanup actions after a collection.
aoqi@0:   // The default is to do nothing.
aoqi@0:   virtual void gc_epilogue(bool full) {};
aoqi@0: 
aoqi@0:   // Save the high water marks for the used space in a generation.
aoqi@0:   virtual void record_spaces_top() {};
aoqi@0: 
aoqi@0:   // Some generations may need to be "fixed-up" after some allocation
aoqi@0:   // activity to make them parsable again. The default is to do nothing.
aoqi@0:   virtual void ensure_parsability() {};
aoqi@0: 
aoqi@0:   // Time (in ms) when we were last collected or now if a collection is
aoqi@0:   // in progress.
aoqi@0:   virtual jlong time_of_last_gc(jlong now) {
aoqi@0:     // Both _time_of_last_gc and now are set using a time source
aoqi@0:     // that guarantees monotonically non-decreasing values provided
aoqi@0:     // the underlying platform provides such a source. So we still
aoqi@0:     // have to guard against non-monotonicity.
aoqi@0:     NOT_PRODUCT(
aoqi@0:       if (now < _time_of_last_gc) {
aoqi@0:         warning("time warp: "INT64_FORMAT" to "INT64_FORMAT, (int64_t)_time_of_last_gc, (int64_t)now);
aoqi@0:       }
aoqi@0:     )
aoqi@0:     return _time_of_last_gc;
aoqi@0:   }
aoqi@0: 
aoqi@0:   virtual void update_time_of_last_gc(jlong now)  {
aoqi@0:     _time_of_last_gc = now;
aoqi@0:   }
aoqi@0: 
aoqi@0:   // Generations may keep statistics about collection.  This
aoqi@0:   // method updates those statistics.  current_level is
aoqi@0:   // the level of the collection that has most recently
aoqi@0:   // occurred.  This allows the generation to decide what
aoqi@0:   // statistics are valid to collect.  For example, the
aoqi@0:   // generation can decide to gather the amount of promoted data
aoqi@0:   // if the collection of the younger generations has completed.
aoqi@0:   GCStats* gc_stats() const { return _gc_stats; }
aoqi@0:   virtual void update_gc_stats(int current_level, bool full) {}
aoqi@0: 
aoqi@0:   // Mark sweep support phase2
aoqi@0:   virtual void prepare_for_compaction(CompactPoint* cp);
aoqi@0:   // Mark sweep support phase3
aoqi@0:   virtual void adjust_pointers();
aoqi@0:   // Mark sweep support phase4
aoqi@0:   virtual void compact();
aoqi@0:   virtual void post_compact() {ShouldNotReachHere();}
aoqi@0: 
aoqi@0:   // Support for CMS's rescan. In this general form we return a pointer
aoqi@0:   // to an abstract object that can be used, based on specific previously
aoqi@0:   // decided protocols, to exchange information between generations,
aoqi@0:   // information that may be useful for speeding up certain types of
aoqi@0:   // garbage collectors. A NULL value indicates to the client that
aoqi@0:   // no data recording is expected by the provider. The data-recorder is
aoqi@0:   // expected to be GC worker thread-local, with the worker index
aoqi@0:   // indicated by "thr_num".
aoqi@0:   virtual void* get_data_recorder(int thr_num) { return NULL; }
aoqi@0:   virtual void sample_eden_chunk() {}
aoqi@0: 
aoqi@0:   // Some generations may require some cleanup actions before allowing
aoqi@0:   // a verification.
aoqi@0:   virtual void prepare_for_verify() {};
aoqi@0: 
aoqi@0:   // Accessing "marks".
aoqi@0: 
aoqi@0:   // This function gives a generation a chance to note a point between
aoqi@0:   // collections.  For example, a contiguous generation might note the
aoqi@0:   // beginning allocation point post-collection, which might allow some later
aoqi@0:   // operations to be optimized.
aoqi@0:   virtual void save_marks() {}
aoqi@0: 
aoqi@0:   // This function allows generations to initialize any "saved marks".  That
aoqi@0:   // is, should only be called when the generation is empty.
aoqi@0:   virtual void reset_saved_marks() {}
aoqi@0: 
aoqi@0:   // This function is "true" iff any no allocations have occurred in the
aoqi@0:   // generation since the last call to "save_marks".
aoqi@0:   virtual bool no_allocs_since_save_marks() = 0;
aoqi@0: 
aoqi@0:   // Apply "cl->apply" to (the addresses of) all reference fields in objects
aoqi@0:   // allocated in the current generation since the last call to "save_marks".
aoqi@0:   // If more objects are allocated in this generation as a result of applying
aoqi@0:   // the closure, iterates over reference fields in those objects as well.
aoqi@0:   // Calls "save_marks" at the end of the iteration.
aoqi@0:   // General signature...
aoqi@0:   virtual void oop_since_save_marks_iterate_v(OopsInGenClosure* cl) = 0;
aoqi@0:   // ...and specializations for de-virtualization.  (The general
aoqi@0:   // implemention of the _nv versions call the virtual version.
aoqi@0:   // Note that the _nv suffix is not really semantically necessary,
aoqi@0:   // but it avoids some not-so-useful warnings on Solaris.)
aoqi@0: #define Generation_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix)             \
aoqi@0:   virtual void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) {    \
aoqi@0:     oop_since_save_marks_iterate_v((OopsInGenClosure*)cl);                      \
aoqi@0:   }
aoqi@0:   SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(Generation_SINCE_SAVE_MARKS_DECL)
aoqi@0: 
aoqi@0: #undef Generation_SINCE_SAVE_MARKS_DECL
aoqi@0: 
aoqi@0:   // The "requestor" generation is performing some garbage collection
aoqi@0:   // action for which it would be useful to have scratch space.  If
aoqi@0:   // the target is not the requestor, no gc actions will be required
aoqi@0:   // of the target.  The requestor promises to allocate no more than
aoqi@0:   // "max_alloc_words" in the target generation (via promotion say,
aoqi@0:   // if the requestor is a young generation and the target is older).
aoqi@0:   // If the target generation can provide any scratch space, it adds
aoqi@0:   // it to "list", leaving "list" pointing to the head of the
aoqi@0:   // augmented list.  The default is to offer no space.
aoqi@0:   virtual void contribute_scratch(ScratchBlock*& list, Generation* requestor,
aoqi@0:                                   size_t max_alloc_words) {}
aoqi@0: 
aoqi@0:   // Give each generation an opportunity to do clean up for any
aoqi@0:   // contributed scratch.
aoqi@0:   virtual void reset_scratch() {};
aoqi@0: 
aoqi@0:   // When an older generation has been collected, and perhaps resized,
aoqi@0:   // this method will be invoked on all younger generations (from older to
aoqi@0:   // younger), allowing them to resize themselves as appropriate.
aoqi@0:   virtual void compute_new_size() = 0;
aoqi@0: 
aoqi@0:   // Printing
aoqi@0:   virtual const char* name() const = 0;
aoqi@0:   virtual const char* short_name() const = 0;
aoqi@0: 
aoqi@0:   int level() const { return _level; }
aoqi@0: 
aoqi@0:   // Attributes
aoqi@0: 
aoqi@0:   // True iff the given generation may only be the youngest generation.
aoqi@0:   virtual bool must_be_youngest() const = 0;
aoqi@0:   // True iff the given generation may only be the oldest generation.
aoqi@0:   virtual bool must_be_oldest() const = 0;
aoqi@0: 
aoqi@0:   // Reference Processing accessor
aoqi@0:   ReferenceProcessor* const ref_processor() { return _ref_processor; }
aoqi@0: 
aoqi@0:   // Iteration.
aoqi@0: 
aoqi@0:   // Iterate over all the ref-containing fields of all objects in the
aoqi@0:   // generation, calling "cl.do_oop" on each.
aoqi@0:   virtual void oop_iterate(ExtendedOopClosure* cl);
aoqi@0: 
aoqi@0:   // Iterate over all objects in the generation, calling "cl.do_object" on
aoqi@0:   // each.
aoqi@0:   virtual void object_iterate(ObjectClosure* cl);
aoqi@0: 
aoqi@0:   // Iterate over all safe objects in the generation, calling "cl.do_object" on
aoqi@0:   // each.  An object is safe if its references point to other objects in
aoqi@0:   // the heap.  This defaults to object_iterate() unless overridden.
aoqi@0:   virtual void safe_object_iterate(ObjectClosure* cl);
aoqi@0: 
aoqi@0:   // Apply "cl->do_oop" to (the address of) all and only all the ref fields
aoqi@0:   // in the current generation that contain pointers to objects in younger
aoqi@0:   // generations. Objects allocated since the last "save_marks" call are
aoqi@0:   // excluded.
aoqi@0:   virtual void younger_refs_iterate(OopsInGenClosure* cl) = 0;
aoqi@0: 
aoqi@0:   // Inform a generation that it longer contains references to objects
aoqi@0:   // in any younger generation.    [e.g. Because younger gens are empty,
aoqi@0:   // clear the card table.]
aoqi@0:   virtual void clear_remembered_set() { }
aoqi@0: 
aoqi@0:   // Inform a generation that some of its objects have moved.  [e.g. The
aoqi@0:   // generation's spaces were compacted, invalidating the card table.]
aoqi@0:   virtual void invalidate_remembered_set() { }
aoqi@0: 
aoqi@0:   // Block abstraction.
aoqi@0: 
aoqi@0:   // Returns the address of the start of the "block" that contains the
aoqi@0:   // address "addr".  We say "blocks" instead of "object" since some heaps
aoqi@0:   // may not pack objects densely; a chunk may either be an object or a
aoqi@0:   // non-object.
aoqi@0:   virtual HeapWord* block_start(const void* addr) const;
aoqi@0: 
aoqi@0:   // Requires "addr" to be the start of a chunk, and returns its size.
aoqi@0:   // "addr + size" is required to be the start of a new chunk, or the end
aoqi@0:   // of the active area of the heap.
aoqi@0:   virtual size_t block_size(const HeapWord* addr) const ;
aoqi@0: 
aoqi@0:   // Requires "addr" to be the start of a block, and returns "TRUE" iff
aoqi@0:   // the block is an object.
aoqi@0:   virtual bool block_is_obj(const HeapWord* addr) const;
aoqi@0: 
aoqi@0: 
aoqi@0:   // PrintGC, PrintGCDetails support
aoqi@0:   void print_heap_change(size_t prev_used) const;
aoqi@0: 
aoqi@0:   // PrintHeapAtGC support
aoqi@0:   virtual void print() const;
aoqi@0:   virtual void print_on(outputStream* st) const;
aoqi@0: 
aoqi@0:   virtual void verify() = 0;
aoqi@0: 
aoqi@0:   struct StatRecord {
aoqi@0:     int invocations;
aoqi@0:     elapsedTimer accumulated_time;
aoqi@0:     StatRecord() :
aoqi@0:       invocations(0),
aoqi@0:       accumulated_time(elapsedTimer()) {}
aoqi@0:   };
aoqi@0: private:
aoqi@0:   StatRecord _stat_record;
aoqi@0: public:
aoqi@0:   StatRecord* stat_record() { return &_stat_record; }
aoqi@0: 
aoqi@0:   virtual void print_summary_info();
aoqi@0:   virtual void print_summary_info_on(outputStream* st);
aoqi@0: 
aoqi@0:   // Performance Counter support
aoqi@0:   virtual void update_counters() = 0;
aoqi@0:   virtual CollectorCounters* counters() { return _gc_counters; }
aoqi@0: };
aoqi@0: 
aoqi@0: // Class CardGeneration is a generation that is covered by a card table,
aoqi@0: // and uses a card-size block-offset array to implement block_start.
aoqi@0: 
aoqi@0: // class BlockOffsetArray;
aoqi@0: // class BlockOffsetArrayContigSpace;
aoqi@0: class BlockOffsetSharedArray;
aoqi@0: 
aoqi@0: class CardGeneration: public Generation {
aoqi@0:   friend class VMStructs;
aoqi@0:  protected:
aoqi@0:   // This is shared with other generations.
aoqi@0:   GenRemSet* _rs;
aoqi@0:   // This is local to this generation.
aoqi@0:   BlockOffsetSharedArray* _bts;
aoqi@0: 
aoqi@0:   // current shrinking effect: this damps shrinking when the heap gets empty.
aoqi@0:   size_t _shrink_factor;
aoqi@0: 
aoqi@0:   size_t _min_heap_delta_bytes;   // Minimum amount to expand.
aoqi@0: 
aoqi@0:   // Some statistics from before gc started.
aoqi@0:   // These are gathered in the gc_prologue (and should_collect)
aoqi@0:   // to control growing/shrinking policy in spite of promotions.
aoqi@0:   size_t _capacity_at_prologue;
aoqi@0:   size_t _used_at_prologue;
aoqi@0: 
aoqi@0:   CardGeneration(ReservedSpace rs, size_t initial_byte_size, int level,
aoqi@0:                  GenRemSet* remset);
aoqi@0: 
aoqi@0:  public:
aoqi@0: 
aoqi@0:   // Attempt to expand the generation by "bytes".  Expand by at a
aoqi@0:   // minimum "expand_bytes".  Return true if some amount (not
aoqi@0:   // necessarily the full "bytes") was done.
aoqi@0:   virtual bool expand(size_t bytes, size_t expand_bytes);
aoqi@0: 
aoqi@0:   // Shrink generation with specified size (returns false if unable to shrink)
aoqi@0:   virtual void shrink(size_t bytes) = 0;
aoqi@0: 
aoqi@0:   virtual void compute_new_size();
aoqi@0: 
aoqi@0:   virtual void clear_remembered_set();
aoqi@0: 
aoqi@0:   virtual void invalidate_remembered_set();
aoqi@0: 
aoqi@0:   virtual void prepare_for_verify();
aoqi@0: 
aoqi@0:   // Grow generation with specified size (returns false if unable to grow)
aoqi@0:   virtual bool grow_by(size_t bytes) = 0;
aoqi@0:   // Grow generation to reserved size.
aoqi@0:   virtual bool grow_to_reserved() = 0;
aoqi@0: };
aoqi@0: 
aoqi@0: // OneContigSpaceCardGeneration models a heap of old objects contained in a single
aoqi@0: // contiguous space.
aoqi@0: //
aoqi@0: // Garbage collection is performed using mark-compact.
aoqi@0: 
aoqi@0: class OneContigSpaceCardGeneration: public CardGeneration {
aoqi@0:   friend class VMStructs;
aoqi@0:   // Abstractly, this is a subtype that gets access to protected fields.
aoqi@0:   friend class VM_PopulateDumpSharedSpace;
aoqi@0: 
aoqi@0:  protected:
aoqi@0:   ContiguousSpace*  _the_space;       // actual space holding objects
aoqi@0:   WaterMark  _last_gc;                // watermark between objects allocated before
aoqi@0:                                       // and after last GC.
aoqi@0: 
aoqi@0:   // Grow generation with specified size (returns false if unable to grow)
aoqi@0:   virtual bool grow_by(size_t bytes);
aoqi@0:   // Grow generation to reserved size.
aoqi@0:   virtual bool grow_to_reserved();
aoqi@0:   // Shrink generation with specified size (returns false if unable to shrink)
aoqi@0:   void shrink_by(size_t bytes);
aoqi@0: 
aoqi@0:   // Allocation failure
aoqi@0:   virtual bool expand(size_t bytes, size_t expand_bytes);
aoqi@0:   void shrink(size_t bytes);
aoqi@0: 
aoqi@0:   // Accessing spaces
aoqi@0:   ContiguousSpace* the_space() const { return _the_space; }
aoqi@0: 
aoqi@0:  public:
aoqi@0:   OneContigSpaceCardGeneration(ReservedSpace rs, size_t initial_byte_size,
aoqi@0:                                int level, GenRemSet* remset,
aoqi@0:                                ContiguousSpace* space) :
aoqi@0:     CardGeneration(rs, initial_byte_size, level, remset),
aoqi@0:     _the_space(space)
aoqi@0:   {}
aoqi@0: 
aoqi@0:   inline bool is_in(const void* p) const;
aoqi@0: 
aoqi@0:   // Space enquiries
aoqi@0:   size_t capacity() const;
aoqi@0:   size_t used() const;
aoqi@0:   size_t free() const;
aoqi@0: 
aoqi@0:   MemRegion used_region() const;
aoqi@0: 
aoqi@0:   size_t unsafe_max_alloc_nogc() const;
aoqi@0:   size_t contiguous_available() const;
aoqi@0: 
aoqi@0:   // Iteration
aoqi@0:   void object_iterate(ObjectClosure* blk);
aoqi@0:   void space_iterate(SpaceClosure* blk, bool usedOnly = false);
aoqi@0: 
aoqi@0:   void younger_refs_iterate(OopsInGenClosure* blk);
aoqi@0: 
aoqi@0:   inline CompactibleSpace* first_compaction_space() const;
aoqi@0: 
aoqi@0:   virtual inline HeapWord* allocate(size_t word_size, bool is_tlab);
aoqi@0:   virtual inline HeapWord* par_allocate(size_t word_size, bool is_tlab);
aoqi@0: 
aoqi@0:   // Accessing marks
aoqi@0:   inline WaterMark top_mark();
aoqi@0:   inline WaterMark bottom_mark();
aoqi@0: 
aoqi@0: #define OneContig_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix)      \
aoqi@0:   void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl);
aoqi@0:   OneContig_SINCE_SAVE_MARKS_DECL(OopsInGenClosure,_v)
aoqi@0:   SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(OneContig_SINCE_SAVE_MARKS_DECL)
aoqi@0: 
aoqi@0:   void save_marks();
aoqi@0:   void reset_saved_marks();
aoqi@0:   bool no_allocs_since_save_marks();
aoqi@0: 
aoqi@0:   inline size_t block_size(const HeapWord* addr) const;
aoqi@0: 
aoqi@0:   inline bool block_is_obj(const HeapWord* addr) const;
aoqi@0: 
aoqi@0:   virtual void collect(bool full,
aoqi@0:                        bool clear_all_soft_refs,
aoqi@0:                        size_t size,
aoqi@0:                        bool is_tlab);
aoqi@0:   HeapWord* expand_and_allocate(size_t size,
aoqi@0:                                 bool is_tlab,
aoqi@0:                                 bool parallel = false);
aoqi@0: 
aoqi@0:   virtual void prepare_for_verify();
aoqi@0: 
aoqi@0:   virtual void gc_epilogue(bool full);
aoqi@0: 
aoqi@0:   virtual void record_spaces_top();
aoqi@0: 
aoqi@0:   virtual void verify();
aoqi@0:   virtual void print_on(outputStream* st) const;
aoqi@0: };
aoqi@0: 
aoqi@0: #endif // SHARE_VM_MEMORY_GENERATION_HPP