jdk8-mips64-public/hotspot: src/share/vm/memory/generation.hpp@7b0e9cba0307 (annotated)

src/share/vm/memory/generation.hpp@7b0e9cba0307 (annotated)

src/share/vm/memory/generation.hpp

Wed, 13 Jan 2010 15:26:39 -0800

author: ysr
date: Wed, 13 Jan 2010 15:26:39 -0800
changeset 1601: 7b0e9cba0307
parent 1580: e018e6884bd8
child 1907: c18cbe5936b8
permissions: -rw-r--r--

6896647: card marks can be deferred too long
Summary: Deferred card marks are now flushed during the gc prologue. Parallel[Scavege,OldGC] and SerialGC no longer defer card marks generated by COMPILER2 as a result of ReduceInitialCardMarks. For these cases, introduced a diagnostic option to defer the card marks, only for the purposes of testing and diagnostics. CMS and G1 continue to defer card marks. Potential performance concern related to single-threaded flushing of deferred card marks in the gc prologue will be addressed in the future.
Reviewed-by: never, johnc

 /*
  * Copyright 1997-2009 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  * CA 95054 USA or visit www.sun.com if you need additional information or
  * have any questions.
  *
  */
 // A Generation models a heap area for similarly-aged objects.
 // It will contain one ore more spaces holding the actual objects.
 //
 // The Generation class hierarchy:
 //
 // Generation                      - abstract base class
 // - DefNewGeneration              - allocation area (copy collected)
 //   - ParNewGeneration            - a DefNewGeneration that is collected by
 //                                   several threads
 // - CardGeneration                 - abstract class adding offset array behavior
 //   - OneContigSpaceCardGeneration - abstract class holding a single
 //                                    contiguous space with card marking
 //     - TenuredGeneration         - tenured (old object) space (markSweepCompact)
 //     - CompactingPermGenGen      - reflective object area (klasses, methods, symbols, ...)
 //   - ConcurrentMarkSweepGeneration - Mostly Concurrent Mark Sweep Generation
 //                                       (Detlefs-Printezis refinement of
 //                                       Boehm-Demers-Schenker)
 //
 // The system configurations currently allowed are:
 //
 //   DefNewGeneration + TenuredGeneration + PermGeneration
 //   DefNewGeneration + ConcurrentMarkSweepGeneration + ConcurrentMarkSweepPermGen
 //
 //   ParNewGeneration + TenuredGeneration + PermGeneration
 //   ParNewGeneration + ConcurrentMarkSweepGeneration + ConcurrentMarkSweepPermGen
 //
 class DefNewGeneration;
 class GenerationSpec;
 class CompactibleSpace;
 class ContiguousSpace;
 class CompactPoint;
 class OopsInGenClosure;
 class OopClosure;
 class ScanClosure;
 class FastScanClosure;
 class GenCollectedHeap;
 class GenRemSet;
 class GCStats;
 // A "ScratchBlock" represents a block of memory in one generation usable by
 // another.  It represents "num_words" free words, starting at and including
 // the address of "this".
 struct ScratchBlock {
   ScratchBlock* next;
   size_t num_words;
   HeapWord scratch_space[1];  // Actually, of size "num_words-2" (assuming
                               // first two fields are word-sized.)
 };
 class Generation: public CHeapObj {
   friend class VMStructs;
  private:
   jlong _time_of_last_gc; // time when last gc on this generation happened (ms)
   MemRegion _prev_used_region; // for collectors that want to "remember" a value for
                                // used region at some specific point during collection.
  protected:
   // Minimum and maximum addresses for memory reserved (not necessarily
   // committed) for generation.
   // Used by card marking code. Must not overlap with address ranges of
   // other generations.
   MemRegion _reserved;
   // Memory area reserved for generation
   VirtualSpace _virtual_space;
   // Level in the generation hierarchy.
   int _level;
   // ("Weak") Reference processing support
   ReferenceProcessor* _ref_processor;
   // Performance Counters
   CollectorCounters* _gc_counters;
   // Statistics for garbage collection
   GCStats* _gc_stats;
   // Returns the next generation in the configuration, or else NULL if this
   // is the highest generation.
   Generation* next_gen() const;
   // Initialize the generation.
   Generation(ReservedSpace rs, size_t initial_byte_size, int level);
   // Apply "cl->do_oop" to (the address of) (exactly) all the ref fields in
   // "sp" that point into younger generations.
   // The iteration is only over objects allocated at the start of the
   // iterations; objects allocated as a result of applying the closure are
   // not included.
   void younger_refs_in_space_iterate(Space* sp, OopsInGenClosure* cl);
  public:
   // The set of possible generation kinds.
   enum Name {
     ASParNew,
     ASConcurrentMarkSweep,
     DefNew,
     ParNew,
     MarkSweepCompact,
     ConcurrentMarkSweep,
     Other
   };
   enum SomePublicConstants {
     // Generations are GenGrain-aligned and have size that are multiples of
     // GenGrain.
     LogOfGenGrain = 16,
     GenGrain = 1 << LogOfGenGrain
   };
   // allocate and initialize ("weak") refs processing support
   virtual void ref_processor_init();
   void set_ref_processor(ReferenceProcessor* rp) {
     assert(_ref_processor == NULL, "clobbering existing _ref_processor");
     _ref_processor = rp;
   }
   virtual Generation::Name kind() { return Generation::Other; }
   GenerationSpec* spec();
   // This properly belongs in the collector, but for now this
   // will do.
   virtual bool refs_discovery_is_atomic() const { return true;  }
   virtual bool refs_discovery_is_mt()     const { return false; }
   // Space enquiries (results in bytes)
   virtual size_t capacity() const = 0;  // The maximum number of object bytes the
                                         // generation can currently hold.
   virtual size_t used() const = 0;      // The number of used bytes in the gen.
   virtual size_t free() const = 0;      // The number of free bytes in the gen.
   // Support for java.lang.Runtime.maxMemory(); see CollectedHeap.
   // Returns the total number of bytes  available in a generation
   // for the allocation of objects.
   virtual size_t max_capacity() const;
   // If this is a young generation, the maximum number of bytes that can be
   // allocated in this generation before a GC is triggered.
   virtual size_t capacity_before_gc() const { return 0; }
   // The largest number of contiguous free bytes in the generation,
   // including expansion  (Assumes called at a safepoint.)
   virtual size_t contiguous_available() const = 0;
   // The largest number of contiguous free bytes in this or any higher generation.
   virtual size_t max_contiguous_available() const;
   // Returns true if promotions of the specified amount can
   // be attempted safely (without a vm failure).
   // Promotion of the full amount is not guaranteed but
   // can be attempted.
   //   younger_handles_promotion_failure
   // is true if the younger generation handles a promotion
   // failure.
   virtual bool promotion_attempt_is_safe(size_t promotion_in_bytes,
     bool younger_handles_promotion_failure) const;
   // For a non-young generation, this interface can be used to inform a
   // generation that a promotion attempt into that generation failed.
   // Typically used to enable diagnostic output for post-mortem analysis,
   // but other uses of the interface are not ruled out.
   virtual void promotion_failure_occurred() { /* does nothing */ }
   // Return an estimate of the maximum allocation that could be performed
   // in the generation without triggering any collection or expansion
   // activity.  It is "unsafe" because no locks are taken; the result
   // should be treated as an approximation, not a guarantee, for use in
   // heuristic resizing decisions.
   virtual size_t unsafe_max_alloc_nogc() const = 0;
   // Returns true if this generation cannot be expanded further
   // without a GC. Override as appropriate.
   virtual bool is_maximal_no_gc() const {
     return _virtual_space.uncommitted_size() == 0;
   }
   MemRegion reserved() const { return _reserved; }
   // Returns a region guaranteed to contain all the objects in the
   // generation.
   virtual MemRegion used_region() const { return _reserved; }
   MemRegion prev_used_region() const { return _prev_used_region; }
   virtual void  save_used_region()   { _prev_used_region = used_region(); }
   // Returns "TRUE" iff "p" points into an allocated object in the generation.
   // For some kinds of generations, this may be an expensive operation.
   // To avoid performance problems stemming from its inadvertent use in
   // product jvm's, we restrict its use to assertion checking or
   // verification only.
   virtual bool is_in(const void* p) const;
   /* Returns "TRUE" iff "p" points into the reserved area of the generation. */
   bool is_in_reserved(const void* p) const {
     return _reserved.contains(p);
   }
   // Check that the generation kind is DefNewGeneration or a sub
   // class of DefNewGeneration and return a DefNewGeneration*
   DefNewGeneration*  as_DefNewGeneration();
   // If some space in the generation contains the given "addr", return a
   // pointer to that space, else return "NULL".
   virtual Space* space_containing(const void* addr) const;
   // Iteration - do not use for time critical operations
   virtual void space_iterate(SpaceClosure* blk, bool usedOnly = false) = 0;
   // Returns the first space, if any, in the generation that can participate
   // in compaction, or else "NULL".
   virtual CompactibleSpace* first_compaction_space() const = 0;
   // Returns "true" iff this generation should be used to allocate an
   // object of the given size.  Young generations might
   // wish to exclude very large objects, for example, since, if allocated
   // often, they would greatly increase the frequency of young-gen
   // collection.
   virtual bool should_allocate(size_t word_size, bool is_tlab) {
     bool result = false;
     size_t overflow_limit = (size_t)1 << (BitsPerSize_t - LogHeapWordSize);
     if (!is_tlab || supports_tlab_allocation()) {
       result = (word_size > 0) && (word_size < overflow_limit);
     }
     return result;
   }
   // Allocate and returns a block of the requested size, or returns "NULL".
   // Assumes the caller has done any necessary locking.
   virtual HeapWord* allocate(size_t word_size, bool is_tlab) = 0;
   // Like "allocate", but performs any necessary locking internally.
   virtual HeapWord* par_allocate(size_t word_size, bool is_tlab) = 0;
   // A 'younger' gen has reached an allocation limit, and uses this to notify
   // the next older gen.  The return value is a new limit, or NULL if none.  The
   // caller must do the necessary locking.
   virtual HeapWord* allocation_limit_reached(Space* space, HeapWord* top,
                                              size_t word_size) {
     return NULL;
   }
   // Some generation may offer a region for shared, contiguous allocation,
   // via inlined code (by exporting the address of the top and end fields
   // defining the extent of the contiguous allocation region.)
   // This function returns "true" iff the heap supports this kind of
   // allocation.  (More precisely, this means the style of allocation that
   // increments *top_addr()" with a CAS.) (Default is "no".)
   // A generation that supports this allocation style must use lock-free
   // allocation for *all* allocation, since there are times when lock free
   // allocation will be concurrent with plain "allocate" calls.
   virtual bool supports_inline_contig_alloc() const { return false; }
   // These functions return the addresses of the fields that define the
   // boundaries of the contiguous allocation area.  (These fields should be
   // physicall near to one another.)
   virtual HeapWord** top_addr() const { return NULL; }
   virtual HeapWord** end_addr() const { return NULL; }
   // Thread-local allocation buffers
   virtual bool supports_tlab_allocation() const { return false; }
   virtual size_t tlab_capacity() const {
     guarantee(false, "Generation doesn't support thread local allocation buffers");
     return 0;
   }
   virtual size_t unsafe_max_tlab_alloc() const {
     guarantee(false, "Generation doesn't support thread local allocation buffers");
     return 0;
   }
   // "obj" is the address of an object in a younger generation.  Allocate space
   // for "obj" in the current (or some higher) generation, and copy "obj" into
   // the newly allocated space, if possible, returning the result (or NULL if
   // the allocation failed).
   //
   // The "obj_size" argument is just obj->size(), passed along so the caller can
   // avoid repeating the virtual call to retrieve it.
   virtual oop promote(oop obj, size_t obj_size);
   // Thread "thread_num" (0 <= i < ParalleGCThreads) wants to promote
   // object "obj", whose original mark word was "m", and whose size is
   // "word_sz".  If possible, allocate space for "obj", copy obj into it
   // (taking care to copy "m" into the mark word when done, since the mark
   // word of "obj" may have been overwritten with a forwarding pointer, and
   // also taking care to copy the klass pointer *last*.  Returns the new
   // object if successful, or else NULL.
   virtual oop par_promote(int thread_num,
                           oop obj, markOop m, size_t word_sz);
   // Undo, if possible, the most recent par_promote_alloc allocation by
   // "thread_num" ("obj", of "word_sz").
   virtual void par_promote_alloc_undo(int thread_num,
                                       HeapWord* obj, size_t word_sz);
   // Informs the current generation that all par_promote_alloc's in the
   // collection have been completed; any supporting data structures can be
   // reset.  Default is to do nothing.
   virtual void par_promote_alloc_done(int thread_num) {}
   // Informs the current generation that all oop_since_save_marks_iterates
   // performed by "thread_num" in the current collection, if any, have been
   // completed; any supporting data structures can be reset.  Default is to
   // do nothing.
   virtual void par_oop_since_save_marks_iterate_done(int thread_num) {}
   // This generation will collect all younger generations
   // during a full collection.
   virtual bool full_collects_younger_generations() const { return false; }
   // This generation does in-place marking, meaning that mark words
   // are mutated during the marking phase and presumably reinitialized
   // to a canonical value after the GC. This is currently used by the
   // biased locking implementation to determine whether additional
   // work is required during the GC prologue and epilogue.
   virtual bool performs_in_place_marking() const { return true; }
   // Returns "true" iff collect() should subsequently be called on this
   // this generation. See comment below.
   // This is a generic implementation which can be overridden.
   //
   // Note: in the current (1.4) implementation, when genCollectedHeap's
   // incremental_collection_will_fail flag is set, all allocations are
   // slow path (the only fast-path place to allocate is DefNew, which
   // will be full if the flag is set).
   // Thus, older generations which collect younger generations should
   // test this flag and collect if it is set.
   virtual bool should_collect(bool   full,
                               size_t word_size,
                               bool   is_tlab) {
     return (full || should_allocate(word_size, is_tlab));
   }
   // Perform a garbage collection.
   // If full is true attempt a full garbage collection of this generation.
   // Otherwise, attempting to (at least) free enough space to support an
   // allocation of the given "word_size".
   virtual void collect(bool   full,
                        bool   clear_all_soft_refs,
                        size_t word_size,
                        bool   is_tlab) = 0;
   // Perform a heap collection, attempting to create (at least) enough
   // space to support an allocation of the given "word_size".  If
   // successful, perform the allocation and return the resulting
   // "oop" (initializing the allocated block). If the allocation is
   // still unsuccessful, return "NULL".
   virtual HeapWord* expand_and_allocate(size_t word_size,
                                         bool is_tlab,
                                         bool parallel = false) = 0;
   // Some generations may require some cleanup or preparation actions before
   // allowing a collection.  The default is to do nothing.
   virtual void gc_prologue(bool full) {};
   // Some generations may require some cleanup actions after a collection.
   // The default is to do nothing.
   virtual void gc_epilogue(bool full) {};
   // Save the high water marks for the used space in a generation.
   virtual void record_spaces_top() {};
   // Some generations may need to be "fixed-up" after some allocation
   // activity to make them parsable again. The default is to do nothing.
   virtual void ensure_parsability() {};
   // Time (in ms) when we were last collected or now if a collection is
   // in progress.
   virtual jlong time_of_last_gc(jlong now) {
     // XXX See note in genCollectedHeap::millis_since_last_gc()
     NOT_PRODUCT(
       if (now < _time_of_last_gc) {
         warning("time warp: %d to %d", _time_of_last_gc, now);
       }
     )
     return _time_of_last_gc;
   }
   virtual void update_time_of_last_gc(jlong now)  {
     _time_of_last_gc = now;
   }
   // Generations may keep statistics about collection.  This
   // method updates those statistics.  current_level is
   // the level of the collection that has most recently
   // occurred.  This allows the generation to decide what
   // statistics are valid to collect.  For example, the
   // generation can decide to gather the amount of promoted data
   // if the collection of the younger generations has completed.
   GCStats* gc_stats() const { return _gc_stats; }
   virtual void update_gc_stats(int current_level, bool full) {}
   // Mark sweep support phase2
   virtual void prepare_for_compaction(CompactPoint* cp);
   // Mark sweep support phase3
   virtual void pre_adjust_pointers() {ShouldNotReachHere();}
   virtual void adjust_pointers();
   // Mark sweep support phase4
   virtual void compact();
   virtual void post_compact() {ShouldNotReachHere();}
   // Support for CMS's rescan. In this general form we return a pointer
   // to an abstract object that can be used, based on specific previously
   // decided protocols, to exchange information between generations,
   // information that may be useful for speeding up certain types of
   // garbage collectors. A NULL value indicates to the client that
   // no data recording is expected by the provider. The data-recorder is
   // expected to be GC worker thread-local, with the worker index
   // indicated by "thr_num".
   virtual void* get_data_recorder(int thr_num) { return NULL; }
   // Some generations may require some cleanup actions before allowing
   // a verification.
   virtual void prepare_for_verify() {};
   // Accessing "marks".
   // This function gives a generation a chance to note a point between
   // collections.  For example, a contiguous generation might note the
   // beginning allocation point post-collection, which might allow some later
   // operations to be optimized.
   virtual void save_marks() {}
   // This function allows generations to initialize any "saved marks".  That
   // is, should only be called when the generation is empty.
   virtual void reset_saved_marks() {}
   // This function is "true" iff any no allocations have occurred in the
   // generation since the last call to "save_marks".
   virtual bool no_allocs_since_save_marks() = 0;
   // Apply "cl->apply" to (the addresses of) all reference fields in objects
   // allocated in the current generation since the last call to "save_marks".
   // If more objects are allocated in this generation as a result of applying
   // the closure, iterates over reference fields in those objects as well.
   // Calls "save_marks" at the end of the iteration.
   // General signature...
   virtual void oop_since_save_marks_iterate_v(OopsInGenClosure* cl) = 0;
   // ...and specializations for de-virtualization.  (The general
   // implemention of the _nv versions call the virtual version.
   // Note that the _nv suffix is not really semantically necessary,
   // but it avoids some not-so-useful warnings on Solaris.)
 #define Generation_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix)             \
   virtual void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) {    \
     oop_since_save_marks_iterate_v((OopsInGenClosure*)cl);                      \
   }
   SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(Generation_SINCE_SAVE_MARKS_DECL)
 #undef Generation_SINCE_SAVE_MARKS_DECL
   // The "requestor" generation is performing some garbage collection
   // action for which it would be useful to have scratch space.  If
   // the target is not the requestor, no gc actions will be required
   // of the target.  The requestor promises to allocate no more than
   // "max_alloc_words" in the target generation (via promotion say,
   // if the requestor is a young generation and the target is older).
   // If the target generation can provide any scratch space, it adds
   // it to "list", leaving "list" pointing to the head of the
   // augmented list.  The default is to offer no space.
   virtual void contribute_scratch(ScratchBlock*& list, Generation* requestor,
                                   size_t max_alloc_words) {}
   // Give each generation an opportunity to do clean up for any
   // contributed scratch.
   virtual void reset_scratch() {};
   // When an older generation has been collected, and perhaps resized,
   // this method will be invoked on all younger generations (from older to
   // younger), allowing them to resize themselves as appropriate.
   virtual void compute_new_size() = 0;
   // Printing
   virtual const char* name() const = 0;
   virtual const char* short_name() const = 0;
   int level() const { return _level; }
   // Attributes
   // True iff the given generation may only be the youngest generation.
   virtual bool must_be_youngest() const = 0;
   // True iff the given generation may only be the oldest generation.
   virtual bool must_be_oldest() const = 0;
   // Reference Processing accessor
   ReferenceProcessor* const ref_processor() { return _ref_processor; }
   // Iteration.
   // Iterate over all the ref-containing fields of all objects in the
   // generation, calling "cl.do_oop" on each.
   virtual void oop_iterate(OopClosure* cl);
   // Same as above, restricted to the intersection of a memory region and
   // the generation.
   virtual void oop_iterate(MemRegion mr, OopClosure* cl);
   // Iterate over all objects in the generation, calling "cl.do_object" on
   // each.
   virtual void object_iterate(ObjectClosure* cl);
   // Iterate over all safe objects in the generation, calling "cl.do_object" on
   // each.  An object is safe if its references point to other objects in
   // the heap.  This defaults to object_iterate() unless overridden.
   virtual void safe_object_iterate(ObjectClosure* cl);
   // Iterate over all objects allocated in the generation since the last
   // collection, calling "cl.do_object" on each.  The generation must have
   // been initialized properly to support this function, or else this call
   // will fail.
   virtual void object_iterate_since_last_GC(ObjectClosure* cl) = 0;
   // Apply "cl->do_oop" to (the address of) all and only all the ref fields
   // in the current generation that contain pointers to objects in younger
   // generations. Objects allocated since the last "save_marks" call are
   // excluded.
   virtual void younger_refs_iterate(OopsInGenClosure* cl) = 0;
   // Inform a generation that it longer contains references to objects
   // in any younger generation.    [e.g. Because younger gens are empty,
   // clear the card table.]
   virtual void clear_remembered_set() { }
   // Inform a generation that some of its objects have moved.  [e.g. The
   // generation's spaces were compacted, invalidating the card table.]
   virtual void invalidate_remembered_set() { }
   // Block abstraction.
   // Returns the address of the start of the "block" that contains the
   // address "addr".  We say "blocks" instead of "object" since some heaps
   // may not pack objects densely; a chunk may either be an object or a
   // non-object.
   virtual HeapWord* block_start(const void* addr) const;
   // Requires "addr" to be the start of a chunk, and returns its size.
   // "addr + size" is required to be the start of a new chunk, or the end
   // of the active area of the heap.
   virtual size_t block_size(const HeapWord* addr) const ;
   // Requires "addr" to be the start of a block, and returns "TRUE" iff
   // the block is an object.
   virtual bool block_is_obj(const HeapWord* addr) const;
   // PrintGC, PrintGCDetails support
   void print_heap_change(size_t prev_used) const;
   // PrintHeapAtGC support
   virtual void print() const;
   virtual void print_on(outputStream* st) const;
   virtual void verify(bool allow_dirty) = 0;
   struct StatRecord {
     int invocations;
     elapsedTimer accumulated_time;
     StatRecord() :
       invocations(0),
       accumulated_time(elapsedTimer()) {}
   };
 private:
   StatRecord _stat_record;
 public:
   StatRecord* stat_record() { return &_stat_record; }
   virtual void print_summary_info();
   virtual void print_summary_info_on(outputStream* st);
   // Performance Counter support
   virtual void update_counters() = 0;
   virtual CollectorCounters* counters() { return _gc_counters; }
 };
 // Class CardGeneration is a generation that is covered by a card table,
 // and uses a card-size block-offset array to implement block_start.
 // class BlockOffsetArray;
 // class BlockOffsetArrayContigSpace;
 class BlockOffsetSharedArray;
 class CardGeneration: public Generation {
   friend class VMStructs;
  protected:
   // This is shared with other generations.
   GenRemSet* _rs;
   // This is local to this generation.
   BlockOffsetSharedArray* _bts;
   CardGeneration(ReservedSpace rs, size_t initial_byte_size, int level,
                  GenRemSet* remset);
  public:
   // Attempt to expand the generation by "bytes".  Expand by at a
   // minimum "expand_bytes".  Return true if some amount (not
   // necessarily the full "bytes") was done.
   virtual bool expand(size_t bytes, size_t expand_bytes);
   virtual void clear_remembered_set();
   virtual void invalidate_remembered_set();
   virtual void prepare_for_verify();
   // Grow generation with specified size (returns false if unable to grow)
   virtual bool grow_by(size_t bytes) = 0;
   // Grow generation to reserved size.
   virtual bool grow_to_reserved() = 0;
 };
 // OneContigSpaceCardGeneration models a heap of old objects contained in a single
 // contiguous space.
 //
 // Garbage collection is performed using mark-compact.
 class OneContigSpaceCardGeneration: public CardGeneration {
   friend class VMStructs;
   // Abstractly, this is a subtype that gets access to protected fields.
   friend class CompactingPermGen;
   friend class VM_PopulateDumpSharedSpace;
  protected:
   size_t     _min_heap_delta_bytes;   // Minimum amount to expand.
   ContiguousSpace*  _the_space;       // actual space holding objects
   WaterMark  _last_gc;                // watermark between objects allocated before
                                       // and after last GC.
   // Grow generation with specified size (returns false if unable to grow)
   virtual bool grow_by(size_t bytes);
   // Grow generation to reserved size.
   virtual bool grow_to_reserved();
   // Shrink generation with specified size (returns false if unable to shrink)
   void shrink_by(size_t bytes);
   // Allocation failure
   virtual bool expand(size_t bytes, size_t expand_bytes);
   void shrink(size_t bytes);
   // Accessing spaces
   ContiguousSpace* the_space() const { return _the_space; }
  public:
   OneContigSpaceCardGeneration(ReservedSpace rs, size_t initial_byte_size,
                                size_t min_heap_delta_bytes,
                                int level, GenRemSet* remset,
                                ContiguousSpace* space) :
     CardGeneration(rs, initial_byte_size, level, remset),
     _the_space(space), _min_heap_delta_bytes(min_heap_delta_bytes)
   {}
   inline bool is_in(const void* p) const;
   // Space enquiries
   size_t capacity() const;
   size_t used() const;
   size_t free() const;
   MemRegion used_region() const;
   size_t unsafe_max_alloc_nogc() const;
   size_t contiguous_available() const;
   // Iteration
   void object_iterate(ObjectClosure* blk);
   void space_iterate(SpaceClosure* blk, bool usedOnly = false);
   void object_iterate_since_last_GC(ObjectClosure* cl);
   void younger_refs_iterate(OopsInGenClosure* blk);
   inline CompactibleSpace* first_compaction_space() const;
   virtual inline HeapWord* allocate(size_t word_size, bool is_tlab);
   virtual inline HeapWord* par_allocate(size_t word_size, bool is_tlab);
   // Accessing marks
   inline WaterMark top_mark();
   inline WaterMark bottom_mark();
 #define OneContig_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix)      \
   void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl);
   OneContig_SINCE_SAVE_MARKS_DECL(OopsInGenClosure,_v)
   SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(OneContig_SINCE_SAVE_MARKS_DECL)
   void save_marks();
   void reset_saved_marks();
   bool no_allocs_since_save_marks();
   inline size_t block_size(const HeapWord* addr) const;
   inline bool block_is_obj(const HeapWord* addr) const;
   virtual void collect(bool full,
                        bool clear_all_soft_refs,
                        size_t size,
                        bool is_tlab);
   HeapWord* expand_and_allocate(size_t size,
                                 bool is_tlab,
                                 bool parallel = false);
   virtual void prepare_for_verify();
   virtual void gc_epilogue(bool full);
   virtual void record_spaces_top();
   virtual void verify(bool allow_dirty);
   virtual void print_on(outputStream* st) const;
 };

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/memory/generation.hpp@7b0e9cba0307 (annotated)

src/share/vm/memory/generation.hpp