1 /*
   2  * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_VM_GC_CMS_CMSHEAP_HPP
  26 #define SHARE_VM_GC_CMS_CMSHEAP_HPP
  27 
  28 #include "gc/shared/genCollectedHeap.hpp"
  29 
  30 class WorkGang;
  31 
  32 class CMSHeap : public GenCollectedHeap {
  33 
  34 private:
  35   WorkGang* _workers;
  36 
  37 public:
  38   CMSHeap(GenCollectorPolicy *policy);
  39 
  40   // Returns JNI_OK on success
  41   virtual jint initialize();
  42 
  43 #ifdef ASSERT
  44   virtual void check_gen_kinds();
  45 #endif
  46 
  47 
  48   // Convenience function to be used in situations where the heap type can be
  49   // asserted to be this type.
  50   static CMSHeap* heap();
  51 
  52   virtual Name kind() const {
  53     return CollectedHeap::CMSHeap;
  54   }
  55 
  56   virtual const char* name() const {
  57     return "Concurrent Mark Sweep";
  58   }
  59 
  60   WorkGang* workers() const { return _workers; }
  61 
  62   virtual void print_gc_threads_on(outputStream* st) const;
  63   virtual void gc_threads_do(ThreadClosure* tc) const;
  64   virtual void print_on_error(outputStream* st) const;
  65 
  66   // Perform a full collection of the heap; intended for use in implementing
  67   // "System.gc". This implies as full a collection as the CollectedHeap
  68   // supports. Caller does not hold the Heap_lock on entry.
  69   void collect(GCCause::Cause cause);
  70 
  71   bool is_in_closed_subset(const void* p) const {
  72     return is_in_reserved(p);
  73   }
  74 
  75   bool card_mark_must_follow_store() const {
  76     return true;
  77   }
  78 
  79   void stop();
  80 
  81   // If "young_gen_as_roots" is false, younger generations are
  82   // not scanned as roots; in this case, the caller must be arranging to
  83   // scan the younger generations itself.  (For example, a generation might
  84   // explicitly mark reachable objects in younger generations, to avoid
  85   // excess storage retention.)
  86   void cms_process_roots(StrongRootsScope* scope,
  87                          bool young_gen_as_roots,
  88                          ScanningOption so,
  89                          bool only_strong_roots,
  90                          OopsInGenClosure* root_closure,
  91                          CLDClosure* cld_closure);
  92 
  93 protected:
  94   void gc_prologue(bool full);
  95   void gc_epilogue(bool full);
  96 
  97 private:
  98   // Returns success or failure.
  99   bool create_cms_collector();
 100 
 101   // In support of ExplicitGCInvokesConcurrent functionality
 102   bool should_do_concurrent_full_gc(GCCause::Cause cause);
 103 
 104   void collect_mostly_concurrent(GCCause::Cause cause);
 105 };
 106 
 107 #endif // SHARE_VM_GC_CMS_CMSHEAP_HPP