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 /*

  * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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  * 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

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 #include "precompiled.hpp"

 #include "classfile/symbolTable.hpp"

 #include "classfile/systemDictionary.hpp"

 #include "memory/compactingPermGenGen.hpp"

 #include "memory/filemap.hpp"

 #include "memory/genOopClosures.inline.hpp"

 #include "memory/generation.inline.hpp"

 #include "memory/generationSpec.hpp"

 #include "oops/oop.inline.hpp"

 #include "runtime/java.hpp"

 #ifndef SERIALGC

 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.inline.hpp"

 #endif

 // An ObjectClosure helper: Recursively adjust all pointers in an object

 // and all objects by referenced it. Clear marks on objects in order to

 // prevent visiting any object twice. This helper is used when the

 // RedefineClasses() API has been called.

 class AdjustSharedObjectClosure : public ObjectClosure {

 public:

   void do_object(oop obj) {

     if (obj->is_shared_readwrite()) {

       if (obj->mark()->is_marked()) {

         obj->init_mark();         // Don't revisit this object.

         obj->adjust_pointers();   // Adjust this object's references.

       }

     }

   }

 };

 // An OopClosure helper: Recursively adjust all pointers in an object

 // and all objects by referenced it. Clear marks on objects in order

 // to prevent visiting any object twice.

 class RecursiveAdjustSharedObjectClosure : public OopClosure {

  protected:

   template <class T> inline void do_oop_work(T* p) {

     oop obj = oopDesc::load_decode_heap_oop_not_null(p);

     if (obj->is_shared_readwrite()) {

       if (obj->mark()->is_marked()) {

         obj->init_mark();         // Don't revisit this object.

         obj->oop_iterate(this);   // Recurse - adjust objects referenced.

         obj->adjust_pointers();   // Adjust this object's references.

         // Special case: if a class has a read-only constant pool,

         // then the read-write objects referenced by the pool must

         // have their marks reset.

         if (obj->klass() == Universe::instanceKlassKlassObj()) {

           instanceKlass* ik = instanceKlass::cast((klassOop)obj);

           constantPoolOop cp = ik->constants();

           if (cp->is_shared_readonly()) {

             cp->oop_iterate(this);

           }

         }

       }

     }

   }

  public:

   virtual void do_oop(oop* p)       { RecursiveAdjustSharedObjectClosure::do_oop_work(p); }

   virtual void do_oop(narrowOop* p) { RecursiveAdjustSharedObjectClosure::do_oop_work(p); }

 };

 // We need to go through all placeholders in the system dictionary and

 // try to resolve them into shared classes. Other threads might be in

 // the process of loading a shared class and have strong roots on

 // their stack to the class without having added the class to the

 // dictionary yet. This means the class will be marked during phase 1

 // but will not be unmarked during the application of the

 // RecursiveAdjustSharedObjectClosure to the SystemDictionary.

 class TraversePlaceholdersClosure {

  public:

   static void placeholders_do(Symbol* sym, oop loader) {

     if (CompactingPermGenGen::is_shared(sym)) {

       oop k = SystemDictionary::find_shared_class(sym);

       if (k != NULL) {

         RecursiveAdjustSharedObjectClosure clo;

         clo.do_oop(&k);

       }

     }

   }

 };

 void CompactingPermGenGen::initialize_performance_counters() {

   const char* gen_name = "perm";

   // Generation Counters - generation 2, 1 subspace

   _gen_counters = new GenerationCounters(gen_name, 2, 1, &_virtual_space);

   _space_counters = new CSpaceCounters(gen_name, 0,

                                        _virtual_space.reserved_size(),

                                       _the_space, _gen_counters);

 }

 void CompactingPermGenGen::update_counters() {

   if (UsePerfData) {

     _space_counters->update_all();

     _gen_counters->update_all();

   }

 }

 CompactingPermGenGen::CompactingPermGenGen(ReservedSpace rs,

                                            ReservedSpace shared_rs,

                                            size_t initial_byte_size,

                                            int level, GenRemSet* remset,

                                            ContiguousSpace* space,

                                            PermanentGenerationSpec* spec_) :

   OneContigSpaceCardGeneration(rs, initial_byte_size, MinPermHeapExpansion,

                                level, remset, space) {

   set_spec(spec_);

   if (!UseSharedSpaces && !DumpSharedSpaces) {

     spec()->disable_sharing();

   }

   // Break virtual space into address ranges for all spaces.

   if (spec()->enable_shared_spaces()) {

     shared_end = (HeapWord*)(shared_rs.base() + shared_rs.size());

       misccode_end = shared_end;

       misccode_bottom = misccode_end - heap_word_size(spec()->misc_code_size());

       miscdata_end = misccode_bottom;

       miscdata_bottom = miscdata_end - heap_word_size(spec()->misc_data_size());

       readwrite_end = miscdata_bottom;

       readwrite_bottom =

         readwrite_end - heap_word_size(spec()->read_write_size());

       readonly_end = readwrite_bottom;

       readonly_bottom =

         readonly_end - heap_word_size(spec()->read_only_size());

     shared_bottom = readonly_bottom;

     unshared_end = shared_bottom;

     assert((char*)shared_bottom == shared_rs.base(), "shared space mismatch");

   } else {

     shared_end = (HeapWord*)(rs.base() + rs.size());

       misccode_end = shared_end;

       misccode_bottom = shared_end;

       miscdata_end = shared_end;

       miscdata_bottom = shared_end;

       readwrite_end = shared_end;

       readwrite_bottom = shared_end;

       readonly_end = shared_end;

       readonly_bottom = shared_end;

     shared_bottom = shared_end;

     unshared_end = shared_bottom;

   }

   unshared_bottom = (HeapWord*) rs.base();

   // Verify shared and unshared spaces adjacent.

   assert((char*)shared_bottom == rs.base()+rs.size(), "shared space mismatch");

   assert(unshared_end > unshared_bottom, "shared space mismatch");

   // Split reserved memory into pieces.

   ReservedSpace ro_rs   = shared_rs.first_part(spec()->read_only_size(),

                                               UseSharedSpaces);

   ReservedSpace tmp_rs1 = shared_rs.last_part(spec()->read_only_size());

   ReservedSpace rw_rs   = tmp_rs1.first_part(spec()->read_write_size(),

                                              UseSharedSpaces);

   ReservedSpace tmp_rs2 = tmp_rs1.last_part(spec()->read_write_size());

   ReservedSpace md_rs   = tmp_rs2.first_part(spec()->misc_data_size(),

                                              UseSharedSpaces);

   ReservedSpace mc_rs   = tmp_rs2.last_part(spec()->misc_data_size());

   _shared_space_size = spec()->read_only_size()

                      + spec()->read_write_size()

                      + spec()->misc_data_size()

                      + spec()->misc_code_size();

   // Allocate the unshared (default) space.

   _the_space = new ContigPermSpace(_bts,

                MemRegion(unshared_bottom, heap_word_size(initial_byte_size)));

   if (_the_space == NULL)

     vm_exit_during_initialization("Could not allocate an unshared"

                                   " CompactingPermGen Space");

   // Allocate shared spaces

   if (spec()->enable_shared_spaces()) {

     // If mapping a shared file, the space is not committed, don't

     // mangle.

     NOT_PRODUCT(bool old_ZapUnusedHeapArea = ZapUnusedHeapArea;)

     NOT_PRODUCT(if (UseSharedSpaces) ZapUnusedHeapArea = false;)

     // Commit the memory behind the shared spaces if dumping (not

     // mapping).

     if (DumpSharedSpaces) {

       _ro_vs.initialize(ro_rs, spec()->read_only_size());

       _rw_vs.initialize(rw_rs, spec()->read_write_size());

       _md_vs.initialize(md_rs, spec()->misc_data_size());

       _mc_vs.initialize(mc_rs, spec()->misc_code_size());

     }

     // Allocate the shared spaces.

     _ro_bts = new BlockOffsetSharedArray(

                   MemRegion(readonly_bottom,

                             heap_word_size(spec()->read_only_size())),

                   heap_word_size(spec()->read_only_size()));

     _ro_space = new OffsetTableContigSpace(_ro_bts,

                   MemRegion(readonly_bottom, readonly_end));

     _rw_bts = new BlockOffsetSharedArray(

                   MemRegion(readwrite_bottom,

                             heap_word_size(spec()->read_write_size())),

                   heap_word_size(spec()->read_write_size()));

     _rw_space = new OffsetTableContigSpace(_rw_bts,

                   MemRegion(readwrite_bottom, readwrite_end));

     // Restore mangling flag.

     NOT_PRODUCT(ZapUnusedHeapArea = old_ZapUnusedHeapArea;)

     if (_ro_space == NULL || _rw_space == NULL)

       vm_exit_during_initialization("Could not allocate a shared space");

     // Cover both shared spaces entirely with cards.

     _rs->resize_covered_region(MemRegion(readonly_bottom, readwrite_end));

     if (UseSharedSpaces) {

       // Map in the regions in the shared file.

       FileMapInfo* mapinfo = FileMapInfo::current_info();

       size_t image_alignment = mapinfo->alignment();

       CollectedHeap* ch = Universe::heap();

       if ((!mapinfo->map_space(ro, ro_rs, _ro_space)) ||

           (!mapinfo->map_space(rw, rw_rs, _rw_space)) ||

           (!mapinfo->map_space(md, md_rs, NULL))      ||

           (!mapinfo->map_space(mc, mc_rs, NULL))      ||

           // check the alignment constraints

           (ch == NULL || ch->kind() != CollectedHeap::GenCollectedHeap ||

            image_alignment !=

            ((GenCollectedHeap*)ch)->gen_policy()->max_alignment())) {

         // Base addresses didn't match; skip sharing, but continue

         shared_rs.release();

         spec()->disable_sharing();

         // If -Xshare:on is specified, print out the error message and exit VM,

         // otherwise, set UseSharedSpaces to false and continue.

         if (RequireSharedSpaces) {

           vm_exit_during_initialization("Unable to use shared archive.", NULL);

         } else {

           FLAG_SET_DEFAULT(UseSharedSpaces, false);

         }

         // Note: freeing the block offset array objects does not

         // currently free up the underlying storage.

         delete _ro_bts;

         _ro_bts = NULL;

         delete _ro_space;

         _ro_space = NULL;

         delete _rw_bts;

         _rw_bts = NULL;

         delete _rw_space;

         _rw_space = NULL;

         shared_end = (HeapWord*)(rs.base() + rs.size());

         _rs->resize_covered_region(MemRegion(shared_bottom, shared_bottom));

       }

     }

     // Reserved region includes shared spaces for oop.is_in_reserved().

     _reserved.set_end(shared_end);

   } else {

     _ro_space = NULL;

     _rw_space = NULL;

   }

 }

 // Do a complete scan of the shared read write space to catch all

 // objects which contain references to any younger generation.  Forward

 // the pointers.  Avoid space_iterate, as actually visiting all the

 // objects in the space will page in more objects than we need.

 // Instead, use the system dictionary as strong roots into the read

 // write space.

 //

 // If a RedefineClasses() call has been made, then we have to iterate

 // over the entire shared read-write space in order to find all the

 // objects that need to be forwarded. For example, it is possible for

 // an nmethod to be found and marked in GC phase-1 only for the nmethod

 // to be freed by the time we reach GC phase-3. The underlying method

 // is still marked, but we can't (easily) find it in GC phase-3 so we

 // blow up in GC phase-4. With RedefineClasses() we want replaced code

 // (EMCP or obsolete) to go away (i.e., be collectible) once it is no

 // longer being executed by any thread so we keep minimal attachments

 // to the replaced code. However, we can't guarantee when those EMCP

 // or obsolete methods will be collected so they may still be out there

 // even after we've severed our minimal attachments.

 void CompactingPermGenGen::pre_adjust_pointers() {

   if (spec()->enable_shared_spaces()) {

     if (JvmtiExport::has_redefined_a_class()) {

       // RedefineClasses() requires a brute force approach

       AdjustSharedObjectClosure blk;

       rw_space()->object_iterate(&blk);

     } else {

       RecursiveAdjustSharedObjectClosure blk;

       Universe::oops_do(&blk);

       StringTable::oops_do(&blk);

       SystemDictionary::always_strong_classes_do(&blk);

       SystemDictionary::placeholders_do(TraversePlaceholdersClosure::placeholders_do);

     }

   }

 }

 #ifdef ASSERT

 class VerifyMarksClearedClosure : public ObjectClosure {

 public:

   void do_object(oop obj) {

     assert(SharedSkipVerify || !obj->mark()->is_marked(),

            "Shared oop still marked?");

   }

 };

 #endif

 void CompactingPermGenGen::post_compact() {

 #ifdef ASSERT

   if (!SharedSkipVerify && spec()->enable_shared_spaces()) {

     VerifyMarksClearedClosure blk;

     rw_space()->object_iterate(&blk);

   }

 #endif

 }

 // Do not use in time-critical operations due to the possibility of paging

 // in otherwise untouched or previously unread portions of the perm gen,

 // for instance, the shared spaces. NOTE: Because CompactingPermGenGen

 // derives from OneContigSpaceCardGeneration which is supposed to have a

 // single space, and does not override its object_iterate() method,

 // object iteration via that interface does not look at the objects in

 // the shared spaces when using CDS. This should be fixed; see CR 6897798.

 void CompactingPermGenGen::space_iterate(SpaceClosure* blk, bool usedOnly) {

   OneContigSpaceCardGeneration::space_iterate(blk, usedOnly);

   if (spec()->enable_shared_spaces()) {

     // Making the rw_space walkable will page in the entire space, and

     // is to be avoided in the case of time-critical operations.

     // However, this is required for Verify and heap dump operations.

     blk->do_space(ro_space());

     blk->do_space(rw_space());

   }

 }

 void CompactingPermGenGen::print_on(outputStream* st) const {

   OneContigSpaceCardGeneration::print_on(st);

   if (spec()->enable_shared_spaces()) {

     st->print("    ro");

     ro_space()->print_on(st);

     st->print("    rw");

     rw_space()->print_on(st);

   } else {

     st->print_cr("No shared spaces configured.");

   }

 }

 // References from the perm gen to the younger generation objects may

 // occur in static fields in Java classes or in constant pool references

 // to String objects.

 void CompactingPermGenGen::younger_refs_iterate(OopsInGenClosure* blk) {

   OneContigSpaceCardGeneration::younger_refs_iterate(blk);

   if (spec()->enable_shared_spaces()) {

     blk->set_generation(this);

     // ro_space has no younger gen refs.

     _rs->younger_refs_in_space_iterate(rw_space(), blk);

     blk->reset_generation();

   }

 }

 // Shared spaces are addressed in pre_adjust_pointers.

 void CompactingPermGenGen::adjust_pointers() {

   the_space()->adjust_pointers();

 }

 void CompactingPermGenGen::compact() {

   the_space()->compact();

 }

 size_t CompactingPermGenGen::contiguous_available() const {

   // Don't include shared spaces.

   return OneContigSpaceCardGeneration::contiguous_available()

          - _shared_space_size;

 }

 size_t CompactingPermGenGen::max_capacity() const {

   // Don't include shared spaces.

   assert(UseSharedSpaces || (_shared_space_size == 0),

     "If not used, the size of shared spaces should be 0");

   return OneContigSpaceCardGeneration::max_capacity()

           - _shared_space_size;

 }

 // No young generation references, clear this generation's main space's

 // card table entries.  Do NOT clear the card table entries for the

 // read-only space (always clear) or the read-write space (valuable

 // information).

 void CompactingPermGenGen::clear_remembered_set() {

   _rs->clear(MemRegion(the_space()->bottom(), the_space()->end()));

 }

 // Objects in this generation's main space may have moved, invalidate

 // that space's cards.  Do NOT invalidate the card table entries for the

 // read-only or read-write spaces, as those objects never move.

 void CompactingPermGenGen::invalidate_remembered_set() {

   _rs->invalidate(used_region());

 }

 void CompactingPermGenGen::verify(bool allow_dirty) {

   the_space()->verify(allow_dirty);

   if (!SharedSkipVerify && spec()->enable_shared_spaces()) {

     ro_space()->verify(allow_dirty);

     rw_space()->verify(allow_dirty);

   }

 }

 HeapWord* CompactingPermGenGen::unshared_bottom;

 HeapWord* CompactingPermGenGen::unshared_end;

 HeapWord* CompactingPermGenGen::shared_bottom;

 HeapWord* CompactingPermGenGen::shared_end;

 HeapWord* CompactingPermGenGen::readonly_bottom;

 HeapWord* CompactingPermGenGen::readonly_end;

 HeapWord* CompactingPermGenGen::readwrite_bottom;

 HeapWord* CompactingPermGenGen::readwrite_end;

 HeapWord* CompactingPermGenGen::miscdata_bottom;

 HeapWord* CompactingPermGenGen::miscdata_end;

 HeapWord* CompactingPermGenGen::misccode_bottom;

 HeapWord* CompactingPermGenGen::misccode_end;

 // JVM/TI RedefineClasses() support:

 bool CompactingPermGenGen::remap_shared_readonly_as_readwrite() {

   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");

   if (UseSharedSpaces) {

     // remap the shared readonly space to shared readwrite, private

     FileMapInfo* mapinfo = FileMapInfo::current_info();

     if (!mapinfo->remap_shared_readonly_as_readwrite()) {

       return false;

     }

   }

   return true;

 }