duke@435: /*
stefank@2314:  * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
duke@435:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435:  *
duke@435:  * This code is free software; you can redistribute it and/or modify it
duke@435:  * under the terms of the GNU General Public License version 2 only, as
duke@435:  * published by the Free Software Foundation.
duke@435:  *
duke@435:  * This code is distributed in the hope that it will be useful, but WITHOUT
duke@435:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
duke@435:  * version 2 for more details (a copy is included in the LICENSE file that
duke@435:  * accompanied this code).
duke@435:  *
duke@435:  * You should have received a copy of the GNU General Public License version
duke@435:  * 2 along with this work; if not, write to the Free Software Foundation,
duke@435:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435:  *
trims@1907:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
trims@1907:  * or visit www.oracle.com if you need additional information or have any
trims@1907:  * questions.
duke@435:  *
duke@435:  */
duke@435: 
stefank@2314: #include "precompiled.hpp"
stefank@2314: #include "classfile/symbolTable.hpp"
stefank@2314: #include "classfile/systemDictionary.hpp"
stefank@2314: #include "memory/compactingPermGenGen.hpp"
stefank@2314: #include "memory/filemap.hpp"
stefank@2314: #include "memory/genOopClosures.inline.hpp"
stefank@2314: #include "memory/generation.inline.hpp"
stefank@2314: #include "memory/generationSpec.hpp"
stefank@2314: #include "oops/oop.inline.hpp"
stefank@2314: #include "runtime/java.hpp"
stefank@2314: #ifndef SERIALGC
stefank@2314: #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.inline.hpp"
stefank@2314: #endif
duke@435: 
duke@435: 
dcubed@482: // An ObjectClosure helper: Recursively adjust all pointers in an object
dcubed@482: // and all objects by referenced it. Clear marks on objects in order to
dcubed@482: // prevent visiting any object twice. This helper is used when the
dcubed@482: // RedefineClasses() API has been called.
dcubed@482: 
dcubed@482: class AdjustSharedObjectClosure : public ObjectClosure {
dcubed@482: public:
dcubed@482:   void do_object(oop obj) {
dcubed@482:     if (obj->is_shared_readwrite()) {
dcubed@482:       if (obj->mark()->is_marked()) {
dcubed@482:         obj->init_mark();         // Don't revisit this object.
dcubed@482:         obj->adjust_pointers();   // Adjust this object's references.
dcubed@482:       }
dcubed@482:     }
dcubed@482:   }
dcubed@482: };
dcubed@482: 
dcubed@482: 
dcubed@482: // An OopClosure helper: Recursively adjust all pointers in an object
dcubed@482: // and all objects by referenced it. Clear marks on objects in order
dcubed@482: // to prevent visiting any object twice.
duke@435: 
duke@435: class RecursiveAdjustSharedObjectClosure : public OopClosure {
coleenp@548:  protected:
coleenp@548:   template <class T> inline void do_oop_work(T* p) {
coleenp@548:     oop obj = oopDesc::load_decode_heap_oop_not_null(p);
duke@435:     if (obj->is_shared_readwrite()) {
duke@435:       if (obj->mark()->is_marked()) {
duke@435:         obj->init_mark();         // Don't revisit this object.
duke@435:         obj->oop_iterate(this);   // Recurse - adjust objects referenced.
duke@435:         obj->adjust_pointers();   // Adjust this object's references.
duke@435: 
duke@435:         // Special case: if a class has a read-only constant pool,
duke@435:         // then the read-write objects referenced by the pool must
duke@435:         // have their marks reset.
duke@435: 
duke@435:         if (obj->klass() == Universe::instanceKlassKlassObj()) {
duke@435:           instanceKlass* ik = instanceKlass::cast((klassOop)obj);
duke@435:           constantPoolOop cp = ik->constants();
duke@435:           if (cp->is_shared_readonly()) {
duke@435:             cp->oop_iterate(this);
duke@435:           }
duke@435:         }
duke@435:       }
duke@435:     }
coleenp@548:   }
coleenp@548:  public:
coleenp@548:   virtual void do_oop(oop* p)       { RecursiveAdjustSharedObjectClosure::do_oop_work(p); }
coleenp@548:   virtual void do_oop(narrowOop* p) { RecursiveAdjustSharedObjectClosure::do_oop_work(p); }
duke@435: };
duke@435: 
duke@435: 
duke@435: // We need to go through all placeholders in the system dictionary and
duke@435: // try to resolve them into shared classes. Other threads might be in
duke@435: // the process of loading a shared class and have strong roots on
duke@435: // their stack to the class without having added the class to the
duke@435: // dictionary yet. This means the class will be marked during phase 1
duke@435: // but will not be unmarked during the application of the
coleenp@2497: // RecursiveAdjustSharedObjectClosure to the SystemDictionary.
coleenp@2497: class TraversePlaceholdersClosure {
coleenp@2497:  public:
coleenp@2497:   static void placeholders_do(Symbol* sym, oop loader) {
coleenp@2497:     if (CompactingPermGenGen::is_shared(sym)) {
duke@435:       oop k = SystemDictionary::find_shared_class(sym);
duke@435:       if (k != NULL) {
duke@435:         RecursiveAdjustSharedObjectClosure clo;
duke@435:         clo.do_oop(&k);
duke@435:       }
duke@435:     }
duke@435:   }
duke@435: };
duke@435: 
duke@435: void CompactingPermGenGen::initialize_performance_counters() {
duke@435: 
duke@435:   const char* gen_name = "perm";
duke@435: 
duke@435:   // Generation Counters - generation 2, 1 subspace
duke@435:   _gen_counters = new GenerationCounters(gen_name, 2, 1, &_virtual_space);
duke@435: 
duke@435:   _space_counters = new CSpaceCounters(gen_name, 0,
duke@435:                                        _virtual_space.reserved_size(),
duke@435:                                       _the_space, _gen_counters);
duke@435: }
duke@435: 
duke@435: void CompactingPermGenGen::update_counters() {
duke@435:   if (UsePerfData) {
duke@435:     _space_counters->update_all();
duke@435:     _gen_counters->update_all();
duke@435:   }
duke@435: }
duke@435: 
duke@435: 
duke@435: CompactingPermGenGen::CompactingPermGenGen(ReservedSpace rs,
duke@435:                                            ReservedSpace shared_rs,
duke@435:                                            size_t initial_byte_size,
duke@435:                                            int level, GenRemSet* remset,
duke@435:                                            ContiguousSpace* space,
duke@435:                                            PermanentGenerationSpec* spec_) :
duke@435:   OneContigSpaceCardGeneration(rs, initial_byte_size, MinPermHeapExpansion,
duke@435:                                level, remset, space) {
duke@435: 
duke@435:   set_spec(spec_);
duke@435:   if (!UseSharedSpaces && !DumpSharedSpaces) {
duke@435:     spec()->disable_sharing();
duke@435:   }
duke@435: 
duke@435:   // Break virtual space into address ranges for all spaces.
duke@435: 
duke@435:   if (spec()->enable_shared_spaces()) {
duke@435:     shared_end = (HeapWord*)(shared_rs.base() + shared_rs.size());
duke@435:       misccode_end = shared_end;
duke@435:       misccode_bottom = misccode_end - heap_word_size(spec()->misc_code_size());
duke@435:       miscdata_end = misccode_bottom;
duke@435:       miscdata_bottom = miscdata_end - heap_word_size(spec()->misc_data_size());
duke@435:       readwrite_end = miscdata_bottom;
duke@435:       readwrite_bottom =
duke@435:         readwrite_end - heap_word_size(spec()->read_write_size());
duke@435:       readonly_end = readwrite_bottom;
duke@435:       readonly_bottom =
duke@435:         readonly_end - heap_word_size(spec()->read_only_size());
duke@435:     shared_bottom = readonly_bottom;
duke@435:     unshared_end = shared_bottom;
duke@435:     assert((char*)shared_bottom == shared_rs.base(), "shared space mismatch");
duke@435:   } else {
duke@435:     shared_end = (HeapWord*)(rs.base() + rs.size());
duke@435:       misccode_end = shared_end;
duke@435:       misccode_bottom = shared_end;
duke@435:       miscdata_end = shared_end;
duke@435:       miscdata_bottom = shared_end;
duke@435:       readwrite_end = shared_end;
duke@435:       readwrite_bottom = shared_end;
duke@435:       readonly_end = shared_end;
duke@435:       readonly_bottom = shared_end;
duke@435:     shared_bottom = shared_end;
duke@435:     unshared_end = shared_bottom;
duke@435:   }
duke@435:   unshared_bottom = (HeapWord*) rs.base();
duke@435: 
duke@435:   // Verify shared and unshared spaces adjacent.
duke@435:   assert((char*)shared_bottom == rs.base()+rs.size(), "shared space mismatch");
duke@435:   assert(unshared_end > unshared_bottom, "shared space mismatch");
duke@435: 
duke@435:   // Split reserved memory into pieces.
duke@435: 
duke@435:   ReservedSpace ro_rs   = shared_rs.first_part(spec()->read_only_size(),
duke@435:                                               UseSharedSpaces);
duke@435:   ReservedSpace tmp_rs1 = shared_rs.last_part(spec()->read_only_size());
duke@435:   ReservedSpace rw_rs   = tmp_rs1.first_part(spec()->read_write_size(),
duke@435:                                              UseSharedSpaces);
duke@435:   ReservedSpace tmp_rs2 = tmp_rs1.last_part(spec()->read_write_size());
duke@435:   ReservedSpace md_rs   = tmp_rs2.first_part(spec()->misc_data_size(),
duke@435:                                              UseSharedSpaces);
duke@435:   ReservedSpace mc_rs   = tmp_rs2.last_part(spec()->misc_data_size());
duke@435: 
duke@435:   _shared_space_size = spec()->read_only_size()
duke@435:                      + spec()->read_write_size()
duke@435:                      + spec()->misc_data_size()
duke@435:                      + spec()->misc_code_size();
duke@435: 
duke@435:   // Allocate the unshared (default) space.
duke@435:   _the_space = new ContigPermSpace(_bts,
duke@435:                MemRegion(unshared_bottom, heap_word_size(initial_byte_size)));
duke@435:   if (_the_space == NULL)
duke@435:     vm_exit_during_initialization("Could not allocate an unshared"
duke@435:                                   " CompactingPermGen Space");
duke@435: 
duke@435:   // Allocate shared spaces
duke@435:   if (spec()->enable_shared_spaces()) {
duke@435: 
duke@435:     // If mapping a shared file, the space is not committed, don't
duke@435:     // mangle.
duke@435:     NOT_PRODUCT(bool old_ZapUnusedHeapArea = ZapUnusedHeapArea;)
duke@435:     NOT_PRODUCT(if (UseSharedSpaces) ZapUnusedHeapArea = false;)
duke@435: 
duke@435:     // Commit the memory behind the shared spaces if dumping (not
duke@435:     // mapping).
duke@435:     if (DumpSharedSpaces) {
duke@435:       _ro_vs.initialize(ro_rs, spec()->read_only_size());
duke@435:       _rw_vs.initialize(rw_rs, spec()->read_write_size());
duke@435:       _md_vs.initialize(md_rs, spec()->misc_data_size());
duke@435:       _mc_vs.initialize(mc_rs, spec()->misc_code_size());
duke@435:     }
duke@435: 
duke@435:     // Allocate the shared spaces.
duke@435:     _ro_bts = new BlockOffsetSharedArray(
duke@435:                   MemRegion(readonly_bottom,
duke@435:                             heap_word_size(spec()->read_only_size())),
duke@435:                   heap_word_size(spec()->read_only_size()));
duke@435:     _ro_space = new OffsetTableContigSpace(_ro_bts,
duke@435:                   MemRegion(readonly_bottom, readonly_end));
duke@435:     _rw_bts = new BlockOffsetSharedArray(
duke@435:                   MemRegion(readwrite_bottom,
duke@435:                             heap_word_size(spec()->read_write_size())),
duke@435:                   heap_word_size(spec()->read_write_size()));
duke@435:     _rw_space = new OffsetTableContigSpace(_rw_bts,
duke@435:                   MemRegion(readwrite_bottom, readwrite_end));
duke@435: 
duke@435:     // Restore mangling flag.
duke@435:     NOT_PRODUCT(ZapUnusedHeapArea = old_ZapUnusedHeapArea;)
duke@435: 
duke@435:     if (_ro_space == NULL || _rw_space == NULL)
duke@435:       vm_exit_during_initialization("Could not allocate a shared space");
duke@435: 
duke@435:     // Cover both shared spaces entirely with cards.
duke@435:     _rs->resize_covered_region(MemRegion(readonly_bottom, readwrite_end));
duke@435: 
duke@435:     if (UseSharedSpaces) {
duke@435: 
duke@435:       // Map in the regions in the shared file.
duke@435:       FileMapInfo* mapinfo = FileMapInfo::current_info();
duke@435:       size_t image_alignment = mapinfo->alignment();
duke@435:       CollectedHeap* ch = Universe::heap();
duke@435:       if ((!mapinfo->map_space(ro, ro_rs, _ro_space)) ||
duke@435:           (!mapinfo->map_space(rw, rw_rs, _rw_space)) ||
duke@435:           (!mapinfo->map_space(md, md_rs, NULL))      ||
duke@435:           (!mapinfo->map_space(mc, mc_rs, NULL))      ||
duke@435:           // check the alignment constraints
duke@435:           (ch == NULL || ch->kind() != CollectedHeap::GenCollectedHeap ||
duke@435:            image_alignment !=
duke@435:            ((GenCollectedHeap*)ch)->gen_policy()->max_alignment())) {
duke@435:         // Base addresses didn't match; skip sharing, but continue
duke@435:         shared_rs.release();
duke@435:         spec()->disable_sharing();
duke@435:         // If -Xshare:on is specified, print out the error message and exit VM,
duke@435:         // otherwise, set UseSharedSpaces to false and continue.
duke@435:         if (RequireSharedSpaces) {
duke@435:           vm_exit_during_initialization("Unable to use shared archive.", NULL);
duke@435:         } else {
duke@435:           FLAG_SET_DEFAULT(UseSharedSpaces, false);
duke@435:         }
duke@435: 
duke@435:         // Note: freeing the block offset array objects does not
duke@435:         // currently free up the underlying storage.
duke@435:         delete _ro_bts;
duke@435:         _ro_bts = NULL;
duke@435:         delete _ro_space;
duke@435:         _ro_space = NULL;
duke@435:         delete _rw_bts;
duke@435:         _rw_bts = NULL;
duke@435:         delete _rw_space;
duke@435:         _rw_space = NULL;
duke@435:         shared_end = (HeapWord*)(rs.base() + rs.size());
duke@435:         _rs->resize_covered_region(MemRegion(shared_bottom, shared_bottom));
duke@435:       }
duke@435:     }
duke@435: 
duke@435:     // Reserved region includes shared spaces for oop.is_in_reserved().
duke@435:     _reserved.set_end(shared_end);
duke@435: 
duke@435:   } else {
duke@435:     _ro_space = NULL;
duke@435:     _rw_space = NULL;
duke@435:   }
duke@435: }
duke@435: 
duke@435: 
duke@435: // Do a complete scan of the shared read write space to catch all
duke@435: // objects which contain references to any younger generation.  Forward
duke@435: // the pointers.  Avoid space_iterate, as actually visiting all the
duke@435: // objects in the space will page in more objects than we need.
duke@435: // Instead, use the system dictionary as strong roots into the read
duke@435: // write space.
dcubed@482: //
dcubed@482: // If a RedefineClasses() call has been made, then we have to iterate
dcubed@482: // over the entire shared read-write space in order to find all the
dcubed@482: // objects that need to be forwarded. For example, it is possible for
dcubed@482: // an nmethod to be found and marked in GC phase-1 only for the nmethod
dcubed@482: // to be freed by the time we reach GC phase-3. The underlying method
dcubed@482: // is still marked, but we can't (easily) find it in GC phase-3 so we
dcubed@482: // blow up in GC phase-4. With RedefineClasses() we want replaced code
dcubed@482: // (EMCP or obsolete) to go away (i.e., be collectible) once it is no
dcubed@482: // longer being executed by any thread so we keep minimal attachments
dcubed@482: // to the replaced code. However, we can't guarantee when those EMCP
dcubed@482: // or obsolete methods will be collected so they may still be out there
dcubed@482: // even after we've severed our minimal attachments.
duke@435: 
duke@435: void CompactingPermGenGen::pre_adjust_pointers() {
duke@435:   if (spec()->enable_shared_spaces()) {
dcubed@482:     if (JvmtiExport::has_redefined_a_class()) {
dcubed@482:       // RedefineClasses() requires a brute force approach
dcubed@482:       AdjustSharedObjectClosure blk;
dcubed@482:       rw_space()->object_iterate(&blk);
dcubed@482:     } else {
dcubed@482:       RecursiveAdjustSharedObjectClosure blk;
dcubed@482:       Universe::oops_do(&blk);
dcubed@482:       StringTable::oops_do(&blk);
dcubed@482:       SystemDictionary::always_strong_classes_do(&blk);
coleenp@2497:       SystemDictionary::placeholders_do(TraversePlaceholdersClosure::placeholders_do);
dcubed@482:     }
duke@435:   }
duke@435: }
duke@435: 
duke@435: 
duke@435: #ifdef ASSERT
duke@435: class VerifyMarksClearedClosure : public ObjectClosure {
duke@435: public:
duke@435:   void do_object(oop obj) {
duke@435:     assert(SharedSkipVerify || !obj->mark()->is_marked(),
duke@435:            "Shared oop still marked?");
duke@435:   }
duke@435: };
duke@435: #endif
duke@435: 
duke@435: 
duke@435: void CompactingPermGenGen::post_compact() {
duke@435: #ifdef ASSERT
duke@435:   if (!SharedSkipVerify && spec()->enable_shared_spaces()) {
duke@435:     VerifyMarksClearedClosure blk;
duke@435:     rw_space()->object_iterate(&blk);
duke@435:   }
duke@435: #endif
duke@435: }
duke@435: 
duke@435: 
ysr@1486: // Do not use in time-critical operations due to the possibility of paging
ysr@1486: // in otherwise untouched or previously unread portions of the perm gen,
ysr@1486: // for instance, the shared spaces. NOTE: Because CompactingPermGenGen
ysr@1486: // derives from OneContigSpaceCardGeneration which is supposed to have a
ysr@1486: // single space, and does not override its object_iterate() method,
ysr@1486: // object iteration via that interface does not look at the objects in
ysr@1486: // the shared spaces when using CDS. This should be fixed; see CR 6897798.
duke@435: void CompactingPermGenGen::space_iterate(SpaceClosure* blk, bool usedOnly) {
duke@435:   OneContigSpaceCardGeneration::space_iterate(blk, usedOnly);
duke@435:   if (spec()->enable_shared_spaces()) {
duke@435:     // Making the rw_space walkable will page in the entire space, and
ysr@1486:     // is to be avoided in the case of time-critical operations.
ysr@1486:     // However, this is required for Verify and heap dump operations.
duke@435:     blk->do_space(ro_space());
duke@435:     blk->do_space(rw_space());
duke@435:   }
duke@435: }
duke@435: 
duke@435: 
duke@435: void CompactingPermGenGen::print_on(outputStream* st) const {
duke@435:   OneContigSpaceCardGeneration::print_on(st);
duke@435:   if (spec()->enable_shared_spaces()) {
duke@435:     st->print("    ro");
duke@435:     ro_space()->print_on(st);
duke@435:     st->print("    rw");
duke@435:     rw_space()->print_on(st);
duke@435:   } else {
duke@435:     st->print_cr("No shared spaces configured.");
duke@435:   }
duke@435: }
duke@435: 
duke@435: 
duke@435: // References from the perm gen to the younger generation objects may
duke@435: // occur in static fields in Java classes or in constant pool references
duke@435: // to String objects.
duke@435: 
duke@435: void CompactingPermGenGen::younger_refs_iterate(OopsInGenClosure* blk) {
duke@435:   OneContigSpaceCardGeneration::younger_refs_iterate(blk);
duke@435:   if (spec()->enable_shared_spaces()) {
duke@435:     blk->set_generation(this);
duke@435:     // ro_space has no younger gen refs.
duke@435:     _rs->younger_refs_in_space_iterate(rw_space(), blk);
duke@435:     blk->reset_generation();
duke@435:   }
duke@435: }
duke@435: 
duke@435: 
duke@435: // Shared spaces are addressed in pre_adjust_pointers.
duke@435: void CompactingPermGenGen::adjust_pointers() {
duke@435:   the_space()->adjust_pointers();
duke@435: }
duke@435: 
duke@435: 
duke@435: void CompactingPermGenGen::compact() {
duke@435:   the_space()->compact();
duke@435: }
duke@435: 
duke@435: 
duke@435: size_t CompactingPermGenGen::contiguous_available() const {
duke@435:   // Don't include shared spaces.
duke@435:   return OneContigSpaceCardGeneration::contiguous_available()
duke@435:          - _shared_space_size;
duke@435: }
duke@435: 
duke@435: size_t CompactingPermGenGen::max_capacity() const {
duke@435:   // Don't include shared spaces.
duke@435:   assert(UseSharedSpaces || (_shared_space_size == 0),
duke@435:     "If not used, the size of shared spaces should be 0");
duke@435:   return OneContigSpaceCardGeneration::max_capacity()
duke@435:           - _shared_space_size;
duke@435: }
duke@435: 
duke@435: 
duke@435: // No young generation references, clear this generation's main space's
duke@435: // card table entries.  Do NOT clear the card table entries for the
duke@435: // read-only space (always clear) or the read-write space (valuable
duke@435: // information).
duke@435: 
duke@435: void CompactingPermGenGen::clear_remembered_set() {
duke@435:   _rs->clear(MemRegion(the_space()->bottom(), the_space()->end()));
duke@435: }
duke@435: 
duke@435: 
duke@435: // Objects in this generation's main space may have moved, invalidate
duke@435: // that space's cards.  Do NOT invalidate the card table entries for the
duke@435: // read-only or read-write spaces, as those objects never move.
duke@435: 
duke@435: void CompactingPermGenGen::invalidate_remembered_set() {
duke@435:   _rs->invalidate(used_region());
duke@435: }
duke@435: 
duke@435: 
duke@435: void CompactingPermGenGen::verify(bool allow_dirty) {
duke@435:   the_space()->verify(allow_dirty);
duke@435:   if (!SharedSkipVerify && spec()->enable_shared_spaces()) {
duke@435:     ro_space()->verify(allow_dirty);
duke@435:     rw_space()->verify(allow_dirty);
duke@435:   }
duke@435: }
duke@435: 
duke@435: 
duke@435: HeapWord* CompactingPermGenGen::unshared_bottom;
duke@435: HeapWord* CompactingPermGenGen::unshared_end;
duke@435: HeapWord* CompactingPermGenGen::shared_bottom;
duke@435: HeapWord* CompactingPermGenGen::shared_end;
duke@435: HeapWord* CompactingPermGenGen::readonly_bottom;
duke@435: HeapWord* CompactingPermGenGen::readonly_end;
duke@435: HeapWord* CompactingPermGenGen::readwrite_bottom;
duke@435: HeapWord* CompactingPermGenGen::readwrite_end;
duke@435: HeapWord* CompactingPermGenGen::miscdata_bottom;
duke@435: HeapWord* CompactingPermGenGen::miscdata_end;
duke@435: HeapWord* CompactingPermGenGen::misccode_bottom;
duke@435: HeapWord* CompactingPermGenGen::misccode_end;
duke@435: 
duke@435: // JVM/TI RedefineClasses() support:
duke@435: bool CompactingPermGenGen::remap_shared_readonly_as_readwrite() {
duke@435:   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
duke@435: 
duke@435:   if (UseSharedSpaces) {
duke@435:     // remap the shared readonly space to shared readwrite, private
duke@435:     FileMapInfo* mapinfo = FileMapInfo::current_info();
duke@435:     if (!mapinfo->remap_shared_readonly_as_readwrite()) {
duke@435:       return false;
duke@435:     }
duke@435:   }
duke@435:   return true;
duke@435: }