1 /*
   2  * Copyright (c) 2017, 2019, 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 #include "precompiled.hpp"
  26 #include "memory/metaspaceClosure.hpp"
  27 
  28 // Update the reference to point to new_loc.
  29 void MetaspaceClosure::Ref::update(address new_loc) const {
  30   log_trace(cds)("Ref: [" PTR_FORMAT "] -> " PTR_FORMAT " => " PTR_FORMAT,
  31                  p2i(mpp()), p2i(obj()), p2i(new_loc));
  32   uintx p = (uintx)new_loc;
  33   p |= flag_bits(); // Make sure the flag bits are copied to the new pointer.
  34   *(address*)mpp() = (address)p;
  35 }
  36 
  37 void MetaspaceClosure::push_impl(MetaspaceClosure::Ref* ref) {
  38   if (_nest_level < MAX_NEST_LEVEL) {
  39     do_push(ref);
  40     delete ref;
  41   } else {
  42     ref->set_next(_pending_refs);
  43     _pending_refs = ref;
  44   }
  45 }
  46 
  47 void MetaspaceClosure::do_push(MetaspaceClosure::Ref* ref) {
  48   if (ref->not_null()) { // FIXME: make this configurable, so DynamicArchiveBuilder mark all pointers
  49     bool read_only;
  50     Writability w = ref->writability();
  51     switch (w) {
  52     case _writable:
  53       read_only = false;
  54       break;
  55     case _not_writable:
  56       read_only = true;
  57       break;
  58     default:
  59       assert(w == _default, "must be");
  60       read_only = ref->is_read_only_by_default();
  61     }
  62     _nest_level ++;
  63     if (do_ref(ref, read_only)) { // true means we want to iterate the embedded pointer in <ref>
  64       ref->metaspace_pointers_do(this);
  65     }
  66     _nest_level --;
  67   }
  68 }
  69 
  70 void MetaspaceClosure::finish() {
  71   assert(_nest_level == 0, "must be");
  72   while (_pending_refs != NULL) {
  73     Ref* ref = _pending_refs;
  74     _pending_refs = _pending_refs->next();
  75     do_push(ref);
  76     delete ref;
  77   }
  78 }
  79 
  80 MetaspaceClosure::~MetaspaceClosure() {
  81   assert(_pending_refs == NULL,
  82          "you must explicitly call MetaspaceClosure::finish() to process all refs!");
  83 }
  84 
  85 bool UniqueMetaspaceClosure::do_ref(MetaspaceClosure::Ref* ref, bool read_only) {
  86   bool* found = _has_been_visited.lookup(ref->obj());
  87   if (found != NULL) {
  88     assert(*found == read_only, "must be");
  89     return false; // Already visited: no need to iterate embedded pointers.
  90   } else {
  91     _has_been_visited.add(ref->obj(), read_only);
  92     if (_has_been_visited.maybe_grow(MAX_TABLE_SIZE)) {
  93       log_info(cds, hashtables)("Expanded _has_been_visited table to %d", _has_been_visited.table_size());
  94     }
  95     return do_unique_ref(ref, read_only);
  96   }
  97 }