coleenp@4490: /*
coleenp@4490:  * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
coleenp@4490:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
coleenp@4490:  *
coleenp@4490:  * This code is free software; you can redistribute it and/or modify it
coleenp@4490:  * under the terms of the GNU General Public License version 2 only, as
coleenp@4490:  * published by the Free Software Foundation.
coleenp@4490:  *
coleenp@4490:  * This code is distributed in the hope that it will be useful, but WITHOUT
coleenp@4490:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
coleenp@4490:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
coleenp@4490:  * version 2 for more details (a copy is included in the LICENSE file that
coleenp@4490:  * accompanied this code).
coleenp@4490:  *
coleenp@4490:  * You should have received a copy of the GNU General Public License version
coleenp@4490:  * 2 along with this work; if not, write to the Free Software Foundation,
coleenp@4490:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
coleenp@4490:  *
coleenp@4490:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
coleenp@4490:  * or visit www.oracle.com if you need additional information or have any
coleenp@4490:  * questions.
coleenp@4490:  *
coleenp@4490:  */
coleenp@4490: 
coleenp@4490: #include "precompiled.hpp"
coleenp@4490: #include "classfile/metadataOnStackMark.hpp"
coleenp@4490: #include "code/codeCache.hpp"
coleenp@4490: #include "compiler/compileBroker.hpp"
coleenp@4490: #include "oops/metadata.hpp"
coleenp@6063: #include "prims/jvmtiImpl.hpp"
coleenp@4490: #include "runtime/synchronizer.hpp"
coleenp@4490: #include "runtime/thread.hpp"
sla@6122: #include "services/threadService.hpp"
stefank@7333: #include "utilities/chunkedList.hpp"
coleenp@4490: 
stefank@7333: volatile MetadataOnStackBuffer* MetadataOnStackMark::_used_buffers = NULL;
stefank@7333: volatile MetadataOnStackBuffer* MetadataOnStackMark::_free_buffers = NULL;
coleenp@4490: 
coleenp@4490: NOT_PRODUCT(bool MetadataOnStackMark::_is_active = false;)
coleenp@4490: 
coleenp@4490: // Walk metadata on the stack and mark it so that redefinition doesn't delete
coleenp@4490: // it.  Class unloading also walks the previous versions and might try to
coleenp@4490: // delete it, so this class is used by class unloading also.
stefank@7333: MetadataOnStackMark::MetadataOnStackMark(bool visit_code_cache) {
coleenp@4490:   assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
stefank@7333:   assert(_used_buffers == NULL, "sanity check");
coleenp@4490:   NOT_PRODUCT(_is_active = true;)
stefank@6992: 
coleenp@4490:   Threads::metadata_do(Metadata::mark_on_stack);
stefank@7333:   if (visit_code_cache) {
stefank@6992:     CodeCache::alive_nmethods_do(nmethod::mark_on_stack);
stefank@6992:   }
coleenp@4490:   CompileBroker::mark_on_stack();
coleenp@6063:   JvmtiCurrentBreakpoints::metadata_do(Metadata::mark_on_stack);
sla@6122:   ThreadService::metadata_do(Metadata::mark_on_stack);
coleenp@4490: }
coleenp@4490: 
coleenp@4490: MetadataOnStackMark::~MetadataOnStackMark() {
coleenp@4490:   assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
coleenp@4490:   // Unmark everything that was marked.   Can't do the same walk because
coleenp@4490:   // redefine classes messes up the code cache so the set of methods
coleenp@4490:   // might not be the same.
stefank@7333: 
stefank@7333:   retire_buffer_for_thread(Thread::current());
stefank@7333: 
stefank@7333:   MetadataOnStackBuffer* buffer = const_cast<MetadataOnStackBuffer* >(_used_buffers);
stefank@7333:   while (buffer != NULL) {
stefank@7333:     // Clear on stack state for all metadata.
stefank@7333:     size_t size = buffer->size();
stefank@7333:     for (size_t i  = 0; i < size; i++) {
stefank@7333:       Metadata* md = buffer->at(i);
stefank@7333:       md->set_on_stack(false);
stefank@7333:     }
stefank@7333: 
stefank@7333:     MetadataOnStackBuffer* next = buffer->next_used();
stefank@7333: 
stefank@7333:     // Move the buffer to the free list.
stefank@7333:     buffer->clear();
stefank@7333:     buffer->set_next_used(NULL);
stefank@7333:     buffer->set_next_free(const_cast<MetadataOnStackBuffer*>(_free_buffers));
stefank@7333:     _free_buffers = buffer;
stefank@7333: 
stefank@7333:     // Step to next used buffer.
stefank@7333:     buffer = next;
coleenp@4490:   }
stefank@7333: 
stefank@7333:   _used_buffers = NULL;
stefank@7333: 
coleenp@4490:   NOT_PRODUCT(_is_active = false;)
coleenp@4490: }
coleenp@4490: 
stefank@7333: void MetadataOnStackMark::retire_buffer(MetadataOnStackBuffer* buffer) {
stefank@7333:   if (buffer == NULL) {
stefank@7333:     return;
stefank@7333:   }
stefank@7333: 
stefank@7333:   MetadataOnStackBuffer* old_head;
stefank@7333: 
stefank@7333:   do {
stefank@7333:     old_head = const_cast<MetadataOnStackBuffer*>(_used_buffers);
stefank@7333:     buffer->set_next_used(old_head);
stefank@7333:   } while (Atomic::cmpxchg_ptr(buffer, &_used_buffers, old_head) != old_head);
stefank@7333: }
stefank@7333: 
stefank@7333: void MetadataOnStackMark::retire_buffer_for_thread(Thread* thread) {
stefank@7333:   retire_buffer(thread->metadata_on_stack_buffer());
stefank@7333:   thread->set_metadata_on_stack_buffer(NULL);
stefank@7333: }
stefank@7333: 
stefank@7333: bool MetadataOnStackMark::has_buffer_for_thread(Thread* thread) {
stefank@7333:   return thread->metadata_on_stack_buffer() != NULL;
stefank@7333: }
stefank@7333: 
stefank@7333: MetadataOnStackBuffer* MetadataOnStackMark::allocate_buffer() {
stefank@7333:   MetadataOnStackBuffer* allocated;
stefank@7333:   MetadataOnStackBuffer* new_head;
stefank@7333: 
stefank@7333:   do {
stefank@7333:     allocated = const_cast<MetadataOnStackBuffer*>(_free_buffers);
stefank@7333:     if (allocated == NULL) {
stefank@7333:       break;
stefank@7333:     }
stefank@7333:     new_head = allocated->next_free();
stefank@7333:   } while (Atomic::cmpxchg_ptr(new_head, &_free_buffers, allocated) != allocated);
stefank@7333: 
stefank@7333:   if (allocated == NULL) {
stefank@7333:     allocated = new MetadataOnStackBuffer();
stefank@7333:   }
stefank@7333: 
stefank@7333:   assert(!allocated->is_full(), err_msg("Should not be full: " PTR_FORMAT, p2i(allocated)));
stefank@7333: 
stefank@7333:   return allocated;
stefank@7333: }
stefank@7333: 
coleenp@4490: // Record which objects are marked so we can unmark the same objects.
stefank@7333: void MetadataOnStackMark::record(Metadata* m, Thread* thread) {
coleenp@4490:   assert(_is_active, "metadata on stack marking is active");
stefank@7333: 
stefank@7333:   MetadataOnStackBuffer* buffer =  thread->metadata_on_stack_buffer();
stefank@7333: 
stefank@7333:   if (buffer != NULL && buffer->is_full()) {
stefank@7333:     retire_buffer(buffer);
stefank@7333:     buffer = NULL;
stefank@7333:   }
stefank@7333: 
stefank@7333:   if (buffer == NULL) {
stefank@7333:     buffer = allocate_buffer();
stefank@7333:     thread->set_metadata_on_stack_buffer(buffer);
stefank@7333:   }
stefank@7333: 
stefank@7333:   buffer->push(m);
coleenp@4490: }