jdk8-mips64-public/hotspot: src/share/vm/runtime/jniHandles.cpp@38e8278318ca (annotated)

src/share/vm/runtime/jniHandles.cpp@38e8278318ca (annotated)

src/share/vm/runtime/jniHandles.cpp

Mon, 21 Jun 2010 14:26:17 -0700

author: never
date: Mon, 21 Jun 2010 14:26:17 -0700
changeset 1971: 38e8278318ca
parent 1907: c18cbe5936b8
child 2314: f95d63e2154a
permissions: -rw-r--r--

6656830: assert((*p)->is_oop(),"expected an oop while scanning weak refs")
Reviewed-by: dcubed, kvn, twisti

 /*
  * Copyright (c) 1998, 2008, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * 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
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 # include "incls/_precompiled.incl"
 # include "incls/_jniHandles.cpp.incl"
 JNIHandleBlock* JNIHandles::_global_handles       = NULL;
 JNIHandleBlock* JNIHandles::_weak_global_handles  = NULL;
 oop             JNIHandles::_deleted_handle       = NULL;
 jobject JNIHandles::make_local(oop obj) {
   if (obj == NULL) {
     return NULL;                // ignore null handles
   } else {
     Thread* thread = Thread::current();
     assert(Universe::heap()->is_in_reserved(obj), "sanity check");
     return thread->active_handles()->allocate_handle(obj);
   }
 }
 // optimized versions
 jobject JNIHandles::make_local(Thread* thread, oop obj) {
   if (obj == NULL) {
     return NULL;                // ignore null handles
   } else {
     assert(Universe::heap()->is_in_reserved(obj), "sanity check");
     return thread->active_handles()->allocate_handle(obj);
   }
 }
 jobject JNIHandles::make_local(JNIEnv* env, oop obj) {
   if (obj == NULL) {
     return NULL;                // ignore null handles
   } else {
     JavaThread* thread = JavaThread::thread_from_jni_environment(env);
     assert(Universe::heap()->is_in_reserved(obj), "sanity check");
     return thread->active_handles()->allocate_handle(obj);
   }
 }
 jobject JNIHandles::make_global(Handle obj) {
   assert(!Universe::heap()->is_gc_active(), "can't extend the root set during GC");
   jobject res = NULL;
   if (!obj.is_null()) {
     // ignore null handles
     MutexLocker ml(JNIGlobalHandle_lock);
     assert(Universe::heap()->is_in_reserved(obj()), "sanity check");
     res = _global_handles->allocate_handle(obj());
   } else {
     CHECK_UNHANDLED_OOPS_ONLY(Thread::current()->clear_unhandled_oops());
   }
   return res;
 }
 jobject JNIHandles::make_weak_global(Handle obj) {
   assert(!Universe::heap()->is_gc_active(), "can't extend the root set during GC");
   jobject res = NULL;
   if (!obj.is_null()) {
     // ignore null handles
     MutexLocker ml(JNIGlobalHandle_lock);
     assert(Universe::heap()->is_in_reserved(obj()), "sanity check");
     res = _weak_global_handles->allocate_handle(obj());
   } else {
     CHECK_UNHANDLED_OOPS_ONLY(Thread::current()->clear_unhandled_oops());
   }
   return res;
 }
 jmethodID JNIHandles::make_jmethod_id(methodHandle mh) {
   return (jmethodID) make_weak_global(mh);
 }
 void JNIHandles::change_method_associated_with_jmethod_id(jmethodID jmid, methodHandle mh) {
   MutexLocker ml(JNIGlobalHandle_lock); // Is this necessary?
   Handle obj = (Handle)mh;
   oop* jobj = (oop*)jmid;
   *jobj = obj();
 }
 void JNIHandles::destroy_global(jobject handle) {
   if (handle != NULL) {
     assert(is_global_handle(handle), "Invalid delete of global JNI handle");
     *((oop*)handle) = deleted_handle(); // Mark the handle as deleted, allocate will reuse it
   }
 }
 void JNIHandles::destroy_weak_global(jobject handle) {
   if (handle != NULL) {
     assert(!CheckJNICalls || is_weak_global_handle(handle), "Invalid delete of weak global JNI handle");
     *((oop*)handle) = deleted_handle(); // Mark the handle as deleted, allocate will reuse it
   }
 }
 void JNIHandles::destroy_jmethod_id(jmethodID mid) {
   destroy_weak_global((jobject)mid);
 }
 void JNIHandles::oops_do(OopClosure* f) {
   f->do_oop(&_deleted_handle);
   _global_handles->oops_do(f);
 }
 void JNIHandles::weak_oops_do(BoolObjectClosure* is_alive, OopClosure* f) {
   _weak_global_handles->weak_oops_do(is_alive, f);
 }
 void JNIHandles::initialize() {
   _global_handles      = JNIHandleBlock::allocate_block();
   _weak_global_handles = JNIHandleBlock::allocate_block();
   EXCEPTION_MARK;
   // We will never reach the CATCH below since Exceptions::_throw will cause
   // the VM to exit if an exception is thrown during initialization
   klassOop k      = SystemDictionary::Object_klass();
   _deleted_handle = instanceKlass::cast(k)->allocate_permanent_instance(CATCH);
 }
 bool JNIHandles::is_local_handle(Thread* thread, jobject handle) {
   JNIHandleBlock* block = thread->active_handles();
   // Look back past possible native calls to jni_PushLocalFrame.
   while (block != NULL) {
     if (block->chain_contains(handle)) {
       return true;
     }
     block = block->pop_frame_link();
   }
   return false;
 }
 // Determine if the handle is somewhere in the current thread's stack.
 // We easily can't isolate any particular stack frame the handle might
 // come from, so we'll check the whole stack.
 bool JNIHandles::is_frame_handle(JavaThread* thr, jobject obj) {
   // If there is no java frame, then this must be top level code, such
   // as the java command executable, in which case, this type of handle
   // is not permitted.
   return (thr->has_last_Java_frame() &&
          (void*)obj < (void*)thr->stack_base() &&
          (void*)obj >= (void*)thr->last_Java_sp());
 }
 bool JNIHandles::is_global_handle(jobject handle) {
   return _global_handles->chain_contains(handle);
 }
 bool JNIHandles::is_weak_global_handle(jobject handle) {
   return _weak_global_handles->chain_contains(handle);
 }
 long JNIHandles::global_handle_memory_usage() {
   return _global_handles->memory_usage();
 }
 long JNIHandles::weak_global_handle_memory_usage() {
   return _weak_global_handles->memory_usage();
 }
 class AlwaysAliveClosure: public BoolObjectClosure {
 public:
   bool do_object_b(oop obj) { return true; }
   void do_object(oop obj) { assert(false, "Don't call"); }
 };
 class CountHandleClosure: public OopClosure {
 private:
   int _count;
 public:
   CountHandleClosure(): _count(0) {}
   virtual void do_oop(oop* unused) {
     _count++;
   }
   virtual void do_oop(narrowOop* unused) { ShouldNotReachHere(); }
   int count() { return _count; }
 };
 // We assume this is called at a safepoint: no lock is needed.
 void JNIHandles::print_on(outputStream* st) {
   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
   assert(_global_handles != NULL && _weak_global_handles != NULL,
          "JNIHandles not initialized");
   CountHandleClosure global_handle_count;
   AlwaysAliveClosure always_alive;
   oops_do(&global_handle_count);
   weak_oops_do(&always_alive, &global_handle_count);
   st->print_cr("JNI global references: %d", global_handle_count.count());
   st->cr();
   st->flush();
 }
 class VerifyHandleClosure: public OopClosure {
 public:
   virtual void do_oop(oop* root) {
     (*root)->verify();
   }
   virtual void do_oop(narrowOop* root) { ShouldNotReachHere(); }
 };
 void JNIHandles::verify() {
   VerifyHandleClosure verify_handle;
   AlwaysAliveClosure always_alive;
   oops_do(&verify_handle);
   weak_oops_do(&always_alive, &verify_handle);
 }
 void jni_handles_init() {
   JNIHandles::initialize();
 }
 int             JNIHandleBlock::_blocks_allocated     = 0;
 JNIHandleBlock* JNIHandleBlock::_block_free_list      = NULL;
 #ifndef PRODUCT
 JNIHandleBlock* JNIHandleBlock::_block_list           = NULL;
 #endif
 void JNIHandleBlock::zap() {
   // Zap block values
   _top  = 0;
   for (int index = 0; index < block_size_in_oops; index++) {
     _handles[index] = badJNIHandle;
   }
 }
 JNIHandleBlock* JNIHandleBlock::allocate_block(Thread* thread)  {
   assert(thread == NULL || thread == Thread::current(), "sanity check");
   JNIHandleBlock* block;
   // Check the thread-local free list for a block so we don't
   // have to acquire a mutex.
   if (thread != NULL && thread->free_handle_block() != NULL) {
     block = thread->free_handle_block();
     thread->set_free_handle_block(block->_next);
   }
   else {
     // locking with safepoint checking introduces a potential deadlock:
     // - we would hold JNIHandleBlockFreeList_lock and then Threads_lock
     // - another would hold Threads_lock (jni_AttachCurrentThread) and then
     //   JNIHandleBlockFreeList_lock (JNIHandleBlock::allocate_block)
     MutexLockerEx ml(JNIHandleBlockFreeList_lock,
                      Mutex::_no_safepoint_check_flag);
     if (_block_free_list == NULL) {
       // Allocate new block
       block = new JNIHandleBlock();
       _blocks_allocated++;
       if (TraceJNIHandleAllocation) {
         tty->print_cr("JNIHandleBlock " INTPTR_FORMAT " allocated (%d total blocks)",
                       block, _blocks_allocated);
       }
       if (ZapJNIHandleArea) block->zap();
       #ifndef PRODUCT
       // Link new block to list of all allocated blocks
       block->_block_list_link = _block_list;
       _block_list = block;
       #endif
     } else {
       // Get block from free list
       block = _block_free_list;
       _block_free_list = _block_free_list->_next;
     }
   }
   block->_top  = 0;
   block->_next = NULL;
   block->_pop_frame_link = NULL;
   // _last, _free_list & _allocate_before_rebuild initialized in allocate_handle
   debug_only(block->_last = NULL);
   debug_only(block->_free_list = NULL);
   debug_only(block->_allocate_before_rebuild = -1);
   return block;
 }
 void JNIHandleBlock::release_block(JNIHandleBlock* block, Thread* thread) {
   assert(thread == NULL || thread == Thread::current(), "sanity check");
   JNIHandleBlock* pop_frame_link = block->pop_frame_link();
   // Put returned block at the beginning of the thread-local free list.
   // Note that if thread == NULL, we use it as an implicit argument that
   // we _don't_ want the block to be kept on the free_handle_block.
   // See for instance JavaThread::exit().
   if (thread != NULL ) {
     if (ZapJNIHandleArea) block->zap();
     JNIHandleBlock* freelist = thread->free_handle_block();
     block->_pop_frame_link = NULL;
     thread->set_free_handle_block(block);
     // Add original freelist to end of chain
     if ( freelist != NULL ) {
       while ( block->_next != NULL ) block = block->_next;
       block->_next = freelist;
     }
     block = NULL;
   }
   if (block != NULL) {
     // Return blocks to free list
     // locking with safepoint checking introduces a potential deadlock:
     // - we would hold JNIHandleBlockFreeList_lock and then Threads_lock
     // - another would hold Threads_lock (jni_AttachCurrentThread) and then
     //   JNIHandleBlockFreeList_lock (JNIHandleBlock::allocate_block)
     MutexLockerEx ml(JNIHandleBlockFreeList_lock,
                      Mutex::_no_safepoint_check_flag);
     while (block != NULL) {
       if (ZapJNIHandleArea) block->zap();
       JNIHandleBlock* next = block->_next;
       block->_next = _block_free_list;
       _block_free_list = block;
       block = next;
     }
   }
   if (pop_frame_link != NULL) {
     // As a sanity check we release blocks pointed to by the pop_frame_link.
     // This should never happen (only if PopLocalFrame is not called the
     // correct number of times).
     release_block(pop_frame_link, thread);
   }
 }
 void JNIHandleBlock::oops_do(OopClosure* f) {
   JNIHandleBlock* current_chain = this;
   // Iterate over chain of blocks, followed by chains linked through the
   // pop frame links.
   while (current_chain != NULL) {
     for (JNIHandleBlock* current = current_chain; current != NULL;
          current = current->_next) {
       assert(current == current_chain || current->pop_frame_link() == NULL,
         "only blocks first in chain should have pop frame link set");
       for (int index = 0; index < current->_top; index++) {
         oop* root = &(current->_handles)[index];
         oop value = *root;
         // traverse heap pointers only, not deleted handles or free list
         // pointers
         if (value != NULL && Universe::heap()->is_in_reserved(value)) {
           f->do_oop(root);
         }
       }
       // the next handle block is valid only if current block is full
       if (current->_top < block_size_in_oops) {
         break;
       }
     }
     current_chain = current_chain->pop_frame_link();
   }
 }
 void JNIHandleBlock::weak_oops_do(BoolObjectClosure* is_alive,
                                   OopClosure* f) {
   for (JNIHandleBlock* current = this; current != NULL; current = current->_next) {
     assert(current->pop_frame_link() == NULL,
       "blocks holding weak global JNI handles should not have pop frame link set");
     for (int index = 0; index < current->_top; index++) {
       oop* root = &(current->_handles)[index];
       oop value = *root;
       // traverse heap pointers only, not deleted handles or free list pointers
       if (value != NULL && Universe::heap()->is_in_reserved(value)) {
         if (is_alive->do_object_b(value)) {
           // The weakly referenced object is alive, update pointer
           f->do_oop(root);
         } else {
           // The weakly referenced object is not alive, clear the reference by storing NULL
           if (TraceReferenceGC) {
             tty->print_cr("Clearing JNI weak reference (" INTPTR_FORMAT ")", root);
           }
           *root = NULL;
         }
       }
     }
     // the next handle block is valid only if current block is full
     if (current->_top < block_size_in_oops) {
       break;
     }
   }
 }
 jobject JNIHandleBlock::allocate_handle(oop obj) {
   assert(Universe::heap()->is_in_reserved(obj), "sanity check");
   if (_top == 0) {
     // This is the first allocation or the initial block got zapped when
     // entering a native function. If we have any following blocks they are
     // not valid anymore.
     for (JNIHandleBlock* current = _next; current != NULL;
          current = current->_next) {
       assert(current->_last == NULL, "only first block should have _last set");
       assert(current->_free_list == NULL,
              "only first block should have _free_list set");
       current->_top = 0;
       if (ZapJNIHandleArea) current->zap();
     }
     // Clear initial block
     _free_list = NULL;
     _allocate_before_rebuild = 0;
     _last = this;
     if (ZapJNIHandleArea) zap();
   }
   // Try last block
   if (_last->_top < block_size_in_oops) {
     oop* handle = &(_last->_handles)[_last->_top++];
     *handle = obj;
     return (jobject) handle;
   }
   // Try free list
   if (_free_list != NULL) {
     oop* handle = _free_list;
     _free_list = (oop*) *_free_list;
     *handle = obj;
     return (jobject) handle;
   }
   // Check if unused block follow last
   if (_last->_next != NULL) {
     // update last and retry
     _last = _last->_next;
     return allocate_handle(obj);
   }
   // No space available, we have to rebuild free list or expand
   if (_allocate_before_rebuild == 0) {
       rebuild_free_list();        // updates _allocate_before_rebuild counter
   } else {
     // Append new block
     Thread* thread = Thread::current();
     Handle obj_handle(thread, obj);
     // This can block, so we need to preserve obj accross call.
     _last->_next = JNIHandleBlock::allocate_block(thread);
     _last = _last->_next;
     _allocate_before_rebuild--;
     obj = obj_handle();
   }
   return allocate_handle(obj);  // retry
 }
 void JNIHandleBlock::rebuild_free_list() {
   assert(_allocate_before_rebuild == 0 && _free_list == NULL, "just checking");
   int free = 0;
   int blocks = 0;
   for (JNIHandleBlock* current = this; current != NULL; current = current->_next) {
     for (int index = 0; index < current->_top; index++) {
       oop* handle = &(current->_handles)[index];
       if (*handle ==  JNIHandles::deleted_handle()) {
         // this handle was cleared out by a delete call, reuse it
         *handle = (oop) _free_list;
         _free_list = handle;
         free++;
       }
     }
     // we should not rebuild free list if there are unused handles at the end
     assert(current->_top == block_size_in_oops, "just checking");
     blocks++;
   }
   // Heuristic: if more than half of the handles are free we rebuild next time
   // as well, otherwise we append a corresponding number of new blocks before
   // attempting a free list rebuild again.
   int total = blocks * block_size_in_oops;
   int extra = total - 2*free;
   if (extra > 0) {
     // Not as many free handles as we would like - compute number of new blocks to append
     _allocate_before_rebuild = (extra + block_size_in_oops - 1) / block_size_in_oops;
   }
   if (TraceJNIHandleAllocation) {
     tty->print_cr("Rebuild free list JNIHandleBlock " INTPTR_FORMAT " blocks=%d used=%d free=%d add=%d",
       this, blocks, total-free, free, _allocate_before_rebuild);
   }
 }
 bool JNIHandleBlock::contains(jobject handle) const {
   return ((jobject)&_handles[0] <= handle && handle<(jobject)&_handles[_top]);
 }
 bool JNIHandleBlock::chain_contains(jobject handle) const {
   for (JNIHandleBlock* current = (JNIHandleBlock*) this; current != NULL; current = current->_next) {
     if (current->contains(handle)) {
       return true;
     }
   }
   return false;
 }
 int JNIHandleBlock::length() const {
   int result = 1;
   for (JNIHandleBlock* current = _next; current != NULL; current = current->_next) {
     result++;
   }
   return result;
 }
 // This method is not thread-safe, i.e., must be called whule holding a lock on the
 // structure.
 long JNIHandleBlock::memory_usage() const {
   return length() * sizeof(JNIHandleBlock);
 }
 #ifndef PRODUCT
 bool JNIHandleBlock::any_contains(jobject handle) {
   for (JNIHandleBlock* current = _block_list; current != NULL; current = current->_block_list_link) {
     if (current->contains(handle)) {
       return true;
     }
   }
   return false;
 }
 void JNIHandleBlock::print_statistics() {
   int used_blocks = 0;
   int free_blocks = 0;
   int used_handles = 0;
   int free_handles = 0;
   JNIHandleBlock* block = _block_list;
   while (block != NULL) {
     if (block->_top > 0) {
       used_blocks++;
     } else {
       free_blocks++;
     }
     used_handles += block->_top;
     free_handles += (block_size_in_oops - block->_top);
     block = block->_block_list_link;
   }
   tty->print_cr("JNIHandleBlocks statistics");
   tty->print_cr("- blocks allocated: %d", used_blocks + free_blocks);
   tty->print_cr("- blocks in use:    %d", used_blocks);
   tty->print_cr("- blocks free:      %d", free_blocks);
   tty->print_cr("- handles in use:   %d", used_handles);
   tty->print_cr("- handles free:     %d", free_handles);
 }
 #endif

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/runtime/jniHandles.cpp@38e8278318ca (annotated)

src/share/vm/runtime/jniHandles.cpp