diff -r 000000000000 -r f90c822e73f8 src/share/vm/runtime/jniHandles.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/vm/runtime/jniHandles.cpp	Wed Apr 27 01:25:04 2016 +0800
@@ -0,0 +1,574 @@
+/*
+ * Copyright (c) 1998, 2014, 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 "precompiled.hpp"
+#include "classfile/systemDictionary.hpp"
+#include "oops/oop.inline.hpp"
+#include "prims/jvmtiExport.hpp"
+#include "runtime/jniHandles.hpp"
+#include "runtime/mutexLocker.hpp"
+#include "runtime/thread.inline.hpp"
+
+PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
+
+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;
+}
+
+
+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::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
+  Klass* k      = SystemDictionary::Object_klass();
+  _deleted_handle = InstanceKlass::cast(k)->allocate_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; }
+};
+
+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;
+    }
+  }
+
+  /*
+   * JVMTI data structures may also contain weak oops.  The iteration of them
+   * is placed here so that we don't need to add it to each of the collectors.
+   */
+  JvmtiExport::weak_oops_do(is_alive, f);
+}
+
+
+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