jdk8-mips64-public/hotspot: comparison src/share/vm/runtime/jniHandles.cpp

--1:000000000000
+:f90c822e73f8
+/*
+* 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

Mercurial > jdk8-mips64-public > hotspot / file comparison

comparison: src/share/vm/runtime/jniHandles.cpp

src/share/vm/runtime/jniHandles.cpp