1 /* 2 * Copyright (c) 2018, 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 #ifndef SHARE_RUNTIME_JNIHANDLES_INLINE_HPP 26 #define SHARE_RUNTIME_JNIHANDLES_INLINE_HPP 27 28 #include "oops/oop.hpp" 29 #include "runtime/jniHandles.hpp" 30 #include "utilities/debug.hpp" 31 #include "utilities/globalDefinitions.hpp" 32 33 inline bool JNIHandles::is_jweak(jobject handle) { 34 STATIC_ASSERT(weak_tag_size == 1); 35 STATIC_ASSERT(weak_tag_value == 1); 36 return (reinterpret_cast<uintptr_t>(handle) & weak_tag_mask) != 0; 37 } 38 39 inline oop& JNIHandles::jobject_ref(jobject handle) { 40 assert(!is_jweak(handle), "precondition"); 41 return *reinterpret_cast<oop*>(handle); 42 } 43 44 inline oop& JNIHandles::jweak_ref(jobject handle) { 45 assert(is_jweak(handle), "precondition"); 46 char* ptr = reinterpret_cast<char*>(handle) - weak_tag_value; 47 return *reinterpret_cast<oop*>(ptr); 48 } 49 50 // external_guard is true if called from resolve_external_guard. 51 template<bool external_guard> 52 inline oop JNIHandles::resolve_impl(jobject handle) { 53 assert(handle != NULL, "precondition"); 54 assert(!current_thread_in_native(), "must not be in native"); 55 oop result; 56 if (is_jweak(handle)) { // Unlikely 57 result = resolve_jweak(handle); 58 } else { 59 result = jobject_ref(handle); 60 // Construction of jobjects canonicalize a null value into a null 61 // jobject, so for non-jweak the pointee should never be null. 62 assert(external_guard || result != NULL, "Invalid JNI handle"); 63 } 64 return result; 65 } 66 67 inline oop JNIHandles::resolve(jobject handle) { 68 oop result = NULL; 69 if (handle != NULL) { 70 result = resolve_impl<false /* external_guard */ >(handle); 71 } 72 return result; 73 } 74 75 inline oop JNIHandles::resolve_non_null(jobject handle) { 76 assert(handle != NULL, "JNI handle should not be null"); 77 oop result = resolve_impl<false /* external_guard */ >(handle); 78 assert(result != NULL, "NULL read from jni handle"); 79 return result; 80 } 81 82 inline void JNIHandles::destroy_local(jobject handle) { 83 if (handle != NULL) { 84 assert(!is_jweak(handle), "Invalid JNI local handle"); 85 jobject_ref(handle) = NULL; 86 } 87 } 88 89 #endif // SHARE_RUNTIME_JNIHANDLES_INLINE_HPP 90