1 /* 2 * Copyright (c) 1998, 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_VM_RUNTIME_SYNCHRONIZER_HPP 26 #define SHARE_VM_RUNTIME_SYNCHRONIZER_HPP 27 28 #include "oops/markOop.hpp" 29 #include "runtime/basicLock.hpp" 30 #include "runtime/handles.hpp" 31 #include "runtime/perfData.hpp" 32 #include "utilities/top.hpp" 33 34 35 class ObjectMonitor; 36 37 class ObjectSynchronizer : AllStatic { 38 friend class VMStructs; 39 public: 40 typedef enum { 41 owner_self, 42 owner_none, 43 owner_other 44 } LockOwnership; 45 46 typedef enum { 47 inflate_cause_vm_internal = 0, 48 inflate_cause_monitor_enter = 1, 49 inflate_cause_wait = 2, 50 inflate_cause_notify = 3, 51 inflate_cause_hash_code = 4, 52 inflate_cause_jni_enter = 5, 53 inflate_cause_jni_exit = 6, 54 inflate_cause_nof = 7 // Number of causes 55 } InflateCause; 56 57 // exit must be implemented non-blocking, since the compiler cannot easily handle 58 // deoptimization at monitor exit. Hence, it does not take a Handle argument. 59 60 // This is full version of monitor enter and exit. I choose not 61 // to use enter() and exit() in order to make sure user be ware 62 // of the performance and semantics difference. They are normally 63 // used by ObjectLocker etc. The interpreter and compiler use 64 // assembly copies of these routines. Please keep them synchornized. 65 // 66 // attempt_rebias flag is used by UseBiasedLocking implementation 67 static void fast_enter (Handle obj, BasicLock* lock, bool attempt_rebias, TRAPS); 68 static void fast_exit (oop obj, BasicLock* lock, Thread* THREAD); 69 70 // WARNING: They are ONLY used to handle the slow cases. They should 71 // only be used when the fast cases failed. Use of these functions 72 // without previous fast case check may cause fatal error. 73 static void slow_enter (Handle obj, BasicLock* lock, TRAPS); 74 static void slow_exit (oop obj, BasicLock* lock, Thread* THREAD); 75 76 // Used only to handle jni locks or other unmatched monitor enter/exit 77 // Internally they will use heavy weight monitor. 78 static void jni_enter (Handle obj, TRAPS); 79 static bool jni_try_enter(Handle obj, Thread* THREAD); // Implements Unsafe.tryMonitorEnter 80 static void jni_exit (oop obj, Thread* THREAD); 81 82 // Handle all interpreter, compiler and jni cases 83 static void wait (Handle obj, jlong millis, TRAPS); 84 static void notify (Handle obj, TRAPS); 85 static void notifyall (Handle obj, TRAPS); 86 87 // Special internal-use-only method for use by JVM infrastructure 88 // that needs to wait() on a java-level object but that can't risk 89 // throwing unexpected InterruptedExecutionExceptions. 90 static void waitUninterruptibly (Handle obj, jlong Millis, Thread * THREAD) ; 91 92 // used by classloading to free classloader object lock, 93 // wait on an internal lock, and reclaim original lock 94 // with original recursion count 95 static intptr_t complete_exit (Handle obj, TRAPS); 96 static void reenter (Handle obj, intptr_t recursion, TRAPS); 97 98 // thread-specific and global objectMonitor free list accessors 99 // static void verifyInUse (Thread * Self) ; too slow for general assert/debug 100 static ObjectMonitor * omAlloc (Thread * Self) ; 101 static void omRelease (Thread * Self, ObjectMonitor * m, bool FromPerThreadAlloc) ; 102 static void omFlush (Thread * Self) ; 103 104 // Inflate light weight monitor to heavy weight monitor 105 static ObjectMonitor* inflate(Thread * Self, oop obj, const InflateCause cause); 106 // This version is only for internal use 107 static ObjectMonitor* inflate_helper(oop obj); 108 static const char* inflate_cause_name(const InflateCause cause); 109 110 // Returns the identity hash value for an oop 111 // NOTE: It may cause monitor inflation 112 static intptr_t identity_hash_value_for(Handle obj); 113 static intptr_t FastHashCode (Thread * Self, oop obj) ; 114 115 // java.lang.Thread support 116 static bool current_thread_holds_lock(JavaThread* thread, Handle h_obj); 117 static LockOwnership query_lock_ownership(JavaThread * self, Handle h_obj); 118 119 static JavaThread* get_lock_owner(Handle h_obj, bool doLock); 120 121 // JNI detach support 122 static void release_monitors_owned_by_thread(TRAPS); 123 static void monitors_iterate(MonitorClosure* m); 124 125 // GC: we current use aggressive monitor deflation policy 126 // Basically we deflate all monitors that are not busy. 127 // An adaptive profile-based deflation policy could be used if needed 128 static void deflate_idle_monitors(); 129 static int walk_monitor_list(ObjectMonitor** listheadp, 130 ObjectMonitor** FreeHeadp, 131 ObjectMonitor** FreeTailp); 132 static bool deflate_monitor(ObjectMonitor* mid, oop obj, ObjectMonitor** FreeHeadp, 133 ObjectMonitor** FreeTailp); 134 static void oops_do(OopClosure* f); 135 136 // debugging 137 static void sanity_checks(const bool verbose, 138 const unsigned int cache_line_size, 139 int *error_cnt_ptr, int *warning_cnt_ptr); 140 static void verify() PRODUCT_RETURN; 141 static int verify_objmon_isinpool(ObjectMonitor *addr) PRODUCT_RETURN0; 142 143 static void RegisterSpinCallback (int (*)(intptr_t, int), intptr_t) ; 144 145 private: 146 enum { _BLOCKSIZE = 128 }; 147 static ObjectMonitor * volatile gBlockList; 148 static ObjectMonitor * volatile gFreeList; 149 static ObjectMonitor * volatile gOmInUseList; // for moribund thread, so monitors they inflated still get scanned 150 static int gOmInUseCount; 151 152 }; 153 154 // ObjectLocker enforced balanced locking and can never thrown an 155 // IllegalMonitorStateException. However, a pending exception may 156 // have to pass through, and we must also be able to deal with 157 // asynchronous exceptions. The caller is responsible for checking 158 // the threads pending exception if needed. 159 // doLock was added to support classloading with UnsyncloadClass which 160 // requires flag based choice of locking the classloader lock. 161 class ObjectLocker : public StackObj { 162 private: 163 Thread* _thread; 164 Handle _obj; 165 BasicLock _lock; 166 bool _dolock; // default true 167 public: 168 ObjectLocker(Handle obj, Thread* thread, bool doLock = true); 169 ~ObjectLocker(); 170 171 // Monitor behavior 172 void wait (TRAPS) { ObjectSynchronizer::wait (_obj, 0, CHECK); } // wait forever 173 void notify_all(TRAPS) { ObjectSynchronizer::notifyall(_obj, CHECK); } 174 void waitUninterruptibly (TRAPS) { ObjectSynchronizer::waitUninterruptibly (_obj, 0, CHECK);} 175 // complete_exit gives up lock completely, returning recursion count 176 // reenter reclaims lock with original recursion count 177 intptr_t complete_exit(TRAPS) { return ObjectSynchronizer::complete_exit(_obj, THREAD); } 178 void reenter(intptr_t recursion, TRAPS) { ObjectSynchronizer::reenter(_obj, recursion, CHECK); } 179 }; 180 181 #endif // SHARE_VM_RUNTIME_SYNCHRONIZER_HPP