/* * Copyright (c) 1998, 2019, 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. * */ #ifndef SHARE_RUNTIME_SYNCHRONIZER_HPP #define SHARE_RUNTIME_SYNCHRONIZER_HPP #include "memory/padded.hpp" #include "oops/markOop.hpp" #include "runtime/basicLock.hpp" #include "runtime/handles.hpp" #include "runtime/perfData.hpp" class ObjectMonitor; class ObjectMonitorHandle; class ThreadsList; struct DeflateMonitorCounters { int nInuse; // currently associated with objects int nInCirculation; // extant int nScavenged; // reclaimed (global and per-thread) int perThreadScavenged; // per-thread scavenge total double perThreadTimes; // per-thread scavenge times }; class ObjectSynchronizer : AllStatic { friend class VMStructs; public: typedef enum { owner_self, owner_none, owner_other } LockOwnership; typedef enum { inflate_cause_vm_internal = 0, inflate_cause_monitor_enter = 1, inflate_cause_wait = 2, inflate_cause_notify = 3, inflate_cause_hash_code = 4, inflate_cause_jni_enter = 5, inflate_cause_jni_exit = 6, inflate_cause_nof = 7 // Number of causes } InflateCause; // exit must be implemented non-blocking, since the compiler cannot easily handle // deoptimization at monitor exit. Hence, it does not take a Handle argument. // This is full version of monitor enter and exit. I choose not // to use enter() and exit() in order to make sure user be ware // of the performance and semantics difference. They are normally // used by ObjectLocker etc. The interpreter and compiler use // assembly copies of these routines. Please keep them synchronized. // // attempt_rebias flag is used by UseBiasedLocking implementation static void fast_enter(Handle obj, BasicLock* lock, bool attempt_rebias, TRAPS); static void fast_exit(oop obj, BasicLock* lock, Thread* THREAD); // WARNING: They are ONLY used to handle the slow cases. They should // only be used when the fast cases failed. Use of these functions // without previous fast case check may cause fatal error. static void slow_enter(Handle obj, BasicLock* lock, TRAPS); static void slow_exit(oop obj, BasicLock* lock, Thread* THREAD); // Used only to handle jni locks or other unmatched monitor enter/exit // Internally they will use heavy weight monitor. static void jni_enter(Handle obj, TRAPS); static void jni_exit(oop obj, Thread* THREAD); // Handle all interpreter, compiler and jni cases static int wait(Handle obj, jlong millis, TRAPS); static void notify(Handle obj, TRAPS); static void notifyall(Handle obj, TRAPS); static bool quick_notify(oopDesc* obj, Thread* Self, bool All); static bool quick_enter(oop obj, Thread* Self, BasicLock* Lock); // Special internal-use-only method for use by JVM infrastructure // that needs to wait() on a java-level object but that can't risk // throwing unexpected InterruptedExecutionExceptions. static void waitUninterruptibly(Handle obj, jlong Millis, Thread * THREAD); // used by classloading to free classloader object lock, // wait on an internal lock, and reclaim original lock // with original recursion count static intptr_t complete_exit(Handle obj, TRAPS); static void reenter (Handle obj, intptr_t recursion, TRAPS); // thread-specific and global objectMonitor free list accessors static ObjectMonitor * omAlloc(Thread * Self, const InflateCause cause); static void omRelease(Thread * Self, ObjectMonitor * m, bool FromPerThreadAlloc); static void omFlush(Thread * Self); // Inflate light weight monitor to heavy weight monitor static void inflate(ObjectMonitorHandle * omh_p, Thread * Self, oop obj, const InflateCause cause); // This version is only for internal use static void inflate_helper(ObjectMonitorHandle * omh_p, oop obj); static const char* inflate_cause_name(const InflateCause cause); // Returns the identity hash value for an oop // NOTE: It may cause monitor inflation static intptr_t identity_hash_value_for(Handle obj); static intptr_t FastHashCode(Thread * Self, oop obj); // java.lang.Thread support static bool current_thread_holds_lock(JavaThread* thread, Handle h_obj); static LockOwnership query_lock_ownership(JavaThread * self, Handle h_obj); static JavaThread* get_lock_owner(ThreadsList * t_list, Handle h_obj); // JNI detach support static void release_monitors_owned_by_thread(TRAPS); static void monitors_iterate(MonitorClosure* m); // GC: we current use aggressive monitor deflation policy // Basically we deflate all monitors that are not busy. // An adaptive profile-based deflation policy could be used if needed static void deflate_idle_monitors(DeflateMonitorCounters* counters); static void deflate_global_idle_monitors_using_JT(); static void deflate_per_thread_idle_monitors_using_JT(); static void deflate_common_idle_monitors_using_JT(bool is_global, JavaThread * self); static void deflate_thread_local_monitors(Thread* thread, DeflateMonitorCounters* counters); static void prepare_deflate_idle_monitors(DeflateMonitorCounters* counters); static void finish_deflate_idle_monitors(DeflateMonitorCounters* counters); // For a given monitor list: global or per-thread, deflate idle monitors static int deflate_monitor_list(ObjectMonitor** listheadp, ObjectMonitor** freeHeadp, ObjectMonitor** freeTailp); // For a given in-use monitor list: global or per-thread, deflate idle // monitors using a JavaThread. static int deflate_monitor_list_using_JT(ObjectMonitor** listHeadp, ObjectMonitor** freeHeadp, ObjectMonitor** freeTailp, ObjectMonitor** savedMidInUsep); static bool deflate_monitor(ObjectMonitor* mid, oop obj, ObjectMonitor** freeHeadp, ObjectMonitor** freeTailp); static bool deflate_monitor_using_JT(ObjectMonitor* mid, ObjectMonitor** freeHeadp, ObjectMonitor** freeTailp); static bool is_async_deflation_needed(); static bool is_safepoint_deflation_needed(); static bool is_async_deflation_requested() { return _is_async_deflation_requested; } static bool is_special_deflation_requested() { return _is_special_deflation_requested; } static void set_is_async_deflation_requested(bool new_value) { _is_async_deflation_requested = new_value; } static void set_is_special_deflation_requested(bool new_value) { _is_special_deflation_requested = new_value; } static jlong time_since_last_async_deflation_ms(); static void oops_do(OopClosure* f); // Process oops in thread local used monitors static void thread_local_used_oops_do(Thread* thread, OopClosure* f); // debugging static void audit_and_print_stats(bool on_exit); static void chk_free_entry(JavaThread * jt, ObjectMonitor * n, outputStream * out, int *error_cnt_p); static void chk_global_free_list_and_count(outputStream * out, int *error_cnt_p); static void chk_global_in_use_list_and_count(outputStream * out, int *error_cnt_p); static void chk_in_use_entry(JavaThread * jt, ObjectMonitor * n, outputStream * out, int *error_cnt_p); static void chk_per_thread_in_use_list_and_count(JavaThread *jt, outputStream * out, int *error_cnt_p); static void chk_per_thread_free_list_and_count(JavaThread *jt, outputStream * out, int *error_cnt_p); static void log_in_use_monitor_details(outputStream * out, bool on_exit); static int log_monitor_list_counts(outputStream * out); static int verify_objmon_isinpool(ObjectMonitor *addr) PRODUCT_RETURN0; static void do_safepoint_work(DeflateMonitorCounters* _counters); private: friend class SynchronizerTest; enum { _BLOCKSIZE = 128 }; // global list of blocks of monitors static PaddedEnd * volatile gBlockList; // global monitor free list static ObjectMonitor * volatile gFreeList; // global monitor in-use list, for moribund threads, // monitors they inflated need to be scanned for deflation static ObjectMonitor * volatile gOmInUseList; // count of entries in gOmInUseList static int gOmInUseCount; static volatile bool _is_async_deflation_requested; static volatile bool _is_special_deflation_requested; static jlong _last_async_deflation_time_ns; // Process oops in all global used monitors (i.e. moribund thread's monitors) static void global_used_oops_do(OopClosure* f); // Process oops in monitors on the given list static void list_oops_do(ObjectMonitor* list, OopClosure* f); // Support for SynchronizerTest access to GVars fields: static u_char* get_gvars_addr(); static u_char* get_gvars_hcSequence_addr(); static size_t get_gvars_size(); static u_char* get_gvars_stwRandom_addr(); }; // ObjectLocker enforces balanced locking and can never throw an // IllegalMonitorStateException. However, a pending exception may // have to pass through, and we must also be able to deal with // asynchronous exceptions. The caller is responsible for checking // the thread's pending exception if needed. class ObjectLocker : public StackObj { private: Thread* _thread; Handle _obj; BasicLock _lock; bool _dolock; // default true public: ObjectLocker(Handle obj, Thread* thread, bool doLock = true); ~ObjectLocker(); // Monitor behavior void wait(TRAPS) { ObjectSynchronizer::wait(_obj, 0, CHECK); } // wait forever void notify_all(TRAPS) { ObjectSynchronizer::notifyall(_obj, CHECK); } void waitUninterruptibly(TRAPS) { ObjectSynchronizer::waitUninterruptibly(_obj, 0, CHECK); } // complete_exit gives up lock completely, returning recursion count // reenter reclaims lock with original recursion count intptr_t complete_exit(TRAPS) { return ObjectSynchronizer::complete_exit(_obj, THREAD); } void reenter(intptr_t recursion, TRAPS) { ObjectSynchronizer::reenter(_obj, recursion, CHECK); } }; #endif // SHARE_RUNTIME_SYNCHRONIZER_HPP