1 /*
   2  * Copyright (c) 1998, 2016, 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
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  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
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  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 
  33 class ObjectMonitor;
  34 
  35 class ObjectSynchronizer : AllStatic {
  36   friend class VMStructs;
  37  public:
  38   typedef enum {
  39     owner_self,
  40     owner_none,
  41     owner_other
  42   } LockOwnership;
  43 
  44   typedef enum {
  45     inflate_cause_vm_internal = 0,
  46     inflate_cause_monitor_enter = 1,
  47     inflate_cause_wait = 2,
  48     inflate_cause_notify = 3,
  49     inflate_cause_hash_code = 4,
  50     inflate_cause_jni_enter = 5,
  51     inflate_cause_jni_exit = 6,
  52     inflate_cause_nof = 7 // Number of causes
  53   } InflateCause;
  54 
  55   // exit must be implemented non-blocking, since the compiler cannot easily handle
  56   // deoptimization at monitor exit. Hence, it does not take a Handle argument.
  57 
  58   // This is full version of monitor enter and exit. I choose not
  59   // to use enter() and exit() in order to make sure user be ware
  60   // of the performance and semantics difference. They are normally
  61   // used by ObjectLocker etc. The interpreter and compiler use
  62   // assembly copies of these routines. Please keep them synchronized.
  63   //
  64   // attempt_rebias flag is used by UseBiasedLocking implementation
  65   static void fast_enter(Handle obj, BasicLock* lock, bool attempt_rebias,
  66                          TRAPS);
  67   static void fast_exit(oop obj, BasicLock* lock, Thread* THREAD);
  68 
  69   // WARNING: They are ONLY used to handle the slow cases. They should
  70   // only be used when the fast cases failed. Use of these functions
  71   // without previous fast case check may cause fatal error.
  72   static void slow_enter(Handle obj, BasicLock* lock, TRAPS);
  73   static void slow_exit(oop obj, BasicLock* lock, Thread* THREAD);
  74 
  75   // Used only to handle jni locks or other unmatched monitor enter/exit
  76   // Internally they will use heavy weight monitor.
  77   static void jni_enter(Handle obj, TRAPS);
  78   static void jni_exit(oop obj, Thread* THREAD);
  79 
  80   // Handle all interpreter, compiler and jni cases
  81   static int  wait(Handle obj, jlong millis, TRAPS);
  82   static void notify(Handle obj, TRAPS);
  83   static void notifyall(Handle obj, TRAPS);
  84 
  85   static bool quick_notify(oopDesc* obj, Thread* Self, bool All);
  86   static bool quick_enter(oop obj, Thread* Self, BasicLock* Lock);
  87 
  88   // Special internal-use-only method for use by JVM infrastructure
  89   // that needs to wait() on a java-level object but that can't risk
  90   // throwing unexpected InterruptedExecutionExceptions.
  91   static void waitUninterruptibly(Handle obj, jlong Millis, Thread * THREAD);
  92 
  93   // used by classloading to free classloader object lock,
  94   // wait on an internal lock, and reclaim original lock
  95   // with original recursion count
  96   static intptr_t complete_exit(Handle obj, TRAPS);
  97   static void reenter (Handle obj, intptr_t recursion, TRAPS);
  98 
  99   // thread-specific and global objectMonitor free list accessors
 100   static void verifyInUse(Thread * Self);
 101   static ObjectMonitor * omAlloc(Thread * Self);
 102   static void omRelease(Thread * Self, ObjectMonitor * m,
 103                         bool FromPerThreadAlloc);
 104   static void omFlush(Thread * Self);
 105 
 106   // Inflate light weight monitor to heavy weight monitor
 107   static ObjectMonitor* inflate(Thread * Self, oop obj, const InflateCause cause);
 108   // This version is only for internal use
 109   static ObjectMonitor* inflate_helper(oop obj);
 110   static const char* inflate_cause_name(const InflateCause cause);
 111 
 112   // Returns the identity hash value for an oop
 113   // NOTE: It may cause monitor inflation
 114   static intptr_t identity_hash_value_for(Handle obj);
 115   static intptr_t FastHashCode(Thread * Self, oop obj);
 116 
 117   // java.lang.Thread support
 118   static bool current_thread_holds_lock(JavaThread* thread, Handle h_obj);
 119   static LockOwnership query_lock_ownership(JavaThread * self, Handle h_obj);
 120 
 121   static JavaThread* get_lock_owner(Handle h_obj, bool doLock);
 122 
 123   // JNI detach support
 124   static void release_monitors_owned_by_thread(TRAPS);
 125   static void monitors_iterate(MonitorClosure* m);
 126 
 127   // GC: we current use aggressive monitor deflation policy
 128   // Basically we deflate all monitors that are not busy.
 129   // An adaptive profile-based deflation policy could be used if needed
 130   static void deflate_idle_monitors();
 131   static void deflate_thread_local_monitors(Thread* thread);
 132 
 133   // For a given monitor list: global or per-thread, deflate idle monitors
 134   static int deflate_monitor_list(ObjectMonitor** listheadp,
 135                                   ObjectMonitor** freeHeadp,
 136                                   ObjectMonitor** freeTailp);
 137   static bool deflate_monitor(ObjectMonitor* mid, oop obj,
 138                               ObjectMonitor** freeHeadp,
 139                               ObjectMonitor** freeTailp);
 140   static void oops_do(OopClosure* f);
 141   // Process oops in thread local used monitors
 142   static void thread_local_used_oops_do(Thread* thread, OopClosure* f);
 143 
 144   // debugging
 145   static void sanity_checks(const bool verbose,
 146                             const unsigned int cache_line_size,
 147                             int *error_cnt_ptr, int *warning_cnt_ptr);
 148   static int  verify_objmon_isinpool(ObjectMonitor *addr) PRODUCT_RETURN0;
 149 
 150  private:
 151   enum { _BLOCKSIZE = 128 };
 152   // global list of blocks of monitors
 153   // gBlockList is really PaddedEnd<ObjectMonitor> *, but we don't
 154   // want to expose the PaddedEnd template more than necessary.
 155   static ObjectMonitor * volatile gBlockList;
 156   // global monitor free list
 157   static ObjectMonitor * volatile gFreeList;
 158   // global monitor in-use list, for moribund threads,
 159   // monitors they inflated need to be scanned for deflation
 160   static ObjectMonitor * volatile gOmInUseList;
 161   // count of entries in gOmInUseList
 162   static int gOmInUseCount;
 163 
 164   // Process oops in all monitors
 165   static void global_oops_do(OopClosure* f);
 166   // Process oops in all global used monitors (i.e. moribund thread's monitors)
 167   static void global_used_oops_do(OopClosure* f);
 168   // Process oops in monitors on the given list
 169   static void list_oops_do(ObjectMonitor* list, OopClosure* f);
 170 
 171 };
 172 
 173 // ObjectLocker enforced balanced locking and can never thrown an
 174 // IllegalMonitorStateException. However, a pending exception may
 175 // have to pass through, and we must also be able to deal with
 176 // asynchronous exceptions. The caller is responsible for checking
 177 // the threads pending exception if needed.
 178 // doLock was added to support classloading with UnsyncloadClass which
 179 // requires flag based choice of locking the classloader lock.
 180 class ObjectLocker : public StackObj {
 181  private:
 182   Thread*   _thread;
 183   Handle    _obj;
 184   BasicLock _lock;
 185   bool      _dolock;   // default true
 186  public:
 187   ObjectLocker(Handle obj, Thread* thread, bool doLock = true);
 188   ~ObjectLocker();
 189 
 190   // Monitor behavior
 191   void wait(TRAPS)  { ObjectSynchronizer::wait(_obj, 0, CHECK); } // wait forever
 192   void notify_all(TRAPS)  { ObjectSynchronizer::notifyall(_obj, CHECK); }
 193   void waitUninterruptibly(TRAPS) { ObjectSynchronizer::waitUninterruptibly(_obj, 0, CHECK); }
 194   // complete_exit gives up lock completely, returning recursion count
 195   // reenter reclaims lock with original recursion count
 196   intptr_t complete_exit(TRAPS)  { return ObjectSynchronizer::complete_exit(_obj, THREAD); }
 197   void reenter(intptr_t recursion, TRAPS)  { ObjectSynchronizer::reenter(_obj, recursion, CHECK); }
 198 };
 199 
 200 #endif // SHARE_VM_RUNTIME_SYNCHRONIZER_HPP