1 /*
   2  * Copyright (c) 1998, 2014, 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  *
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  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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  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 #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   // exit must be implemented non-blocking, since the compiler cannot easily handle
  46   // deoptimization at monitor exit. Hence, it does not take a Handle argument.
  47 
  48   // This is full version of monitor enter and exit. I choose not
  49   // to use enter() and exit() in order to make sure user be ware
  50   // of the performance and semantics difference. They are normally
  51   // used by ObjectLocker etc. The interpreter and compiler use
  52   // assembly copies of these routines. Please keep them synchronized.
  53   //
  54   // attempt_rebias flag is used by UseBiasedLocking implementation
  55   static void fast_enter(Handle obj, BasicLock* lock, bool attempt_rebias,
  56                          TRAPS);
  57   static void fast_exit(oop obj, BasicLock* lock, Thread* THREAD);
  58 
  59   // WARNING: They are ONLY used to handle the slow cases. They should
  60   // only be used when the fast cases failed. Use of these functions
  61   // without previous fast case check may cause fatal error.
  62   static void slow_enter(Handle obj, BasicLock* lock, TRAPS);
  63   static void slow_exit(oop obj, BasicLock* lock, Thread* THREAD);
  64 
  65   // Used only to handle jni locks or other unmatched monitor enter/exit
  66   // Internally they will use heavy weight monitor.
  67   static void jni_enter(Handle obj, TRAPS);
  68   static bool jni_try_enter(Handle obj, Thread* THREAD); // Implements Unsafe.tryMonitorEnter
  69   static void jni_exit(oop obj, Thread* THREAD);
  70 
  71   // Handle all interpreter, compiler and jni cases
  72   static int  wait(Handle obj, jlong millis, TRAPS);
  73   static void notify(Handle obj, TRAPS);
  74   static void notifyall(Handle obj, TRAPS);
  75 
  76   // Special internal-use-only method for use by JVM infrastructure
  77   // that needs to wait() on a java-level object but that can't risk
  78   // throwing unexpected InterruptedExecutionExceptions.
  79   static void waitUninterruptibly(Handle obj, jlong Millis, Thread * THREAD);
  80 
  81   // used by classloading to free classloader object lock,
  82   // wait on an internal lock, and reclaim original lock
  83   // with original recursion count
  84   static intptr_t complete_exit(Handle obj, TRAPS);
  85   static void reenter (Handle obj, intptr_t recursion, TRAPS);
  86 
  87   // thread-specific and global objectMonitor free list accessors
  88   static void verifyInUse(Thread * Self);
  89   static ObjectMonitor * omAlloc(Thread * Self);
  90   static void omRelease(Thread * Self, ObjectMonitor * m,
  91                         bool FromPerThreadAlloc);
  92   static void omFlush(Thread * Self);
  93 
  94   // Inflate light weight monitor to heavy weight monitor
  95   static ObjectMonitor* inflate(Thread * Self, oop obj);
  96   // This version is only for internal use
  97   static ObjectMonitor* inflate_helper(oop obj);
  98 
  99   // Returns the identity hash value for an oop
 100   // NOTE: It may cause monitor inflation
 101   static intptr_t identity_hash_value_for(Handle obj);
 102   static intptr_t FastHashCode(Thread * Self, oop obj);
 103 
 104   // java.lang.Thread support
 105   static bool current_thread_holds_lock(JavaThread* thread, Handle h_obj);
 106   static LockOwnership query_lock_ownership(JavaThread * self, Handle h_obj);
 107 
 108   static JavaThread* get_lock_owner(Handle h_obj, bool doLock);
 109 
 110   // JNI detach support
 111   static void release_monitors_owned_by_thread(TRAPS);
 112   static void monitors_iterate(MonitorClosure* m);
 113 
 114   // GC: we current use aggressive monitor deflation policy
 115   // Basically we deflate all monitors that are not busy.
 116   // An adaptive profile-based deflation policy could be used if needed
 117   static void deflate_idle_monitors();
 118   static int walk_monitor_list(ObjectMonitor** listheadp,
 119                                ObjectMonitor** freeHeadp,
 120                                ObjectMonitor** freeTailp);
 121   static bool deflate_monitor(ObjectMonitor* mid, oop obj,
 122                               ObjectMonitor** freeHeadp,
 123                               ObjectMonitor** freeTailp);
 124   static void oops_do(OopClosure* f);
 125 
 126   // debugging
 127   static void sanity_checks(const bool verbose,
 128                             const unsigned int cache_line_size,
 129                             int *error_cnt_ptr, int *warning_cnt_ptr);
 130   static void verify() PRODUCT_RETURN;
 131   static int  verify_objmon_isinpool(ObjectMonitor *addr) PRODUCT_RETURN0;
 132 
 133   static void RegisterSpinCallback(int(*)(intptr_t, int), intptr_t);
 134 
 135  private:
 136   enum { _BLOCKSIZE = 128 };
 137   // gBlockList is really PaddedEnd<ObjectMonitor> *, but we don't
 138   // want to expose the PaddedEnd template more than necessary.
 139   static ObjectMonitor* gBlockList;
 140   static ObjectMonitor * volatile gFreeList;
 141   // global monitor in use list, for moribund threads,
 142   // monitors they inflated need to be scanned for deflation
 143   static ObjectMonitor * volatile gOmInUseList;
 144   // count of entries in gOmInUseList
 145   static int gOmInUseCount;
 146 
 147 };
 148 
 149 // ObjectLocker enforced balanced locking and can never thrown an
 150 // IllegalMonitorStateException. However, a pending exception may
 151 // have to pass through, and we must also be able to deal with
 152 // asynchronous exceptions. The caller is responsible for checking
 153 // the threads pending exception if needed.
 154 // doLock was added to support classloading with UnsyncloadClass which
 155 // requires flag based choice of locking the classloader lock.
 156 class ObjectLocker : public StackObj {
 157  private:
 158   Thread*   _thread;
 159   Handle    _obj;
 160   BasicLock _lock;
 161   bool      _dolock;   // default true
 162  public:
 163   ObjectLocker(Handle obj, Thread* thread, bool doLock = true);
 164   ~ObjectLocker();
 165 
 166   // Monitor behavior
 167   void wait(TRAPS)  { ObjectSynchronizer::wait(_obj, 0, CHECK); } // wait forever
 168   void notify_all(TRAPS)  { ObjectSynchronizer::notifyall(_obj, CHECK); }
 169   void waitUninterruptibly(TRAPS) { ObjectSynchronizer::waitUninterruptibly(_obj, 0, CHECK); }
 170   // complete_exit gives up lock completely, returning recursion count
 171   // reenter reclaims lock with original recursion count
 172   intptr_t complete_exit(TRAPS)  { return ObjectSynchronizer::complete_exit(_obj, THREAD); }
 173   void reenter(intptr_t recursion, TRAPS)  { ObjectSynchronizer::reenter(_obj, recursion, CHECK); }
 174 };
 175 
 176 #endif // SHARE_VM_RUNTIME_SYNCHRONIZER_HPP