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
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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 #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