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
  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
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  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 
  33 class ObjectMonitor;
  34 
  35 
  36 class ParallelObjectSynchronizerIterator VALUE_OBJ_CLASS_SPEC {
  37   friend class ObjectSynchronizer;
  38 
  39   private:
  40     ObjectMonitor*  volatile _cur;
  41 
  42   private:
  43     ParallelObjectSynchronizerIterator(ObjectMonitor* head);
  44     ObjectMonitor* claim();
  45 
  46   public:
  47     bool parallel_oops_do(OopClosure* f);
  48 };
  49 
  50 
  51 class ObjectSynchronizer : AllStatic {
  52   friend class VMStructs;
  53   friend class ParallelObjectSynchronizerIterator;
  54  public:
  55   typedef enum {
  56     owner_self,
  57     owner_none,
  58     owner_other
  59   } LockOwnership;
  60 
  61   typedef enum {
  62     inflate_cause_vm_internal = 0,
  63     inflate_cause_monitor_enter = 1,
  64     inflate_cause_wait = 2,
  65     inflate_cause_notify = 3,
  66     inflate_cause_hash_code = 4,
  67     inflate_cause_jni_enter = 5,
  68     inflate_cause_jni_exit = 6,
  69     inflate_cause_nof = 7 // Number of causes
  70   } InflateCause;
  71 
  72   // exit must be implemented non-blocking, since the compiler cannot easily handle
  73   // deoptimization at monitor exit. Hence, it does not take a Handle argument.
  74 
  75   // This is full version of monitor enter and exit. I choose not
  76   // to use enter() and exit() in order to make sure user be ware
  77   // of the performance and semantics difference. They are normally
  78   // used by ObjectLocker etc. The interpreter and compiler use
  79   // assembly copies of these routines. Please keep them synchronized.
  80   //
  81   // attempt_rebias flag is used by UseBiasedLocking implementation
  82   static void fast_enter(Handle obj, BasicLock* lock, bool attempt_rebias,
  83                          TRAPS);
  84   static void fast_exit(oop obj, BasicLock* lock, Thread* THREAD);
  85 
  86   // WARNING: They are ONLY used to handle the slow cases. They should
  87   // only be used when the fast cases failed. Use of these functions
  88   // without previous fast case check may cause fatal error.
  89   static void slow_enter(Handle obj, BasicLock* lock, TRAPS);
  90   static void slow_exit(oop obj, BasicLock* lock, Thread* THREAD);
  91 
  92   // Used only to handle jni locks or other unmatched monitor enter/exit
  93   // Internally they will use heavy weight monitor.
  94   static void jni_enter(Handle obj, TRAPS);
  95   static void jni_exit(oop obj, Thread* THREAD);
  96 
  97   // Handle all interpreter, compiler and jni cases
  98   static int  wait(Handle obj, jlong millis, TRAPS);
  99   static void notify(Handle obj, TRAPS);
 100   static void notifyall(Handle obj, TRAPS);
 101 
 102   static bool quick_notify(oopDesc* obj, Thread* Self, bool All);
 103   static bool quick_enter(oop obj, Thread* Self, BasicLock* Lock);
 104 
 105   // Special internal-use-only method for use by JVM infrastructure
 106   // that needs to wait() on a java-level object but that can't risk
 107   // throwing unexpected InterruptedExecutionExceptions.
 108   static void waitUninterruptibly(Handle obj, jlong Millis, Thread * THREAD);
 109 
 110   // used by classloading to free classloader object lock,
 111   // wait on an internal lock, and reclaim original lock
 112   // with original recursion count
 113   static intptr_t complete_exit(Handle obj, TRAPS);
 114   static void reenter (Handle obj, intptr_t recursion, TRAPS);
 115 
 116   // thread-specific and global objectMonitor free list accessors
 117   static void verifyInUse(Thread * Self);
 118   static ObjectMonitor * omAlloc(Thread * Self);
 119   static void omRelease(Thread * Self, ObjectMonitor * m,
 120                         bool FromPerThreadAlloc);
 121   static void omFlush(Thread * Self);
 122 
 123   // Inflate light weight monitor to heavy weight monitor
 124   static ObjectMonitor* inflate(Thread * Self, oop obj, const InflateCause cause);
 125   // This version is only for internal use
 126   static ObjectMonitor* inflate_helper(oop obj);
 127   static const char* inflate_cause_name(const InflateCause cause);
 128 
 129   // Returns the identity hash value for an oop
 130   // NOTE: It may cause monitor inflation
 131   static intptr_t identity_hash_value_for(Handle obj);
 132   static intptr_t FastHashCode(Thread * Self, oop obj);
 133 
 134   // java.lang.Thread support
 135   static bool current_thread_holds_lock(JavaThread* thread, Handle h_obj);
 136   static LockOwnership query_lock_ownership(JavaThread * self, Handle h_obj);
 137 
 138   static JavaThread* get_lock_owner(Handle h_obj, bool doLock);
 139 
 140   // JNI detach support
 141   static void release_monitors_owned_by_thread(TRAPS);
 142   static void monitors_iterate(MonitorClosure* m);
 143 
 144   // GC: we current use aggressive monitor deflation policy
 145   // Basically we deflate all monitors that are not busy.
 146   // An adaptive profile-based deflation policy could be used if needed
 147   // When deflate_tl is true, also deflate thread-local monitors. Otherwise only
 148   // deflate global monitors.
 149   static void deflate_idle_monitors(bool deflate_tl);
 150   static void deflate_idle_monitors_and_oops_do(Thread* thread, OopClosure* cl);
 151   static void deflate_idle_monitors_all_threads();
 152 
 153   // For a given monitor list: global or per-thread, deflate idle monitors
 154   static int deflate_monitor_list(ObjectMonitor** listheadp,
 155                                   ObjectMonitor** freeHeadp,
 156                                   ObjectMonitor** freeTailp,
 157                                   OopClosure* cl = NULL);
 158   static bool deflate_monitor(ObjectMonitor* mid, oop obj,
 159                               ObjectMonitor** freeHeadp,
 160                               ObjectMonitor** freeTailp);
 161   static void oops_do(OopClosure* f);
 162   // Process oops in thread local used monitors
 163   static void thread_local_used_oops_do(Thread* thread, OopClosure* f);
 164 
 165   // Parallel GC support
 166   static ParallelObjectSynchronizerIterator parallel_iterator();
 167 
 168   // debugging
 169   static void sanity_checks(const bool verbose,
 170                             const unsigned int cache_line_size,
 171                             int *error_cnt_ptr, int *warning_cnt_ptr);
 172   static void verify() PRODUCT_RETURN;
 173   static int  verify_objmon_isinpool(ObjectMonitor *addr) PRODUCT_RETURN0;
 174 
 175  private:
 176   enum { _BLOCKSIZE = 128 };
 177   // global list of blocks of monitors
 178   // gBlockList is really PaddedEnd<ObjectMonitor> *, but we don't
 179   // want to expose the PaddedEnd template more than necessary.
 180   static ObjectMonitor * volatile gBlockList;
 181   // global monitor free list
 182   static ObjectMonitor * volatile gFreeList;
 183   // global monitor in-use list, for moribund threads,
 184   // monitors they inflated need to be scanned for deflation
 185   static ObjectMonitor * volatile gOmInUseList;
 186   // count of entries in gOmInUseList
 187   static int gOmInUseCount;
 188 
 189   // Process oops in all monitors
 190   static void global_oops_do(OopClosure* f);
 191   // Process oops in all global used monitors (i.e. moribund thread's monitors)
 192   static void global_used_oops_do(OopClosure* f);
 193   // Process oops in monitors on the given list
 194   static void list_oops_do(ObjectMonitor* list, OopClosure* f);
 195 
 196 };
 197 
 198 // ObjectLocker enforced balanced locking and can never thrown an
 199 // IllegalMonitorStateException. However, a pending exception may
 200 // have to pass through, and we must also be able to deal with
 201 // asynchronous exceptions. The caller is responsible for checking
 202 // the threads pending exception if needed.
 203 // doLock was added to support classloading with UnsyncloadClass which
 204 // requires flag based choice of locking the classloader lock.
 205 class ObjectLocker : public StackObj {
 206  private:
 207   Thread*   _thread;
 208   Handle    _obj;
 209   BasicLock _lock;
 210   bool      _dolock;   // default true
 211  public:
 212   ObjectLocker(Handle obj, Thread* thread, bool doLock = true);
 213   ~ObjectLocker();
 214 
 215   // Monitor behavior
 216   void wait(TRAPS)  { ObjectSynchronizer::wait(_obj, 0, CHECK); } // wait forever
 217   void notify_all(TRAPS)  { ObjectSynchronizer::notifyall(_obj, CHECK); }
 218   void waitUninterruptibly(TRAPS) { ObjectSynchronizer::waitUninterruptibly(_obj, 0, CHECK); }
 219   // complete_exit gives up lock completely, returning recursion count
 220   // reenter reclaims lock with original recursion count
 221   intptr_t complete_exit(TRAPS)  { return ObjectSynchronizer::complete_exit(_obj, THREAD); }
 222   void reenter(intptr_t recursion, TRAPS)  { ObjectSynchronizer::reenter(_obj, recursion, CHECK); }
 223 };
 224 
 225 #endif // SHARE_VM_RUNTIME_SYNCHRONIZER_HPP