1 /*
   2  * Copyright (c) 1998, 2019, 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
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_RUNTIME_SYNCHRONIZER_HPP
  26 #define SHARE_RUNTIME_SYNCHRONIZER_HPP
  27 
  28 #include "memory/padded.hpp"
  29 #include "oops/markWord.hpp"
  30 #include "runtime/basicLock.hpp"
  31 #include "runtime/handles.hpp"
  32 #include "runtime/perfData.hpp"
  33 
  34 class ObjectMonitor;
  35 class ThreadsList;
  36 
  37 struct DeflateMonitorCounters {
  38   int nInuse;              // currently associated with objects
  39   int nInCirculation;      // extant
  40   int nScavenged;          // reclaimed (global and per-thread)
  41   int perThreadScavenged;  // per-thread scavenge total
  42   double perThreadTimes;   // per-thread scavenge times
  43 };
  44 
  45 class ObjectSynchronizer : AllStatic {
  46   friend class VMStructs;
  47  public:
  48   typedef enum {
  49     owner_self,
  50     owner_none,
  51     owner_other
  52   } LockOwnership;
  53 
  54   typedef enum {
  55     inflate_cause_vm_internal = 0,
  56     inflate_cause_monitor_enter = 1,
  57     inflate_cause_wait = 2,
  58     inflate_cause_notify = 3,
  59     inflate_cause_hash_code = 4,
  60     inflate_cause_jni_enter = 5,
  61     inflate_cause_jni_exit = 6,
  62     inflate_cause_nof = 7 // Number of causes
  63   } InflateCause;
  64 
  65   // exit must be implemented non-blocking, since the compiler cannot easily handle
  66   // deoptimization at monitor exit. Hence, it does not take a Handle argument.
  67 
  68   // This is full version of monitor enter and exit.
  69   // The interpreter and compiler use  assembly copies of these routines.
  70   // Please keep them synchronized.
  71   static void enter(Handle obj, BasicLock* lock, TRAPS);
  72   static void exit(oop obj, BasicLock* lock, Thread* THREAD);











  73 
  74   // Used only to handle jni locks or other unmatched monitor enter/exit
  75   // Internally they will use heavy weight monitor.
  76   static void jni_enter(Handle obj, TRAPS);
  77   static void jni_exit(oop obj, Thread* THREAD);
  78 
  79   // Handle all interpreter, compiler and jni cases
  80   static int  wait(Handle obj, jlong millis, TRAPS);
  81   static void notify(Handle obj, TRAPS);
  82   static void notifyall(Handle obj, TRAPS);
  83 
  84   static bool quick_notify(oopDesc* obj, Thread* Self, bool All);
  85   static bool quick_enter(oop obj, Thread* Self, BasicLock* Lock);
  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 ObjectMonitor * omAlloc(Thread * Self);
 100   static void omRelease(Thread * Self, ObjectMonitor * m,
 101                         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 void 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(ThreadsList * t_list, Handle h_obj);
 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(DeflateMonitorCounters* counters);
 129   static void deflate_thread_local_monitors(Thread* thread, DeflateMonitorCounters* counters);
 130   static void prepare_deflate_idle_monitors(DeflateMonitorCounters* counters);
 131   static void finish_deflate_idle_monitors(DeflateMonitorCounters* counters);
 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 bool is_cleanup_needed();
 141   static void oops_do(OopClosure* f);
 142   // Process oops in thread local used monitors
 143   static void thread_local_used_oops_do(Thread* thread, OopClosure* f);
 144 
 145   // debugging
 146   static void audit_and_print_stats(bool on_exit);
 147   static void chk_free_entry(JavaThread * jt, ObjectMonitor * n,
 148                              outputStream * out, int *error_cnt_p);
 149   static void chk_global_free_list_and_count(outputStream * out,
 150                                              int *error_cnt_p);
 151   static void chk_global_in_use_list_and_count(outputStream * out,
 152                                                int *error_cnt_p);
 153   static void chk_in_use_entry(JavaThread * jt, ObjectMonitor * n,
 154                                outputStream * out, int *error_cnt_p);
 155   static void chk_per_thread_in_use_list_and_count(JavaThread *jt,
 156                                                    outputStream * out,
 157                                                    int *error_cnt_p);
 158   static void chk_per_thread_free_list_and_count(JavaThread *jt,
 159                                                  outputStream * out,
 160                                                  int *error_cnt_p);
 161   static void log_in_use_monitor_details(outputStream * out, bool on_exit);
 162   static int  log_monitor_list_counts(outputStream * out);
 163   static int  verify_objmon_isinpool(ObjectMonitor *addr) PRODUCT_RETURN0;
 164 
 165  private:
 166   friend class SynchronizerTest;
 167 
 168   enum { _BLOCKSIZE = 128 };
 169   // global list of blocks of monitors
 170   static PaddedEnd<ObjectMonitor> * volatile gBlockList;
 171   // global monitor free list
 172   static ObjectMonitor * volatile gFreeList;
 173   // global monitor in-use list, for moribund threads,
 174   // monitors they inflated need to be scanned for deflation
 175   static ObjectMonitor * volatile gOmInUseList;
 176   // count of entries in gOmInUseList
 177   static int gOmInUseCount;
 178 
 179   // Process oops in all global used monitors (i.e. moribund thread's monitors)
 180   static void global_used_oops_do(OopClosure* f);
 181   // Process oops in monitors on the given list
 182   static void list_oops_do(ObjectMonitor* list, OopClosure* f);
 183 
 184   // Support for SynchronizerTest access to GVars fields:
 185   static u_char* get_gvars_addr();
 186   static u_char* get_gvars_hcSequence_addr();
 187   static size_t get_gvars_size();
 188   static u_char* get_gvars_stwRandom_addr();
 189 };
 190 
 191 // ObjectLocker enforces balanced locking and can never throw an
 192 // IllegalMonitorStateException. However, a pending exception may
 193 // have to pass through, and we must also be able to deal with
 194 // asynchronous exceptions. The caller is responsible for checking
 195 // the thread's pending exception if needed.
 196 class ObjectLocker : public StackObj {
 197  private:
 198   Thread*   _thread;
 199   Handle    _obj;
 200   BasicLock _lock;
 201   bool      _dolock;   // default true
 202  public:
 203   ObjectLocker(Handle obj, Thread* thread, bool doLock = true);
 204   ~ObjectLocker();
 205 
 206   // Monitor behavior
 207   void wait(TRAPS)  { ObjectSynchronizer::wait(_obj, 0, CHECK); } // wait forever
 208   void notify_all(TRAPS)  { ObjectSynchronizer::notifyall(_obj, CHECK); }
 209   void waitUninterruptibly(TRAPS) { ObjectSynchronizer::waitUninterruptibly(_obj, 0, CHECK); }
 210   // complete_exit gives up lock completely, returning recursion count
 211   // reenter reclaims lock with original recursion count
 212   intptr_t complete_exit(TRAPS)  { return ObjectSynchronizer::complete_exit(_obj, THREAD); }
 213   void reenter(intptr_t recursion, TRAPS)  { ObjectSynchronizer::reenter(_obj, recursion, CHECK); }
 214 };
 215 
 216 #endif // SHARE_RUNTIME_SYNCHRONIZER_HPP
--- EOF ---