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1 /*
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2 * Copyright 1998-2007 Sun Microsystems, Inc. All Rights Reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 class BasicLock VALUE_OBJ_CLASS_SPEC {
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26 friend class VMStructs;
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27 private:
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28 volatile markOop _displaced_header;
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29 public:
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30 markOop displaced_header() const { return _displaced_header; }
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31 void set_displaced_header(markOop header) { _displaced_header = header; }
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32
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33 void print_on(outputStream* st) const;
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34
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35 // move a basic lock (used during deoptimization
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36 void move_to(oop obj, BasicLock* dest);
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37
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38 static int displaced_header_offset_in_bytes() { return offset_of(BasicLock, _displaced_header); }
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39 };
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40
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41 // A BasicObjectLock associates a specific Java object with a BasicLock.
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42 // It is currently embedded in an interpreter frame.
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43
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44 // Because some machines have alignment restrictions on the control stack,
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45 // the actual space allocated by the interpreter may include padding words
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46 // after the end of the BasicObjectLock. Also, in order to guarantee
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47 // alignment of the embedded BasicLock objects on such machines, we
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48 // put the embedded BasicLock at the beginning of the struct.
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49
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50 class BasicObjectLock VALUE_OBJ_CLASS_SPEC {
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51 friend class VMStructs;
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52 private:
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53 BasicLock _lock; // the lock, must be double word aligned
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54 oop _obj; // object holds the lock;
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55
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56 public:
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57 // Manipulation
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58 oop obj() const { return _obj; }
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59 void set_obj(oop obj) { _obj = obj; }
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60 BasicLock* lock() { return &_lock; }
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61
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62 // Note: Use frame::interpreter_frame_monitor_size() for the size of BasicObjectLocks
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63 // in interpreter activation frames since it includes machine-specific padding.
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64 static int size() { return sizeof(BasicObjectLock)/wordSize; }
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65
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66 // GC support
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67 void oops_do(OopClosure* f) { f->do_oop(&_obj); }
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68
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69 static int obj_offset_in_bytes() { return offset_of(BasicObjectLock, _obj); }
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70 static int lock_offset_in_bytes() { return offset_of(BasicObjectLock, _lock); }
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71 };
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72
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73 class ObjectMonitor;
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74
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75 class ObjectSynchronizer : AllStatic {
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76 friend class VMStructs;
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77 public:
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78 typedef enum {
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79 owner_self,
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80 owner_none,
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81 owner_other
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82 } LockOwnership;
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83 // exit must be implemented non-blocking, since the compiler cannot easily handle
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84 // deoptimization at monitor exit. Hence, it does not take a Handle argument.
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85
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86 // This is full version of monitor enter and exit. I choose not
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87 // to use enter() and exit() in order to make sure user be ware
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88 // of the performance and semantics difference. They are normally
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89 // used by ObjectLocker etc. The interpreter and compiler use
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90 // assembly copies of these routines. Please keep them synchornized.
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91 //
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92 // attempt_rebias flag is used by UseBiasedLocking implementation
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93 static void fast_enter (Handle obj, BasicLock* lock, bool attempt_rebias, TRAPS);
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94 static void fast_exit (oop obj, BasicLock* lock, Thread* THREAD);
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95
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96 // WARNING: They are ONLY used to handle the slow cases. They should
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97 // only be used when the fast cases failed. Use of these functions
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98 // without previous fast case check may cause fatal error.
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99 static void slow_enter (Handle obj, BasicLock* lock, TRAPS);
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100 static void slow_exit (oop obj, BasicLock* lock, Thread* THREAD);
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101
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102 // Used only to handle jni locks or other unmatched monitor enter/exit
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103 // Internally they will use heavy weight monitor.
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104 static void jni_enter (Handle obj, TRAPS);
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105 static bool jni_try_enter(Handle obj, Thread* THREAD); // Implements Unsafe.tryMonitorEnter
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106 static void jni_exit (oop obj, Thread* THREAD);
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107
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108 // Handle all interpreter, compiler and jni cases
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109 static void wait (Handle obj, jlong millis, TRAPS);
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110 static void notify (Handle obj, TRAPS);
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111 static void notifyall (Handle obj, TRAPS);
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112
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113 // Special internal-use-only method for use by JVM infrastructure
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114 // that needs to wait() on a java-level object but that can't risk
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115 // throwing unexpected InterruptedExecutionExceptions.
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116 static void waitUninterruptibly (Handle obj, jlong Millis, Thread * THREAD) ;
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117
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118 // used by classloading to free classloader object lock,
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119 // wait on an internal lock, and reclaim original lock
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120 // with original recursion count
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121 static intptr_t complete_exit (Handle obj, TRAPS);
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122 static void reenter (Handle obj, intptr_t recursion, TRAPS);
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123
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124 // thread-specific and global objectMonitor free list accessors
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125 static ObjectMonitor * omAlloc (Thread * Self) ;
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126 static void omRelease (Thread * Self, ObjectMonitor * m) ;
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127 static void omFlush (Thread * Self) ;
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128
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129 // Inflate light weight monitor to heavy weight monitor
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130 static ObjectMonitor* inflate(Thread * Self, oop obj);
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131 // This version is only for internal use
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132 static ObjectMonitor* inflate_helper(oop obj);
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133
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134 // Returns the identity hash value for an oop
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135 // NOTE: It may cause monitor inflation
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136 static intptr_t identity_hash_value_for(Handle obj);
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137 static intptr_t FastHashCode (Thread * Self, oop obj) ;
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138
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139 // java.lang.Thread support
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140 static bool current_thread_holds_lock(JavaThread* thread, Handle h_obj);
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141 static LockOwnership query_lock_ownership(JavaThread * self, Handle h_obj);
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142
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143 static JavaThread* get_lock_owner(Handle h_obj, bool doLock);
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144
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145 // JNI detach support
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146 static void release_monitors_owned_by_thread(TRAPS);
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147 static void monitors_iterate(MonitorClosure* m);
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148
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149 // GC: we current use aggressive monitor deflation policy
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150 // Basically we deflate all monitors that are not busy.
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151 // An adaptive profile-based deflation policy could be used if needed
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152 static void deflate_idle_monitors();
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1587
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153 static bool deflate_monitor(ObjectMonitor* mid, oop obj, ObjectMonitor** FreeHeadp,
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154 ObjectMonitor** FreeTailp);
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155 static void oops_do(OopClosure* f);
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156
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157 // debugging
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158 static void trace_locking(Handle obj, bool is_compiled, bool is_method, bool is_locking) PRODUCT_RETURN;
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159 static void verify() PRODUCT_RETURN;
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160 static int verify_objmon_isinpool(ObjectMonitor *addr) PRODUCT_RETURN0;
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161
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162 private:
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163 enum { _BLOCKSIZE = 128 };
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164 static ObjectMonitor* gBlockList;
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165 static ObjectMonitor * volatile gFreeList;
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166
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167 public:
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168 static void Initialize () ;
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169 static PerfCounter * _sync_ContendedLockAttempts ;
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170 static PerfCounter * _sync_FutileWakeups ;
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171 static PerfCounter * _sync_Parks ;
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172 static PerfCounter * _sync_EmptyNotifications ;
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173 static PerfCounter * _sync_Notifications ;
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174 static PerfCounter * _sync_SlowEnter ;
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175 static PerfCounter * _sync_SlowExit ;
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176 static PerfCounter * _sync_SlowNotify ;
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177 static PerfCounter * _sync_SlowNotifyAll ;
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178 static PerfCounter * _sync_FailedSpins ;
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179 static PerfCounter * _sync_SuccessfulSpins ;
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180 static PerfCounter * _sync_PrivateA ;
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181 static PerfCounter * _sync_PrivateB ;
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182 static PerfCounter * _sync_MonInCirculation ;
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183 static PerfCounter * _sync_MonScavenged ;
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184 static PerfCounter * _sync_Inflations ;
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185 static PerfCounter * _sync_Deflations ;
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186 static PerfLongVariable * _sync_MonExtant ;
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187
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188 public:
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189 static void RegisterSpinCallback (int (*)(intptr_t, int), intptr_t) ;
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190
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191 };
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192
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193 // ObjectLocker enforced balanced locking and can never thrown an
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194 // IllegalMonitorStateException. However, a pending exception may
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195 // have to pass through, and we must also be able to deal with
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196 // asynchronous exceptions. The caller is responsible for checking
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197 // the threads pending exception if needed.
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198 // doLock was added to support classloading with UnsyncloadClass which
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199 // requires flag based choice of locking the classloader lock.
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200 class ObjectLocker : public StackObj {
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201 private:
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202 Thread* _thread;
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203 Handle _obj;
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204 BasicLock _lock;
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205 bool _dolock; // default true
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206 public:
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207 ObjectLocker(Handle obj, Thread* thread, bool doLock = true);
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208 ~ObjectLocker();
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209
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210 // Monitor behavior
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211 void wait (TRAPS) { ObjectSynchronizer::wait (_obj, 0, CHECK); } // wait forever
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212 void notify_all(TRAPS) { ObjectSynchronizer::notifyall(_obj, CHECK); }
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213 void waitUninterruptibly (TRAPS) { ObjectSynchronizer::waitUninterruptibly (_obj, 0, CHECK);}
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214 // complete_exit gives up lock completely, returning recursion count
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215 // reenter reclaims lock with original recursion count
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216 intptr_t complete_exit(TRAPS) { return ObjectSynchronizer::complete_exit(_obj, CHECK_0); }
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217 void reenter(intptr_t recursion, TRAPS) { ObjectSynchronizer::reenter(_obj, recursion, CHECK); }
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218 };
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