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1 /*
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2 * Copyright 1998-2006 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 // do not include precompiled header file
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26 # include "incls/_osThread_solaris.cpp.incl"
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27 # include <signal.h>
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28
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29 // ***************************************************************
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30 // Platform dependent initialization and cleanup
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31 // ***************************************************************
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32
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33 void OSThread::pd_initialize() {
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34 _thread_id = 0;
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35 sigemptyset(&_caller_sigmask);
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36
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37 _current_callback = NULL;
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38 _current_callback_lock = VM_Version::supports_compare_and_exchange() ? NULL
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39 : new Mutex(Mutex::suspend_resume, "Callback_lock", true);
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40
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41 _saved_interrupt_thread_state = _thread_new;
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42 _vm_created_thread = false;
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43 }
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44
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45 void OSThread::pd_destroy() {
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46 }
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47
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48 // Synchronous interrupt support
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49 //
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50 // _current_callback == NULL no pending callback
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51 // == 1 callback_in_progress
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52 // == other value pointer to the pending callback
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53 //
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54
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55 // CAS on v8 is implemented by using a global atomic_memory_operation_lock,
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56 // which is shared by other atomic functions. It is OK for normal uses, but
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57 // dangerous if used after some thread is suspended or if used in signal
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58 // handlers. Instead here we use a special per-thread lock to synchronize
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59 // updating _current_callback if we are running on v8. Note in general trying
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60 // to grab locks after a thread is suspended is not safe, but it is safe for
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61 // updating _current_callback, because synchronous interrupt callbacks are
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62 // currently only used in:
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63 // 1. GetThreadPC_Callback - used by WatcherThread to profile VM thread
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64 // There is no overlap between the callbacks, which means we won't try to
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65 // grab a thread's sync lock after the thread has been suspended while holding
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66 // the same lock.
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67
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68 // used after a thread is suspended
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69 static intptr_t compare_and_exchange_current_callback (
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70 intptr_t callback, intptr_t *addr, intptr_t compare_value, Mutex *sync) {
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71 if (VM_Version::supports_compare_and_exchange()) {
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72 return Atomic::cmpxchg_ptr(callback, addr, compare_value);
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73 } else {
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74 MutexLockerEx(sync, Mutex::_no_safepoint_check_flag);
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75 if (*addr == compare_value) {
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76 *addr = callback;
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77 return compare_value;
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78 } else {
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79 return callback;
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80 }
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81 }
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82 }
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83
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84 // used in signal handler
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85 static intptr_t exchange_current_callback(intptr_t callback, intptr_t *addr, Mutex *sync) {
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86 if (VM_Version::supports_compare_and_exchange()) {
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87 return Atomic::xchg_ptr(callback, addr);
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88 } else {
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89 MutexLockerEx(sync, Mutex::_no_safepoint_check_flag);
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90 intptr_t cb = *addr;
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91 *addr = callback;
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92 return cb;
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93 }
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94 }
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95
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96 // one interrupt at a time. spin if _current_callback != NULL
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97 int OSThread::set_interrupt_callback(Sync_Interrupt_Callback * cb) {
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98 int count = 0;
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99 while (compare_and_exchange_current_callback(
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100 (intptr_t)cb, (intptr_t *)&_current_callback, (intptr_t)NULL, _current_callback_lock) != NULL) {
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101 while (_current_callback != NULL) {
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102 count++;
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103 #ifdef ASSERT
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104 if ((WarnOnStalledSpinLock > 0) &&
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105 (count % WarnOnStalledSpinLock == 0)) {
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106 warning("_current_callback seems to be stalled: %p", _current_callback);
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107 }
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108 #endif
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109 os::yield_all(count);
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110 }
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111 }
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112 return 0;
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113 }
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114
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115 // reset _current_callback, spin if _current_callback is callback_in_progress
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116 void OSThread::remove_interrupt_callback(Sync_Interrupt_Callback * cb) {
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117 int count = 0;
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118 while (compare_and_exchange_current_callback(
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119 (intptr_t)NULL, (intptr_t *)&_current_callback, (intptr_t)cb, _current_callback_lock) != (intptr_t)cb) {
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120 #ifdef ASSERT
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121 intptr_t p = (intptr_t)_current_callback;
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122 assert(p == (intptr_t)callback_in_progress ||
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123 p == (intptr_t)cb, "wrong _current_callback value");
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124 #endif
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125 while (_current_callback != cb) {
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126 count++;
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127 #ifdef ASSERT
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128 if ((WarnOnStalledSpinLock > 0) &&
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129 (count % WarnOnStalledSpinLock == 0)) {
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130 warning("_current_callback seems to be stalled: %p", _current_callback);
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131 }
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132 #endif
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133 os::yield_all(count);
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134 }
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135 }
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136 }
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137
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138 void OSThread::do_interrupt_callbacks_at_interrupt(InterruptArguments *args) {
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139 Sync_Interrupt_Callback * cb;
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140 cb = (Sync_Interrupt_Callback *)exchange_current_callback(
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141 (intptr_t)callback_in_progress, (intptr_t *)&_current_callback, _current_callback_lock);
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142
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143 if (cb == NULL) {
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144 // signal is delivered too late (thread is masking interrupt signal??).
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145 // there is nothing we need to do because requesting thread has given up.
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146 } else if ((intptr_t)cb == (intptr_t)callback_in_progress) {
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147 fatal("invalid _current_callback state");
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148 } else {
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149 assert(cb->target()->osthread() == this, "wrong target");
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150 cb->execute(args);
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151 cb->leave_callback(); // notify the requester
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152 }
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153
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154 // restore original _current_callback value
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155 intptr_t p;
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156 p = exchange_current_callback((intptr_t)cb, (intptr_t *)&_current_callback, _current_callback_lock);
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157 assert(p == (intptr_t)callback_in_progress, "just checking");
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158 }
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159
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160 // Called by the requesting thread to send a signal to target thread and
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161 // execute "this" callback from the signal handler.
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162 int OSThread::Sync_Interrupt_Callback::interrupt(Thread * target, int timeout) {
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163 // Let signals to the vm_thread go even if the Threads_lock is not acquired
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164 assert(Threads_lock->owned_by_self() || (target == VMThread::vm_thread()),
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165 "must have threads lock to call this");
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166
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167 OSThread * osthread = target->osthread();
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168
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169 // may block if target thread already has a pending callback
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170 osthread->set_interrupt_callback(this);
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171
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172 _target = target;
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173
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174 int rslt = thr_kill(osthread->thread_id(), os::Solaris::SIGasync());
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175 assert(rslt == 0, "thr_kill != 0");
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176
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177 bool status = false;
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178 jlong t1 = os::javaTimeMillis();
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179 { // don't use safepoint check because we might be the watcher thread.
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180 MutexLockerEx ml(_sync, Mutex::_no_safepoint_check_flag);
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181 while (!is_done()) {
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182 status = _sync->wait(Mutex::_no_safepoint_check_flag, timeout);
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183
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184 // status == true if timed out
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185 if (status) break;
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186
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187 // update timeout
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188 jlong t2 = os::javaTimeMillis();
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189 timeout -= t2 - t1;
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190 t1 = t2;
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191 }
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192 }
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193
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194 // reset current_callback
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195 osthread->remove_interrupt_callback(this);
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196
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197 return status;
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198 }
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199
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200 void OSThread::Sync_Interrupt_Callback::leave_callback() {
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201 if (!_sync->owned_by_self()) {
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202 // notify requesting thread
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203 MutexLockerEx ml(_sync, Mutex::_no_safepoint_check_flag);
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204 _is_done = true;
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205 _sync->notify_all();
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206 } else {
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207 // Current thread is interrupted while it is holding the _sync lock, trying
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208 // to grab it again will deadlock. The requester will timeout anyway,
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209 // so just return.
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210 _is_done = true;
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211 }
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212 }
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213
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214 // copied from synchronizer.cpp
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215
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216 void OSThread::handle_spinlock_contention(int tries) {
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217 if (NoYieldsInMicrolock) return;
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218
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219 if (tries > 10) {
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220 os::yield_all(tries); // Yield to threads of any priority
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221 } else if (tries > 5) {
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222 os::yield(); // Yield to threads of same or higher priority
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223 }
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224 }
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