Andreas Gampe | 319dbe8 | 2017-01-09 16:42:21 -0800 | [diff] [blame] | 1 | /* Copyright (C) 2017 The Android Open Source Project |
| 2 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 3 | * |
| 4 | * This file implements interfaces from the file jvmti.h. This implementation |
| 5 | * is licensed under the same terms as the file jvmti.h. The |
| 6 | * copyright and license information for the file jvmti.h follows. |
| 7 | * |
| 8 | * Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved. |
| 9 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 10 | * |
| 11 | * This code is free software; you can redistribute it and/or modify it |
| 12 | * under the terms of the GNU General Public License version 2 only, as |
| 13 | * published by the Free Software Foundation. Oracle designates this |
| 14 | * particular file as subject to the "Classpath" exception as provided |
| 15 | * by Oracle in the LICENSE file that accompanied this code. |
| 16 | * |
| 17 | * This code is distributed in the hope that it will be useful, but WITHOUT |
| 18 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 19 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 20 | * version 2 for more details (a copy is included in the LICENSE file that |
| 21 | * accompanied this code). |
| 22 | * |
| 23 | * You should have received a copy of the GNU General Public License version |
| 24 | * 2 along with this work; if not, write to the Free Software Foundation, |
| 25 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| 26 | * |
| 27 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| 28 | * or visit www.oracle.com if you need additional information or have any |
| 29 | * questions. |
| 30 | */ |
| 31 | |
| 32 | #include "ti_monitor.h" |
| 33 | |
| 34 | #include <atomic> |
Igor Murashkin | 5573c37 | 2017-11-16 13:34:30 -0800 | [diff] [blame^] | 35 | #include <chrono> |
| 36 | #include <condition_variable> |
| 37 | #include <mutex> |
Andreas Gampe | 319dbe8 | 2017-01-09 16:42:21 -0800 | [diff] [blame] | 38 | |
| 39 | #include "art_jvmti.h" |
Alex Light | 41006c6 | 2017-09-14 09:51:14 -0700 | [diff] [blame] | 40 | #include "monitor.h" |
Andreas Gampe | 319dbe8 | 2017-01-09 16:42:21 -0800 | [diff] [blame] | 41 | #include "runtime.h" |
| 42 | #include "scoped_thread_state_change-inl.h" |
Andreas Gampe | b486a98 | 2017-06-01 13:45:54 -0700 | [diff] [blame] | 43 | #include "thread-current-inl.h" |
Alex Light | 23aa748 | 2017-08-16 10:01:13 -0700 | [diff] [blame] | 44 | #include "ti_thread.h" |
Alex Light | 41006c6 | 2017-09-14 09:51:14 -0700 | [diff] [blame] | 45 | #include "thread.h" |
| 46 | #include "thread_pool.h" |
Andreas Gampe | 319dbe8 | 2017-01-09 16:42:21 -0800 | [diff] [blame] | 47 | |
| 48 | namespace openjdkjvmti { |
| 49 | |
| 50 | // We cannot use ART monitors, as they require the mutator lock for contention locking. We |
| 51 | // also cannot use pthread mutexes and condition variables (or C++11 abstractions) directly, |
| 52 | // as the do not have the right semantics for recursive mutexes and waiting (wait only unlocks |
| 53 | // the mutex once). |
| 54 | // So go ahead and use a wrapper that does the counting explicitly. |
| 55 | |
| 56 | class JvmtiMonitor { |
| 57 | public: |
Alex Light | 23aa748 | 2017-08-16 10:01:13 -0700 | [diff] [blame] | 58 | JvmtiMonitor() : owner_(nullptr), count_(0) { } |
Andreas Gampe | 319dbe8 | 2017-01-09 16:42:21 -0800 | [diff] [blame] | 59 | |
David Sehr | ae3bcac | 2017-02-03 15:19:00 -0800 | [diff] [blame] | 60 | static bool Destroy(art::Thread* self, JvmtiMonitor* monitor) NO_THREAD_SAFETY_ANALYSIS { |
Andreas Gampe | 319dbe8 | 2017-01-09 16:42:21 -0800 | [diff] [blame] | 61 | // Check whether this thread holds the monitor, or nobody does. |
| 62 | art::Thread* owner_thread = monitor->owner_.load(std::memory_order_relaxed); |
| 63 | if (owner_thread != nullptr && self != owner_thread) { |
| 64 | return false; |
| 65 | } |
| 66 | |
| 67 | if (monitor->count_ > 0) { |
| 68 | monitor->count_ = 0; |
| 69 | monitor->owner_.store(nullptr, std::memory_order_relaxed); |
| 70 | monitor->mutex_.unlock(); |
| 71 | } |
| 72 | |
| 73 | delete monitor; |
| 74 | return true; |
| 75 | } |
| 76 | |
David Sehr | ae3bcac | 2017-02-03 15:19:00 -0800 | [diff] [blame] | 77 | void MonitorEnter(art::Thread* self) NO_THREAD_SAFETY_ANALYSIS { |
Alex Light | 23aa748 | 2017-08-16 10:01:13 -0700 | [diff] [blame] | 78 | // Perform a suspend-check. The spec doesn't require this but real-world agents depend on this |
| 79 | // behavior. We do this by performing a suspend-check then retrying if the thread is suspended |
| 80 | // before or after locking the internal mutex. |
| 81 | do { |
| 82 | ThreadUtil::SuspendCheck(self); |
| 83 | if (ThreadUtil::WouldSuspendForUserCode(self)) { |
| 84 | continue; |
| 85 | } |
Andreas Gampe | 319dbe8 | 2017-01-09 16:42:21 -0800 | [diff] [blame] | 86 | |
Alex Light | 23aa748 | 2017-08-16 10:01:13 -0700 | [diff] [blame] | 87 | // Check for recursive enter. |
| 88 | if (IsOwner(self)) { |
| 89 | count_++; |
| 90 | return; |
| 91 | } |
| 92 | |
| 93 | // Checking for user-code suspension takes acquiring 2 art::Mutexes so we want to avoid doing |
| 94 | // that if possible. To avoid it we try to get the internal mutex without sleeping. If we do |
| 95 | // this we don't bother doing another suspend check since it can linearize after the lock. |
| 96 | if (mutex_.try_lock()) { |
| 97 | break; |
| 98 | } else { |
| 99 | // Lock with sleep. We will need to check for suspension after this to make sure that agents |
| 100 | // won't deadlock. |
| 101 | mutex_.lock(); |
| 102 | if (!ThreadUtil::WouldSuspendForUserCode(self)) { |
| 103 | break; |
| 104 | } else { |
| 105 | // We got suspended in the middle of waiting for the mutex. We should release the mutex |
| 106 | // and try again so we can get it while not suspended. This lets some other |
| 107 | // (non-suspended) thread acquire the mutex in case it's waiting to wake us up. |
| 108 | mutex_.unlock(); |
| 109 | continue; |
| 110 | } |
| 111 | } |
| 112 | } while (true); |
Andreas Gampe | 319dbe8 | 2017-01-09 16:42:21 -0800 | [diff] [blame] | 113 | |
| 114 | DCHECK(owner_.load(std::memory_order_relaxed) == nullptr); |
| 115 | owner_.store(self, std::memory_order_relaxed); |
| 116 | DCHECK_EQ(0u, count_); |
| 117 | count_ = 1; |
| 118 | } |
| 119 | |
David Sehr | ae3bcac | 2017-02-03 15:19:00 -0800 | [diff] [blame] | 120 | bool MonitorExit(art::Thread* self) NO_THREAD_SAFETY_ANALYSIS { |
Andreas Gampe | 319dbe8 | 2017-01-09 16:42:21 -0800 | [diff] [blame] | 121 | if (!IsOwner(self)) { |
| 122 | return false; |
| 123 | } |
| 124 | |
| 125 | --count_; |
| 126 | if (count_ == 0u) { |
| 127 | owner_.store(nullptr, std::memory_order_relaxed); |
| 128 | mutex_.unlock(); |
| 129 | } |
| 130 | |
| 131 | return true; |
| 132 | } |
| 133 | |
| 134 | bool Wait(art::Thread* self) { |
| 135 | auto wait_without_timeout = [&](std::unique_lock<std::mutex>& lk) { |
| 136 | cond_.wait(lk); |
| 137 | }; |
| 138 | return Wait(self, wait_without_timeout); |
| 139 | } |
| 140 | |
| 141 | bool Wait(art::Thread* self, uint64_t timeout_in_ms) { |
| 142 | auto wait_with_timeout = [&](std::unique_lock<std::mutex>& lk) { |
| 143 | cond_.wait_for(lk, std::chrono::milliseconds(timeout_in_ms)); |
| 144 | }; |
| 145 | return Wait(self, wait_with_timeout); |
| 146 | } |
| 147 | |
| 148 | bool Notify(art::Thread* self) { |
| 149 | return Notify(self, [&]() { cond_.notify_one(); }); |
| 150 | } |
| 151 | |
| 152 | bool NotifyAll(art::Thread* self) { |
| 153 | return Notify(self, [&]() { cond_.notify_all(); }); |
| 154 | } |
| 155 | |
| 156 | private: |
Alex Light | 23aa748 | 2017-08-16 10:01:13 -0700 | [diff] [blame] | 157 | bool IsOwner(art::Thread* self) const { |
Andreas Gampe | 319dbe8 | 2017-01-09 16:42:21 -0800 | [diff] [blame] | 158 | // There's a subtle correctness argument here for a relaxed load outside the critical section. |
| 159 | // A thread is guaranteed to see either its own latest store or another thread's store. If a |
| 160 | // thread sees another thread's store than it cannot be holding the lock. |
| 161 | art::Thread* owner_thread = owner_.load(std::memory_order_relaxed); |
| 162 | return self == owner_thread; |
| 163 | } |
| 164 | |
| 165 | template <typename T> |
| 166 | bool Wait(art::Thread* self, T how_to_wait) { |
| 167 | if (!IsOwner(self)) { |
| 168 | return false; |
| 169 | } |
| 170 | |
| 171 | size_t old_count = count_; |
| 172 | |
| 173 | count_ = 0; |
| 174 | owner_.store(nullptr, std::memory_order_relaxed); |
| 175 | |
| 176 | { |
| 177 | std::unique_lock<std::mutex> lk(mutex_, std::adopt_lock); |
| 178 | how_to_wait(lk); |
| 179 | lk.release(); // Do not unlock the mutex. |
| 180 | } |
| 181 | |
| 182 | DCHECK(owner_.load(std::memory_order_relaxed) == nullptr); |
| 183 | owner_.store(self, std::memory_order_relaxed); |
| 184 | DCHECK_EQ(0u, count_); |
| 185 | count_ = old_count; |
| 186 | |
| 187 | return true; |
| 188 | } |
| 189 | |
| 190 | template <typename T> |
| 191 | bool Notify(art::Thread* self, T how_to_notify) { |
| 192 | if (!IsOwner(self)) { |
| 193 | return false; |
| 194 | } |
| 195 | |
| 196 | how_to_notify(); |
| 197 | |
| 198 | return true; |
| 199 | } |
| 200 | |
| 201 | std::mutex mutex_; |
| 202 | std::condition_variable cond_; |
| 203 | std::atomic<art::Thread*> owner_; |
| 204 | size_t count_; |
| 205 | }; |
| 206 | |
| 207 | static jrawMonitorID EncodeMonitor(JvmtiMonitor* monitor) { |
| 208 | return reinterpret_cast<jrawMonitorID>(monitor); |
| 209 | } |
| 210 | |
| 211 | static JvmtiMonitor* DecodeMonitor(jrawMonitorID id) { |
| 212 | return reinterpret_cast<JvmtiMonitor*>(id); |
| 213 | } |
| 214 | |
| 215 | jvmtiError MonitorUtil::CreateRawMonitor(jvmtiEnv* env ATTRIBUTE_UNUSED, |
| 216 | const char* name, |
| 217 | jrawMonitorID* monitor_ptr) { |
| 218 | if (name == nullptr || monitor_ptr == nullptr) { |
| 219 | return ERR(NULL_POINTER); |
| 220 | } |
| 221 | |
| 222 | JvmtiMonitor* monitor = new JvmtiMonitor(); |
| 223 | *monitor_ptr = EncodeMonitor(monitor); |
| 224 | |
| 225 | return ERR(NONE); |
| 226 | } |
| 227 | |
| 228 | jvmtiError MonitorUtil::DestroyRawMonitor(jvmtiEnv* env ATTRIBUTE_UNUSED, jrawMonitorID id) { |
| 229 | if (id == nullptr) { |
| 230 | return ERR(INVALID_MONITOR); |
| 231 | } |
| 232 | |
| 233 | JvmtiMonitor* monitor = DecodeMonitor(id); |
| 234 | art::Thread* self = art::Thread::Current(); |
| 235 | |
| 236 | if (!JvmtiMonitor::Destroy(self, monitor)) { |
| 237 | return ERR(NOT_MONITOR_OWNER); |
| 238 | } |
| 239 | |
| 240 | return ERR(NONE); |
| 241 | } |
| 242 | |
| 243 | jvmtiError MonitorUtil::RawMonitorEnter(jvmtiEnv* env ATTRIBUTE_UNUSED, jrawMonitorID id) { |
| 244 | if (id == nullptr) { |
| 245 | return ERR(INVALID_MONITOR); |
| 246 | } |
| 247 | |
| 248 | JvmtiMonitor* monitor = DecodeMonitor(id); |
| 249 | art::Thread* self = art::Thread::Current(); |
| 250 | |
| 251 | monitor->MonitorEnter(self); |
| 252 | |
| 253 | return ERR(NONE); |
| 254 | } |
| 255 | |
| 256 | jvmtiError MonitorUtil::RawMonitorExit(jvmtiEnv* env ATTRIBUTE_UNUSED, jrawMonitorID id) { |
| 257 | if (id == nullptr) { |
| 258 | return ERR(INVALID_MONITOR); |
| 259 | } |
| 260 | |
| 261 | JvmtiMonitor* monitor = DecodeMonitor(id); |
| 262 | art::Thread* self = art::Thread::Current(); |
| 263 | |
| 264 | if (!monitor->MonitorExit(self)) { |
| 265 | return ERR(NOT_MONITOR_OWNER); |
| 266 | } |
| 267 | |
| 268 | return ERR(NONE); |
| 269 | } |
| 270 | |
| 271 | jvmtiError MonitorUtil::RawMonitorWait(jvmtiEnv* env ATTRIBUTE_UNUSED, |
| 272 | jrawMonitorID id, |
| 273 | jlong millis) { |
| 274 | if (id == nullptr) { |
| 275 | return ERR(INVALID_MONITOR); |
| 276 | } |
| 277 | |
| 278 | JvmtiMonitor* monitor = DecodeMonitor(id); |
| 279 | art::Thread* self = art::Thread::Current(); |
| 280 | |
Alex Light | 6ced091 | 2017-08-16 15:16:13 -0700 | [diff] [blame] | 281 | // What millis < 0 means is not defined in the spec. Real world agents seem to assume that it is a |
| 282 | // valid call though. We treat it as though it was 0 and wait indefinitely. |
Andreas Gampe | 319dbe8 | 2017-01-09 16:42:21 -0800 | [diff] [blame] | 283 | bool result = (millis > 0) |
| 284 | ? monitor->Wait(self, static_cast<uint64_t>(millis)) |
| 285 | : monitor->Wait(self); |
| 286 | |
| 287 | if (!result) { |
| 288 | return ERR(NOT_MONITOR_OWNER); |
| 289 | } |
| 290 | |
| 291 | // TODO: Make sure that is really what we should be checking here. |
| 292 | if (self->IsInterrupted()) { |
| 293 | return ERR(INTERRUPT); |
| 294 | } |
| 295 | |
| 296 | return ERR(NONE); |
| 297 | } |
| 298 | |
| 299 | jvmtiError MonitorUtil::RawMonitorNotify(jvmtiEnv* env ATTRIBUTE_UNUSED, jrawMonitorID id) { |
| 300 | if (id == nullptr) { |
| 301 | return ERR(INVALID_MONITOR); |
| 302 | } |
| 303 | |
| 304 | JvmtiMonitor* monitor = DecodeMonitor(id); |
| 305 | art::Thread* self = art::Thread::Current(); |
| 306 | |
| 307 | if (!monitor->Notify(self)) { |
| 308 | return ERR(NOT_MONITOR_OWNER); |
| 309 | } |
| 310 | |
| 311 | return ERR(NONE); |
| 312 | } |
| 313 | |
| 314 | jvmtiError MonitorUtil::RawMonitorNotifyAll(jvmtiEnv* env ATTRIBUTE_UNUSED, jrawMonitorID id) { |
| 315 | if (id == nullptr) { |
| 316 | return ERR(INVALID_MONITOR); |
| 317 | } |
| 318 | |
| 319 | JvmtiMonitor* monitor = DecodeMonitor(id); |
| 320 | art::Thread* self = art::Thread::Current(); |
| 321 | |
| 322 | if (!monitor->NotifyAll(self)) { |
| 323 | return ERR(NOT_MONITOR_OWNER); |
| 324 | } |
| 325 | |
| 326 | return ERR(NONE); |
| 327 | } |
| 328 | |
Alex Light | 41006c6 | 2017-09-14 09:51:14 -0700 | [diff] [blame] | 329 | jvmtiError MonitorUtil::GetCurrentContendedMonitor(jvmtiEnv* env ATTRIBUTE_UNUSED, |
| 330 | jthread thread, |
| 331 | jobject* monitor) { |
| 332 | if (monitor == nullptr) { |
| 333 | return ERR(NULL_POINTER); |
| 334 | } |
| 335 | art::Thread* self = art::Thread::Current(); |
| 336 | art::ScopedObjectAccess soa(self); |
Alex Light | b1e31a8 | 2017-10-04 16:57:36 -0700 | [diff] [blame] | 337 | art::Locks::thread_list_lock_->ExclusiveLock(self); |
Alex Light | 7ddc23d | 2017-09-22 15:33:41 -0700 | [diff] [blame] | 338 | art::Thread* target = nullptr; |
| 339 | jvmtiError err = ERR(INTERNAL); |
| 340 | if (!ThreadUtil::GetAliveNativeThread(thread, soa, &target, &err)) { |
Alex Light | b1e31a8 | 2017-10-04 16:57:36 -0700 | [diff] [blame] | 341 | art::Locks::thread_list_lock_->ExclusiveUnlock(self); |
Alex Light | 7ddc23d | 2017-09-22 15:33:41 -0700 | [diff] [blame] | 342 | return err; |
Alex Light | 41006c6 | 2017-09-14 09:51:14 -0700 | [diff] [blame] | 343 | } |
| 344 | struct GetContendedMonitorClosure : public art::Closure { |
| 345 | public: |
| 346 | explicit GetContendedMonitorClosure(art::Thread* current, jobject* out) |
| 347 | : result_thread_(current), out_(out) {} |
| 348 | |
| 349 | void Run(art::Thread* target_thread) REQUIRES_SHARED(art::Locks::mutator_lock_) { |
| 350 | switch (target_thread->GetState()) { |
| 351 | // These three we are actually currently waiting on a monitor and have sent the appropriate |
| 352 | // events (if anyone is listening). |
| 353 | case art::kBlocked: |
| 354 | case art::kTimedWaiting: |
| 355 | case art::kWaiting: { |
| 356 | art::mirror::Object* mon = art::Monitor::GetContendedMonitor(target_thread); |
| 357 | *out_ = (mon == nullptr) ? nullptr |
| 358 | : result_thread_->GetJniEnv()->AddLocalReference<jobject>(mon); |
| 359 | return; |
| 360 | } |
| 361 | case art::kTerminated: |
| 362 | case art::kRunnable: |
| 363 | case art::kSleeping: |
| 364 | case art::kWaitingForLockInflation: |
| 365 | case art::kWaitingForTaskProcessor: |
| 366 | case art::kWaitingForGcToComplete: |
| 367 | case art::kWaitingForCheckPointsToRun: |
| 368 | case art::kWaitingPerformingGc: |
| 369 | case art::kWaitingForDebuggerSend: |
| 370 | case art::kWaitingForDebuggerToAttach: |
| 371 | case art::kWaitingInMainDebuggerLoop: |
| 372 | case art::kWaitingForDebuggerSuspension: |
| 373 | case art::kWaitingForJniOnLoad: |
| 374 | case art::kWaitingForSignalCatcherOutput: |
| 375 | case art::kWaitingInMainSignalCatcherLoop: |
| 376 | case art::kWaitingForDeoptimization: |
| 377 | case art::kWaitingForMethodTracingStart: |
| 378 | case art::kWaitingForVisitObjects: |
| 379 | case art::kWaitingForGetObjectsAllocated: |
| 380 | case art::kWaitingWeakGcRootRead: |
| 381 | case art::kWaitingForGcThreadFlip: |
| 382 | case art::kStarting: |
| 383 | case art::kNative: |
| 384 | case art::kSuspended: { |
| 385 | // We aren't currently (explicitly) waiting for a monitor anything so just return null. |
| 386 | *out_ = nullptr; |
| 387 | return; |
| 388 | } |
| 389 | } |
| 390 | } |
| 391 | |
| 392 | private: |
| 393 | art::Thread* result_thread_; |
| 394 | jobject* out_; |
| 395 | }; |
| 396 | GetContendedMonitorClosure closure(self, monitor); |
Alex Light | b1e31a8 | 2017-10-04 16:57:36 -0700 | [diff] [blame] | 397 | // RequestSynchronousCheckpoint releases the thread_list_lock_ as a part of its execution. |
Alex Light | d9aff13 | 2017-10-31 22:30:05 +0000 | [diff] [blame] | 398 | if (!ThreadUtil::RequestGCSafeSynchronousCheckpoint(target, &closure)) { |
Alex Light | 7ddc23d | 2017-09-22 15:33:41 -0700 | [diff] [blame] | 399 | return ERR(THREAD_NOT_ALIVE); |
| 400 | } |
Alex Light | 41006c6 | 2017-09-14 09:51:14 -0700 | [diff] [blame] | 401 | return OK; |
| 402 | } |
| 403 | |
Andreas Gampe | 319dbe8 | 2017-01-09 16:42:21 -0800 | [diff] [blame] | 404 | } // namespace openjdkjvmti |