1 /* 2 * Copyright (c) 2003, 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_SERVICES_THREADSERVICE_HPP 26 #define SHARE_SERVICES_THREADSERVICE_HPP 27 28 #include "classfile/javaClasses.hpp" 29 #include "runtime/handles.hpp" 30 #include "runtime/init.hpp" 31 #include "runtime/jniHandles.hpp" 32 #include "runtime/objectMonitor.hpp" 33 #include "runtime/perfData.hpp" 34 #include "runtime/safepoint.hpp" 35 #include "runtime/thread.hpp" 36 #include "runtime/threadSMR.hpp" 37 #include "services/management.hpp" 38 39 class OopClosure; 40 class ThreadDumpResult; 41 class ThreadStackTrace; 42 class ThreadSnapshot; 43 class StackFrameInfo; 44 class ThreadConcurrentLocks; 45 class DeadlockCycle; 46 47 // VM monitoring and management support for the thread and 48 // synchronization subsystem 49 // 50 // Thread contention monitoring is disabled by default. 51 // When enabled, the VM will begin measuring the accumulated 52 // elapsed time a thread blocked on synchronization. 53 // 54 class ThreadService : public AllStatic { 55 private: 56 // These counters could be moved to Threads class 57 static PerfCounter* _total_threads_count; 58 static PerfVariable* _live_threads_count; 59 static PerfVariable* _peak_threads_count; 60 static PerfVariable* _daemon_threads_count; 61 62 // These 2 counters are like the above thread counts, but are 63 // atomically decremented in ThreadService::current_thread_exiting instead of 64 // ThreadService::remove_thread, so that the thread count is updated before 65 // Thread.join() returns. 66 static volatile int _atomic_threads_count; 67 static volatile int _atomic_daemon_threads_count; 68 69 static bool _thread_monitoring_contention_enabled; 70 static bool _thread_cpu_time_enabled; 71 static bool _thread_allocated_memory_enabled; 72 73 // Need to keep the list of thread dump result that 74 // keep references to Method* since thread dump can be 75 // requested by multiple threads concurrently. 76 static ThreadDumpResult* _threaddump_list; 77 78 static void decrement_thread_counts(JavaThread* jt, bool daemon); 79 80 public: 81 static void init(); 82 static void add_thread(JavaThread* thread, bool daemon); 83 static void remove_thread(JavaThread* thread, bool daemon); 84 static void current_thread_exiting(JavaThread* jt, bool daemon); 85 86 static bool set_thread_monitoring_contention(bool flag); 87 static bool is_thread_monitoring_contention() { return _thread_monitoring_contention_enabled; } 88 89 static bool set_thread_cpu_time_enabled(bool flag); 90 static bool is_thread_cpu_time_enabled() { return _thread_cpu_time_enabled; } 91 92 static bool set_thread_allocated_memory_enabled(bool flag); 93 static bool is_thread_allocated_memory_enabled() { return _thread_allocated_memory_enabled; } 94 95 static jlong get_total_thread_count() { return _total_threads_count->get_value(); } 96 static jlong get_peak_thread_count() { return _peak_threads_count->get_value(); } 97 static jlong get_live_thread_count() { return _atomic_threads_count; } 98 static jlong get_daemon_thread_count() { return _atomic_daemon_threads_count; } 99 100 // Support for thread dump 101 static void add_thread_dump(ThreadDumpResult* dump); 102 static void remove_thread_dump(ThreadDumpResult* dump); 103 104 static Handle get_current_contended_monitor(JavaThread* thread); 105 106 // This function is called by JVM_DumpThreads. 107 static Handle dump_stack_traces(GrowableArray<instanceHandle>* threads, 108 int num_threads, TRAPS); 109 110 static void reset_peak_thread_count(); 111 static void reset_contention_count_stat(JavaThread* thread); 112 static void reset_contention_time_stat(JavaThread* thread); 113 114 static DeadlockCycle* find_deadlocks_at_safepoint(ThreadsList * t_list, bool object_monitors_only); 115 116 // GC support 117 static void oops_do(OopClosure* f); 118 static void metadata_do(void f(Metadata*)); 119 }; 120 121 // Per-thread Statistics for synchronization 122 class ThreadStatistics : public CHeapObj<mtInternal> { 123 private: 124 // The following contention statistics are only updated by 125 // the thread owning these statistics when contention occurs. 126 127 jlong _contended_enter_count; 128 elapsedTimer _contended_enter_timer; 129 jlong _monitor_wait_count; 130 elapsedTimer _monitor_wait_timer; 131 jlong _sleep_count; 132 elapsedTimer _sleep_timer; 133 134 135 // These two reset flags are set to true when another thread 136 // requests to reset the statistics. The actual statistics 137 // are reset when the thread contention occurs and attempts 138 // to update the statistics. 139 bool _count_pending_reset; 140 bool _timer_pending_reset; 141 142 // Keep accurate times for potentially recursive class operations 143 int _perf_recursion_counts[6]; 144 elapsedTimer _perf_timers[6]; 145 146 // utility functions 147 void check_and_reset_count() { 148 if (!_count_pending_reset) return; 149 _contended_enter_count = 0; 150 _monitor_wait_count = 0; 151 _sleep_count = 0; 152 _count_pending_reset = 0; 153 } 154 void check_and_reset_timer() { 155 if (!_timer_pending_reset) return; 156 _contended_enter_timer.reset(); 157 _monitor_wait_timer.reset(); 158 _sleep_timer.reset(); 159 _timer_pending_reset = 0; 160 } 161 162 public: 163 ThreadStatistics(); 164 165 jlong contended_enter_count() { return (_count_pending_reset ? 0 : _contended_enter_count); } 166 jlong contended_enter_ticks() { return (_timer_pending_reset ? 0 : _contended_enter_timer.active_ticks()); } 167 jlong monitor_wait_count() { return (_count_pending_reset ? 0 : _monitor_wait_count); } 168 jlong monitor_wait_ticks() { return (_timer_pending_reset ? 0 : _monitor_wait_timer.active_ticks()); } 169 jlong sleep_count() { return (_count_pending_reset ? 0 : _sleep_count); } 170 jlong sleep_ticks() { return (_timer_pending_reset ? 0 : _sleep_timer.active_ticks()); } 171 172 void monitor_wait() { check_and_reset_count(); _monitor_wait_count++; } 173 void monitor_wait_begin() { check_and_reset_timer(); _monitor_wait_timer.start(); } 174 void monitor_wait_end() { _monitor_wait_timer.stop(); check_and_reset_timer(); } 175 176 void thread_sleep() { check_and_reset_count(); _sleep_count++; } 177 void thread_sleep_begin() { check_and_reset_timer(); _sleep_timer.start(); } 178 void thread_sleep_end() { _sleep_timer.stop(); check_and_reset_timer(); } 179 180 void contended_enter() { check_and_reset_count(); _contended_enter_count++; } 181 void contended_enter_begin() { check_and_reset_timer(); _contended_enter_timer.start(); } 182 void contended_enter_end() { _contended_enter_timer.stop(); check_and_reset_timer(); } 183 184 void reset_count_stat() { _count_pending_reset = true; } 185 void reset_time_stat() { _timer_pending_reset = true; } 186 187 int* perf_recursion_counts_addr() { return _perf_recursion_counts; } 188 elapsedTimer* perf_timers_addr() { return _perf_timers; } 189 }; 190 191 // Thread snapshot to represent the thread state and statistics 192 class ThreadSnapshot : public CHeapObj<mtInternal> { 193 private: 194 // This JavaThread* is protected by being stored in objects that are 195 // protected by a ThreadsListSetter (ThreadDumpResult). 196 JavaThread* _thread; 197 oop _threadObj; 198 java_lang_Thread::ThreadStatus _thread_status; 199 200 bool _is_ext_suspended; 201 bool _is_in_native; 202 203 jlong _contended_enter_ticks; 204 jlong _contended_enter_count; 205 jlong _monitor_wait_ticks; 206 jlong _monitor_wait_count; 207 jlong _sleep_ticks; 208 jlong _sleep_count; 209 oop _blocker_object; 210 oop _blocker_object_owner; 211 212 ThreadStackTrace* _stack_trace; 213 ThreadConcurrentLocks* _concurrent_locks; 214 ThreadSnapshot* _next; 215 216 // ThreadSnapshot instances should only be created via 217 // ThreadDumpResult::add_thread_snapshot. 218 friend class ThreadDumpResult; 219 ThreadSnapshot() : _thread(NULL), _threadObj(NULL), 220 _blocker_object(NULL), _blocker_object_owner(NULL), 221 _stack_trace(NULL), _concurrent_locks(NULL), _next(NULL) {}; 222 void initialize(ThreadsList * t_list, JavaThread* thread); 223 224 public: 225 ~ThreadSnapshot(); 226 227 java_lang_Thread::ThreadStatus thread_status() { return _thread_status; } 228 229 oop threadObj() const { return _threadObj; } 230 231 void set_next(ThreadSnapshot* n) { _next = n; } 232 233 bool is_ext_suspended() { return _is_ext_suspended; } 234 bool is_in_native() { return _is_in_native; } 235 236 jlong contended_enter_count() { return _contended_enter_count; } 237 jlong contended_enter_ticks() { return _contended_enter_ticks; } 238 jlong monitor_wait_count() { return _monitor_wait_count; } 239 jlong monitor_wait_ticks() { return _monitor_wait_ticks; } 240 jlong sleep_count() { return _sleep_count; } 241 jlong sleep_ticks() { return _sleep_ticks; } 242 243 244 oop blocker_object() { return _blocker_object; } 245 oop blocker_object_owner() { return _blocker_object_owner; } 246 247 ThreadSnapshot* next() const { return _next; } 248 ThreadStackTrace* get_stack_trace() { return _stack_trace; } 249 ThreadConcurrentLocks* get_concurrent_locks() { return _concurrent_locks; } 250 251 void dump_stack_at_safepoint(int max_depth, bool with_locked_monitors); 252 void set_concurrent_locks(ThreadConcurrentLocks* l) { _concurrent_locks = l; } 253 void oops_do(OopClosure* f); 254 void metadata_do(void f(Metadata*)); 255 }; 256 257 class ThreadStackTrace : public CHeapObj<mtInternal> { 258 private: 259 JavaThread* _thread; 260 int _depth; // number of stack frames added 261 bool _with_locked_monitors; 262 GrowableArray<StackFrameInfo*>* _frames; 263 GrowableArray<oop>* _jni_locked_monitors; 264 265 public: 266 267 ThreadStackTrace(JavaThread* thread, bool with_locked_monitors); 268 ~ThreadStackTrace(); 269 270 JavaThread* thread() { return _thread; } 271 StackFrameInfo* stack_frame_at(int i) { return _frames->at(i); } 272 int get_stack_depth() { return _depth; } 273 274 void add_stack_frame(javaVFrame* jvf); 275 void dump_stack_at_safepoint(int max_depth); 276 Handle allocate_fill_stack_trace_element_array(TRAPS); 277 void oops_do(OopClosure* f); 278 void metadata_do(void f(Metadata*)); 279 GrowableArray<oop>* jni_locked_monitors() { return _jni_locked_monitors; } 280 int num_jni_locked_monitors() { return (_jni_locked_monitors != NULL ? _jni_locked_monitors->length() : 0); } 281 282 bool is_owned_monitor_on_stack(oop object); 283 void add_jni_locked_monitor(oop object) { _jni_locked_monitors->append(object); } 284 }; 285 286 // StackFrameInfo for keeping Method* and bci during 287 // stack walking for later construction of StackTraceElement[] 288 // Java instances 289 class StackFrameInfo : public CHeapObj<mtInternal> { 290 private: 291 Method* _method; 292 int _bci; 293 GrowableArray<oop>* _locked_monitors; // list of object monitors locked by this frame 294 // We need to save the mirrors in the backtrace to keep the class 295 // from being unloaded while we still have this stack trace. 296 oop _class_holder; 297 298 public: 299 300 StackFrameInfo(javaVFrame* jvf, bool with_locked_monitors); 301 ~StackFrameInfo() { 302 if (_locked_monitors != NULL) { 303 delete _locked_monitors; 304 } 305 }; 306 Method* method() const { return _method; } 307 int bci() const { return _bci; } 308 void oops_do(OopClosure* f); 309 void metadata_do(void f(Metadata*)); 310 311 int num_locked_monitors() { return (_locked_monitors != NULL ? _locked_monitors->length() : 0); } 312 GrowableArray<oop>* locked_monitors() { return _locked_monitors; } 313 314 void print_on(outputStream* st) const; 315 }; 316 317 class ThreadConcurrentLocks : public CHeapObj<mtInternal> { 318 private: 319 GrowableArray<instanceOop>* _owned_locks; 320 ThreadConcurrentLocks* _next; 321 // This JavaThread* is protected in one of two different ways 322 // depending on the usage of the ThreadConcurrentLocks object: 323 // 1) by being stored in objects that are only allocated and used at a 324 // safepoint (ConcurrentLocksDump), or 2) by being stored in objects 325 // that are protected by a ThreadsListSetter (ThreadSnapshot inside 326 // ThreadDumpResult). 327 JavaThread* _thread; 328 public: 329 ThreadConcurrentLocks(JavaThread* thread); 330 ~ThreadConcurrentLocks(); 331 332 void add_lock(instanceOop o); 333 void set_next(ThreadConcurrentLocks* n) { _next = n; } 334 ThreadConcurrentLocks* next() { return _next; } 335 JavaThread* java_thread() { return _thread; } 336 GrowableArray<instanceOop>* owned_locks() { return _owned_locks; } 337 void oops_do(OopClosure* f); 338 }; 339 340 class ConcurrentLocksDump : public StackObj { 341 private: 342 ThreadConcurrentLocks* _map; 343 ThreadConcurrentLocks* _last; // Last ThreadConcurrentLocks in the map 344 bool _retain_map_on_free; 345 346 void build_map(GrowableArray<oop>* aos_objects); 347 void add_lock(JavaThread* thread, instanceOop o); 348 349 public: 350 ConcurrentLocksDump(bool retain_map_on_free) : _map(NULL), _last(NULL), _retain_map_on_free(retain_map_on_free) { 351 assert(SafepointSynchronize::is_at_safepoint(), "Must be constructed at a safepoint."); 352 }; 353 ConcurrentLocksDump() : _map(NULL), _last(NULL), _retain_map_on_free(false) { 354 assert(SafepointSynchronize::is_at_safepoint(), "Must be constructed at a safepoint."); 355 }; 356 ~ConcurrentLocksDump(); 357 358 void dump_at_safepoint(); 359 ThreadConcurrentLocks* thread_concurrent_locks(JavaThread* thread); 360 void print_locks_on(JavaThread* t, outputStream* st); 361 }; 362 363 class ThreadDumpResult : public StackObj { 364 private: 365 int _num_threads; 366 int _num_snapshots; 367 ThreadSnapshot* _snapshots; 368 ThreadSnapshot* _last; 369 ThreadDumpResult* _next; 370 ThreadsListSetter _setter; // Helper to set hazard ptr in the originating thread 371 // which protects the JavaThreads in _snapshots. 372 373 void link_thread_snapshot(ThreadSnapshot* ts); 374 375 public: 376 ThreadDumpResult(); 377 ThreadDumpResult(int num_threads); 378 ~ThreadDumpResult(); 379 380 ThreadSnapshot* add_thread_snapshot(); 381 ThreadSnapshot* add_thread_snapshot(JavaThread* thread); 382 383 void set_next(ThreadDumpResult* next) { _next = next; } 384 ThreadDumpResult* next() { return _next; } 385 int num_threads() { return _num_threads; } 386 int num_snapshots() { return _num_snapshots; } 387 ThreadSnapshot* snapshots() { return _snapshots; } 388 void set_t_list() { _setter.set(); } 389 ThreadsList* t_list(); 390 bool t_list_has_been_set() { return _setter.is_set(); } 391 void oops_do(OopClosure* f); 392 void metadata_do(void f(Metadata*)); 393 }; 394 395 class DeadlockCycle : public CHeapObj<mtInternal> { 396 private: 397 bool _is_deadlock; 398 GrowableArray<JavaThread*>* _threads; 399 DeadlockCycle* _next; 400 public: 401 DeadlockCycle(); 402 ~DeadlockCycle(); 403 404 DeadlockCycle* next() { return _next; } 405 void set_next(DeadlockCycle* d) { _next = d; } 406 void add_thread(JavaThread* t) { _threads->append(t); } 407 void reset() { _is_deadlock = false; _threads->clear(); } 408 void set_deadlock(bool value) { _is_deadlock = value; } 409 bool is_deadlock() { return _is_deadlock; } 410 int num_threads() { return _threads->length(); } 411 GrowableArray<JavaThread*>* threads() { return _threads; } 412 void print_on_with(ThreadsList * t_list, outputStream* st) const; 413 }; 414 415 // Utility class to get list of java threads. 416 class ThreadsListEnumerator : public StackObj { 417 private: 418 GrowableArray<instanceHandle>* _threads_array; 419 public: 420 ThreadsListEnumerator(Thread* cur_thread, 421 bool include_jvmti_agent_threads = false, 422 bool include_jni_attaching_threads = true); 423 int num_threads() { return _threads_array->length(); } 424 instanceHandle get_threadObj(int index) { return _threads_array->at(index); } 425 }; 426 427 428 // abstract utility class to set new thread states, and restore previous after the block exits 429 class JavaThreadStatusChanger : public StackObj { 430 private: 431 java_lang_Thread::ThreadStatus _old_state; 432 JavaThread* _java_thread; 433 bool _is_alive; 434 435 void save_old_state(JavaThread* java_thread) { 436 _java_thread = java_thread; 437 _is_alive = is_alive(java_thread); 438 if (is_alive()) { 439 _old_state = java_lang_Thread::get_thread_status(_java_thread->threadObj()); 440 } 441 } 442 443 public: 444 static void set_thread_status(JavaThread* java_thread, 445 java_lang_Thread::ThreadStatus state) { 446 java_lang_Thread::set_thread_status(java_thread->threadObj(), state); 447 } 448 449 void set_thread_status(java_lang_Thread::ThreadStatus state) { 450 if (is_alive()) { 451 set_thread_status(_java_thread, state); 452 } 453 } 454 455 JavaThreadStatusChanger(JavaThread* java_thread, 456 java_lang_Thread::ThreadStatus state) : _old_state(java_lang_Thread::NEW) { 457 save_old_state(java_thread); 458 set_thread_status(state); 459 } 460 461 JavaThreadStatusChanger(JavaThread* java_thread) : _old_state(java_lang_Thread::NEW) { 462 save_old_state(java_thread); 463 } 464 465 ~JavaThreadStatusChanger() { 466 set_thread_status(_old_state); 467 } 468 469 static bool is_alive(JavaThread* java_thread) { 470 return java_thread != NULL && java_thread->threadObj() != NULL; 471 } 472 473 bool is_alive() { 474 return _is_alive; 475 } 476 }; 477 478 // Change status to waiting on an object (timed or indefinite) 479 class JavaThreadInObjectWaitState : public JavaThreadStatusChanger { 480 private: 481 ThreadStatistics* _stat; 482 bool _active; 483 484 public: 485 JavaThreadInObjectWaitState(JavaThread *java_thread, bool timed) : 486 JavaThreadStatusChanger(java_thread, 487 timed ? java_lang_Thread::IN_OBJECT_WAIT_TIMED : java_lang_Thread::IN_OBJECT_WAIT) { 488 if (is_alive()) { 489 _stat = java_thread->get_thread_stat(); 490 _active = ThreadService::is_thread_monitoring_contention(); 491 _stat->monitor_wait(); 492 if (_active) { 493 _stat->monitor_wait_begin(); 494 } 495 } else { 496 _active = false; 497 } 498 } 499 500 ~JavaThreadInObjectWaitState() { 501 if (_active) { 502 _stat->monitor_wait_end(); 503 } 504 } 505 }; 506 507 // Change status to parked (timed or indefinite) 508 class JavaThreadParkedState : public JavaThreadStatusChanger { 509 private: 510 ThreadStatistics* _stat; 511 bool _active; 512 513 public: 514 JavaThreadParkedState(JavaThread *java_thread, bool timed) : 515 JavaThreadStatusChanger(java_thread, 516 timed ? java_lang_Thread::PARKED_TIMED : java_lang_Thread::PARKED) { 517 if (is_alive()) { 518 _stat = java_thread->get_thread_stat(); 519 _active = ThreadService::is_thread_monitoring_contention(); 520 _stat->monitor_wait(); 521 if (_active) { 522 _stat->monitor_wait_begin(); 523 } 524 } else { 525 _active = false; 526 } 527 } 528 529 ~JavaThreadParkedState() { 530 if (_active) { 531 _stat->monitor_wait_end(); 532 } 533 } 534 }; 535 536 // Change status to blocked on (re-)entering a synchronization block 537 class JavaThreadBlockedOnMonitorEnterState : public JavaThreadStatusChanger { 538 private: 539 ThreadStatistics* _stat; 540 bool _active; 541 542 static bool contended_enter_begin(JavaThread *java_thread) { 543 set_thread_status(java_thread, java_lang_Thread::BLOCKED_ON_MONITOR_ENTER); 544 ThreadStatistics* stat = java_thread->get_thread_stat(); 545 stat->contended_enter(); 546 bool active = ThreadService::is_thread_monitoring_contention(); 547 if (active) { 548 stat->contended_enter_begin(); 549 } 550 return active; 551 } 552 553 public: 554 // java_thread is waiting thread being blocked on monitor reenter. 555 // Current thread is the notifying thread which holds the monitor. 556 static bool wait_reenter_begin(JavaThread *java_thread, ObjectMonitor *obj_m) { 557 assert((java_thread != NULL), "Java thread should not be null here"); 558 bool active = false; 559 if (is_alive(java_thread)) { 560 active = contended_enter_begin(java_thread); 561 } 562 return active; 563 } 564 565 static void wait_reenter_end(JavaThread *java_thread, bool active) { 566 if (active) { 567 java_thread->get_thread_stat()->contended_enter_end(); 568 } 569 set_thread_status(java_thread, java_lang_Thread::RUNNABLE); 570 } 571 572 JavaThreadBlockedOnMonitorEnterState(JavaThread *java_thread, ObjectMonitor *obj_m) : 573 JavaThreadStatusChanger(java_thread), _stat(NULL), _active(false) { 574 assert((java_thread != NULL), "Java thread should not be null here"); 575 // Change thread status and collect contended enter stats for monitor contended 576 // enter done for external java world objects and it is contended. All other cases 577 // like for vm internal objects and for external objects which are not contended 578 // thread status is not changed and contended enter stat is not collected. 579 _active = false; 580 if (is_alive() && obj_m->contentions() > 0) { 581 _stat = java_thread->get_thread_stat(); 582 _active = contended_enter_begin(java_thread); 583 } 584 } 585 586 ~JavaThreadBlockedOnMonitorEnterState() { 587 if (_active) { 588 _stat->contended_enter_end(); 589 } 590 } 591 }; 592 593 // Change status to sleeping 594 class JavaThreadSleepState : public JavaThreadStatusChanger { 595 private: 596 ThreadStatistics* _stat; 597 bool _active; 598 public: 599 JavaThreadSleepState(JavaThread *java_thread) : 600 JavaThreadStatusChanger(java_thread, java_lang_Thread::SLEEPING) { 601 if (is_alive()) { 602 _stat = java_thread->get_thread_stat(); 603 _active = ThreadService::is_thread_monitoring_contention(); 604 _stat->thread_sleep(); 605 if (_active) { 606 _stat->thread_sleep_begin(); 607 } 608 } else { 609 _active = false; 610 } 611 } 612 613 ~JavaThreadSleepState() { 614 if (_active) { 615 _stat->thread_sleep_end(); 616 } 617 } 618 }; 619 620 #endif // SHARE_SERVICES_THREADSERVICE_HPP