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test/hotspot/jtreg/serviceability/jvmti/HeapMonitor/libHeapMonitor.c

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rev 49264 : [mq]: event-only
rev 49266 : [mq]: event4
rev 49267 : [mq]: event5
rev 49268 : [mq]: event6


  43 #endif
  44 
  45 #endif
  46 
  47 #define TRUE 1
  48 #define FALSE 0
  49 #define PRINT_OUT 1
  50 #define MAX_TRACES 400
  51 
  52 static jvmtiEnv *jvmti = NULL;
  53 
  54 typedef struct _ObjectTrace{
  55   jweak object;
  56   size_t size;
  57   jvmtiFrameInfo* frames;
  58   size_t frame_count;
  59   jthread thread;
  60 } ObjectTrace;
  61 
  62 typedef struct _EventStorage {
  63   int compaction_required;
  64   int live_object_size;
  65   int live_object_count;
  66   ObjectTrace** live_objects;
  67 
  68   int garbage_history_size;
  69   int garbage_history_index;
  70   ObjectTrace** garbage_collected_objects;
  71 
  72   pthread_mutex_t mutex;





  73 } EventStorage;
  74 
  75 typedef struct _ExpectedContentFrame {
  76   const char *name;
  77   const char *signature;
  78   const char *file_name;
  79   int line_number;
  80 } ExpectedContentFrame;
  81 
  82 // Given a method and a location, this method gets the line number.
  83 static
  84 jint get_line_number(jvmtiEnv *jvmti, jmethodID method,
  85                      jlocation location) {
  86   // Read the line number table.
  87   jvmtiLineNumberEntry *table_ptr = 0;
  88   jint line_number_table_entries;
  89   int jvmti_error = (*jvmti)->GetLineNumberTable(jvmti, method,
  90                                                  &line_number_table_entries,
  91                                                  &table_ptr);
  92 


 217     string_object = (jstring) (*env)->GetObjectField(env, obj, string_id);
 218     const char* file_name = (*env)->GetStringUTFChars(env, string_object, 0);
 219 
 220     string_id = (*env)->GetFieldID(env, frame_class, "signature",
 221                                    "Ljava/lang/String;");
 222     string_object = (jstring) (*env)->GetObjectField(env, obj, string_id);
 223     const char* signature= (*env)->GetStringUTFChars(env, string_object, 0);
 224 
 225     native_frames[i].name = method;
 226     native_frames[i].file_name = file_name;
 227     native_frames[i].signature = signature;
 228     native_frames[i].line_number = line_number;
 229   }
 230 }
 231 
 232 // Internal storage system implementation.
 233 
 234 static EventStorage global_event_storage;
 235 
 236 static void event_storage_set_compaction_required(EventStorage* storage) {
 237   pthread_mutex_lock(&storage->mutex);
 238   storage->compaction_required = 1;
 239   pthread_mutex_unlock(&storage->mutex);
 240 }
 241 
 242 static int event_storage_get_compaction_required(EventStorage* storage) {
 243   pthread_mutex_lock(&storage->mutex);
 244   int result = storage->compaction_required;
 245   pthread_mutex_unlock(&storage->mutex);
 246   return result;
 247 }
 248 
 249 static void event_storage_set_garbage_history(EventStorage* storage, int value) {
 250   pthread_mutex_lock(&storage->mutex);
 251   global_event_storage.garbage_history_size = value;
 252   free(global_event_storage.garbage_collected_objects);
 253   size_t size =
 254       sizeof(*global_event_storage.garbage_collected_objects) * value;
 255   global_event_storage.garbage_collected_objects = malloc(size);
 256   memset(global_event_storage.garbage_collected_objects, 0, size);
 257   pthread_mutex_unlock(&storage->mutex);
 258 }
 259 
 260 // No mutex here, it is handled by the caller.
 261 static void event_storage_add_garbage_collected_object(EventStorage* storage,
 262                                                        ObjectTrace* object) {
 263   int idx = storage->garbage_history_index;
 264   free(storage->garbage_collected_objects[idx]);
 265   storage->garbage_collected_objects[idx] = object;
 266   storage->garbage_history_index = (idx + 1) % storage->garbage_history_size;
 267 }
 268 
 269 static int event_storage_get_count(EventStorage* storage) {
 270   pthread_mutex_lock(&storage->mutex);
 271   int result = storage->live_object_count;
 272   pthread_mutex_unlock(&storage->mutex);
 273   return result;
 274 }
 275 
 276 static double event_storage_get_average_rate(EventStorage* storage) {
 277   double accumulation = 0;
 278 
 279   pthread_mutex_lock(&storage->mutex);
 280   int max_size = storage->live_object_count;
 281 
 282   for (int i = 0; i < max_size; i++) {

 283     accumulation += storage->live_objects[i]->size;
 284   }
 285   pthread_mutex_unlock(&storage->mutex);
 286   return accumulation / max_size;
 287 }
 288 
 289 static jboolean event_storage_contains(JNIEnv* env,
 290                                        EventStorage* storage,
 291                                        ExpectedContentFrame* frames,
 292                                        size_t size) {
 293   pthread_mutex_lock(&storage->mutex);
 294   fprintf(stderr, "Checking storage count %d\n", storage->live_object_count);
 295   int i;
 296   for (i = 0; i < storage->live_object_count; i++) {
 297     ObjectTrace* trace = storage->live_objects[i];
 298 
 299     if (check_sample_content(env, trace, frames, size, PRINT_OUT)) {
 300       pthread_mutex_unlock(&storage->mutex);
 301       return TRUE;
 302     }
 303   }
 304   pthread_mutex_unlock(&storage->mutex);
 305   return FALSE;
 306 }
 307 
 308 static jboolean event_storage_garbage_contains(JNIEnv* env,
 309                                                EventStorage* storage,
 310                                                ExpectedContentFrame* frames,
 311                                                size_t size) {
 312   pthread_mutex_lock(&storage->mutex);
 313   fprintf(stderr, "Checking garbage storage count %d\n",
 314           storage->garbage_history_size);
 315   int i;
 316   for (i = 0; i < storage->garbage_history_size; i++) {
 317     ObjectTrace* trace = storage->garbage_collected_objects[i];
 318 
 319     if (trace == NULL) {
 320       continue;
 321     }
 322 
 323     if (check_sample_content(env, trace, frames, size, PRINT_OUT)) {
 324       pthread_mutex_unlock(&storage->mutex);
 325       return TRUE;
 326     }
 327   }
 328   pthread_mutex_unlock(&storage->mutex);
 329   return FALSE;
 330 }
 331 
 332 // No mutex here, handled by the caller.
 333 static void event_storage_augment_storage(EventStorage* storage) {
 334   int new_max = (storage->live_object_size * 2) + 1;
 335   ObjectTrace** new_objects = malloc(new_max * sizeof(*new_objects));
 336 
 337   int current_count = storage->live_object_count;
 338   memcpy(new_objects, storage->live_objects, current_count * sizeof(*new_objects));
 339   free(storage->live_objects);
 340   storage->live_objects = new_objects;
 341 
 342   storage->live_object_size = new_max;
 343 }
 344 
 345 static void event_storage_add(EventStorage* storage,
 346                               JNIEnv* jni,
 347                               jthread thread,
 348                               jobject object,
 349                               jclass klass,
 350                               jlong size) {
 351   jvmtiFrameInfo frames[64];
 352   jint count;
 353   jvmtiError err;
 354 
 355   err = (*jvmti)->GetStackTrace(jvmti, thread, 0, 64, frames, &count);
 356   if (err == JVMTI_ERROR_NONE && count >= 1) {
 357     pthread_mutex_lock(&storage->mutex);
 358 
 359     if (storage->live_object_count >= storage->live_object_size) {
 360       event_storage_augment_storage(storage);
 361     }
 362     assert(storage->live_object_count < storage->live_object_size);
 363 
 364     jvmtiFrameInfo* allocated_frames = malloc(count * sizeof(*allocated_frames));
 365     memcpy(allocated_frames, frames, count * sizeof(*allocated_frames));
 366 
 367     ObjectTrace* live_object = malloc(sizeof(*live_object));
 368     live_object->frames = allocated_frames;
 369     live_object->frame_count = count;
 370     live_object->size = size;
 371     live_object->thread = thread;
 372     live_object->object = (*jni)->NewWeakGlobalRef(jni, object);









 373     storage->live_objects[storage->live_object_count] = live_object;
 374     storage->live_object_count++;
 375 
 376     pthread_mutex_unlock(&storage->mutex);
 377   }
 378 }
 379 
 380 static void event_storage_compact(EventStorage* storage, JNIEnv* jni) {
 381   pthread_mutex_lock(&storage->mutex);
 382   storage->compaction_required = 0;



 383 
 384   int max = storage->live_object_count;
 385   int i, dest;
 386   ObjectTrace** live_objects = storage->live_objects;
 387 
 388   for (i = 0, dest = 0; i < max; i++) {
 389     ObjectTrace* live_object = live_objects[i];
 390     jweak object = live_object->object;
 391 
 392     if (!(*jni)->IsSameObject(jni, object, NULL)) {
 393       if (dest != i) {
 394         live_objects[dest] = live_object;
 395         dest++;
 396       }
 397     } else {
 398       event_storage_add_garbage_collected_object(storage, live_object);
 399     }
 400   }
 401 
 402   storage->live_object_count = dest;
 403   pthread_mutex_unlock(&storage->mutex);
 404 }
 405 
 406 static void event_storage_free_objects(ObjectTrace** array, int max) {
 407   int i;
 408   for (i = 0; i < max; i++) {
 409     free(array[i]), array[i] = NULL;
 410   }
 411 }
 412 
 413 static void event_storage_reset(EventStorage* storage) {
 414   pthread_mutex_lock(&storage->mutex);
 415 
 416   // Reset everything except the mutex and the garbage collection.
 417   event_storage_free_objects(storage->live_objects,
 418                              storage->live_object_count);
 419   storage->live_object_size = 0;
 420   storage->live_object_count = 0;
 421   free(storage->live_objects), storage->live_objects = NULL;
 422 
 423   event_storage_free_objects(storage->garbage_collected_objects,
 424                              storage->garbage_history_size);
 425 
 426   storage->compaction_required = 0;
 427   storage->garbage_history_index = 0;
 428 
 429   pthread_mutex_unlock(&storage->mutex);
 430 }
 431 
 432 // Start of the JVMTI agent code.
 433 
 434 static const char *EXC_CNAME = "java/lang/Exception";
 435 
 436 static int check_error(jvmtiError err, const char *s) {
 437   if (err != JVMTI_ERROR_NONE) {
 438     printf("  ## %s error: %d\n", s, err);
 439     return 1;
 440   }
 441   return 0;
 442 }
 443 
 444 static int check_capability_error(jvmtiError err, const char *s) {
 445   if (err != JVMTI_ERROR_NONE) {
 446     if (err == JVMTI_ERROR_MUST_POSSESS_CAPABILITY) {
 447       return 0;
 448     }
 449     printf("  ## %s error: %d\n", s, err);


 506                      "Set event notifications")) {
 507     return 1;
 508   }
 509 
 510   return check_error((*jvmti)->SetEventNotificationMode(
 511       jvmti, JVMTI_ENABLE, JVMTI_EVENT_SAMPLED_OBJECT_ALLOC, NULL),
 512                      "Set event notifications");
 513 }
 514 
 515 static
 516 jint Agent_Initialize(JavaVM *jvm, char *options, void *reserved) {
 517   jint res;
 518 
 519   res = JNI_ENV_PTR(jvm)->GetEnv(JNI_ENV_ARG(jvm, (void **) &jvmti),
 520                                  JVMTI_VERSION_9);
 521   if (res != JNI_OK || jvmti == NULL) {
 522     printf("    Error: wrong result of a valid call to GetEnv!\n");
 523     return JNI_ERR;
 524   }
 525 
 526   pthread_mutex_init(&global_event_storage.mutex, 0);

 527   event_storage_set_garbage_history(&global_event_storage, 200);
 528 
 529   jvmtiEventCallbacks callbacks;
 530   memset(&callbacks, 0, sizeof(callbacks));
 531   callbacks.SampledObjectAlloc = &SampledObjectAlloc;
 532   callbacks.GarbageCollectionFinish = &GarbageCollectionFinish;
 533 
 534   jvmtiCapabilities caps;
 535   memset(&caps, 0, sizeof(caps));
 536   // Get line numbers, sample heap, sample events, and filename for the test.
 537   caps.can_get_line_numbers = 1;
 538   caps.can_sample_heap = 1;
 539   caps.can_get_source_file_name = 1;
 540   caps.can_generate_garbage_collection_events = 1;
 541   if (check_error((*jvmti)->AddCapabilities(jvmti, &caps), "Add capabilities")){
 542     return JNI_ERR;
 543   }
 544 
 545   if (enable_notifications()) {
 546     return JNI_ERR;
 547   }
 548 
 549   if (check_error((*jvmti)->SetEventCallbacks(jvmti, &callbacks,
 550                                               sizeof(jvmtiEventCallbacks)),
 551                   " Set Event Callbacks")) {
 552     return JNI_ERR;
 553   }
 554   return JNI_OK;
 555 }
 556 
 557 JNIEXPORT void JNICALL
 558 Java_MyPackage_HeapMonitor_setSamplingRate(JNIEnv* env, jclass cls, jint value) {
 559   (*jvmti)->SetHeapSamplingRate(jvmti, value);
 560 }
 561 
 562 JNIEXPORT void JNICALL
 563 Java_MyPackage_HeapMonitor_setGarbageHistory(JNIEnv* env, jclass cls, jint value) {
 564   event_storage_set_garbage_history(&global_event_storage, value);
 565 }
 566 
 567 JNIEXPORT jboolean JNICALL
 568 Java_MyPackage_HeapMonitor_eventStorageIsEmpty(JNIEnv* env, jclass cls) {


 605   fill_native_frames(env, frames, native_frames, size);
 606   return event_storage_garbage_contains(env, &global_event_storage, native_frames, size);
 607 }
 608 
 609 JNIEXPORT void JNICALL
 610 Java_MyPackage_HeapMonitor_forceGarbageCollection(JNIEnv* env, jclass cls) {
 611   check_error((*jvmti)->ForceGarbageCollection(jvmti),
 612               "Forced Garbage Collection");
 613 }
 614 
 615 JNIEXPORT void JNICALL
 616 Java_MyPackage_HeapMonitor_resetEventStorage(JNIEnv* env, jclass cls) {
 617   return event_storage_reset(&global_event_storage);
 618 }
 619 
 620 JNIEXPORT jboolean JNICALL
 621 Java_MyPackage_HeapMonitorNoCapabilityTest_allSamplingMethodsFail(JNIEnv *env,
 622                                                                   jclass cls) {
 623   jvmtiCapabilities caps;
 624   memset(&caps, 0, sizeof(caps));
 625   caps.can_sample_heap= 1;
 626   if (check_error((*jvmti)->RelinquishCapabilities(jvmti, &caps),
 627                   "Add capabilities\n")){
 628     return FALSE;
 629   }
 630 
 631   if (check_capability_error((*jvmti)->SetHeapSamplingRate(jvmti, 1<<19),
 632                              "Set Heap Sampling Rate")) {
 633     return FALSE;
 634   }
 635   return TRUE;
 636 }
 637 
 638 JNIEXPORT jdouble JNICALL
 639 Java_MyPackage_HeapMonitorStatRateTest_getAverageRate(JNIEnv *env, jclass cls) {
 640   return event_storage_get_average_rate(&global_event_storage);
 641 }
 642 
 643 typedef struct sThreadsFound {
 644   jthread* threads;
 645   int num_threads;


 679     int found = 0;
 680     int j;
 681     for (j = 0; j < num_threads; j++) {
 682       if (thread == threads[j]) {
 683         found = 1;
 684         break;
 685       }
 686     }
 687 
 688     if (!found) {
 689       threads[num_threads] = thread;
 690       num_threads++;
 691     }
 692   }
 693   thread_data->num_threads = num_threads;
 694 }
 695 
 696 JNIEXPORT jboolean JNICALL
 697 Java_MyPackage_HeapMonitorThreadTest_checkSamples(JNIEnv* env, jclass cls,
 698                                                   jint num_threads) {
 699   pthread_mutex_lock(&global_event_storage.mutex);
 700   jint trace_counter;
 701 
 702   ThreadsFound thread_data;
 703   thread_data.num_threads = 0;
 704   thread_data.threads = malloc(sizeof(jthread) * num_threads);
 705   memset(thread_data.threads, 0, sizeof(jthread) * num_threads);
 706 
 707   find_threads_in_array(&thread_data, global_event_storage.live_objects,
 708                         global_event_storage.live_object_count);
 709   find_threads_in_array(&thread_data,
 710                         global_event_storage.garbage_collected_objects,
 711                         global_event_storage.garbage_history_size);
 712 
 713   free(thread_data.threads);
 714   pthread_mutex_unlock(&global_event_storage.mutex);
 715   return thread_data.num_threads == num_threads;
 716 }
 717 
 718 #ifdef __cplusplus
 719 }
 720 #endif


  43 #endif
  44 
  45 #endif
  46 
  47 #define TRUE 1
  48 #define FALSE 0
  49 #define PRINT_OUT 1
  50 #define MAX_TRACES 400
  51 
  52 static jvmtiEnv *jvmti = NULL;
  53 
  54 typedef struct _ObjectTrace{
  55   jweak object;
  56   size_t size;
  57   jvmtiFrameInfo* frames;
  58   size_t frame_count;
  59   jthread thread;
  60 } ObjectTrace;
  61 
  62 typedef struct _EventStorage {

  63   int live_object_size;
  64   int live_object_count;
  65   ObjectTrace** live_objects;
  66 
  67   int garbage_history_size;
  68   int garbage_history_index;
  69   ObjectTrace** garbage_collected_objects;
  70 
  71   // Two separate mutexes to separate storage data race and the compaction field
  72   // data race.
  73   pthread_mutex_t storage_mutex;
  74 
  75   int compaction_required;
  76   pthread_mutex_t compaction_mutex;
  77 } EventStorage;
  78 
  79 typedef struct _ExpectedContentFrame {
  80   const char *name;
  81   const char *signature;
  82   const char *file_name;
  83   int line_number;
  84 } ExpectedContentFrame;
  85 
  86 // Given a method and a location, this method gets the line number.
  87 static
  88 jint get_line_number(jvmtiEnv *jvmti, jmethodID method,
  89                      jlocation location) {
  90   // Read the line number table.
  91   jvmtiLineNumberEntry *table_ptr = 0;
  92   jint line_number_table_entries;
  93   int jvmti_error = (*jvmti)->GetLineNumberTable(jvmti, method,
  94                                                  &line_number_table_entries,
  95                                                  &table_ptr);
  96 


 221     string_object = (jstring) (*env)->GetObjectField(env, obj, string_id);
 222     const char* file_name = (*env)->GetStringUTFChars(env, string_object, 0);
 223 
 224     string_id = (*env)->GetFieldID(env, frame_class, "signature",
 225                                    "Ljava/lang/String;");
 226     string_object = (jstring) (*env)->GetObjectField(env, obj, string_id);
 227     const char* signature= (*env)->GetStringUTFChars(env, string_object, 0);
 228 
 229     native_frames[i].name = method;
 230     native_frames[i].file_name = file_name;
 231     native_frames[i].signature = signature;
 232     native_frames[i].line_number = line_number;
 233   }
 234 }
 235 
 236 // Internal storage system implementation.
 237 
 238 static EventStorage global_event_storage;
 239 
 240 static void event_storage_set_compaction_required(EventStorage* storage) {
 241   pthread_mutex_lock(&storage->compaction_mutex);
 242   storage->compaction_required = 1;
 243   pthread_mutex_unlock(&storage->compaction_mutex);
 244 }
 245 
 246 static int event_storage_get_compaction_required(EventStorage* storage) {
 247   pthread_mutex_lock(&storage->compaction_mutex);
 248   int result = storage->compaction_required;
 249   pthread_mutex_unlock(&storage->compaction_mutex);
 250   return result;
 251 }
 252 
 253 static void event_storage_set_garbage_history(EventStorage* storage, int value) {
 254   pthread_mutex_lock(&storage->storage_mutex);
 255   global_event_storage.garbage_history_size = value;
 256   free(global_event_storage.garbage_collected_objects);
 257   size_t size =
 258       sizeof(*global_event_storage.garbage_collected_objects) * value;
 259   global_event_storage.garbage_collected_objects = malloc(size);
 260   memset(global_event_storage.garbage_collected_objects, 0, size);
 261   pthread_mutex_unlock(&storage->storage_mutex);
 262 }
 263 
 264 // No mutex here, it is handled by the caller.
 265 static void event_storage_add_garbage_collected_object(EventStorage* storage,
 266                                                        ObjectTrace* object) {
 267   int idx = storage->garbage_history_index;
 268   free(storage->garbage_collected_objects[idx]);
 269   storage->garbage_collected_objects[idx] = object;
 270   storage->garbage_history_index = (idx + 1) % storage->garbage_history_size;
 271 }
 272 
 273 static int event_storage_get_count(EventStorage* storage) {
 274   pthread_mutex_lock(&storage->storage_mutex);
 275   int result = storage->live_object_count;
 276   pthread_mutex_unlock(&storage->storage_mutex);
 277   return result;
 278 }
 279 
 280 static double event_storage_get_average_rate(EventStorage* storage) {
 281   double accumulation = 0;
 282 
 283   pthread_mutex_lock(&storage->storage_mutex);
 284   int max_size = storage->live_object_count;
 285 
 286   int i;
 287   for (i = 0; i < max_size; i++) {
 288     accumulation += storage->live_objects[i]->size;
 289   }
 290   pthread_mutex_unlock(&storage->storage_mutex);
 291   return accumulation / max_size;
 292 }
 293 
 294 static jboolean event_storage_contains(JNIEnv* env,
 295                                        EventStorage* storage,
 296                                        ExpectedContentFrame* frames,
 297                                        size_t size) {
 298   pthread_mutex_lock(&storage->storage_mutex);
 299   fprintf(stderr, "Checking storage count %d\n", storage->live_object_count);
 300   int i;
 301   for (i = 0; i < storage->live_object_count; i++) {
 302     ObjectTrace* trace = storage->live_objects[i];
 303 
 304     if (check_sample_content(env, trace, frames, size, PRINT_OUT)) {
 305       pthread_mutex_unlock(&storage->storage_mutex);
 306       return TRUE;
 307     }
 308   }
 309   pthread_mutex_unlock(&storage->storage_mutex);
 310   return FALSE;
 311 }
 312 
 313 static jboolean event_storage_garbage_contains(JNIEnv* env,
 314                                                EventStorage* storage,
 315                                                ExpectedContentFrame* frames,
 316                                                size_t size) {
 317   pthread_mutex_lock(&storage->storage_mutex);
 318   fprintf(stderr, "Checking garbage storage count %d\n",
 319           storage->garbage_history_size);
 320   int i;
 321   for (i = 0; i < storage->garbage_history_size; i++) {
 322     ObjectTrace* trace = storage->garbage_collected_objects[i];
 323 
 324     if (trace == NULL) {
 325       continue;
 326     }
 327 
 328     if (check_sample_content(env, trace, frames, size, PRINT_OUT)) {
 329       pthread_mutex_unlock(&storage->storage_mutex);
 330       return TRUE;
 331     }
 332   }
 333   pthread_mutex_unlock(&storage->storage_mutex);
 334   return FALSE;
 335 }
 336 
 337 // No mutex here, handled by the caller.
 338 static void event_storage_augment_storage(EventStorage* storage) {
 339   int new_max = (storage->live_object_size * 2) + 1;
 340   ObjectTrace** new_objects = malloc(new_max * sizeof(*new_objects));
 341 
 342   int current_count = storage->live_object_count;
 343   memcpy(new_objects, storage->live_objects, current_count * sizeof(*new_objects));
 344   free(storage->live_objects);
 345   storage->live_objects = new_objects;
 346 
 347   storage->live_object_size = new_max;
 348 }
 349 
 350 static void event_storage_add(EventStorage* storage,
 351                               JNIEnv* jni,
 352                               jthread thread,
 353                               jobject object,
 354                               jclass klass,
 355                               jlong size) {
 356   jvmtiFrameInfo frames[64];
 357   jint count;
 358   jvmtiError err;
 359 
 360   err = (*jvmti)->GetStackTrace(jvmti, thread, 0, 64, frames, &count);
 361   if (err == JVMTI_ERROR_NONE && count >= 1) {
 362     jvmtiFrameInfo* allocated_frames = (jvmtiFrameInfo*) malloc(count * sizeof(*allocated_frames));







 363     memcpy(allocated_frames, frames, count * sizeof(*allocated_frames));
 364 
 365     ObjectTrace* live_object = (ObjectTrace*) malloc(sizeof(*live_object));
 366     live_object->frames = allocated_frames;
 367     live_object->frame_count = count;
 368     live_object->size = size;
 369     live_object->thread = thread;
 370     live_object->object = (*jni)->NewWeakGlobalRef(jni, object);
 371 
 372     // Only now lock and get things done quickly.
 373     pthread_mutex_lock(&storage->storage_mutex);
 374 
 375     if (storage->live_object_count >= storage->live_object_size) {
 376       event_storage_augment_storage(storage);
 377     }
 378     assert(storage->live_object_count < storage->live_object_size);
 379 
 380     storage->live_objects[storage->live_object_count] = live_object;
 381     storage->live_object_count++;
 382 
 383     pthread_mutex_unlock(&storage->storage_mutex);
 384   }
 385 }
 386 
 387 static void event_storage_compact(EventStorage* storage, JNIEnv* jni) {
 388   pthread_mutex_lock(&storage->compaction_mutex);
 389   storage->compaction_required = 0;
 390   pthread_mutex_unlock(&storage->compaction_mutex);
 391 
 392   pthread_mutex_lock(&storage->storage_mutex);
 393 
 394   int max = storage->live_object_count;
 395   int i, dest;
 396   ObjectTrace** live_objects = storage->live_objects;
 397 
 398   for (i = 0, dest = 0; i < max; i++) {
 399     ObjectTrace* live_object = live_objects[i];
 400     jweak object = live_object->object;
 401 
 402     if (!(*jni)->IsSameObject(jni, object, NULL)) {
 403       if (dest != i) {
 404         live_objects[dest] = live_object;
 405         dest++;
 406       }
 407     } else {
 408       event_storage_add_garbage_collected_object(storage, live_object);
 409     }
 410   }
 411 
 412   storage->live_object_count = dest;
 413   pthread_mutex_unlock(&storage->storage_mutex);
 414 }
 415 
 416 static void event_storage_free_objects(ObjectTrace** array, int max) {
 417   int i;
 418   for (i = 0; i < max; i++) {
 419     free(array[i]), array[i] = NULL;
 420   }
 421 }
 422 
 423 static void event_storage_reset(EventStorage* storage) {
 424   pthread_mutex_lock(&storage->storage_mutex);
 425 
 426   // Reset everything except the mutex and the garbage collection.
 427   event_storage_free_objects(storage->live_objects,
 428                              storage->live_object_count);
 429   storage->live_object_size = 0;
 430   storage->live_object_count = 0;
 431   free(storage->live_objects), storage->live_objects = NULL;
 432 
 433   event_storage_free_objects(storage->garbage_collected_objects,
 434                              storage->garbage_history_size);
 435 
 436   storage->compaction_required = 0;
 437   storage->garbage_history_index = 0;
 438 
 439   pthread_mutex_unlock(&storage->storage_mutex);
 440 }
 441 
 442 // Start of the JVMTI agent code.
 443 
 444 static const char *EXC_CNAME = "java/lang/Exception";
 445 
 446 static int check_error(jvmtiError err, const char *s) {
 447   if (err != JVMTI_ERROR_NONE) {
 448     printf("  ## %s error: %d\n", s, err);
 449     return 1;
 450   }
 451   return 0;
 452 }
 453 
 454 static int check_capability_error(jvmtiError err, const char *s) {
 455   if (err != JVMTI_ERROR_NONE) {
 456     if (err == JVMTI_ERROR_MUST_POSSESS_CAPABILITY) {
 457       return 0;
 458     }
 459     printf("  ## %s error: %d\n", s, err);


 516                      "Set event notifications")) {
 517     return 1;
 518   }
 519 
 520   return check_error((*jvmti)->SetEventNotificationMode(
 521       jvmti, JVMTI_ENABLE, JVMTI_EVENT_SAMPLED_OBJECT_ALLOC, NULL),
 522                      "Set event notifications");
 523 }
 524 
 525 static
 526 jint Agent_Initialize(JavaVM *jvm, char *options, void *reserved) {
 527   jint res;
 528 
 529   res = JNI_ENV_PTR(jvm)->GetEnv(JNI_ENV_ARG(jvm, (void **) &jvmti),
 530                                  JVMTI_VERSION_9);
 531   if (res != JNI_OK || jvmti == NULL) {
 532     printf("    Error: wrong result of a valid call to GetEnv!\n");
 533     return JNI_ERR;
 534   }
 535 
 536   pthread_mutex_init(&global_event_storage.storage_mutex, 0);
 537   pthread_mutex_init(&global_event_storage.compaction_mutex, 0);
 538   event_storage_set_garbage_history(&global_event_storage, 200);
 539 
 540   jvmtiEventCallbacks callbacks;
 541   memset(&callbacks, 0, sizeof(callbacks));
 542   callbacks.SampledObjectAlloc = &SampledObjectAlloc;
 543   callbacks.GarbageCollectionFinish = &GarbageCollectionFinish;
 544 
 545   jvmtiCapabilities caps;
 546   memset(&caps, 0, sizeof(caps));
 547   // Get line numbers, sample heap, sample events, and filename for the test.
 548   caps.can_get_line_numbers = 1;
 549   caps.can_generate_sampled_alloc_events = 1;
 550   caps.can_get_source_file_name = 1;
 551   caps.can_generate_garbage_collection_events = 1;
 552   if (check_error((*jvmti)->AddCapabilities(jvmti, &caps), "Add capabilities")){
 553     return JNI_ERR;
 554   }
 555 




 556  if (check_error((*jvmti)->SetEventCallbacks(jvmti, &callbacks,
 557                                               sizeof(jvmtiEventCallbacks)),
 558                   " Set Event Callbacks")) {
 559     return JNI_ERR;
 560   }
 561   return JNI_OK;
 562 }
 563 
 564 JNIEXPORT void JNICALL
 565 Java_MyPackage_HeapMonitor_setSamplingRate(JNIEnv* env, jclass cls, jint value) {
 566   (*jvmti)->SetHeapSamplingRate(jvmti, value);
 567 }
 568 
 569 JNIEXPORT void JNICALL
 570 Java_MyPackage_HeapMonitor_setGarbageHistory(JNIEnv* env, jclass cls, jint value) {
 571   event_storage_set_garbage_history(&global_event_storage, value);
 572 }
 573 
 574 JNIEXPORT jboolean JNICALL
 575 Java_MyPackage_HeapMonitor_eventStorageIsEmpty(JNIEnv* env, jclass cls) {


 612   fill_native_frames(env, frames, native_frames, size);
 613   return event_storage_garbage_contains(env, &global_event_storage, native_frames, size);
 614 }
 615 
 616 JNIEXPORT void JNICALL
 617 Java_MyPackage_HeapMonitor_forceGarbageCollection(JNIEnv* env, jclass cls) {
 618   check_error((*jvmti)->ForceGarbageCollection(jvmti),
 619               "Forced Garbage Collection");
 620 }
 621 
 622 JNIEXPORT void JNICALL
 623 Java_MyPackage_HeapMonitor_resetEventStorage(JNIEnv* env, jclass cls) {
 624   return event_storage_reset(&global_event_storage);
 625 }
 626 
 627 JNIEXPORT jboolean JNICALL
 628 Java_MyPackage_HeapMonitorNoCapabilityTest_allSamplingMethodsFail(JNIEnv *env,
 629                                                                   jclass cls) {
 630   jvmtiCapabilities caps;
 631   memset(&caps, 0, sizeof(caps));
 632   caps.can_generate_sampled_alloc_events = 1;
 633   if (check_error((*jvmti)->RelinquishCapabilities(jvmti, &caps),
 634                   "Add capabilities\n")){
 635     return FALSE;
 636   }
 637 
 638   if (check_capability_error((*jvmti)->SetHeapSamplingRate(jvmti, 1<<19),
 639                              "Set Heap Sampling Rate")) {
 640     return FALSE;
 641   }
 642   return TRUE;
 643 }
 644 
 645 JNIEXPORT jdouble JNICALL
 646 Java_MyPackage_HeapMonitorStatRateTest_getAverageRate(JNIEnv *env, jclass cls) {
 647   return event_storage_get_average_rate(&global_event_storage);
 648 }
 649 
 650 typedef struct sThreadsFound {
 651   jthread* threads;
 652   int num_threads;


 686     int found = 0;
 687     int j;
 688     for (j = 0; j < num_threads; j++) {
 689       if (thread == threads[j]) {
 690         found = 1;
 691         break;
 692       }
 693     }
 694 
 695     if (!found) {
 696       threads[num_threads] = thread;
 697       num_threads++;
 698     }
 699   }
 700   thread_data->num_threads = num_threads;
 701 }
 702 
 703 JNIEXPORT jboolean JNICALL
 704 Java_MyPackage_HeapMonitorThreadTest_checkSamples(JNIEnv* env, jclass cls,
 705                                                   jint num_threads) {
 706   pthread_mutex_lock(&global_event_storage.storage_mutex);
 707   jint trace_counter;
 708 
 709   ThreadsFound thread_data;
 710   thread_data.num_threads = 0;
 711   thread_data.threads = malloc(sizeof(jthread) * num_threads);
 712   memset(thread_data.threads, 0, sizeof(jthread) * num_threads);
 713 
 714   find_threads_in_array(&thread_data, global_event_storage.live_objects,
 715                         global_event_storage.live_object_count);
 716   find_threads_in_array(&thread_data,
 717                         global_event_storage.garbage_collected_objects,
 718                         global_event_storage.garbage_history_size);
 719 
 720   free(thread_data.threads);
 721   pthread_mutex_unlock(&global_event_storage.storage_mutex);
 722   return thread_data.num_threads == num_threads;
 723 }
 724 
 725 #ifdef __cplusplus
 726 }
 727 #endif
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