feat: add core TaskBlock event recording support

ddprof-lib/src/main/cpp/counters.h

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023 Datadog, Inc
+ * Copyright 2023, 2026 Datadog, Inc
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -60,6 +60,8 @@
   X(THREAD_NAMES_COUNT, "thread_names_count")                                  \
   X(THREAD_FILTER_PAGES, "thread_filter_pages")                                \
   X(THREAD_FILTER_BYTES, "thread_filter_bytes")                                \
+  X(THREAD_REGISTRY_CAPACITY_EXHAUSTED, "thread_registry_capacity_exhausted")  \
+  X(THREAD_REGISTRY_INDEX_FAILURES, "thread_registry_index_failures")          \
   X(JMETHODID_SKIPPED, "jmethodid_skipped_count")                              \
   X(CODECACHE_NATIVE_SIZE_BYTES, "codecache_native_size_bytes")                \
   X(CODECACHE_NATIVE_COUNT, "native_codecache_count")                          \
@@ -69,10 +71,19 @@
   X(AGCT_NATIVE_NO_JAVA_CONTEXT, "agct_native_no_java_context")                \
   X(AGCT_BLOCKED_IN_VM, "agct_blocked_in_vm")                                  \
   X(SKIPPED_WALLCLOCK_UNWINDS, "skipped_wallclock_unwinds")                    \
-  X(WC_SIGNAL_SUPPRESSED_SAMPLED_RUN, "wc_signals_suppressed_sampled_run")     \
+  X(WC_PRECHECK_REGISTRY_LOOKUPS, "wc_precheck_registry_lookups")             \
+  X(WC_PRECHECK_CANDIDATES_REJECTED, "wc_precheck_candidates_rejected")       \
+  X(WC_PRECHECK_LOOKUP_BUDGET_EXHAUSTED, "wc_precheck_lookup_budget_exhausted") \
+  X(WC_SIGNAL_SUPPRESSED_OWNED_BLOCK, "wc_signals_suppressed_owned_block")     \
   X(WC_UNOWNED_BLOCKED_SUPPRESSED, "wc_unowned_blocked_suppressed")            \
   X(WC_UNOWNED_BLOCKED_RECORDED, "wc_unowned_blocked_recorded")                \
   X(WC_SIGNAL_QUEUE_FULL, "wc_signals_queue_full")                             \
+  X(TASK_BLOCK_EMITTED, "task_block_emitted")                                 \
+  X(TASK_BLOCK_SKIPPED_TRACE_CONTEXT, "task_block_skipped_trace_context")     \
+  X(TASK_BLOCK_SKIPPED_TOO_SHORT, "task_block_skipped_too_short")             \
+  X(TASK_BLOCK_STACK_CAPTURE_FAILED, "task_block_stack_capture_failed")      \
+  X(TASK_BLOCK_RECORD_FAILED, "task_block_record_failed")                     \
+  X(TASK_BLOCK_DROPPED_ROTATION, "task_block_dropped_rotation")               \
   X(UNWINDING_TIME_ASYNC, "unwinding_ticks_async")                             \
   X(UNWINDING_TIME_JVMTI, "unwinding_ticks_jvmti")                             \
   X(CALLTRACE_STORAGE_DROPPED, "calltrace_storage_dropped_traces")             \

ddprof-lib/src/main/cpp/engine.h

@@ -1,5 +1,6 @@
 /*
  * Copyright 2017 Andrei Pangin
+ * Copyright 2026, Datadog, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -51,6 +52,9 @@ class Engine {
   virtual void stop();
   virtual long interval() const { return 0L; }
 
+  // Whether empty-filter wall prechecks can consume ThreadFilter registry state.
+  virtual bool supportsUnfilteredWallPrecheck() const { return false; }
+
   virtual int registerThread(int tid) { return -1; }
   virtual void unregisterThread(int tid) {}
 

ddprof-lib/src/main/cpp/event.h

@@ -58,7 +58,7 @@ class ExecutionEvent : public Event {
   OSThreadState _thread_state;
   ExecutionMode _execution_mode;
   u64 _weight;
-  u32 _call_trace_id;
+  u64 _call_trace_id;
 
   ExecutionEvent()
       : Event(), _thread_state(OSThreadState::RUNNABLE), _execution_mode(ExecutionMode::UNKNOWN),
@@ -123,13 +123,13 @@ class WallClockEpochEvent {
   u32 _num_failed_samples;
   u32 _num_exited_threads;
   u32 _num_permission_denied;
-  u64 _num_suppressed_sampled_run;
+  u64 _num_suppressed_owned_block;
 
   WallClockEpochEvent(u64 start_time)
       : _dirty(false), _start_time(start_time), _duration_millis(0),
         _num_samplable_threads(0), _num_successful_samples(0),
         _num_failed_samples(0), _num_exited_threads(0),
-        _num_permission_denied(0), _num_suppressed_sampled_run(0) {}
+        _num_permission_denied(0), _num_suppressed_owned_block(0) {}
 
   bool hasChanged() { return _dirty; }
 
@@ -168,10 +168,10 @@ class WallClockEpochEvent {
     }
   }
 
-  void addNumSuppressedSampledRun(u64 n) {
+  void addNumSuppressedOwnedBlock(u64 n) {
     if (n > 0) {
       _dirty = true;
-      _num_suppressed_sampled_run += n;
+      _num_suppressed_owned_block += n;
     }
   }
 
@@ -182,7 +182,7 @@ class WallClockEpochEvent {
   void newEpoch(u64 start_time) {
     _dirty = false;
     _start_time = start_time;
-    _num_suppressed_sampled_run = 0;
+    _num_suppressed_owned_block = 0;
   }
 };
 
@@ -207,4 +207,14 @@ typedef struct QueueTimeEvent {
   u32 _queueLength;
 } QueueTimeEvent;
 
+typedef struct TaskBlockEvent {
+  u64 _start;
+  u64 _end;
+  u64 _blocker;
+  u64 _unblockingSpanId;
+  Context _ctx;
+  u64 _callTraceId;
+  OSThreadState _observedBlockingState;
+} TaskBlockEvent;
+
 #endif // _EVENT_H

ddprof-lib/src/main/cpp/flightRecorder.cpp

@@ -1945,6 +1945,21 @@ void Recording::recordMethodSample(Buffer *buf, int tid, u64 call_trace_id,
   flushIfNeeded(buf);
 }
 
+void Recording::recordTaskBlock(Buffer *buf, int tid, TaskBlockEvent *event) {
+  int start = buf->skip(1);
+  buf->putVar64(T_TASK_BLOCK);
+  buf->putVar64(event->_start);
+  buf->putVar64(event->_end - event->_start);
+  buf->putVar64(tid);
+  buf->putVar64(event->_blocker);
+  buf->putVar64(event->_unblockingSpanId);
+  buf->putVar64(event->_callTraceId);
+  buf->put8(static_cast<int>(event->_observedBlockingState));
+  writeContextSnapshot(buf, event->_ctx);
+  writeEventSizePrefix(buf, start);
+  flushIfNeeded(buf);
+}
+
 void Recording::recordWallClockEpoch(Buffer *buf, WallClockEpochEvent *event) {
   int start = buf->skip(1);
   buf->putVar64(T_WALLCLOCK_SAMPLE_EPOCH);
@@ -1955,7 +1970,7 @@ void Recording::recordWallClockEpoch(Buffer *buf, WallClockEpochEvent *event) {
   buf->putVar64(event->_num_failed_samples);
   buf->putVar64(event->_num_exited_threads);
   buf->putVar64(event->_num_permission_denied);
-  buf->putVar64(event->_num_suppressed_sampled_run);
+  buf->putVar64(event->_num_suppressed_owned_block);
   writeEventSizePrefix(buf, start);
   flushIfNeeded(buf);
 }
@@ -2218,6 +2233,21 @@ void FlightRecorder::recordQueueTime(int lock_index, int tid,
   }
 }
 
+bool FlightRecorder::recordTaskBlock(int lock_index, int tid,
+                                     TaskBlockEvent *event) {
+  OptionalSharedLockGuard locker(&_rec_lock);
+  if (locker.ownsLock()) {
+    Recording* rec = _rec;
+    if (rec != nullptr) {
+      Buffer *buf = rec->buffer(lock_index);
+      rec->addThread(lock_index, tid);
+      rec->recordTaskBlock(buf, tid, event);
+      return true;
+    }
+  }
+  return false;
+}
+
 void FlightRecorder::recordDatadogSetting(int lock_index, int length,
                                           const char *name, const char *value,
                                           const char *unit) {

ddprof-lib/src/main/cpp/flightRecorder.h

@@ -319,6 +319,7 @@ class Recording {
   void recordWallClockEpoch(Buffer *buf, WallClockEpochEvent *event);
   void recordTraceRoot(Buffer *buf, int tid, TraceRootEvent *event);
   void recordQueueTime(Buffer *buf, int tid, QueueTimeEvent *event);
+  void recordTaskBlock(Buffer *buf, int tid, TaskBlockEvent *event);
   void recordAllocation(RecordingBuffer *buf, int tid, u64 call_trace_id,
                         AllocEvent *event);
   void recordMallocSample(Buffer *buf, int tid, u64 call_trace_id,
@@ -427,6 +428,7 @@ class FlightRecorder {
   void wallClockEpoch(int lock_index, WallClockEpochEvent *event);
   void recordTraceRoot(int lock_index, int tid, TraceRootEvent *event);
   void recordQueueTime(int lock_index, int tid, QueueTimeEvent *event);
+  bool recordTaskBlock(int lock_index, int tid, TaskBlockEvent *event);
 
   bool active() const { return _rec != NULL; }
 

ddprof-lib/src/main/cpp/frames.h

@@ -1,9 +1,39 @@
+/*
+ * Copyright 2026, Datadog, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
 #ifndef _FRAMES_H
 #define _FRAMES_H
 
 #include <jni.h>
+#include <jvmti.h>
 #include "vmEntry.h"
 
+inline void copyJvmtiFrames(ASGCT_CallFrame *frames,
+                            const jvmtiFrameInfo *jvmti_frames,
+                            jint num_frames) {
+  // The source and destination commonly refer to the two views of the same
+  // CallTraceBuffer union. Read both source fields before either write.
+  for (jint i = 0; i < num_frames; ++i) {
+    jmethodID method = jvmti_frames[i].method;
+    jlocation location = jvmti_frames[i].location;
+    frames[i].method_id = method;
+    frames[i].bci = static_cast<jint>(location);
+    LP64_ONLY(frames[i].padding = 0;)
+  }
+}
+
 inline int makeFrame(ASGCT_CallFrame *frames, jint type, jmethodID id) {
   frames[0].bci = type;
   frames[0].method_id = id;