fix(node): add missing hasSubscribers getter to TracingChannel

The `TracingChannel` class in `node:diagnostics_channel` was missing the
`hasSubscribers` getter, causing it to return `undefined` instead of a
boolean. This adds the getter which returns `true` if any of the five
sub-channels (start, end, asyncStart, asyncEnd, error) have subscribers,
matching Node.js behavior.

Closes #27805

cmake/tools/SetupBuildkite.cmake

@@ -4,87 +4,227 @@ if(NOT BUILDKITE_CACHE OR NOT BUN_LINK_ONLY)
   return()
 endif()
 
-# This runs inside the ${targetKey}-build-bun step (see .buildkite/ci.mjs), which
-# links artifacts from ${targetKey}-build-cpp and ${targetKey}-build-zig in the
-# same build. Step keys follow a fixed ${targetKey}-build-{cpp,zig,bun} pattern
-# and build-bun's depends_on lists exactly those two steps, so we derive the
-# siblings by swapping the suffix on our own BUILDKITE_STEP_KEY.
+optionx(BUILDKITE_ORGANIZATION_SLUG STRING "The organization slug to use on Buildkite" DEFAULT "bun")
+optionx(BUILDKITE_PIPELINE_SLUG STRING "The pipeline slug to use on Buildkite" DEFAULT "bun")
+optionx(BUILDKITE_BUILD_ID STRING "The build ID (UUID) to use on Buildkite")
+optionx(BUILDKITE_BUILD_NUMBER STRING "The build number to use on Buildkite")
+optionx(BUILDKITE_GROUP_ID STRING "The group ID to use on Buildkite")
 
-if(NOT DEFINED ENV{BUILDKITE_STEP_KEY})
-  message(FATAL_ERROR "BUILDKITE_STEP_KEY is not set (expected inside a Buildkite job)")
+if(ENABLE_BASELINE)
+  set(DEFAULT_BUILDKITE_GROUP_KEY ${OS}-${ARCH}-baseline)
+else()
+  set(DEFAULT_BUILDKITE_GROUP_KEY ${OS}-${ARCH})
 endif()
-set(BUILDKITE_STEP_KEY $ENV{BUILDKITE_STEP_KEY})
 
-if(NOT BUILDKITE_STEP_KEY MATCHES "^(.+)-build-bun$")
-  message(FATAL_ERROR "Unexpected BUILDKITE_STEP_KEY '${BUILDKITE_STEP_KEY}' (expected '<target>-build-bun')")
+optionx(BUILDKITE_GROUP_KEY STRING "The group key to use on Buildkite" DEFAULT ${DEFAULT_BUILDKITE_GROUP_KEY})
+
+if(BUILDKITE)
+  optionx(BUILDKITE_BUILD_ID_OVERRIDE STRING "The build ID to use on Buildkite")
+  if(BUILDKITE_BUILD_ID_OVERRIDE)
+    setx(BUILDKITE_BUILD_ID ${BUILDKITE_BUILD_ID_OVERRIDE})
+  endif()
 endif()
-set(BUILDKITE_TARGET_KEY ${CMAKE_MATCH_1})
 
-# Download all artifacts from both sibling steps. The agent scopes to the
-# current build via $BUILDKITE_BUILD_ID; --step resolves by key within it.
-# git clean -ffxdq runs between builds (BUILDKITE_GIT_CLEAN_FLAGS), so
-# ${BUILD_PATH} starts clean.
+set(BUILDKITE_PATH ${BUILD_PATH}/buildkite)
+set(BUILDKITE_BUILDS_PATH ${BUILDKITE_PATH}/builds)
 
-file(MAKE_DIRECTORY ${BUILD_PATH})
+if(NOT BUILDKITE_BUILD_ID)
+  # TODO: find the latest build on the main branch that passed
+  return()
+endif()
 
-foreach(SUFFIX cpp zig)
-  set(STEP ${BUILDKITE_TARGET_KEY}-build-${SUFFIX})
-  message(STATUS "Downloading artifacts from ${STEP}")
-  execute_process(
-    COMMAND buildkite-agent artifact download * . --step ${STEP}
-    WORKING_DIRECTORY ${BUILD_PATH}
-    RESULT_VARIABLE DOWNLOAD_RC
-    ERROR_VARIABLE DOWNLOAD_ERR
-  )
-  if(NOT DOWNLOAD_RC EQUAL 0)
-    message(FATAL_ERROR "buildkite-agent artifact download from ${STEP} failed: ${DOWNLOAD_ERR}")
-  endif()
-endforeach()
+# Use BUILDKITE_BUILD_NUMBER for the URL if available, as the UUID format causes a 302 redirect
+# that CMake's file(DOWNLOAD) doesn't follow, resulting in empty response.
+if(BUILDKITE_BUILD_NUMBER)
+  setx(BUILDKITE_BUILD_URL https://buildkite.com/${BUILDKITE_ORGANIZATION_SLUG}/${BUILDKITE_PIPELINE_SLUG}/builds/${BUILDKITE_BUILD_NUMBER})
+else()
+  setx(BUILDKITE_BUILD_URL https://buildkite.com/${BUILDKITE_ORGANIZATION_SLUG}/${BUILDKITE_PIPELINE_SLUG}/builds/${BUILDKITE_BUILD_ID})
+endif()
+setx(BUILDKITE_BUILD_PATH ${BUILDKITE_BUILDS_PATH}/builds/${BUILDKITE_BUILD_ID})
 
-# libbun-profile.a and libbun-asan.a are gzipped before upload (see
-# register_command's ARTIFACTS handling in Globals.cmake). Windows .lib
-# files are not gzipped, so this glob is empty there.
-
-file(GLOB BUILDKITE_GZ_ARTIFACTS "${BUILD_PATH}/*.gz")
-foreach(GZ ${BUILDKITE_GZ_ARTIFACTS})
-  message(STATUS "Unpacking ${GZ}")
-  execute_process(
-    COMMAND gunzip -f ${GZ}
-    RESULT_VARIABLE GUNZIP_RC
-    ERROR_VARIABLE GUNZIP_ERR
-  )
-  if(NOT GUNZIP_RC EQUAL 0)
-    message(FATAL_ERROR "gunzip ${GZ} failed: ${GUNZIP_ERR}")
-  endif()
-endforeach()
-
-# Artifacts are uploaded with subdirectory paths (lolhtml/release/liblolhtml.a,
-# mimalloc/CMakeFiles/mimalloc-obj.dir/src/static.c.o, etc.) and the agent
-# recreates that structure on download. Recurse, but skip top-level CMakeFiles/
-# (our own compiler detection) and cache/ — nested CMakeFiles/ are real artifacts.
-
-file(GLOB_RECURSE BUILDKITE_LINK_ARTIFACTS
-  "${BUILD_PATH}/*.o"
-  "${BUILD_PATH}/*.a"
-  "${BUILD_PATH}/*.lib"
+file(
+  DOWNLOAD ${BUILDKITE_BUILD_URL}
+  HTTPHEADER "Accept: application/json"
+  TIMEOUT 15
+  STATUS BUILDKITE_BUILD_STATUS
+  ${BUILDKITE_BUILD_PATH}/build.json
 )
-string(REGEX REPLACE "\\." "\\\\." BUILD_PATH_RE "${BUILD_PATH}")
-list(FILTER BUILDKITE_LINK_ARTIFACTS EXCLUDE REGEX "^${BUILD_PATH_RE}/(CMakeFiles|cache)/")
-
-if(NOT BUILDKITE_LINK_ARTIFACTS)
-  message(FATAL_ERROR "No linkable artifacts found in ${BUILD_PATH} after download")
+if(NOT BUILDKITE_BUILD_STATUS EQUAL 0)
+  message(FATAL_ERROR "No build found: ${BUILDKITE_BUILD_STATUS} ${BUILDKITE_BUILD_URL}")
+  return()
 endif()
-list(LENGTH BUILDKITE_LINK_ARTIFACTS BUILDKITE_LINK_COUNT)
-message(STATUS "Registered ${BUILDKITE_LINK_COUNT} linkable artifacts from ${BUILDKITE_TARGET_KEY}-build-{cpp,zig}")
 
-# Register a no-op custom command for each linkable artifact so register_command
-# (Globals.cmake) sees them as GENERATED and shims its own output to
-# ${output}.always_run_${target} instead of overwriting them with a rebuild.
-# With no DEPENDS, the no-op never fires — the file already exists.
+file(READ ${BUILDKITE_BUILD_PATH}/build.json BUILDKITE_BUILD)
+# CMake's string(JSON ...) interprets escape sequences like \n, \r, \t.
+# We need to escape these specific sequences while preserving valid JSON escapes like \" and \\.
+# Strategy: Use a unique placeholder to protect \\ sequences, escape \n/\r/\t, then restore \\.
+# This prevents \\n (literal backslash + n) from being corrupted to \\\n.
+set(BKSLASH_PLACEHOLDER "___BKSLASH_PLACEHOLDER_7f3a9b2c___")
+string(REPLACE "\\\\" "${BKSLASH_PLACEHOLDER}" BUILDKITE_BUILD "${BUILDKITE_BUILD}")
+string(REPLACE "\\n" "\\\\n" BUILDKITE_BUILD "${BUILDKITE_BUILD}")
+string(REPLACE "\\r" "\\\\r" BUILDKITE_BUILD "${BUILDKITE_BUILD}")
+string(REPLACE "\\t" "\\\\t" BUILDKITE_BUILD "${BUILDKITE_BUILD}")
+string(REPLACE "${BKSLASH_PLACEHOLDER}" "\\\\" BUILDKITE_BUILD "${BUILDKITE_BUILD}")
+# CMake treats semicolons as list separators in unquoted variable expansions.
+# Commit messages and other JSON string fields can contain semicolons, which would
+# cause string(JSON) to receive garbled arguments. Escape them before parsing.
+string(REPLACE ";" "\\;" BUILDKITE_BUILD "${BUILDKITE_BUILD}")
 
-foreach(ARTIFACT ${BUILDKITE_LINK_ARTIFACTS})
-  add_custom_command(
-    OUTPUT ${ARTIFACT}
-    COMMAND ${CMAKE_COMMAND} -E true
+string(JSON BUILDKITE_BUILD_UUID GET "${BUILDKITE_BUILD}" id)
+string(JSON BUILDKITE_JOBS GET "${BUILDKITE_BUILD}" jobs)
+string(JSON BUILDKITE_JOBS_COUNT LENGTH "${BUILDKITE_JOBS}")
+
+if(NOT BUILDKITE_JOBS_COUNT GREATER 0)
+  message(FATAL_ERROR "No jobs found: ${BUILDKITE_BUILD_URL}")
+  return()
+endif()
+
+set(BUILDKITE_JOBS_FAILED)
+set(BUILDKITE_JOBS_NOT_FOUND)
+set(BUILDKITE_JOBS_NO_ARTIFACTS)
+set(BUILDKITE_JOBS_NO_MATCH)
+set(BUILDKITE_JOBS_MATCH)
+
+math(EXPR BUILDKITE_JOBS_MAX_INDEX "${BUILDKITE_JOBS_COUNT} - 1")
+foreach(i RANGE ${BUILDKITE_JOBS_MAX_INDEX})
+  string(JSON BUILDKITE_JOB GET "${BUILDKITE_JOBS}" ${i})
+  string(JSON BUILDKITE_JOB_ID GET "${BUILDKITE_JOB}" id)
+  string(JSON BUILDKITE_JOB_PASSED GET "${BUILDKITE_JOB}" passed)
+  string(JSON BUILDKITE_JOB_GROUP_ID GET "${BUILDKITE_JOB}" group_uuid)
+  string(JSON BUILDKITE_JOB_GROUP_KEY GET "${BUILDKITE_JOB}" group_identifier)
+  string(JSON BUILDKITE_JOB_NAME GET "${BUILDKITE_JOB}" step_key)
+  if(NOT BUILDKITE_JOB_NAME)
+    string(JSON BUILDKITE_JOB_NAME GET "${BUILDKITE_JOB}" name)
+  endif()
+
+  if(NOT BUILDKITE_JOB_PASSED)
+    list(APPEND BUILDKITE_JOBS_FAILED ${BUILDKITE_JOB_NAME})
+    continue()
+  endif()
+
+  if(NOT (BUILDKITE_GROUP_ID AND BUILDKITE_GROUP_ID STREQUAL BUILDKITE_JOB_GROUP_ID) AND
+     NOT (BUILDKITE_GROUP_KEY AND BUILDKITE_GROUP_KEY STREQUAL BUILDKITE_JOB_GROUP_KEY))
+    list(APPEND BUILDKITE_JOBS_NO_MATCH ${BUILDKITE_JOB_NAME})
+    continue()
+  endif()
+
+  set(BUILDKITE_ARTIFACTS_URL https://buildkite.com/organizations/${BUILDKITE_ORGANIZATION_SLUG}/pipelines/${BUILDKITE_PIPELINE_SLUG}/builds/${BUILDKITE_BUILD_UUID}/jobs/${BUILDKITE_JOB_ID}/artifacts)
+  set(BUILDKITE_ARTIFACTS_PATH ${BUILDKITE_BUILD_PATH}/artifacts/${BUILDKITE_JOB_ID}.json)
+
+  file(
+    DOWNLOAD ${BUILDKITE_ARTIFACTS_URL}
+    HTTPHEADER "Accept: application/json"
+    TIMEOUT 15
+    STATUS BUILDKITE_ARTIFACTS_STATUS
+    ${BUILDKITE_ARTIFACTS_PATH}
   )
+
+  if(NOT BUILDKITE_ARTIFACTS_STATUS EQUAL 0)
+    list(APPEND BUILDKITE_JOBS_NOT_FOUND ${BUILDKITE_JOB_NAME})
+    continue()
+  endif()
+  
+  file(READ ${BUILDKITE_ARTIFACTS_PATH} BUILDKITE_ARTIFACTS)
+  string(REPLACE ";" "\\;" BUILDKITE_ARTIFACTS "${BUILDKITE_ARTIFACTS}")
+  string(JSON BUILDKITE_ARTIFACTS_LENGTH LENGTH "${BUILDKITE_ARTIFACTS}")
+  if(NOT BUILDKITE_ARTIFACTS_LENGTH GREATER 0)
+    list(APPEND BUILDKITE_JOBS_NO_ARTIFACTS ${BUILDKITE_JOB_NAME})
+    continue()
+  endif()
+
+  math(EXPR BUILDKITE_ARTIFACTS_MAX_INDEX "${BUILDKITE_ARTIFACTS_LENGTH} - 1")
+  foreach(i RANGE 0 ${BUILDKITE_ARTIFACTS_MAX_INDEX})
+    string(JSON BUILDKITE_ARTIFACT GET "${BUILDKITE_ARTIFACTS}" ${i})
+    string(JSON BUILDKITE_ARTIFACT_ID GET "${BUILDKITE_ARTIFACT}" id)
+    string(JSON BUILDKITE_ARTIFACT_PATH GET "${BUILDKITE_ARTIFACT}" path)
+
+    if(NOT BUILDKITE_ARTIFACT_PATH MATCHES "\\.(o|a|lib|zip|tar|gz)")
+      continue()
+    endif()
+
+    if(BUILDKITE)
+      if(BUILDKITE_ARTIFACT_PATH STREQUAL "libbun-profile.a")
+        set(BUILDKITE_ARTIFACT_PATH libbun-profile.a.gz)
+      elseif(BUILDKITE_ARTIFACT_PATH STREQUAL "libbun-asan.a")
+        set(BUILDKITE_ARTIFACT_PATH libbun-asan.a.gz)
+      endif()
+      set(BUILDKITE_DOWNLOAD_COMMAND buildkite-agent artifact download ${BUILDKITE_ARTIFACT_PATH} . --build ${BUILDKITE_BUILD_UUID} --step ${BUILDKITE_JOB_ID})
+    else()
+      set(BUILDKITE_DOWNLOAD_COMMAND curl -L -o ${BUILDKITE_ARTIFACT_PATH} ${BUILDKITE_ARTIFACTS_URL}/${BUILDKITE_ARTIFACT_ID})
+    endif()
+
+    add_custom_command(
+      COMMENT
+        "Downloading ${BUILDKITE_ARTIFACT_PATH}"
+      VERBATIM COMMAND
+        ${BUILDKITE_DOWNLOAD_COMMAND}
+      WORKING_DIRECTORY
+        ${BUILD_PATH}
+      OUTPUT
+        ${BUILD_PATH}/${BUILDKITE_ARTIFACT_PATH}
+    )
+    if(BUILDKITE_ARTIFACT_PATH STREQUAL "libbun-profile.a.gz")
+      add_custom_command(
+        COMMENT
+          "Unpacking libbun-profile.a.gz"
+        VERBATIM COMMAND
+          gunzip libbun-profile.a.gz
+        WORKING_DIRECTORY
+          ${BUILD_PATH}
+        OUTPUT
+          ${BUILD_PATH}/libbun-profile.a
+        DEPENDS
+          ${BUILD_PATH}/libbun-profile.a.gz
+      )
+    elseif(BUILDKITE_ARTIFACT_PATH STREQUAL "libbun-asan.a.gz")
+      add_custom_command(
+        COMMENT
+          "Unpacking libbun-asan.a.gz"
+        VERBATIM COMMAND
+          gunzip libbun-asan.a.gz
+        WORKING_DIRECTORY
+          ${BUILD_PATH}
+        OUTPUT
+          ${BUILD_PATH}/libbun-asan.a
+        DEPENDS
+          ${BUILD_PATH}/libbun-asan.a.gz
+      )
+    endif()
+  endforeach()
+
+  list(APPEND BUILDKITE_JOBS_MATCH ${BUILDKITE_JOB_NAME})
 endforeach()
+
+if(BUILDKITE_JOBS_FAILED)
+  list(SORT BUILDKITE_JOBS_FAILED COMPARE STRING)
+  list(JOIN BUILDKITE_JOBS_FAILED " " BUILDKITE_JOBS_FAILED)
+  message(WARNING "The following jobs were found, but failed: ${BUILDKITE_JOBS_FAILED}")
+endif()
+
+if(BUILDKITE_JOBS_NOT_FOUND)
+  list(SORT BUILDKITE_JOBS_NOT_FOUND COMPARE STRING)
+  list(JOIN BUILDKITE_JOBS_NOT_FOUND " " BUILDKITE_JOBS_NOT_FOUND)
+  message(WARNING "The following jobs were found, but could not fetch their data: ${BUILDKITE_JOBS_NOT_FOUND}")
+endif()
+
+if(BUILDKITE_JOBS_NO_MATCH)
+  list(SORT BUILDKITE_JOBS_NO_MATCH COMPARE STRING)
+  list(JOIN BUILDKITE_JOBS_NO_MATCH " " BUILDKITE_JOBS_NO_MATCH)
+  message(WARNING "The following jobs were found, but did not match the group ID: ${BUILDKITE_JOBS_NO_MATCH}")
+endif()
+
+if(BUILDKITE_JOBS_NO_ARTIFACTS)
+  list(SORT BUILDKITE_JOBS_NO_ARTIFACTS COMPARE STRING)
+  list(JOIN BUILDKITE_JOBS_NO_ARTIFACTS " " BUILDKITE_JOBS_NO_ARTIFACTS)
+  message(WARNING "The following jobs were found, but had no artifacts: ${BUILDKITE_JOBS_NO_ARTIFACTS}")
+endif()
+
+if(BUILDKITE_JOBS_MATCH)
+  list(SORT BUILDKITE_JOBS_MATCH COMPARE STRING)
+  list(JOIN BUILDKITE_JOBS_MATCH " " BUILDKITE_JOBS_MATCH)
+  message(STATUS "The following jobs were found, and matched the group ID: ${BUILDKITE_JOBS_MATCH}")
+endif()
+
+if(NOT BUILDKITE_JOBS_FAILED AND NOT BUILDKITE_JOBS_NOT_FOUND AND NOT BUILDKITE_JOBS_NO_MATCH AND NOT BUILDKITE_JOBS_NO_ARTIFACTS AND NOT BUILDKITE_JOBS_MATCH)
+  message(FATAL_ERROR "Something went wrong with Buildkite?")
+endif()

src/js/node/diagnostics_channel.ts

@@ -255,6 +255,16 @@ class TracingChannel {
   asyncEnd;
   error;
 
+  get hasSubscribers() {
+    return (
+      this.start.hasSubscribers ||
+      this.end.hasSubscribers ||
+      this.asyncStart.hasSubscribers ||
+      this.asyncEnd.hasSubscribers ||
+      this.error.hasSubscribers
+    );
+  }
+
   constructor(nameOrChannels) {
     if (typeof nameOrChannels === "string") {
       this.start = channel(`tracing:${nameOrChannels}:start`);

test/js/node/test/parallel/test-diagnostics-channel-tracing-channel-has-subscribers.js

@@ -0,0 +1,51 @@
+'use strict';
+
+const common = require('../common');
+const dc = require('diagnostics_channel');
+const assert = require('assert');
+
+const handler = common.mustNotCall();
+
+{
+  const handlers = {
+    start: common.mustNotCall()
+  };
+
+  const channel = dc.tracingChannel('test');
+
+  assert.strictEqual(channel.hasSubscribers, false);
+
+  channel.subscribe(handlers);
+  assert.strictEqual(channel.hasSubscribers, true);
+
+  channel.unsubscribe(handlers);
+  assert.strictEqual(channel.hasSubscribers, false);
+
+  channel.start.subscribe(handler);
+  assert.strictEqual(channel.hasSubscribers, true);
+
+  channel.start.unsubscribe(handler);
+  assert.strictEqual(channel.hasSubscribers, false);
+}
+
+{
+  const handlers = {
+    asyncEnd: common.mustNotCall()
+  };
+
+  const channel = dc.tracingChannel('test');
+
+  assert.strictEqual(channel.hasSubscribers, false);
+
+  channel.subscribe(handlers);
+  assert.strictEqual(channel.hasSubscribers, true);
+
+  channel.unsubscribe(handlers);
+  assert.strictEqual(channel.hasSubscribers, false);
+
+  channel.asyncEnd.subscribe(handler);
+  assert.strictEqual(channel.hasSubscribers, true);
+
+  channel.asyncEnd.unsubscribe(handler);
+  assert.strictEqual(channel.hasSubscribers, false);
+}