All files / lib/internal async_hooks.js

99.16% Statements 590/595
98.44% Branches 126/128
100% Functions 38/38
99.16% Lines 590/595

Press n or j to go to the next uncovered block, b, p or k for the previous block.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 59625x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 168x 168x 168x 25x 28567x 28567x 28567x 28567x 28567x 28567x 28567x 28567x 28567x 1698x 1698x 28565x 26869x 26869x 27604x 28567x 28567x 27604x 27604x 27604x 28567x 25x 25x 25x 25x 25x 5034x 5034x 5034x 5034x 5034x 5034x 5034x 5034x 5034x 5034x 5034x 5034x 25x 10x 10x 10x 10x 25x 25x 12x 12x 2x 12x 10x 10x 10x 10x 12x 12x 12x     12x 12x 25x 118472x 118472x 118471x 118471x 118471x 118471x 118471x 117937x 118472x 25x 25x 25x 25x 25x 25x 113470x 113470x 113470x 113470x 113470x 113470x 113470x 113470x 7341484x 7341484x 7341484x 7341484x 7341484x 7341484x 7341484x 113470x 3x 113470x 113467x 113467x 113467x 113467x 113467x 113467x 113467x 113470x 4x 4x 113470x 25x 25x 25x 174871x 174871x 174871x 174871x 174871x 174871x 174871x 174871x 7332022x 7331857x 7331857x 7332022x 174871x 9x 174871x 174862x 174862x 174862x 174862x 174862x 174862x 174862x 174871x 2477x 2477x 174871x 25x 1680x 1680x 1680x 1680x 1680x 1680x 1680x 1680x 1680x 25x 25x 25x 5719x 5719x 5719x 2484x 2484x 2484x 2484x 2484x 3762x 2484x 5719x 25x 25x 2481x 2481x 2481x 2481x 2481x 2481x 2481x 25x 4962x 4962x 4962x 4962x 4962x 4962x 4962x 25x 25x 25x 25x 2481x 2481x 2481x 2481x 2481x 2481x 2481x 25x 134x 134x 134x 134x 134x 134x 134x 97x 97x 97x 134x 25x 147x 147x 134x 134x 60x 118x 74x 74x 132x 132x 134x 16x 16x 16x 39x 6x 6x 6x 147x 6x 6x 6x 4x 3x 3x 3x 3x 3x 3x 3x 4x 147x 4x 4x 147x 147x 25x 25x 416x 416x 416x 25x 25x 2888x 2888x 2888x 2714x 247x 247x 247x 2886x 64x 64x 64x 2888x 25x 168x 168x 168x 168x 168x 168x 168x 168x 168x 25x 171x 171x 64x 64x 64x 171x 25x 25x 25x 25x 25x 25x 1238277x 1238277x 1238277x 25x 2434x 2434x 2286x 2286x 148x 148x 2434x 25x 25x 25x 25x 25x 1238118x 1238118x 1238118x 1238118x 1238118x 17724x 1238118x 25x 25x 1448x 1448x 1448x 25x 25x 17140x 17140x 17140x 17124x 17124x 17124x 17124x 17124x 17124x 17124x 17124x 17124x 17124x 17140x 25x 6348067x 6348067x 6348067x 25x 1238305x 1238305x 1238305x 25x 1238176x 1238176x 1238176x 25x 1199x 1199x 1199x 25x 1238796x 1238796x 1238796x 25x 25x 75309x 75309x 75309x 75309x 75309x 75308x 75308x 1x 1x 75308x 75308x 75309x 25x 25x 1232992x 1232992x 1232992x 1232992x 1232992x 1232992x 25x 25x 1233781x 1233781x 1233781x 1233781x 1233781x 1233781x 25x 25x 71759x 71759x 71759x 71759x 70448x 71759x 25x 25x 4594x 4594x 4594x 25x 25x 25x 1233999x 1233999x 1233999x 1233999x 1233999x 1233989x 1233989x 1233989x 1233989x 1233989x 1233999x 25x 25x 25x 1234792x 1234792x 1234792x 1234790x 1234792x       1234790x 1234790x 1234790x 1234790x 1234790x 1234790x 1234790x 1234792x 25x 25x 12368x 12368x 12368x 25x 10249x 10249x 10249x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x 25x  
'use strict';
 
const {
  ArrayPrototypePop,
  ArrayPrototypeSlice,
  ArrayPrototypeUnshift,
  ErrorCaptureStackTrace,
  FunctionPrototypeBind,
  ObjectPrototypeHasOwnProperty,
  ObjectDefineProperty,
  Promise,
  ReflectApply,
  Symbol,
} = primordials;
 
const async_wrap = internalBinding('async_wrap');
const { setCallbackTrampoline } = async_wrap;
/* async_hook_fields is a Uint32Array wrapping the uint32_t array of
 * Environment::AsyncHooks::fields_[]. Each index tracks the number of active
 * hooks for each type.
 *
 * async_id_fields is a Float64Array wrapping the double array of
 * Environment::AsyncHooks::async_id_fields_[]. Each index contains the ids for
 * the various asynchronous states of the application. These are:
 *  kExecutionAsyncId: The async_id assigned to the resource responsible for the
 *    current execution stack.
 *  kTriggerAsyncId: The async_id of the resource that caused (or 'triggered')
 *    the resource corresponding to the current execution stack.
 *  kAsyncIdCounter: Incremental counter tracking the next assigned async_id.
 *  kDefaultTriggerAsyncId: Written immediately before a resource's constructor
 *    that sets the value of the init()'s triggerAsyncId. The precedence order
 *    of retrieving the triggerAsyncId value is:
 *    1. the value passed directly to the constructor
 *    2. value set in kDefaultTriggerAsyncId
 *    3. executionAsyncId of the current resource.
 *
 * async_ids_stack is a Float64Array that contains part of the async ID
 * stack. Each pushAsyncContext() call adds two doubles to it, and each
 * popAsyncContext() call removes two doubles from it.
 * It has a fixed size, so if that is exceeded, calls to the native
 * side are used instead in pushAsyncContext() and popAsyncContext().
 */
const {
  async_hook_fields,
  async_id_fields,
  execution_async_resources
} = async_wrap;
// Store the pair executionAsyncId and triggerAsyncId in a AliasedFloat64Array
// in Environment::AsyncHooks::async_ids_stack_ which tracks the resource
// responsible for the current execution stack. This is unwound as each resource
// exits. In the case of a fatal exception this stack is emptied after calling
// each hook's after() callback.
const {
  pushAsyncContext: pushAsyncContext_,
  popAsyncContext: popAsyncContext_,
  executionAsyncResource: executionAsyncResource_,
  clearAsyncIdStack,
} = async_wrap;
// For performance reasons, only track Promises when a hook is enabled.
const { enablePromiseHook, disablePromiseHook } = async_wrap;
// Properties in active_hooks are used to keep track of the set of hooks being
// executed in case another hook is enabled/disabled. The new set of hooks is
// then restored once the active set of hooks is finished executing.
const active_hooks = {
  // Array of all AsyncHooks that will be iterated whenever an async event
  // fires. Using var instead of (preferably const) in order to assign
  // active_hooks.tmp_array if a hook is enabled/disabled during hook
  // execution.
  array: [],
  // Use a counter to track nested calls of async hook callbacks and make sure
  // the active_hooks.array isn't altered mid execution.
  call_depth: 0,
  // Use to temporarily store and updated active_hooks.array if the user
  // enables or disables a hook while hooks are being processed. If a hook is
  // enabled() or disabled() during hook execution then the current set of
  // active hooks is duplicated and set equal to active_hooks.tmp_array. Any
  // subsequent changes are on the duplicated array. When all hooks have
  // completed executing active_hooks.tmp_array is assigned to
  // active_hooks.array.
  tmp_array: null,
  // Keep track of the field counts held in active_hooks.tmp_array. Because the
  // async_hook_fields can't be reassigned, store each uint32 in an array that
  // is written back to async_hook_fields when active_hooks.array is restored.
  tmp_fields: null
};
 
const { registerDestroyHook } = async_wrap;
const { enqueueMicrotask } = internalBinding('task_queue');
const { resource_symbol, owner_symbol } = internalBinding('symbols');
 
// Each constant tracks how many callbacks there are for any given step of
// async execution. These are tracked so if the user didn't include callbacks
// for a given step, that step can bail out early.
const {
  kInit, kBefore, kAfter, kDestroy, kTotals, kPromiseResolve,
  kCheck, kExecutionAsyncId, kAsyncIdCounter, kTriggerAsyncId,
  kDefaultTriggerAsyncId, kStackLength, kUsesExecutionAsyncResource,
} = async_wrap.constants;
 
const { async_id_symbol,
        trigger_async_id_symbol } = internalBinding('symbols');
 
// Lazy load of internal/util/inspect;
let inspect;
 
// Used in AsyncHook and AsyncResource.
const init_symbol = Symbol('init');
const before_symbol = Symbol('before');
const after_symbol = Symbol('after');
const destroy_symbol = Symbol('destroy');
const promise_resolve_symbol = Symbol('promiseResolve');
const emitBeforeNative = emitHookFactory(before_symbol, 'emitBeforeNative');
const emitAfterNative = emitHookFactory(after_symbol, 'emitAfterNative');
const emitDestroyNative = emitHookFactory(destroy_symbol, 'emitDestroyNative');
const emitPromiseResolveNative =
    emitHookFactory(promise_resolve_symbol, 'emitPromiseResolveNative');
 
let domain_cb;
function useDomainTrampoline(fn) {
  domain_cb = fn;
}
 
function callbackTrampoline(asyncId, resource, cb, ...args) {
  const index = async_hook_fields[kStackLength] - 1;
  execution_async_resources[index] = resource;
 
  if (asyncId !== 0 && hasHooks(kBefore))
    emitBeforeNative(asyncId);
 
  let result;
  if (asyncId === 0 && typeof domain_cb === 'function') {
    ArrayPrototypeUnshift(args, cb);
    result = ReflectApply(domain_cb, this, args);
  } else {
    result = ReflectApply(cb, this, args);
  }
 
  if (asyncId !== 0 && hasHooks(kAfter))
    emitAfterNative(asyncId);
 
  ArrayPrototypePop(execution_async_resources);
  return result;
}
 
setCallbackTrampoline(callbackTrampoline);
 
const topLevelResource = {};
 
function executionAsyncResource() {
  // Indicate to the native layer that this function is likely to be used,
  // in which case it will inform JS about the current async resource via
  // the trampoline above.
  async_hook_fields[kUsesExecutionAsyncResource] = 1;
 
  const index = async_hook_fields[kStackLength] - 1;
  if (index === -1) return topLevelResource;
  const resource = execution_async_resources[index] ||
    executionAsyncResource_(index);
  return lookupPublicResource(resource);
}
 
function inspectExceptionValue(e) {
  inspect ??= require('internal/util/inspect').inspect;
  return { message: inspect(e) };
}
 
// Used to fatally abort the process if a callback throws.
function fatalError(e) {
  if (typeof e?.stack === 'string') {
    process._rawDebug(e.stack);
  } else {
    const o = inspectExceptionValue(e);
    ErrorCaptureStackTrace(o, fatalError);
    process._rawDebug(o.stack);
  }
 
  const { getOptionValue } = require('internal/options');
  if (getOptionValue('--abort-on-uncaught-exception')) {
    process.abort();
  }
  process.exit(1);
}
 
function lookupPublicResource(resource) {
  if (typeof resource !== 'object' || resource === null) return resource;
  // TODO(addaleax): Merge this with owner_symbol and use it across all
  // AsyncWrap instances.
  const publicResource = resource[resource_symbol];
  if (publicResource !== undefined)
    return publicResource;
  return resource;
}
 
// Emit From Native //
 
// Used by C++ to call all init() callbacks. Because some state can be setup
// from C++ there's no need to perform all the same operations as in
// emitInitScript.
function emitInitNative(asyncId, type, triggerAsyncId, resource) {
  active_hooks.call_depth += 1;
  resource = lookupPublicResource(resource);
  // Use a single try/catch for all hooks to avoid setting up one per iteration.
  try {
    // Using var here instead of let because "for (var ...)" is faster than let.
    // Refs: https://github.com/nodejs/node/pull/30380#issuecomment-552948364
    for (var i = 0; i < active_hooks.array.length; i++) {
      if (typeof active_hooks.array[i][init_symbol] === 'function') {
        active_hooks.array[i][init_symbol](
          asyncId, type, triggerAsyncId,
          resource
        );
      }
    }
  } catch (e) {
    fatalError(e);
  } finally {
    active_hooks.call_depth -= 1;
  }
 
  // Hooks can only be restored if there have been no recursive hook calls.
  // Also the active hooks do not need to be restored if enable()/disable()
  // weren't called during hook execution, in which case active_hooks.tmp_array
  // will be null.
  if (active_hooks.call_depth === 0 && active_hooks.tmp_array !== null) {
    restoreActiveHooks();
  }
}
 
// Called from native. The asyncId stack handling is taken care of there
// before this is called.
function emitHook(symbol, asyncId) {
  active_hooks.call_depth += 1;
  // Use a single try/catch for all hook to avoid setting up one per
  // iteration.
  try {
    // Using var here instead of let because "for (var ...)" is faster than let.
    // Refs: https://github.com/nodejs/node/pull/30380#issuecomment-552948364
    for (var i = 0; i < active_hooks.array.length; i++) {
      if (typeof active_hooks.array[i][symbol] === 'function') {
        active_hooks.array[i][symbol](asyncId);
      }
    }
  } catch (e) {
    fatalError(e);
  } finally {
    active_hooks.call_depth -= 1;
  }
 
  // Hooks can only be restored if there have been no recursive hook calls.
  // Also the active hooks do not need to be restored if enable()/disable()
  // weren't called during hook execution, in which case
  // active_hooks.tmp_array will be null.
  if (active_hooks.call_depth === 0 && active_hooks.tmp_array !== null) {
    restoreActiveHooks();
  }
}
 
function emitHookFactory(symbol, name) {
  const fn = FunctionPrototypeBind(emitHook, undefined, symbol);
 
  // Set the name property of the function as it looks good in the stack trace.
  ObjectDefineProperty(fn, 'name', {
    value: name
  });
  return fn;
}
 
// Manage Active Hooks //
 
function getHookArrays() {
  if (active_hooks.call_depth === 0)
    return [active_hooks.array, async_hook_fields];
  // If this hook is being enabled while in the middle of processing the array
  // of currently active hooks then duplicate the current set of active hooks
  // and store this there. This shouldn't fire until the next time hooks are
  // processed.
  if (active_hooks.tmp_array === null)
    storeActiveHooks();
  return [active_hooks.tmp_array, active_hooks.tmp_fields];
}
 
 
function storeActiveHooks() {
  active_hooks.tmp_array = ArrayPrototypeSlice(active_hooks.array);
  // Don't want to make the assumption that kInit to kDestroy are indexes 0 to
  // 4. So do this the long way.
  active_hooks.tmp_fields = [];
  copyHooks(active_hooks.tmp_fields, async_hook_fields);
}
 
function copyHooks(destination, source) {
  destination[kInit] = source[kInit];
  destination[kBefore] = source[kBefore];
  destination[kAfter] = source[kAfter];
  destination[kDestroy] = source[kDestroy];
  destination[kPromiseResolve] = source[kPromiseResolve];
}
 
 
// Then restore the correct hooks array in case any hooks were added/removed
// during hook callback execution.
function restoreActiveHooks() {
  active_hooks.array = active_hooks.tmp_array;
  copyHooks(async_hook_fields, active_hooks.tmp_fields);
 
  active_hooks.tmp_array = null;
  active_hooks.tmp_fields = null;
}
 
function trackPromise(promise, parent, silent) {
  const asyncId = getOrSetAsyncId(promise);
 
  promise[trigger_async_id_symbol] = parent ? getOrSetAsyncId(parent) :
    getDefaultTriggerAsyncId();
 
  if (!silent && initHooksExist()) {
    const triggerId = promise[trigger_async_id_symbol];
    emitInitScript(asyncId, 'PROMISE', triggerId, promise);
  }
}
 
function fastPromiseHook(type, promise, parent) {
  if (type === kInit || !promise[async_id_symbol]) {
    const silent = type !== kInit;
    if (parent instanceof Promise) {
      trackPromise(promise, parent, silent);
    } else {
      trackPromise(promise, null, silent);
    }
 
    if (!silent) return;
  }
 
  const asyncId = promise[async_id_symbol];
  switch (type) {
    case kBefore:
      const triggerId = promise[trigger_async_id_symbol];
      emitBeforeScript(asyncId, triggerId, promise);
      break;
    case kAfter:
      if (hasHooks(kAfter)) {
        emitAfterNative(asyncId);
      }
      if (asyncId === executionAsyncId()) {
        // This condition might not be true if async_hooks was enabled during
        // the promise callback execution.
        // Popping it off the stack can be skipped in that case, because it is
        // known that it would correspond to exactly one call with
        // PromiseHookType::kBefore that was not witnessed by the PromiseHook.
        popAsyncContext(asyncId);
      }
      break;
    case kPromiseResolve:
      emitPromiseResolveNative(asyncId);
      break;
  }
}
 
let wantPromiseHook = false;
function enableHooks() {
  async_hook_fields[kCheck] += 1;
}
 
let promiseHookMode = -1;
function updatePromiseHookMode() {
  wantPromiseHook = true;
  if (destroyHooksExist()) {
    if (promiseHookMode !== 1) {
      promiseHookMode = 1;
      enablePromiseHook();
    }
  } else if (promiseHookMode !== 0) {
    promiseHookMode = 0;
    enablePromiseHook(fastPromiseHook);
  }
}
 
function disableHooks() {
  async_hook_fields[kCheck] -= 1;
 
  wantPromiseHook = false;
 
  // Delay the call to `disablePromiseHook()` because we might currently be
  // between the `before` and `after` calls of a Promise.
  enqueueMicrotask(disablePromiseHookIfNecessary);
}
 
function disablePromiseHookIfNecessary() {
  if (!wantPromiseHook) {
    promiseHookMode = -1;
    disablePromiseHook();
  }
}
 
// Internal Embedder API //
 
// Increment the internal id counter and return the value. Important that the
// counter increment first. Since it's done the same way in
// Environment::new_async_uid()
function newAsyncId() {
  return ++async_id_fields[kAsyncIdCounter];
}
 
function getOrSetAsyncId(object) {
  if (ObjectPrototypeHasOwnProperty(object, async_id_symbol)) {
    return object[async_id_symbol];
  }
 
  return object[async_id_symbol] = newAsyncId();
}
 
 
// Return the triggerAsyncId meant for the constructor calling it. It's up to
// the user to safeguard this call and make sure it's zero'd out when the
// constructor is complete.
function getDefaultTriggerAsyncId() {
  const defaultTriggerAsyncId = async_id_fields[kDefaultTriggerAsyncId];
  // If defaultTriggerAsyncId isn't set, use the executionAsyncId
  if (defaultTriggerAsyncId < 0)
    return async_id_fields[kExecutionAsyncId];
  return defaultTriggerAsyncId;
}
 
 
function clearDefaultTriggerAsyncId() {
  async_id_fields[kDefaultTriggerAsyncId] = -1;
}
 
 
function defaultTriggerAsyncIdScope(triggerAsyncId, block, ...args) {
  if (triggerAsyncId === undefined)
    return ReflectApply(block, null, args);
  // CHECK(NumberIsSafeInteger(triggerAsyncId))
  // CHECK(triggerAsyncId > 0)
  const oldDefaultTriggerAsyncId = async_id_fields[kDefaultTriggerAsyncId];
  async_id_fields[kDefaultTriggerAsyncId] = triggerAsyncId;
 
  try {
    return ReflectApply(block, null, args);
  } finally {
    async_id_fields[kDefaultTriggerAsyncId] = oldDefaultTriggerAsyncId;
  }
}
 
function hasHooks(key) {
  return async_hook_fields[key] > 0;
}
 
function enabledHooksExist() {
  return hasHooks(kCheck);
}
 
function initHooksExist() {
  return hasHooks(kInit);
}
 
function afterHooksExist() {
  return hasHooks(kAfter);
}
 
function destroyHooksExist() {
  return hasHooks(kDestroy);
}
 
 
function emitInitScript(asyncId, type, triggerAsyncId, resource) {
  // Short circuit all checks for the common case. Which is that no hooks have
  // been set. Do this to remove performance impact for embedders (and core).
  if (!hasHooks(kInit))
    return;
 
  if (triggerAsyncId === null) {
    triggerAsyncId = getDefaultTriggerAsyncId();
  }
 
  emitInitNative(asyncId, type, triggerAsyncId, resource);
}
 
 
function emitBeforeScript(asyncId, triggerAsyncId, resource) {
  pushAsyncContext(asyncId, triggerAsyncId, resource);
 
  if (hasHooks(kBefore))
    emitBeforeNative(asyncId);
}
 
 
function emitAfterScript(asyncId) {
  if (hasHooks(kAfter))
    emitAfterNative(asyncId);
 
  popAsyncContext(asyncId);
}
 
 
function emitDestroyScript(asyncId) {
  // Return early if there are no destroy callbacks, or invalid asyncId.
  if (!hasHooks(kDestroy) || asyncId <= 0)
    return;
  async_wrap.queueDestroyAsyncId(asyncId);
}
 
 
function hasAsyncIdStack() {
  return hasHooks(kStackLength);
}
 
 
// This is the equivalent of the native push_async_ids() call.
function pushAsyncContext(asyncId, triggerAsyncId, resource) {
  const offset = async_hook_fields[kStackLength];
  execution_async_resources[offset] = resource;
  if (offset * 2 >= async_wrap.async_ids_stack.length)
    return pushAsyncContext_(asyncId, triggerAsyncId);
  async_wrap.async_ids_stack[offset * 2] = async_id_fields[kExecutionAsyncId];
  async_wrap.async_ids_stack[offset * 2 + 1] = async_id_fields[kTriggerAsyncId];
  async_hook_fields[kStackLength]++;
  async_id_fields[kExecutionAsyncId] = asyncId;
  async_id_fields[kTriggerAsyncId] = triggerAsyncId;
}
 
 
// This is the equivalent of the native pop_async_ids() call.
function popAsyncContext(asyncId) {
  const stackLength = async_hook_fields[kStackLength];
  if (stackLength === 0) return false;
 
  if (enabledHooksExist() && async_id_fields[kExecutionAsyncId] !== asyncId) {
    // Do the same thing as the native code (i.e. crash hard).
    return popAsyncContext_(asyncId);
  }
 
  const offset = stackLength - 1;
  async_id_fields[kExecutionAsyncId] = async_wrap.async_ids_stack[2 * offset];
  async_id_fields[kTriggerAsyncId] = async_wrap.async_ids_stack[2 * offset + 1];
  ArrayPrototypePop(execution_async_resources);
  async_hook_fields[kStackLength] = offset;
  return offset > 0;
}
 
 
function executionAsyncId() {
  return async_id_fields[kExecutionAsyncId];
}
 
function triggerAsyncId() {
  return async_id_fields[kTriggerAsyncId];
}
 
 
module.exports = {
  executionAsyncId,
  triggerAsyncId,
  // Private API
  getHookArrays,
  symbols: {
    async_id_symbol, trigger_async_id_symbol,
    init_symbol, before_symbol, after_symbol, destroy_symbol,
    promise_resolve_symbol, owner_symbol
  },
  constants: {
    kInit, kBefore, kAfter, kDestroy, kTotals, kPromiseResolve
  },
  enableHooks,
  disableHooks,
  updatePromiseHookMode,
  clearDefaultTriggerAsyncId,
  clearAsyncIdStack,
  hasAsyncIdStack,
  executionAsyncResource,
  // Internal Embedder API
  newAsyncId,
  getOrSetAsyncId,
  getDefaultTriggerAsyncId,
  defaultTriggerAsyncIdScope,
  enabledHooksExist,
  initHooksExist,
  afterHooksExist,
  destroyHooksExist,
  emitInit: emitInitScript,
  emitBefore: emitBeforeScript,
  emitAfter: emitAfterScript,
  emitDestroy: emitDestroyScript,
  pushAsyncContext,
  popAsyncContext,
  registerDestroyHook,
  useDomainTrampoline,
  nativeHooks: {
    init: emitInitNative,
    before: emitBeforeNative,
    after: emitAfterNative,
    destroy: emitDestroyNative,
    promise_resolve: emitPromiseResolveNative
  }
};