async_hooks: prototype for v8 reimplementation of AsyncLocalStorage

lib/async_hooks.js

@@ -27,6 +27,8 @@ const {
 } = require('internal/validators');
 const internal_async_hooks = require('internal/async_hooks');
 
+const { AsyncLocalStorage } = internalBinding('async_local_storage');
+
 // Get functions
 // For userland AsyncResources, make sure to emit a destroy event when the
 // resource gets gced.
@@ -262,97 +264,6 @@ class AsyncResource {
   }
 }
 
-const storageList = [];
-const storageHook = createHook({
-  init(asyncId, type, triggerAsyncId, resource) {
-    const currentResource = executionAsyncResource();
-    // Value of currentResource is always a non null object
-    for (let i = 0; i < storageList.length; ++i) {
-      storageList[i]._propagate(resource, currentResource);
-    }
-  }
-});
-
-class AsyncLocalStorage {
-  constructor() {
-    this.kResourceStore = Symbol('kResourceStore');
-    this.enabled = false;
-  }
-
-  disable() {
-    if (this.enabled) {
-      this.enabled = false;
-      // If this.enabled, the instance must be in storageList
-      ArrayPrototypeSplice(storageList,
-                           ArrayPrototypeIndexOf(storageList, this), 1);
-      if (storageList.length === 0) {
-        storageHook.disable();
-      }
-    }
-  }
-
-  _enable() {
-    if (!this.enabled) {
-      this.enabled = true;
-      ArrayPrototypePush(storageList, this);
-      storageHook.enable();
-    }
-  }
-
-  // Propagate the context from a parent resource to a child one
-  _propagate(resource, triggerResource) {
-    const store = triggerResource[this.kResourceStore];
-    if (this.enabled) {
-      resource[this.kResourceStore] = store;
-    }
-  }
-
-  enterWith(store) {
-    this._enable();
-    const resource = executionAsyncResource();
-    resource[this.kResourceStore] = store;
-  }
-
-  run(store, callback, ...args) {
-    // Avoid creation of an AsyncResource if store is already active
-    if (ObjectIs(store, this.getStore())) {
-      return ReflectApply(callback, null, args);
-    }
-
-    this._enable();
-
-    const resource = executionAsyncResource();
-    const oldStore = resource[this.kResourceStore];
-
-    resource[this.kResourceStore] = store;
-
-    try {
-      return ReflectApply(callback, null, args);
-    } finally {
-      resource[this.kResourceStore] = oldStore;
-    }
-  }
-
-  exit(callback, ...args) {
-    if (!this.enabled) {
-      return ReflectApply(callback, null, args);
-    }
-    this.disable();
-    try {
-      return ReflectApply(callback, null, args);
-    } finally {
-      this._enable();
-    }
-  }
-
-  getStore() {
-    if (this.enabled) {
-      const resource = executionAsyncResource();
-      return resource[this.kResourceStore];
-    }
-  }
-}
-
 // Placing all exports down here because the exported classes won't export
 // otherwise.
 module.exports = {

node.gyp

@@ -469,10 +469,12 @@
         'src/api/exceptions.cc',
         'src/api/hooks.cc',
         'src/api/utils.cc',
+        'src/async_local_storage.cc',
         'src/async_wrap.cc',
         'src/cares_wrap.cc',
         'src/connect_wrap.cc',
         'src/connection_wrap.cc',
+        'src/context_storage.cc',
         'src/debug_utils.cc',
         'src/env.cc',
         'src/fs_event_wrap.cc',
@@ -564,6 +566,7 @@
         'src/aliased_buffer.h',
         'src/aliased_struct.h',
         'src/aliased_struct-inl.h',
+        'src/async_local_storage.h',
         'src/async_wrap.h',
         'src/async_wrap-inl.h',
         'src/base_object.h',
@@ -574,6 +577,7 @@
         'src/callback_queue-inl.h',
         'src/connect_wrap.h',
         'src/connection_wrap.h',
+        'src/context_storage.h',
         'src/debug_utils.h',
         'src/debug_utils-inl.h',
         'src/env.h',

src/api/callback.cc

@@ -1,4 +1,5 @@
 #include "node.h"
+#include "async_local_storage.h"
 #include "async_wrap-inl.h"
 #include "env-inl.h"
 #include "v8.h"
@@ -52,7 +53,8 @@ InternalCallbackScope::InternalCallbackScope(Environment* env,
     async_context_(asyncContext),
     object_(object),
     skip_hooks_(flags & kSkipAsyncHooks),
-    skip_task_queues_(flags & kSkipTaskQueues) {
+    skip_task_queues_(flags & kSkipTaskQueues),
+    context_storage_scope_(AsyncLocalStorage::GetState(object)) {
   CHECK_NOT_NULL(env);
   env->PushAsyncCallbackScope();