lib: diagnostics_channel use AsyncLocalStorage for suppression context

Signed-off-by: Divyanshu Sharma <divyanshu88999@gmail.com>

Author: DivyanshuX9

lib/diagnostics_channel.js

@@ -36,6 +36,33 @@ const { subscribers: subscriberCounts } = dc_binding;
 const { WeakReference } = require('internal/util');
 const { isPromise } = require('internal/util/types');
 
+// Internal only: tracks a Set of active suppression keys for the current async
+// context. Uses a simple stack-based approach to avoid bootstrap issues with
+// async_hooks. This is a simplified implementation that works for typical usage.
+let suppressionStorage = null;
+
+function getSuppressionsStorage() {
+  if (suppressionStorage === null) {
+    try {
+      const { AsyncLocalStorage } = require('async_hooks');
+      suppressionStorage = new AsyncLocalStorage();
+    } catch {
+      // If AsyncLocalStorage fails to initialize (rare), use a fallback
+      // that won't provide async context isolation but at least works
+      suppressionStorage = false; // Marker for "tried and failed"
+    }
+  }
+  return suppressionStorage || undefined;
+}
+
+function withSuppressionsContext(set, fn, thisArg, args) {
+  const storage = getSuppressionsStorage();
+  if (storage) {
+    return storage.run(set, () => ReflectApply(fn, thisArg, args));
+  }
+  // Fallback: just call the function without context
+  return ReflectApply(fn, thisArg, args);
+}
 // Can't delete when weakref count reaches 0 as it could increment again.
 // Only GC can be used as a valid time to clean up the channels map.
 class WeakRefMap extends SafeMap {
@@ -93,9 +120,17 @@ class RunStoresScope {
 
     // Enter stores using withScope
     if (activeChannel._stores) {
+      const storage = getSuppressionsStorage();
+      const activeKeys = storage ? storage.getStore() : undefined;
       for (const entry of activeChannel._stores.entries()) {
         const store = entry[0];
-        const transform = entry[1];
+        const { transform, suppressedBy = null } = entry[1];
+
+        // Skip this bound store if it opted into suppression and its key
+        // is active in the current async context.
+        if (suppressedBy !== null && activeKeys?.has(suppressedBy)) {
+          continue;
+        }
 
         let newContext = data;
         if (transform) {
@@ -127,16 +162,32 @@ class RunStoresScope {
 
 // TODO(qard): should there be a C++ channel interface?
 class ActiveChannel {
-  subscribe(subscription) {
+  subscribe(subscription, options = {}) {
     validateFunction(subscription, 'subscription');
+    let suppressedBy = options && options.suppressedBy !== undefined ? options.suppressedBy : null;
+    if (suppressedBy !== null) {
+      const t = typeof suppressedBy;
+      if (t === 'string' || t === 'number' || t === 'bigint' || t === 'boolean') {
+        throw new ERR_INVALID_ARG_TYPE('suppressedBy', ['object', 'symbol', 'function'], suppressedBy);
+      }
+    }
+
+    const handler = subscription;
     this._subscribers = ArrayPrototypeSlice(this._subscribers);
-    ArrayPrototypePush(this._subscribers, subscription);
+    ArrayPrototypePush(this._subscribers, { handler, suppressedBy });
     channels.incRef(this.name);
     if (this._index !== undefined) subscriberCounts[this._index]++;
   }
 
   unsubscribe(subscription) {
-    const index = ArrayPrototypeIndexOf(this._subscribers, subscription);
+    // Find subscriber entry by handler identity.
+    let index = -1;
+    for (let i = 0; i < (this._subscribers?.length || 0); i++) {
+      if (this._subscribers[i].handler === subscription) {
+        index = i;
+        break;
+      }
+    }
     if (index === -1) return false;
 
     const before = ArrayPrototypeSlice(this._subscribers, 0, index);
@@ -151,13 +202,21 @@ class ActiveChannel {
     return true;
   }
 
-  bindStore(store, transform) {
+  bindStore(store, transform, options = {}) {
+    const suppressedBy = options && options.suppressedBy !== undefined ? options.suppressedBy : null;
+    if (suppressedBy !== null) {
+      const t = typeof suppressedBy;
+      if (t === 'string' || t === 'number' || t === 'bigint' || t === 'boolean') {
+        throw new ERR_INVALID_ARG_TYPE('suppressedBy', ['object', 'symbol', 'function'], suppressedBy);
+      }
+    }
+
     const replacing = this._stores.has(store);
     if (!replacing) {
       channels.incRef(this.name);
       if (this._index !== undefined) subscriberCounts[this._index]++;
     }
-    this._stores.set(store, transform);
+    this._stores.set(store, { transform, suppressedBy });
   }
 
   unbindStore(store) {
@@ -180,10 +239,15 @@ class ActiveChannel {
 
   publish(data) {
     const subscribers = this._subscribers;
+    const storage = getSuppressionsStorage();
+    const activeKeys = storage ? storage.getStore() : undefined;
     for (let i = 0; i < (subscribers?.length || 0); i++) {
       try {
-        const onMessage = subscribers[i];
-        onMessage(data, this.name);
+        const { handler, suppressedBy = null } = subscribers[i];
+        if (suppressedBy !== null && activeKeys?.has(suppressedBy)) {
+          continue;
+        }
+        handler(data, this.name);
       } catch (err) {
         process.nextTick(() => {
           triggerUncaughtException(err, false);
@@ -221,18 +285,18 @@ class Channel {
            prototype === ActiveChannel.prototype;
   }
 
-  subscribe(subscription) {
+  subscribe(subscription, options) {
     markActive(this);
-    this.subscribe(subscription);
+    this.subscribe(subscription, options);
   }
 
   unsubscribe() {
     return false;
   }
 
-  bindStore(store, transform) {
+  bindStore(store, transform, options) {
     markActive(this);
-    this.bindStore(store, transform);
+    this.bindStore(store, transform, options);
   }
 
   unbindStore() {
@@ -366,12 +430,12 @@ class BoundedChannel {
       this.end?.hasSubscribers;
   }
 
-  subscribe(handlers) {
+  subscribe(handlers, options) {
     for (let i = 0; i < boundedEvents.length; ++i) {
       const name = boundedEvents[i];
       if (!handlers[name]) continue;
 
-      this[name]?.subscribe(handlers[name]);
+      this[name]?.subscribe(handlers[name], options);
     }
   }
 
@@ -458,26 +522,26 @@ class TracingChannel {
       this.error?.hasSubscribers;
   }
 
-  subscribe(handlers) {
+  subscribe(handlers, options) {
     // Subscribe to call window (start/end)
     if (handlers.start || handlers.end) {
       this.#callWindow.subscribe({
         start: handlers.start,
         end: handlers.end,
-      });
+      }, options);
     }
 
     // Subscribe to continuation window (asyncStart/asyncEnd)
     if (handlers.asyncStart || handlers.asyncEnd) {
       this.#continuationWindow.subscribe({
         start: handlers.asyncStart,
         end: handlers.asyncEnd,
-      });
+      }, options);
     }
 
     // Subscribe to error channel
     if (handlers.error) {
-      this.error.subscribe(handlers.error);
+      this.error.subscribe(handlers.error, options);
     }
   }
 
@@ -633,10 +697,38 @@ function tracingChannel(nameOrChannels) {
 
 dc_binding.linkNativeChannel((name) => channel(name));
 
+function suppressed(key, fn, thisArg, ...args) {
+  validateFunction(fn, 'fn');
+
+  if (key === null || key === undefined) {
+    throw new ERR_INVALID_ARG_TYPE('key', ['object', 'symbol', 'function'], key);
+  }
+  const t = typeof key;
+  if (t === 'string' || t === 'number' || t === 'bigint' || t === 'boolean') {
+    throw new ERR_INVALID_ARG_TYPE('key', ['object', 'symbol', 'function'], key);
+  }
+
+  const storage = getSuppressionsStorage();
+  let currentSet;
+  if (storage) {
+    currentSet = storage.getStore();
+  }
+  const next = currentSet ? new Set(currentSet) : new Set();
+  next.add(key);
+  const wrapped = function() {
+    try {
+      console.error('diagnostics_channel: suppressed() executing callback');
+    } catch (_) {}
+    return ReflectApply(fn, thisArg, args);
+  };
+  return withSuppressionsContext(next, wrapped, thisArg, []);
+}
+
 module.exports = {
   channel,
   hasSubscribers,
   subscribe,
+  suppressed,
   tracingChannel,
   unsubscribe,
   boundedChannel,