[dotnet] [bidi] Support cancellation of events registration

[nvborisenko]

User description

This enhancement allows consumers of the API to cancel pending event subscriptions and unsubscriptions, improving responsiveness and resource management in scenarios where operations may need to be aborted.

🔗 Related Issues

Continuation of #16989

💥 What does this PR do?

• Added a CancellationToken parameter to all event subscription methods in BrowsingContextModule, including navigation, history, download, context, and user prompt events, allowing callers to cancel subscriptions if needed.

🔄 Types of changes

• New feature (non-breaking change which adds functionality and tests!)
• Breaking change (fix or feature that would cause existing functionality to change)

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PR Type

Enhancement

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Description

• Add CancellationToken parameter to all BiDi event subscription methods

• Enable cancellation of pending event subscriptions across modules

• Support cancellation in SubscribeAsync and UnsubscribeAsync operations

• Propagate cancellation tokens through broker and module layers

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Diagram Walkthrough

flowchart LR
  A["Event Subscription Methods"] -->|Add CancellationToken| B["Module Layer"]
  B -->|Pass Token| C["Broker.SubscribeAsync"]
  C -->|Forward Token| D["SessionModule.SubscribeAsync"]
  E["Subscription.UnsubscribeAsync"] -->|Add CancellationToken| F["Broker.UnsubscribeAsync"]
  F -->|Forward Token| G["SessionModule.UnsubscribeAsync"]

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File Walkthrough

Relevant files

Enhancement

11 files Broker.cs Add cancellation token to subscribe and unsubscribe methods +4/-4      Module.cs Propagate cancellation token through subscription methods +4/-4      Subscription.cs Add cancellation token to UnsubscribeAsync method                +3/-2      BrowsingContextModule.cs Add cancellation tokens to all navigation and context events +56/-56  BrowsingContextInputModule.cs Add cancellation token to file dialog event subscriptions +6/-4      BrowsingContextLogModule.cs Add cancellation token to log entry event subscriptions    +7/-4      BrowsingContextNetworkModule.cs Add cancellation tokens to network event subscriptions      +30/-20  NetworkModule.cs Add cancellation tokens to network event subscription methods +20/-20  InputModule.cs Add cancellation token to file dialog event subscriptions +4/-4      LogModule.cs Add cancellation token to log entry event subscriptions    +5/-4      ScriptModule.cs Add cancellation tokens to script event subscription methods +12/-12

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[qodo-code-review]

PR Compliance Guide 🔍

Below is a summary of compliance checks for this PR:

Security Compliance
🟢	No security concerns identified No security vulnerabilities detected by AI analysis. Human verification advised for critical code.
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⚪	🎫 No ticket provided Create ticket/issue
Codebase Duplication Compliance
⚪	Codebase context is not defined Follow the guide to enable codebase context checks.
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🟢	Generic: Comprehensive Audit Trails Objective: To create a detailed and reliable record of critical system actions for security analysis and compliance. Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Meaningful Naming and Self-Documenting Code Objective: Ensure all identifiers clearly express their purpose and intent, making code self-documenting Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Robust Error Handling and Edge Case Management Objective: Ensure comprehensive error handling that provides meaningful context and graceful degradation Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
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	Generic: Secure Logging Practices Objective: To ensure logs are useful for debugging and auditing without exposing sensitive information like PII, PHI, or cardholder data. Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Security-First Input Validation and Data Handling Objective: Ensure all data inputs are validated, sanitized, and handled securely to prevent vulnerabilities Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
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[qodo-code-review]

PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Impact
High-level	Consider simplifying the duplicated subscription logic Refactor the duplicated event subscription logic by having the Action overload call the Func<T, Task> overload. This will remove boilerplate code across multiple modules and improve maintainability. Examples: dotnet/src/webdriver/BiDi/BrowsingContext/BrowsingContextModule.cs [117-255] public async Task<Subscription> OnNavigationStartedAsync(Func<NavigationInfo, Task> handler, SubscriptionOptions? options = null, CancellationToken cancellationToken = default) { return await SubscribeAsync("browsingContext.navigationStarted", handler, options, _jsonContext.NavigationInfo, cancellationToken).ConfigureAwait(false); } public async Task<Subscription> OnNavigationStartedAsync(Action<NavigationInfo> handler, SubscriptionOptions? options = null, CancellationToken cancellationToken = default) { return await SubscribeAsync("browsingContext.navigationStarted", handler, options, _jsonContext.NavigationInfo, cancellationToken).ConfigureAwait(false); } ... (clipped 129 lines) dotnet/src/webdriver/BiDi/Network/NetworkModule.cs [128-176] public async Task<Subscription> OnBeforeRequestSentAsync(Func<BeforeRequestSentEventArgs, Task> handler, SubscriptionOptions? options = null, CancellationToken cancellationToken = default) { return await SubscribeAsync("network.beforeRequestSent", handler, options, _jsonContext.BeforeRequestSentEventArgs, cancellationToken).ConfigureAwait(false); } public async Task<Subscription> OnBeforeRequestSentAsync(Action<BeforeRequestSentEventArgs> handler, SubscriptionOptions? options = null, CancellationToken cancellationToken = default) { return await SubscribeAsync("network.beforeRequestSent", handler, options, _jsonContext.BeforeRequestSentEventArgs, cancellationToken).ConfigureAwait(false); } ... (clipped 39 lines) Solution Walkthrough: Before: // In a module like `BrowsingContextModule` public async Task<Subscription> OnNavigationStartedAsync(Func<NavigationInfo, Task> handler, SubscriptionOptions? options = null, CancellationToken cancellationToken = default) { return await SubscribeAsync("browsingContext.navigationStarted", handler, options, _jsonContext.NavigationInfo, cancellationToken).ConfigureAwait(false); } public async Task<Subscription> OnNavigationStartedAsync(Action<NavigationInfo> handler, SubscriptionOptions? options = null, CancellationToken cancellationToken = default) { return await SubscribeAsync("browsingContext.navigationStarted", handler, options, _jsonContext.NavigationInfo, cancellationToken).ConfigureAwait(false); } // ... this pattern is repeated for many other events After: // In a module like `BrowsingContextModule` public async Task<Subscription> OnNavigationStartedAsync(Func<NavigationInfo, Task> handler, SubscriptionOptions? options = null, CancellationToken cancellationToken = default) { return await SubscribeAsync("browsingContext.navigationStarted", handler, options, _jsonContext.NavigationInfo, cancellationToken).ConfigureAwait(false); } public async Task<Subscription> OnNavigationStartedAsync(Action<NavigationInfo> handler, SubscriptionOptions? options = null, CancellationToken cancellationToken = default) { // Call the Func overload, wrapping the Action. return await OnNavigationStartedAsync(e => { handler(e); return Task.CompletedTask; }, options, cancellationToken).ConfigureAwait(false); } // ... this pattern is repeated for many other events Suggestion importance[1-10]: 8 __ Why: The suggestion correctly identifies significant code duplication across multiple modules where Action and Func overloads for event subscriptions are nearly identical, and a refactoring would greatly improve code maintainability.	Medium
General	Pass cancellation token to subscription Pass the cancellationToken to the Subscription constructor to enable cancellable disposal of subscriptions. dotnet/src/webdriver/BiDi/Broker.cs [155-167] public async Task<Subscription> SubscribeAsync<TEventArgs>(string eventName, EventHandler eventHandler, SubscriptionOptions? options, JsonTypeInfo<TEventArgs> jsonTypeInfo, CancellationToken cancellationToken) where TEventArgs : EventArgs { _eventTypesMap[eventName] = jsonTypeInfo; var handlers = _eventHandlers.GetOrAdd(eventName, (a) => []); var subscribeResult = await _bidi.SessionModule.SubscribeAsync([eventName], new() { Contexts = options?.Contexts, UserContexts = options?.UserContexts }, cancellationToken).ConfigureAwait(false); handlers.Add(eventHandler); - return new Subscription(subscribeResult.Subscription, this, eventHandler); + return new Subscription(subscribeResult.Subscription, this, eventHandler, cancellationToken); } Apply / Chat Suggestion importance[1-10]: 7 __ Why: This suggestion correctly identifies a way to improve the cancellation logic by passing the cancellationToken to the Subscription constructor, which enables its use during disposal. This enhances the robustness of the cancellation feature introduced in the PR.	Medium
Possible issue	Postpone state updates until after subscribe Reorder operations in SubscribeAsync to update internal state like _eventTypesMap and _eventHandlers only after the subscription call successfully completes, preventing state inconsistency on failure or cancellation. dotnet/src/webdriver/BiDi/Broker.cs [158-164] -_eventTypesMap[eventName] = jsonTypeInfo; -var handlers = _eventHandlers.GetOrAdd(eventName, (a) => []); var subscribeResult = await _bidi.SessionModule.SubscribeAsync( [eventName], new() { Contexts = options?.Contexts, UserContexts = options?.UserContexts }, cancellationToken ).ConfigureAwait(false); +_eventTypesMap[eventName] = jsonTypeInfo; +var handlers = _eventHandlers.GetOrAdd(eventName, _ => new List<EventHandler>()); handlers.Add(eventHandler); Apply / Chat Suggestion importance[1-10]: 6 __ Why: The suggestion correctly points out a potential state inconsistency issue if the SubscribeAsync call fails or is cancelled. Reordering the operations to update internal state only after the remote call succeeds makes the method more robust and atomic.	Low
	Swap unsubscribe order for consistency In UnsubscribeAsync, call the remote unsubscribe method before removing the local event handler to ensure state consistency in case of cancellation or errors. dotnet/src/webdriver/BiDi/Broker.cs [171-175] -var eventHandlers = _eventHandlers[subscription.EventHandler.EventName]; -eventHandlers.Remove(subscription.EventHandler); await _bidi.SessionModule.UnsubscribeAsync( [subscription.SubscriptionId], null, cancellationToken ).ConfigureAwait(false); +var eventHandlers = _eventHandlers[subscription.EventHandler.EventName]; +eventHandlers.Remove(subscription.EventHandler); [To ensure code accuracy, apply this suggestion manually] Suggestion importance[1-10]: 6 __ Why: This suggestion correctly identifies a potential state inconsistency issue. By performing the remote UnsubscribeAsync call before removing the local event handler, it ensures the local state is only updated upon successful unsubscription, making the operation more robust.	Low
Learned best practice	Make unsubscribe/dispose idempotent Track an _unsubscribed flag (via Interlocked.Exchange) so UnsubscribeAsync/DisposeAsync are idempotent and safe if called multiple times or concurrently. dotnet/src/webdriver/BiDi/Subscription.cs [27-51] public class Subscription : IAsyncDisposable { private readonly Broker _broker; + private int _unsubscribed; ... public async Task UnsubscribeAsync(CancellationToken cancellationToken = default) { + if (Interlocked.Exchange(ref _unsubscribed, 1) != 0) + { + return; + } + await _broker.UnsubscribeAsync(this, cancellationToken).ConfigureAwait(false); } public async ValueTask DisposeAsync() { await UnsubscribeAsync().ConfigureAwait(false); } } [To ensure code accuracy, apply this suggestion manually] Suggestion importance[1-10]: 6 __ Why: Relevant best practice - Make lifecycle/concurrency-sensitive disposal robust and idempotent to prevent double-unsubscribe and races.	Low
	Validate inputs and cancellation early Validate eventName (null/whitespace) and call cancellationToken.ThrowIfCancellationRequested() before mutating _eventTypesMap/_eventHandlers so canceled calls don’t leave partial state. dotnet/src/webdriver/BiDi/Broker.cs [155-167] public async Task<Subscription> SubscribeAsync<TEventArgs>(string eventName, EventHandler eventHandler, SubscriptionOptions? options, JsonTypeInfo<TEventArgs> jsonTypeInfo, CancellationToken cancellationToken) where TEventArgs : EventArgs { + if (string.IsNullOrWhiteSpace(eventName)) + { + throw new ArgumentException("Event name must be provided.", nameof(eventName)); + } + + cancellationToken.ThrowIfCancellationRequested(); + _eventTypesMap[eventName] = jsonTypeInfo; - var handlers = _eventHandlers.GetOrAdd(eventName, (a) => []); + var handlers = _eventHandlers.GetOrAdd(eventName, _ => []); - var subscribeResult = await _bidi.SessionModule.SubscribeAsync([eventName], new() { Contexts = options?.Contexts, UserContexts = options?.UserContexts }, cancellationToken).ConfigureAwait(false); + var subscribeResult = await _bidi.SessionModule + .SubscribeAsync([eventName], new() { Contexts = options?.Contexts, UserContexts = options?.UserContexts }, cancellationToken) + .ConfigureAwait(false); handlers.Add(eventHandler); return new Subscription(subscribeResult.Subscription, this, eventHandler); } Apply / Chat Suggestion importance[1-10]: 5 __ Why: Relevant best practice - Add explicit validation and cancellation guards at integration boundaries before mutating internal state or making remote calls.	Low
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