Class: Google::Cloud::Debugger::Middleware

Inherits:
Object
  • Object
show all
Defined in:
lib/google/cloud/debugger/middleware.rb

Overview

Rack Middleware implementation that supports Stackdriver Debugger Agent in Rack-based Ruby frameworks. It instantiates a new debugger agent if one isn't given already. It helps optimize Debugger Agent Tracer performance by suspend and resume tracer between each request.

Instance Method Summary collapse

Constructor Details

#initialize(app, debugger: nil, **kwargs) ⇒ Google::Cloud::Debugger::Middleware

Create a new Debugger Middleware.

Parameters:

  • app (Rack Application) —

    Rack application

  • debugger (Google::Cloud::Debugger::Project) —

    A debugger to be used by this middleware. If not given, will construct a new one using the other parameters.

  • *kwargs (Hash) —

    Hash of configuration settings. Used for backward API compatibility. See the Configuration Guide for the prefered way to set configuration parameters.



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# File 'lib/google/cloud/debugger/middleware.rb', line 43

def initialize app, debugger: nil, **kwargs
  @app = app

  load_config kwargs

  if debugger
    @debugger = debugger
  else
    @debugger =
      Debugger.new(project_id: configuration.project_id,
                   credentials: configuration.credentials,
                   service_name: configuration.service_name,
                   service_version: configuration.service_version)

    @debugger.agent.quota_manager =
      Google::Cloud::Debugger::RequestQuotaManager.new
  end

  # Immediately start the debugger agent
  @debugger.start
end

Instance Method Details

#call(env) ⇒ Rack::Response

Rack middleware entry point. In most Rack based frameworks, a request is served by one thread. It enables/resume the debugger breakpoints tracing and stops/pauses the tracing afterwards to help improve debugger performance.

Parameters:

  • env (Hash) —

    Rack environment hash

Returns:

  • (Rack::Response) —

    The response from downstream Rack app



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# File 'lib/google/cloud/debugger/middleware.rb', line 75

def call env
  # Enable/resume breakpoints tracing
  @debugger.agent.tracer.start

  # Use Stackdriver Logger for debugger if available
  if env["rack.logger"].is_a? Google::Cloud::Logging::Logger
    @debugger.agent.logger = env["rack.logger"]
  end

  @app.call env
ensure
  # Stop breakpoints tracing beyond this point
  @debugger.agent.tracer.disable_traces_for_thread

  # Reset quotas after each request finishes.
  @debugger.agent.quota_manager.reset if @debugger.agent.quota_manager
end