module LittleGhost::Instrumentation

Instrumentation turns agent work into structured lifecycle notifications. Applications can measure agents, models, tools, workflows, and sessions with the telemetry backend they already use.

class TimingSubscriber < LittleGhost::Instrumentation::Subscriber
  def finish(name, attributes)
    puts "#{name}: #{attributes.fetch(:duration_ms)}ms"
  end
end

LittleGhost.configure do |config|
  config.instrument TimingSubscriber.new
end

A subscriber receives structured attributes when an operation starts, finishes, or emits a point-in-time event. Subscriber failures are reported once and kept separate from agent execution.

`Content` and trust

Diagnostic content is excluded unless the application installs an explicit Support::ContentCapture policy. One process is one telemetry and content policy boundary; applications that need different exporters or data policies should use separate processes.

Public Class Methods

capture_content (...)

Source

# File lib/little_ghost/instrumentation.rb, line 433
def capture_content(...) = bus.capture_content(...)

Installs the process-wide diagnostic content policy.

context ()

Source

# File lib/little_ghost/instrumentation.rb, line 445
def context = bus.context

Copies the current instrumentation context.

current ()

Source

# File lib/little_ghost/instrumentation.rb, line 441
def current = bus.current

Returns the current fiber’s active Handle.

flush (...)

Source

# File lib/little_ghost/instrumentation.rb, line 447
def flush(...) = bus.flush(...)

Flushes process-wide subscribers.

instrument (...)

Source

# File lib/little_ghost/instrumentation.rb, line 439
def instrument(...) = bus.instrument(...)

Wraps a block in a lifecycle operation.

notifier ()

Source

# File lib/little_ghost/instrumentation.rb, line 413
def notifier = bus

Accesses the process-wide Bus.

notifier= (value)

Source

# File lib/little_ghost/instrumentation.rb, line 416
def notifier=(value)
  raise ArgumentError, "notifier must be an instrumentation bus" unless value.is_a?(Bus)

  notifier_mutex.synchronize do
    if @bus && !@bus.equal?(value) && @bus.active?
      raise Error, "cannot replace instrumentation notifier with active operations"
    end

    @bus = value
  end
end

Replaces the process-wide bus when it has no active operations.

publish (...)

Source

# File lib/little_ghost/instrumentation.rb, line 435
def publish(...) = bus.publish(...)

Publishes a point event on the process-wide bus.

shutdown (...)

Source

# File lib/little_ghost/instrumentation.rb, line 449
def shutdown(...) = bus.shutdown(...)

Shuts down the process-wide bus.

start (...)

Source

# File lib/little_ghost/instrumentation.rb, line 437
def start(...) = bus.start(...)

Starts a lifecycle operation on the process-wide bus.

subscribed (subscriber, prepend: false) { || ... }

Source

# File lib/little_ghost/instrumentation.rb, line 454
def subscribed(subscriber, prepend: false)
  unless subscriber.is_a?(Subscriber)
    raise ArgumentError, "instrumentation subscriber must be a LittleGhost::Instrumentation::Subscriber"
  end

  subscribers = ExecutionState[:instrumentation_subscribers] || []
  entry = {subscriber:, prepend:}
  ExecutionState.with(instrumentation_subscribers: subscribers + [entry]) { yield }
end

Temporarily subscribes a backend for the block’s execution state.

trace_context (...)

Source

# File lib/little_ghost/instrumentation.rb, line 451
def trace_context(...) = bus.trace_context(...)

Gets downstream trace fields from process-wide subscribers.

unsubscribe (...)

Source

# File lib/little_ghost/instrumentation.rb, line 431
def unsubscribe(...) = bus.unsubscribe(...)

Unsubscribes a process-wide backend.

with_context (attributes, &block)

Source

# File lib/little_ghost/instrumentation.rb, line 443
def with_context(attributes, &block) = bus.with_context(attributes, &block)

Adds attributes while the block runs.

module LittleGhost::Instrumentation

Content and trust

`Content` and trust