Module: Protobuf::Nats

Defined in:
lib/protobuf/nats.rb,
lib/protobuf/nats/client.rb,
lib/protobuf/nats/config.rb,
lib/protobuf/nats/errors.rb,
lib/protobuf/nats/runner.rb,
lib/protobuf/nats/server.rb,
lib/protobuf/nats/version.rb,
lib/protobuf/nats/thread_pool.rb,
lib/protobuf/nats/uuidv7_helper.rb,
lib/protobuf/nats/response_muxer.rb,
lib/protobuf/nats/response_muxer_request.rb,
lib/protobuf/nats/super_subscription_manager.rb

Defined Under Namespace

Modules: Errors, Messages Classes: Client, Config, ResponseMuxer, ResponseMuxerRequest, Runner, Server, SuperSubscriptionManager, ThreadPool, UUIDv7Helper

Constant Summary collapse

NatsClient = 
::NATS::IO::Client
GET_CONNECTED_MUTEX = 
::Mutex.new
ERROR_CALLBACK_EXECUTOR =

Bounded, single-thread executor for running error callbacks OFF hot/shared threads (notably nats-pure’s read/flush thread via on_error). A slow user callback must not stall message processing for every subject. The queue is bounded and over-capacity notifications are discarded (they’re advisory).

::Concurrent::ThreadPoolExecutor.new(
  :min_threads => 0,
  :max_threads => 1,
  :max_queue => 1024,
  :fallback_policy => :discard
)
ERROR_CALLBACK_DROP_COUNT =

Count of error callbacks discarded because the bounded executor was saturated. Lets a flood of dropped callbacks during an incident be observed instead of vanishing silently.

::Concurrent::AtomicFixnum.new(0)
VERSION = 
"0.13.1.pre2"

Class Attribute Summary collapse

Class Method Summary collapse

Class Attribute Details

.client_nats_connection ⇒ Object

Returns the value of attribute client_nats_connection.



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# File 'lib/protobuf/nats.rb', line 25

def client_nats_connection
  @client_nats_connection
end

Class Method Details

.config ⇒ Object 



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# File 'lib/protobuf/nats.rb', line 37

def self.config
  @config ||= begin
    config = ::Protobuf::Nats::Config.new
    config.load_from_yml
    config
  end
end

.crash_backoff_seconds(crash_count, cap = 60) ⇒ Object

Exponential backoff (seconds) for self-healing worker threads after a fatal crash, capped. Shared by the ResponseMuxer dispatcher pool and the server SuperSubscriptionManager handler pool so the formula can’t drift between them.



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# File 'lib/protobuf/nats.rb', line 197

def self.crash_backoff_seconds(crash_count, cap = 60)
  [(crash_count**2), cap].min
end

.error_callback_drop_count ⇒ Object 



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# File 'lib/protobuf/nats.rb', line 98

def self.error_callback_drop_count
  ERROR_CALLBACK_DROP_COUNT.value
end

.error_callbacks ⇒ Object

We will always log an error.



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# File 'lib/protobuf/nats.rb', line 49

def self.error_callbacks
  @error_callbacks ||= [lambda { |error| log_error(error) }]
end

.instrument(event, payload = {}, &block) ⇒ Object

Single instrumentation entry point. Appends the gem’s ‘.protobuf-nats` suffix so callers don’t repeat it (and can’t typo it). Supports both the value form ‘instrument(“server.x”, 5)` and the block form `instrument(“client.request_duration”) { … }`.



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# File 'lib/protobuf/nats.rb', line 66

def self.instrument(event, payload = {}, &block)
  ::ActiveSupport::Notifications.instrument("#{event}.protobuf-nats", payload, &block)
end

.log_error(error) ⇒ Object 



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# File 'lib/protobuf/nats.rb', line 201

def self.log_error(error)
  logger.error error.to_s
  logger.error error.class.to_s
  if error.respond_to?(:backtrace) && error.backtrace.is_a?(::Array)
    logger.error error.backtrace.join("\n")
  end
end

.logger ⇒ Object 



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# File 'lib/protobuf/nats.rb', line 209

def self.logger
  ::Protobuf::Logging.logger
end

.monotonic_time ⇒ Object

Monotonic clock for durations/ages; immune to wall-clock (NTP) jumps. Single source of truth shared by the client muxer and server pools.



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# File 'lib/protobuf/nats.rb', line 190

def self.monotonic_time
  ::Process.clock_gettime(::Process::CLOCK_MONOTONIC)
end

.notify_error_callbacks(error) ⇒ Object 



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# File 'lib/protobuf/nats.rb', line 70

def self.notify_error_callbacks(error)
  error_callbacks.each do |callback|
    begin
      callback.call(error)
    rescue => callback_error
      log_error(callback_error)
    end
  end

  nil
end

.notify_error_callbacks_async(error) ⇒ Object 



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# File 'lib/protobuf/nats.rb', line 102

def self.notify_error_callbacks_async(error)
  # #post returns false when the job is rejected. With the :discard fallback
  # policy the job is silently dropped (returning false) rather than raising,
  # so the false return is the only drop signal to handle.
  accepted = ERROR_CALLBACK_EXECUTOR.post { notify_error_callbacks(error) }
  record_dropped_error_callback unless accepted
  nil
end

.on_error(&block) ⇒ Object 



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# File 'lib/protobuf/nats.rb', line 56

def self.on_error(&block)
  fail ::ArgumentError unless block.arity == 1
  error_callbacks << block
  nil
end

.record_dropped_error_callback ⇒ Object

Record a discarded error callback. Kept cheap – this runs on nats-pure’s read/flush thread, so it must NOT format/log the error synchronously (the whole point of the async path). The atomic counter is the durable signal; the instrument gauge emits a discrete event for dashboards (drops only happen under a severe flood, so a notification per drop is acceptable).



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# File 'lib/protobuf/nats.rb', line 116

def self.record_dropped_error_callback
  ERROR_CALLBACK_DROP_COUNT.increment
  instrument("error_callback_dropped", 1)
  nil
end

.start_client_nats_connection ⇒ Object 



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# File 'lib/protobuf/nats.rb', line 130

def self.start_client_nats_connection
  return true if @client_nats_connection

  GET_CONNECTED_MUTEX.synchronize do
    break true if @client_nats_connection

    # NOTE: nats-pure has no :disable_reconnect_buffer option (it was a
    # jnats concept). During a reconnect nats-pure buffers publishes and,
    # if the connection is fully closed, raises ConnectionClosedError --
    # both of which the client's transient-error retry path now handles.
    options = config.connection_options

    client = NatsClient.new

    # Register lifecycle callbacks BEFORE connecting so a disconnect or
    # error during the initial handshake is still observed.
    client.on_disconnect do
      logger.warn("Client NATS connection was disconnected")
    end

    client.on_reconnect do
      logger.warn("Client NATS connection was reconnected")
    end

    client.on_close do
      logger.warn("Client NATS connection was closed")
      # A close is terminal for this client object (nats-pure only reconnects
      # via on_disconnect/on_reconnect; on_close means it gave up). Drop the
      # memoized reference so the next start_client_nats_connection rebuilds a
      # fresh connection instead of reusing a permanently-dead one. In-flight
      # callers keep their own local reference; only new calls rebuild.
      @client_nats_connection = nil
    end

    client.on_error do |error|
      # Runs on nats-pure's read/flush thread -- offload so a slow callback
      # can't stall message processing.
      notify_error_callbacks_async(error)
    end

    begin
      client.connect(options)
      # Ensure we have a valid connection to the NATS server.
      client.flush(5)
    rescue => e
      # A failed handshake can leave nats-pure's reader/flusher threads
      # running on a half-open client; close it so we don't leak them, then
      # surface the failure (the next call will retry with a fresh client).
      client.close rescue nil
      raise e
    end

    @client_nats_connection = client

    true
  end
end

.subscription_key(service_klass, service_method) ⇒ Object 



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# File 'lib/protobuf/nats.rb', line 122

def self.subscription_key(service_klass, service_method)
  service_class_name = service_klass.name.underscore.gsub("/", ".")
  service_method_name = service_method.to_s.underscore

  subscription_key = "rpc.#{service_class_name}.#{service_method_name}"
  subscription_key = config.make_subscription_key_replacements(subscription_key)
end