Class: Quonfig::Telemetry::FailoverAggregator

Inherits:
Object
  • Object
show all
Defined in:
lib/quonfig/telemetry/failover_aggregator.rb

Overview

Accumulates failover-behavior counters over a flush window: how many times the config-fetch hedge fired its secondary leg, how many installs the reject-older ordering guard dropped, and which upstream leg served each successful HTTP install. Every counter is additive and carries NO user data.

The aggregator is independently thread-safe (its own mutex) and is written directly from the failover call sites in ConfigLoader rather than through any queue — the call rate is per-config-refresh, not per-evaluation, so a plain mutex has negligible overhead.

Wire shape matches sdk-go's FailoverEvent (the canonical reference) and api-telemetry's failover schema EXACTLY — camelCase keys, unix-millis window. #drain_event returns nil when every counter is zero, so a healthy steady-state client emits no failover event at all.

{ "failover": {
  "start": <int ms>, "end": <int ms>,
  "hedgeFired": <int>, "guardRejected": <int>,
  "resolvedFromPrimary": <int>, "resolvedFromSecondary": <int>,
  "resolvedFromLkg": <int>
} }

Instance Method Summary collapse

Constructor Details

#initialize ⇒ FailoverAggregator

Returns a new instance of FailoverAggregator.



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# File 'lib/quonfig/telemetry/failover_aggregator.rb', line 28

def initialize
  @mutex = Mutex.new
  @start_at_ms = nil
  @hedge_fired = 0
  @guard_rejected = 0
  @resolved_from_primary = 0
  @resolved_from_secondary = 0
  # Reserved for a future last-known-good delivery path; backends emit 0.
  @resolved_from_lkg = 0
end

Instance Method Details

#drain_event ⇒ Object

Return the window's counters as a telemetry event hash and reset state. Returns nil when no failover activity occurred (every counter zero).



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# File 'lib/quonfig/telemetry/failover_aggregator.rb', line 75

def drain_event
  @mutex.synchronize do
    if @hedge_fired.zero? && @guard_rejected.zero? &&
       @resolved_from_primary.zero? && @resolved_from_secondary.zero? &&
       @resolved_from_lkg.zero?
      return nil
    end

    event = {
      'failover' => {
        'start' => @start_at_ms || Quonfig::TimeHelpers.now_in_ms,
        'end' => Quonfig::TimeHelpers.now_in_ms,
        'hedgeFired' => @hedge_fired,
        'guardRejected' => @guard_rejected,
        'resolvedFromPrimary' => @resolved_from_primary,
        'resolvedFromSecondary' => @resolved_from_secondary,
        'resolvedFromLkg' => @resolved_from_lkg
      }
    }

    reset
    event
  end
end

#record_guard_rejected ⇒ Object

Count one install dropped by the reject-older ordering guard (an equal-or-older snapshot on any install path — HTTP config-fetch or SSE).



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# File 'lib/quonfig/telemetry/failover_aggregator.rb', line 50

def record_guard_rejected
  @mutex.synchronize do
    @start_at_ms ||= Quonfig::TimeHelpers.now_in_ms
    @guard_rejected += 1
  end
end

#record_hedge_fired ⇒ Object

Count one config-fetch cycle whose hedge fired the secondary leg (the primary was slow past the hedge delay or errored fast).



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# File 'lib/quonfig/telemetry/failover_aggregator.rb', line 41

def record_hedge_fired
  @mutex.synchronize do
    @start_at_ms ||= Quonfig::TimeHelpers.now_in_ms
    @hedge_fired += 1
  end
end

#record_resolved_from(source_index) ⇒ Object

Count one successful HTTP install by the leg that served it: source_index 0 is the primary, any index > 0 is a failover/secondary leg. A nil or negative index (SSE / datadir install with no HTTP leg) is ignored.



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# File 'lib/quonfig/telemetry/failover_aggregator.rb', line 60

def record_resolved_from(source_index)
  return if source_index.nil? || source_index.negative?

  @mutex.synchronize do
    @start_at_ms ||= Quonfig::TimeHelpers.now_in_ms
    if source_index.zero?
      @resolved_from_primary += 1
    else
      @resolved_from_secondary += 1
    end
  end
end