wikimedia/objectcache

Statistics

Sent to StatsD under MediaWiki's namespace.

WANObjectCache

The default WANObjectCache provided by MediaWikiServices disables these statistics in entry points where MW_ENTRY_POINT is 'cli'.

wanobjectcache.{kClass}.{cache_action_and_result}

Upon cache access via WANObjectCache::getWithSetCallback(), this measures the total time spent in this method from start to end for all cases, except process-cache hits.

See also wanobjectcache.{kClass}.regen_walltime, which, during misses/renews, measures just the portion of time spent in the callback to regenerate the value.

• Type: Measure (in milliseconds).
• Variable kClass: The first part of your cache key.
• Variable result: One of:
  • "hit.good": A non-expired value was returned (and call did not get chosen for pre-emptive refresh).
  • "hit.refresh": A non-expired value was returned (and call was chosen for a pre-emptive refresh, and an async refresh was scheduled).
  • "hit.volatile": A value was found that was generated and stored less than 0.1s ago, and returned as-is despite appearing to also be expired already. This amount of time is considered negligible in terms of clock accuracy, and by random chance we usually decide to treat these as a cache hit (see RECENT_SET_HIGH_MS).
  • "hit.stale": An expired value was found, but we are within the allowed stale period specified by a lockTSE option, and the current request did not get the regeneration lock. The stale value is returned as-is.
  • "miss.compute": A new value was computed by the callback and returned. No non-expired value was found, and if this key needed a regeneration lock, we got the lock.
  • "miss.busy": A busy value was produced by a busyValue callback and returned. No non-expired value was found, and we tried to use a regeneration lock (per the busyValue option), but the current request did not get the lock.
  • "renew.compute": Artificial demand from an async refresh, led to a new value being computed by the callback. These are like "miss.compute", but in response to "hit.refresh".
  • "renew.busy": Artificial demand from an async refresh failed to produce a value. The key used the busyValue option, and could not get a regeneration lock.

wanobjectcache.{kClass}.regen_walltime

Upon cache update due to a cache miss or async refresh, this measures the time spent in the regeneration callback when computing a new value.

• Type: Measure (in milliseconds).
• Variable kClass: The first part of your cache key.

wanobjectcache.{kClass}.ck_touch.{result}

Call counter from WANObjectCache::touchCheckKey().

• Type: Counter.
• Variable kClass: The first part of your cache key.
• Variable result: One of "ok" or "error".

wanobjectcache.{kClass}.ck_reset.{result}

Call counter from WANObjectCache::resetCheckKey().

• Type: Counter.
• Variable kClass: The first part of your cache key.
• Variable result: One of "ok" or "error".

wanobjectcache.{kClass}.delete.{result}

Call counter from WANObjectCache::delete().

• Type: Counter.
• Variable kClass: The first part of your cache key.
• Variable result: One of "ok" or "error".