Class: Vangrail::ResultCache

Inherits:
Object
  • Object
show all
Defined in:
lib/vangrail/result_cache.rb

Overview

Bounded in-process memo for rail results.

A reader who rephrases, retries, or clicks a suggested follow-up sends text a rail has already judged, and each repeat costs another round trip. Keyed on side, rail name, and whatever that rail says its decision depends on, so a changed model or a changed policy never reads a stale decision.

Only decided results are stored. A result with certain? == false records a rail that failed or did not run, and caching that would turn one unlucky moment into a session-long hole.

Constant Summary collapse

DEFAULT_LIMIT = 
256

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(limit: DEFAULT_LIMIT) ⇒ ResultCache

Returns a new instance of ResultCache.



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# File 'lib/vangrail/result_cache.rb', line 19

def initialize(limit: DEFAULT_LIMIT)
  @limit = limit
  @store = {}
  @hits = 0
  @misses = 0
  @mutex = Mutex.new
end

Instance Attribute Details

#hits ⇒ Object (readonly)

Returns the value of attribute hits.



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# File 'lib/vangrail/result_cache.rb', line 17

def hits
  @hits
end

#limit ⇒ Object (readonly)

Returns the value of attribute limit.



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# File 'lib/vangrail/result_cache.rb', line 17

def limit
  @limit
end

#misses ⇒ Object (readonly)

Returns the value of attribute misses.



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# File 'lib/vangrail/result_cache.rb', line 17

def misses
  @misses
end

Instance Method Details

#clear ⇒ Object 



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# File 'lib/vangrail/result_cache.rb', line 51

def clear
  @mutex.synchronize { @store.clear }
end

#fetch(side, name, key) ⇒ Object

Yields on a miss and stores what the block returns. Hits move to the newest slot so the oldest unused key is the one shift drops.



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# File 'lib/vangrail/result_cache.rb', line 29

def fetch(side, name, key)
  store_key = [side, name, key]
  hit = @mutex.synchronize do
    next unless @store.key?(store_key)

    @hits += 1
    value = @store.delete(store_key)
    @store[store_key] = value
    value
  end
  return hit if hit

  @mutex.synchronize { @misses += 1 }
  result = yield
  store(store_key, result)
  result
end

#size ⇒ Object 



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# File 'lib/vangrail/result_cache.rb', line 47

def size
  @mutex.synchronize { @store.size }
end

#to_h ⇒ Object 



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# File 'lib/vangrail/result_cache.rb', line 55

def to_h
  { 'size' => size, 'limit' => limit, 'hits' => hits, 'misses' => misses }
end