Class: SciYAG::Backends::Cache

Inherits:
Object
  • Object
show all
Defined in:
lib/SciYAG/Backends/cache.rb

Overview

The Cache class aims at providing a small and easy-to-use cache with validation checking, usage statistics and flushing (automatically removes some entries when it grows too big).

Defined Under Namespace

Classes: CacheEntry

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Cache

Creates a Cache



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# File 'lib/SciYAG/Backends/cache.rb', line 57

def initialize
  # The cache itself
  @cache = {}

  @statistics = {}
end

Instance Attribute Details

#statistics ⇒ Object

Records all accessed items and the number of cache misses/succes and so on.



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# File 'lib/SciYAG/Backends/cache.rb', line 54

def statistics
  @statistics
end

Instance Method Details

#get_cache(name, meta_data, &code) ⇒ Object

Look inside the cache for a cached element. If it is found and up-to-date, it is returned. If not, #get_cache runs code, stores its return value as a new cache for (name, meta_data) and returns it.



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# File 'lib/SciYAG/Backends/cache.rb', line 68

def get_cache(name, meta_data, &code)
  if (@cache.key?(name)) and
      ((cached = @cache[name]).relevant?(meta_data))
    stats(name)[:accesses] += 1
    return cached.data
  elsif @cache.key?(name)
    stats(name)[:updates] += 1
  end
  stats(name)[:misses] += 1
  
  # Now, we run the code to update the cache entry:
  data = code.call
  @cache[name] = CacheEntry.new(name, data, meta_data)
  return data
end

#stats(name) ⇒ Object

Returns the statistics for the given item, or create them on the fly if necessary:



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# File 'lib/SciYAG/Backends/cache.rb', line 86

def stats(name)
  if @statistics[name]
    return @statistics[name]
  else
    @statistics[name] = {
      :accesses => 0,
      :misses => 0,
      :updates => 0
    }
    return @statistics[name]
  end
end