Class: Opod::PStoreCache

Inherits:
Object
  • Object
show all
Defined in:
lib/opod/pstore.rb

Instance Method Summary collapse

Constructor Details

#initialize(keepalive = nil) ⇒ PStoreCache 



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# File 'lib/opod/pstore.rb', line 17

def initialize(keepalive = nil)
  @keepalive = keepalive
  initialize_store
end

Instance Method Details

#[](key) ⇒ Object Also known as: get, read

Return the object stored under key from the cache. If the object isn’t present in the cache nil is returned.



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# File 'lib/opod/pstore.rb', line 25

def [](key)
  current_try = 0
  begin
    current_try += 1
    @store.transaction(true) do
      @store.fetch(key, nil)[1]
    end
  rescue PStore::Error
    # Unable to return the requested object from the cache.
    # Create a new store and retry.
    initialize_store
    unless current_try > PStoreCache.max_tries
      retry
    else
      raise Exception.new("Unable to read from cache file #{@store.path}!")
    end
  end
end

#[]=(key, obj) ⇒ Object Also known as: put, write

Store obj under key in the cache.



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# File 'lib/opod/pstore.rb', line 46

def []=(key, obj)
  current_try = 0
  begin
    current_try += 1
    @store.transaction(false) do
      if @keepalive
        @store[key] = [Time.now + @keepalive, obj]
      else
        @store[key] = [nil, obj]
      end
    end
  rescue PStore::Error
    # Unable to store object.
    # Create a new store and retry.
    initialize_store
    unless current_try > PStoreCache.max_tries
      retry
    else
      raise Exception.new("Unable to write to cache file #{@store.path}!")
    end
  end
end

#all ⇒ Object Also known as: values

Return all objects stored in the cache.



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# File 'lib/opod/pstore.rb', line 71

def all
  current_try = 0
  begin
    current_try += 1
    @store.transaction(true) do
      @store.roots.inject([]) do |result, current|
        result << @store[current][1]
      end
    end
  rescue PStore::Error
    # Unable to return stored objects from cache.
    # Create a new store and retry.
    initialize_store
    unless current_try > PStoreCache.max_tries
      retry
    else
      raise Exception.new("Unable to read from cache file #{@store.path}!")
    end
  end
end

#delete(key) ⇒ Object

Delete the object stored under key in the cache.



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# File 'lib/opod/pstore.rb', line 94

def delete(key)
  begin
    @store.transaction(false) do
      @store.delete(key)
    end
  rescue PStore::Error
    # Unable to delete object from the cache.
    # Create a new store.
    initialize_store
  end
end

#gc! ⇒ Object

Remove all expired objects from the cache.



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# File 'lib/opod/pstore.rb', line 108

def gc!
  return unless @keepalive
  begin
    now = Time.now
    @store.transaction(false) do
      @store.roots.each do |r|
        @store.delete(r) if now > @store[r][0]
      end
    end
  rescue PStore::Error
    # Unable to delete object from the cache.
    # Create a new store.
    initialize_store
  end
end