Class: WeatherSage::Cache

Inherits:
Object
  • Object
show all
Defined in:
lib/weather-sage/cache.rb

Overview

Minimal cache implementation.

Instance Method Summary collapse

Constructor Details

#initialize(path) ⇒ Cache

Create a new Cache instance bound to file at path path.



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# File 'lib/weather-sage/cache.rb', line 10

def initialize(path)
  @pstore = ::PStore.new(path)
end

Instance Method Details

#delete(key) ⇒ Object

Delete entry in cache with key key.



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# File 'lib/weather-sage/cache.rb', line 60

def delete(key)
  @pstore.transaction do
    @pstore.delete(key)
  end
end

#get(key) ⇒ Object Also known as: []

Get entry in cache with key key.

Returns nil if no such entry exists.



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# File 'lib/weather-sage/cache.rb', line 50

def get(key)
  @pstore.transaction(true) do
    return nil unless entry = @pstore[key]
    entry.valid? ? entry.value : nil
  end
end

#key?(key) ⇒ Boolean

Returns true if the key exists and is it still valid.

Returns:

  • (Boolean) 


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# File 'lib/weather-sage/cache.rb', line 17

def key?(key)
  @pstore.transaction(true) do
    return false unless entry = @pstore[key]
    entry.valid?
  end
end

#set(key, val, timeout = nil) ⇒ Object Also known as: []=

Set entry in cache with key key to value val.

An optional timeout (in seconds) may be provided with timout.



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# File 'lib/weather-sage/cache.rb', line 29

def set(key, val, timeout = nil)
  @pstore.transaction do
    # calculate expiration time
    expires = timeout ? (Time.now.to_i + timeout) : nil

    # save entry
    @pstore[key] = ::WeatherSage::CacheEntry.new(expires, val)

    # purge any expired entries
    flush
  end

  # return value
  val
end