Class: FileCache

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

Overview

A file-based caching library. It uses Marshal::dump and Marshal::load to serialize/deserialize cache values - so you should be OK to cache object values.

Constant Summary collapse

MAX_DEPTH = 
32

Instance Method Summary collapse

Constructor Details

#initialize(domain = "default", root_dir = "/tmp", expiry = 0, depth = 2) ⇒ FileCache

Create a new reference to a file cache system.

domain

A string that uniquely identifies this caching system on the given host

root_dir

The root directory of the cache file hierarchy The cache will be rooted at root_dir/domain/

expiry

The expiry time for cache entries, in seconds. Use 0 if you want cached values never to expire.

depth

The depth of the file tree storing the cache. Should be large enough that no cache directory has more than a couple of hundred objects in it



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# File 'lib/filecache.rb', line 21

def initialize(domain = "default", root_dir = "/tmp", expiry = 0, depth = 2)
  @domain  = domain
  @root_dir = root_dir
  @expiry  = expiry
  @depth   = depth > MAX_DEPTH ? MAX_DEPTH : depth
  FileUtils.mkdir_p(get_root)
end

Instance Method Details

#clear ⇒ Object

Delete ALL data from the cache, regardless of expiry time



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# File 'lib/filecache.rb', line 63

def clear
  if File.exists?(get_root)
    FileUtils.rm_r(get_root)
    FileUtils.mkdir_p(get_root)
  end
end

#delete(key) ⇒ Object

Delete the value for the given key from the cache



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# File 'lib/filecache.rb', line 58

def delete(key)
  FileUtils.rm(get_path(key))
end

#get(key) ⇒ Object

Return the value for the specified key from the cache. Returns nil if the value isn’t found.



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# File 'lib/filecache.rb', line 39

def get(key)
  path = get_path(key)

  # expire
  if @expiry > 0 && File.exists?(path) && Time.new - File.new(path).mtime >= @expiry
    FileUtils.rm(path)
  end
  
  if File.exists?(path)
    f = File.open(path, "r")
    result = Marshal.load(f)
    f.close
    return result
  else
    return nil
  end
end

#purge ⇒ Object

Delete all expired data from the cache



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# File 'lib/filecache.rb', line 71

def purge
  @t_purge = Time.new
  purge_dir(get_root) if @expiry > 0
end

#set(key, value) ⇒ Object

Set a cache value for the given key. If the cache contains an existing value for the key it will be overwritten.



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# File 'lib/filecache.rb', line 31

def set(key, value)
  f = File.open(get_path(key), "w")
  Marshal.dump(value, f)
  f.close
end