Class: Piggly::Compiler::CacheDir

Inherits:
Object
  • Object
show all
Defined in:
lib/piggly/compiler/cache_dir.rb

Overview

Each cache unit (any group of data that should be expired and created together) can be broken apart, to prevent unmarshaling a huge block of data all at once.

The interface works like a Hash, so the compile method should return a hash of objects. Each object is writen to a different file (named by the hash key) within the same directory. String objects are (usually) read and written directly to disk, while all other objects are (un-)Marshal’d

Cache invalidation is done by comparing mtime timestamps on the cached object’s file to all the “source” files (ruby libs, input files, etc) required to regenerate the data.

Constant Summary collapse

HINT =

Non-printable ASCII char indicates data should be Marshal’d

/[\000-\010\016-\037\177-\300]/

Instance Method Summary collapse

Constructor Details

#initialize(dir) ⇒ CacheDir

Returns a new instance of CacheDir.



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# File 'lib/piggly/compiler/cache_dir.rb', line 24

def initialize(dir)
  @dir  = dir
  @data = Hash.new do |h, k|
    path = File.join(@dir, k.to_s)
    if File.exists?(path)
      h[k.to_s] = File.open(path, "rb") do |io|
        # Detect Marshal'd data
        if io.read(2) !~ HINT
          io.rewind
          io.read
        else
          io.rewind
          Marshal.load(io)
        end
      end
    end
  end
end

Instance Method Details

#[](key) ⇒ Object

Load given key from file system into memory if needed

@return [Object]



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# File 'lib/piggly/compiler/cache_dir.rb', line 45

def [](key)
  @data[key.to_s]
end

#[]=(key, value) ⇒ Object

Writes through to file system

@return [void]



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# File 'lib/piggly/compiler/cache_dir.rb', line 51

def []=(key, value)
  @data[key.to_s] = value
  write(key.to_s => value)
end

#clear ⇒ Object

Creates cachedir, destroys its contents, and returns self

@return [CacheDir] self



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# File 'lib/piggly/compiler/cache_dir.rb', line 77

def clear
  @data.clear

  if File.exists?(@dir)
    FileUtils.rm(Dir["#{@dir}/*"])
    FileUtils.touch(@dir)
  else
    FileUtils.mkdir(@dir) 
  end

  self
end

#delete(key) ⇒ void

This method returns an undefined value.



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# File 'lib/piggly/compiler/cache_dir.rb', line 64

def delete(key)
  path = File.join(@dir, key.to_s)
  File.unlink(path) if File.exists?(path)
  @data.delete(key)
end

#keys ⇒ Array<String>

Returns:



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# File 'lib/piggly/compiler/cache_dir.rb', line 71

def keys
  Dir[@dir + "/*"].map{|f| File.basename(f) }
end

#replace(hash) ⇒ Object

Clears entire cache, replaces contents, and returns self

@return [CacheDir] self



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# File 'lib/piggly/compiler/cache_dir.rb', line 92

def replace(hash)
  clear
  update(hash)
end

#update(hash) ⇒ Object

Writes through to file system and returns self

@return [CacheDir] self



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# File 'lib/piggly/compiler/cache_dir.rb', line 58

def update(hash)
  hash.each{|k,v| self[k] = v }
  self
end