Class: Chef::Provider::RemoteFile::CacheControlData

Inherits:
Object
  • Object
show all
Defined in:
lib/chef/provider/remote_file/cache_control_data.rb

Overview

CacheControlData

Implements per-uri storage of cache control data for a remote resource along with a sanity check checksum of the file in question. Provider::RemoteFile protocol implementation classes can use this information to avoid re-fetching files when the current copy is up to date. The way this information is used is protocol-dependent. For HTTP, this information is sent to the origin server via headers to make a conditional GET request.

API

The general shape of the API is active-record-the-pattern-like. New instances should be instantiated via ‘CacheControlData.load_and_validate`, which will do a find-or-create operation and then sanity check the data against the checksum of the current copy of the file. If there is no data or the sanity check fails, the `etag` and `mtime` attributes will be set to nil; otherwise they are populated with the previously saved values.

After fetching a file, the CacheControlData instance should be updated with new etag, mtime and checksum values in whatever format is preferred by the protocol used. Then call #save to save the data to disk.

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(uri) ⇒ CacheControlData

Returns a new instance of CacheControlData.



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# File 'lib/chef/provider/remote_file/cache_control_data.rb', line 83

def initialize(uri)
  uri = uri.dup
  uri.password = "XXXX" unless uri.userinfo.nil?
  @uri = uri.to_s
end

Instance Attribute Details

#checksum ⇒ Object

SHA2-256 Hash of the file as last fetched.



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# File 'lib/chef/provider/remote_file/cache_control_data.rb', line 77

def checksum
  @checksum
end

#etag ⇒ Object

Entity Tag of the resource. HTTP-specific. See also: www.w3.org/Protocols/rfc2616/rfc2616-sec13.html#sec13.3.2 www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.19



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# File 'lib/chef/provider/remote_file/cache_control_data.rb', line 65

def etag
  @etag
end

#mtime ⇒ Object

Last modified time of the remote resource. Different protocols will use different types for this field (e.g., string representation of a specific date format, integer, etc.) For HTTP-specific references, see:



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# File 'lib/chef/provider/remote_file/cache_control_data.rb', line 74

def mtime
  @mtime
end

#uri ⇒ Object (readonly)

URI of the resource as a String. This is the “primary key” used for storage and retrieval.



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# File 'lib/chef/provider/remote_file/cache_control_data.rb', line 81

def uri
  @uri
end

Class Method Details

.load_and_validate(uri, current_copy_checksum) ⇒ Object 



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# File 'lib/chef/provider/remote_file/cache_control_data.rb', line 55

def self.load_and_validate(uri, current_copy_checksum)
  ccdata = new(uri)
  ccdata.load
  ccdata.validate!(current_copy_checksum)
  ccdata
end

Instance Method Details

#json_data ⇒ Object

:nodoc: JSON representation of this object for storage.



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# File 'lib/chef/provider/remote_file/cache_control_data.rb', line 117

def json_data
  Chef::JSONCompat.to_json(hash_data)
end

#load ⇒ Object 



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# File 'lib/chef/provider/remote_file/cache_control_data.rb', line 89

def load
  if previous_cc_data = load_data
    apply(previous_cc_data)
    self
  else
    false
  end
end

#save ⇒ Object

Saves the data to disk using Chef::FileCache. The filename is a sanitized version of the URI with a MD5 of the same URI appended (to avoid collisions between different URIs having the same sanitized form).



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# File 'lib/chef/provider/remote_file/cache_control_data.rb', line 111

def save
  Chef::FileCache.store("remote_file/#{sanitized_cache_file_basename}", json_data)
end

#validate!(current_copy_checksum) ⇒ Object 



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# File 'lib/chef/provider/remote_file/cache_control_data.rb', line 98

def validate!(current_copy_checksum)
  if current_copy_checksum.nil? || checksum != current_copy_checksum
    reset!
    false
  else
    true
  end
end