Class: Wrest::CacheProxy::DefaultCacheProxy

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

Constant Summary collapse

HOP_BY_HOP_HEADERS = 
["connection",
"keep-alive",
"proxy-authenticate",
"proxy-authorization",
"te",
"trailers",
"transfer-encoding",
"upgrade"]

Instance Method Summary collapse

Constructor Details

#initialize(get, cache_store) ⇒ DefaultCacheProxy

Returns a new instance of DefaultCacheProxy.



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# File 'lib/wrest/cache_proxy.rb', line 33

def initialize(get, cache_store)
  @get         = get
  @cache_store = cache_store
end

Instance Method Details

#cache(response) ⇒ Object 



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# File 'lib/wrest/cache_proxy.rb', line 63

def cache(response)
  @cache_store[@get.full_uri_string] = response.clone if response && response.cacheable?
end

#get ⇒ Object 



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# File 'lib/wrest/cache_proxy.rb', line 42

def get
  cached_response = @cache_store[@get.full_uri_string]
  return get_fresh_response if cached_response.nil?

  if cached_response.expired?
    if cached_response.can_be_validated?
      get_validated_response_for(cached_response)
    else
      get_fresh_response
    end
  else
    log_cached_response
    cached_response
  end
end

#get_fresh_response ⇒ Object

:nodoc:



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# File 'lib/wrest/cache_proxy.rb', line 68

def get_fresh_response
  @cache_store.delete @get.full_uri_string

  response = @get.invoke_without_cache_check

  cache(response)

  response
end

#get_validated_response_for(cached_response) ⇒ Object

:nodoc:



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# File 'lib/wrest/cache_proxy.rb', line 79

def get_validated_response_for(cached_response)
  new_response = send_validation_request_for(cached_response)
  if new_response.code == "304"
    update_cache_headers_for(cached_response, new_response)
    log_cached_response
    cached_response
  else
    cache(new_response)
    new_response
  end
end

#log_cached_response ⇒ Object 



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# File 'lib/wrest/cache_proxy.rb', line 38

def log_cached_response
    Wrest.logger.debug "<*> (GET #{@get.hash}) #{@get.uri.protocol}://#{@get.uri.host}:#{@get.uri.port}#{@get.http_request.path}"
end

#send_validation_request_for(cached_response) ⇒ Object

:nodoc: Send a cache-validation request to the server. This would be the actual Get request with extra cache-validation headers. If a 304 (Not Modified) is received, Wrest would use the cached_response itself. Otherwise the new response is cached and used.



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# File 'lib/wrest/cache_proxy.rb', line 94

def send_validation_request_for(cached_response)
  last_modified            = cached_response.last_modified
  etag                     = cached_response.headers["etag"]

  cache_validation_headers = {}
  cache_validation_headers["if-modified-since"] = last_modified unless last_modified.nil?
  cache_validation_headers["if-none-match"] = etag unless etag.nil?

  new_request = @get.build_request_without_cache_store(cache_validation_headers)

  new_request.invoke
end

#update_cache_headers_for(cached_response, new_response) ⇒ Object 



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# File 'lib/wrest/cache_proxy.rb', line 58

def update_cache_headers_for(cached_response, new_response)
  # RFC 2616 13.5.3 (Combining Headers)
  cached_response.headers.merge!(new_response.headers.select {|key, value| not (HOP_BY_HOP_HEADERS.include? key.downcase)})
end