Module: ServerSide::HTTP::Caching

Defined in:
lib/serverside/http/caching.rb

Overview

HTTP Caching behavior

Constant Summary collapse

COMMA = 
','.freeze

Instance Method Summary collapse

Instance Method Details

#cache(opts) ⇒ Object

Sets caching-related headers (Cache-Control and Expires).



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# File 'lib/serverside/http/caching.rb', line 5

def cache(opts)
  # check cache-control
  remove_cache_control
  if cache_control = opts[:cache_control]
    add_header(CACHE_CONTROL, cache_control)
  end
  
  # add an expires header
  if expires = opts[:expires] || (opts[:ttl] && (Time.now + opts[:ttl]))
    add_header(EXPIRES, expires.httpdate)
  end
end

#etag_match(etag) ⇒ Object

Matches the supplied etag against any of the entities in the If-None-Match header.



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# File 'lib/serverside/http/caching.rb', line 49

def etag_match(etag)
  return false unless @request
  matches = @request.headers[IF_NONE_MATCH]
  if matches
    matches.split(COMMA).each do |e|
      return true if e.strip == etag
    end
  end
  false
end

#modified_match(last_modified) ⇒ Object

Matches the supplied last modified date against the If-Modified-Since header.



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# File 'lib/serverside/http/caching.rb', line 62

def modified_match(last_modified)
  return false unless @request
  if modified_since = @request.headers[IF_MODIFIED_SINCE]
    last_modified.to_i == Time.parse(modified_since).to_i
  else
    false
  end
rescue => e
  raise BadRequestError, "Invalid value in If-Modified-Since header"
end

#remove_cache_control ⇒ Object 



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# File 'lib/serverside/http/caching.rb', line 82

def remove_cache_control
  @headers.reject! {|h| h =~ /^#{CACHE_CONTROL}/}
end

#set_cache_control(directive) ⇒ Object

Sets the Cache-Control header.



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# File 'lib/serverside/http/caching.rb', line 74

def set_cache_control(directive)
  add_header(CACHE_CONTROL, directive)
end

#set_no_cache ⇒ Object 



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# File 'lib/serverside/http/caching.rb', line 78

def set_no_cache
  set_cache_control(NO_CACHE)
end

#validate_cache(opts, &block) ⇒ Object

Validates the supplied request against specified validators (etag and last-modified stamp). If a match is found, the status is changed to 304 Not Modified. Otherwise, the supplied block is invoked.



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# File 'lib/serverside/http/caching.rb', line 21

def validate_cache(opts, &block)
  valid_cache = false
  
  # check etag
  if etag = opts[:etag]
    etag = "\"#{etag}\""
    add_header(ETAG, etag) if etag
    valid_cache = etag_match(etag)
  end
  
  # check last_modified
  if last_modified = opts[:last_modified]
    add_header(LAST_MODIFIED, last_modified.httpdate)
    valid_cache ||= modified_match(last_modified)
  end
  
  # set cache-related headers
  cache(opts)
  
  # if not modified, we have a 304 response. Otherwise we yield to the
  # supplied block.
  valid_cache ? (@status = STATUS_NOT_MODIFIED) : yield(self)
end