Class: Faraday::HttpCache::Response

Inherits:
Object
  • Object
show all
Defined in:
lib/faraday/http_cache/response.rb

Overview

Internal: A class to represent a response from a Faraday request. It decorates the response hash into a smarter object that queries the response headers and status informations about how the caching middleware should handle this specific response.

Constant Summary collapse

CACHEABLE_STATUS_CODES =

Internal: List of status codes that can be cached:

  • 200 - ‘OK’

  • 203 - ‘Non-Authoritative Information’

  • 300 - ‘Multiple Choices’

  • 301 - ‘Moved Permanently’

  • 302 - ‘Found’

  • 404 - ‘Not Found’

  • 410 - ‘Gone’

[200, 203, 300, 301, 302, 307, 404, 410].freeze

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(payload = {}) ⇒ Response

Internal: Initialize a new Response with the response payload from a Faraday request.

payload - the response Hash returned by a Faraday request.

:status - the status code from the response.
:response_headers - a 'Hash' like object with the headers.
:body - the response body.



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# File 'lib/faraday/http_cache/response.rb', line 39

def initialize(payload = {})
  @now = Time.now
  @payload = payload
  wrap_headers!
  ensure_date_header!

  @last_modified = headers['Last-Modified']
  @etag = headers['ETag']
end

Instance Attribute Details

#etag ⇒ Object (readonly)

Internal: Gets the ‘ETag’ header from the headers Hash.



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# File 'lib/faraday/http_cache/response.rb', line 30

def etag
  @etag
end

#last_modified ⇒ Object (readonly)

Internal: Gets the ‘Last-Modified’ header from the headers Hash.



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# File 'lib/faraday/http_cache/response.rb', line 27

def last_modified
  @last_modified
end

#payload ⇒ Object (readonly)

Internal: Gets the actual response Hash (status, headers and body).



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# File 'lib/faraday/http_cache/response.rb', line 24

def payload
  @payload
end

Instance Method Details

#age ⇒ Object

Internal: Gets the response age in seconds.

Returns the ‘Age’ header if present, or subtracts the response ‘date’ from the current time.



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# File 'lib/faraday/http_cache/response.rb', line 105

def age
  (headers['Age'] || (@now - date)).to_i
end

#cacheable_in_private_cache? ⇒ Boolean

Internal: Checks if the response can be cached by the client when the client is acting as a private cache per RFC 2616. This is validated by the ‘Cache-Control’ directives, the response status code and it’s freshness or validation status.

Returns false if the ‘Cache-Control’ says that we can’t store the response, or if isn’t fresh or it can’t be revalidated with the origin server. Otherwise, returns true.

Returns:

  • (Boolean) 


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# File 'lib/faraday/http_cache/response.rb', line 97

def cacheable_in_private_cache?
  cacheable?(false)
end

#cacheable_in_shared_cache? ⇒ Boolean

Internal: Checks if the response can be cached by the client when the client is acting as a shared cache per RFC 2616. This is validated by the ‘Cache-Control’ directives, the response status code and it’s freshness or validation status.

Returns false if the ‘Cache-Control’ says that we can’t store the response, or it can be stored in private caches only, or if isn’t fresh or it can’t be revalidated with the origin server. Otherwise, returns true.

Returns:

  • (Boolean) 


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# File 'lib/faraday/http_cache/response.rb', line 85

def cacheable_in_shared_cache?
  cacheable?(true)
end

#date ⇒ Object

Internal: Parses the ‘Date’ header back into a Time instance.

Returns the Time object.



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# File 'lib/faraday/http_cache/response.rb', line 120

def date
  Time.httpdate(headers['Date'])
end

#fresh? ⇒ Boolean

Internal: Checks the response freshness based on expiration headers. The calculated ‘ttl’ should be present and bigger than 0.

Returns true if the response is fresh, otherwise false.

Returns:

  • (Boolean) 


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# File 'lib/faraday/http_cache/response.rb', line 53

def fresh?
  !cache_control.no_cache? && ttl && ttl > 0
end

#max_age ⇒ Object

Internal: Gets the response max age. The max age is extracted from one of the following:

  • The shared max age directive from the ‘Cache-Control’ header;

  • The max age directive from the ‘Cache-Control’ header;

  • The difference between the ‘Expires’ header and the response date.

Returns the max age value in seconds or nil if all options above fails.



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# File 'lib/faraday/http_cache/response.rb', line 132

def max_age
  cache_control.shared_max_age ||
    cache_control.max_age ||
    (expires && (expires - @now))
end

#not_modified? ⇒ Boolean

Internal: Checks if the Response returned a ‘Not Modified’ status.

Returns true if the response status code is 304.

Returns:

  • (Boolean) 


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# File 'lib/faraday/http_cache/response.rb', line 72

def not_modified?
  @payload[:status] == 304
end

#serializable_hash ⇒ Object

Internal: Exposes a representation of the current payload that we can serialize and cache properly.

Returns a ‘Hash’.



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# File 'lib/faraday/http_cache/response.rb', line 158

def serializable_hash
  prepare_to_cache

  {
    status: @payload[:status],
    body: @payload[:body],
    response_headers: @payload[:response_headers],
    reason_phrase: @payload[:reason_phrase]
  }
end

#stale_while_revalidate ⇒ Object

Internal: Gets the stale-while-revalidate value in seconds.

Returns an Integer or nil.



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# File 'lib/faraday/http_cache/response.rb', line 141

def stale_while_revalidate
  cache_control.stale_while_revalidate
end

#stale_while_revalidate? ⇒ Boolean

Internal: Checks if the response is stale but can still be served while revalidating in the background.

Returns true when the response has exceeded freshness lifetime, but is still inside the stale-while-revalidate window.

Returns:

  • (Boolean) 


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# File 'lib/faraday/http_cache/response.rb', line 62

def stale_while_revalidate?
  return false if cache_control.no_cache?
  return false unless ttl && stale_while_revalidate

  ttl <= 0 && -ttl <= stale_while_revalidate
end

#to_response(env) ⇒ Object

Internal: Creates a new ‘Faraday::Response’, merging the stored response with the supplied ‘env’ object.

Returns a new instance of a ‘Faraday::Response’ with the payload.



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# File 'lib/faraday/http_cache/response.rb', line 149

def to_response(env)
  env.update(@payload)
  Faraday::Response.new(env)
end

#ttl ⇒ Object

Internal: Calculates the ‘Time to live’ left on the Response.

Returns the remaining seconds for the response, or nil the ‘max_age’ isn’t present.



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# File 'lib/faraday/http_cache/response.rb', line 113

def ttl
  max_age - age if max_age
end