Class: Canonicurl::Cache

Inherits:
Object
  • Object
show all
Defined in:
lib/canonicurl/cache.rb

Constant Summary collapse

CANONICAL = 
'C'
ERROR = 
'E'
RESOLVING = 
'R'
TTL =

90 days ~ 3 months

60 * 60 * 24 * 90
REDIRECTS = 
5
CONNECTION_TIMEOUT = 
5
KEY_PREFIX = 
'curl:'

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(options = {}) ⇒ Cache

Returns a new instance of Cache.



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# File 'lib/canonicurl/cache.rb', line 23

def initialize(options={})
  @db         = options[:db] || Redis.connect
  @ttl        = options[:ttl] || TTL
  @timeout    = options[:timeout] || CONNECTION_TIMEOUT
  @redirects  = options[:redirects] || REDIRECTS
  @key_prefix = options[:key_prefix] || KEY_PREFIX
end

Instance Attribute Details

#db ⇒ Object

Returns the value of attribute db.



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# File 'lib/canonicurl/cache.rb', line 15

def db
  @db
end

#key_prefix ⇒ Object (readonly)

Returns the value of attribute key_prefix.



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# File 'lib/canonicurl/cache.rb', line 16

def key_prefix
  @key_prefix
end

#redirects ⇒ Object

Returns the value of attribute redirects.



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# File 'lib/canonicurl/cache.rb', line 15

def redirects
  @redirects
end

#timeout ⇒ Object

Returns the value of attribute timeout.



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# File 'lib/canonicurl/cache.rb', line 15

def timeout
  @timeout
end

#ttl ⇒ Object

Returns the value of attribute ttl.



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# File 'lib/canonicurl/cache.rb', line 15

def ttl
  @ttl
end

Class Method Details

.url(code_or_url) ⇒ Object 



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# File 'lib/canonicurl/cache.rb', line 18

def self.url(code_or_url)
  code_or_url && code_or_url.size > 1 ? code_or_url : nil
end

Instance Method Details

#fetch(url, resolver) ⇒ Object 



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# File 'lib/canonicurl/cache.rb', line 37

def fetch(url, resolver)
  k = key(url)

  # New URL resolve it
  if @db.setnx(k, RESOLVING) #  lock it if key doesn't exist
    return resolve(url, k, resolver)
  end

  result = @db.get(k)
  if !result.nil? && result.size > 1
    return result # Found old noncanonical URL mapping
  end

  # CANONICAL, ERROR or RESOLVING
  result == CANONICAL ? url : result
end

#get(url) ⇒ Object 



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# File 'lib/canonicurl/cache.rb', line 32

def get(url)
  @db.get key(url)
end

#key(url) ⇒ Object 



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# File 'lib/canonicurl/cache.rb', line 66

def key(url)
  "#{@key_prefix}#{Digest::MD5.hexdigest(url)}"
end

#set(url, canonical_url, url_key = nil) ⇒ Object 



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# File 'lib/canonicurl/cache.rb', line 55

def set(url, canonical_url, url_key=nil)
  url_key = url_key || key(url)
  if url == canonical_url
    @db.setex(url_key, @ttl, CANONICAL)
  else
    @db.setex(url_key, @ttl, canonical_url)
    @db.setex(key(canonical_url), @ttl, CANONICAL) # preemptively set the canonical_url
  end
end