Class: Browser::Cache

Inherits:
Object show all
Includes:
Enumerable
Defined in:
lib/epitools/browser/cache.rb

Overview

An SQLite3-backed browser cache (with gzip compressed pages)

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Enumerable

#*, #**, #average, #blank?, #combination, #counts, #cross_product, #foldl, #group_neighbours_by, #grouped_to_h, #groups, #map_recursively, #parallel_map, #permutation, #powerset, #reverse, #reverse_each, #rle, #rzip, #select_recursively, #skip, #sort_numerically, #split_after, #split_at, #split_before, #split_between, #sum, #to_iter, #uniq, #unzip

Methods included from Array::ToCSV

#to_csv, #to_tsv

Constructor Details

#initialize(filename = "browsercache.db", agent = nil) ⇒ Cache

Returns a new instance of Cache.



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# File 'lib/epitools/browser/cache.rb', line 15

def initialize(filename="browsercache.db", agent=nil)
  @agent    = agent
  @filename = filename

  @db = SQLite3::Database.new(filename)
  @db.busy_timeout(50)

  create_tables
end

Instance Attribute Details

#agent ⇒ Object (readonly)

Returns the value of attribute agent.



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# File 'lib/epitools/browser/cache.rb', line 13

def agent
  @agent
end

#db ⇒ Object (readonly)

Returns the value of attribute db.



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# File 'lib/epitools/browser/cache.rb', line 13

def db
  @db
end

Instance Method Details

#clear(pattern = nil) ⇒ Object 



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# File 'lib/epitools/browser/cache.rb', line 152

def clear(pattern=nil)
  if pattern
    db.execute("DELETE FROM cache WHERE url LIKE '%#{pattern}%'")
  else
    db.execute("DELETE FROM cache")
  end
end

#count ⇒ Object Also known as: size 



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# File 'lib/epitools/browser/cache.rb', line 29

def count
  db.execute("SELECT COUNT(1) FROM cache").first.first.to_i
end

#delete! ⇒ Object 



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# File 'lib/epitools/browser/cache.rb', line 179

def delete!
  db.close
  File.unlink @filename
end

#each(&block) ⇒ Object 



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# File 'lib/epitools/browser/cache.rb', line 160

def each(&block)
  pages_via_sql("SELECT * FROM cache", &block)
end

#each_url ⇒ Object 



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# File 'lib/epitools/browser/cache.rb', line 164

def each_url
  db.execute("SELECT url FROM cache") do |row|
    yield row.first
  end
end

#expire(url) ⇒ Object 



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# File 'lib/epitools/browser/cache.rb', line 170

def expire(url)
  db.execute("DELETE FROM cache WHERE url = ?", url)
end

#get(url) ⇒ Object 



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# File 'lib/epitools/browser/cache.rb', line 127

def get(url)
  pages = pages_via_sql("SELECT * FROM cache WHERE url = ?", url.to_s)

  if pages.any?
    pages.first
  else
    nil
  end
end

#grep(pattern, &block) ⇒ Object 



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# File 'lib/epitools/browser/cache.rb', line 123

def grep(pattern, &block)
  pages_via_sql("SELECT * FROM cache WHERE url like '%#{pattern}%'", &block)
end

#includes?(url) ⇒ Boolean Also known as: include?

Returns:

  • (Boolean) 


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# File 'lib/epitools/browser/cache.rb', line 137

def includes?(url)
  db.execute("SELECT url FROM cache WHERE url = ?", url.to_s).any?
end

#inspect ⇒ Object 



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# File 'lib/epitools/browser/cache.rb', line 25

def inspect
  "#<Browser::Cache filename=#{@filename.inspect}, count=#{count}, size=#{File.size @filename} bytes>"
end

#pages_via_sql(*args, &block) ⇒ Object 



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# File 'lib/epitools/browser/cache.rb', line 112

def pages_via_sql(*args, &block)
  dmsg [:pages_via_sql, args]
  if block_given?
    db.execute(*args) do |row|
      yield row_to_page(row)
    end
  else
    db.execute(*args).map{|row| row_to_page(row) }
  end
end

#put(page, original_url = nil, **options) ⇒ Object 



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# File 'lib/epitools/browser/cache.rb', line 40

def put(page, original_url=nil, **options)
  dmsg [:put, original_url]

  raise "Invalid page" unless valid_page?(page)

  url = page.uri.to_s

  dmsg [:page_uri, url]
  dmsg [:original_url, url]

  if url != original_url
    # redirect original_url to url
    expire(original_url) if options[:overwrite]
    db.execute(
      "INSERT INTO cache VALUES ( ?, ?, ?, ? )",
      original_url,
      page.content_type,
      nil,
      url
    )
  end

  #compressed_body = page.body
  compressed_body = Zlib::Deflate.deflate(page.body)

  expire(url) if options[:overwrite]
  db.execute(
    "INSERT INTO cache VALUES ( ?, ?, ?, ? )",
    url,
    page.content_type,
    SQLite3::Blob.new( compressed_body  ),
    nil
  )

  true

rescue SQLite3::SQLException => e
  p [:exception, e]
  false
end

#recreate_tables ⇒ Object 



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# File 'lib/epitools/browser/cache.rb', line 174

def recreate_tables
  drop_tables rescue nil
  create_tables
end

#row_to_page(row) ⇒ Object 



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# File 'lib/epitools/browser/cache.rb', line 81

def row_to_page(row)
  url, content_type, compressed_body, redirect = row

  if redirect
    get(redirect)
  else
    #body = compressed_body
    body = Zlib::Inflate.inflate(compressed_body)

    if content_type =~ %r{^(text/html|text/xml|application/xhtml\+xml)}i
      Mechanize::Page.new(
        #initialize(uri=nil, response=nil, body=nil, code=nil, mech=nil)
        URI.parse(url),
        {'content-type'=>content_type},
        body,
        nil,
        agent
      )
    else
      Mechanize::File.new(
        #initialize(uri=nil, response=nil, body=nil, code=nil
        URI.parse(url),
        {'content-type'=>content_type},
        body,
        nil
      )
    end

  end
end

#urls(pattern = nil) ⇒ Object 



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# File 'lib/epitools/browser/cache.rb', line 143

def urls(pattern=nil)
  if pattern
    rows = db.execute("SELECT url FROM cache WHERE url LIKE '%#{pattern}%'")
  else
    rows = db.execute('SELECT url FROM cache')
  end
  rows.map{|row| row.first}
end

#valid_page?(page) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/epitools/browser/cache.rb', line 35

def valid_page?(page)
  [:body, :content_type, :uri].all?{|m| page.respond_to? m }
end