Class: WebVac::Table

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

Overview

Sits in front of Redis (just Redis right now), and handles the mapping of vac hashes to pathnames, as well as the metadata (in JSON and in the form of HTTP headers, which allows HEAD requests to be cheap). Also does some of the bookkeeping necessary for that, like the interaction with libmagic.

Relatively threadsafe, but maintains one Redis connection per active thread (created on demand).

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(cfg) ⇒ Table

Takes an instance of Config.



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# File 'lib/webvac.rb', line 119

def initialize cfg
	@config = cfg
end

Instance Attribute Details

#config ⇒ Object (readonly)

Returns the value of attribute config.



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# File 'lib/webvac.rb', line 116

def config
  @config
end

Instance Method Details

#fn2md(f) ⇒ Object

Takes a filename, returns the filename’s metadata. Stateless-ish.



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# File 'lib/webvac.rb', line 124

def fn2md f
	s = File.stat(f)
	m = {
		'Content-Type' => Magic.guess_file_mime_type(f),
		'Content-Length' => s.size.to_s,
		'Last-Modified' => s.mtime.rfc822,
	} rescue nil
end

#guess_mime(contents) ⇒ Object 



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# File 'lib/webvac.rb', line 159

def guess_mime contents
	Magic.guess_string_mime_type(contents)
end

#meta_save!(fn, sc) ⇒ Object 



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# File 'lib/webvac.rb', line 133

def meta_save! fn, sc
	md = fn2md(fn)
	return unless md
	redis.call 'HSET', 'score2md', sc, md.to_json
end

#metadata(score) ⇒ Object 



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# File 'lib/webvac.rb', line 139

def metadata score
	# Overall, doesn't really matter if this fails.
	JSON.parse(
		redis.call('HGET', 'score2md', score.sub(/^vac:/, ''))
	) rescue nil
end

#path2score(p) ⇒ Object 



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# File 'lib/webvac.rb', line 154

def path2score p
	r = redis.call 'HGET', 'path2score', p
	return "vac:#{r}" if r
end

#rec_score!(fn, sc) ⇒ Object 



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# File 'lib/webvac.rb', line 146

def rec_score! fn, sc
	redis.call 'HSET', 'path2score', fn, sc
end

#redis ⇒ Object 



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# File 'lib/webvac.rb', line 150

def redis
	Thread.current[:webvac_redis] ||= Redic.new(config.redis_url)
end