class Dalli::Ring
Constants
- POINTS_PER_SERVER
Attributes
continuum[RW]
servers[RW]
Public Class Methods
new(servers, options)
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# File lib/dalli/ring.rb, line 10 def initialize(servers, options) @servers = servers @continuum = nil if servers.size > 1 total_weight = servers.inject(0) { |memo, srv| memo + srv.weight } continuum = [] servers.each do |server| entry_count_for(server, servers.size, total_weight).times do |idx| hash = Digest::SHA1.hexdigest("#{server.name}:#{idx}") value = Integer("0x#{hash[0..7]}") continuum << Dalli::Ring::Entry.new(value, server) end end @continuum = continuum.sort { |a, b| a.value <=> b.value } end threadsafe! unless options[:threadsafe] == false @failover = options[:failover] != false end
Public Instance Methods
lock() { || ... }
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# File lib/dalli/ring.rb, line 48 def lock @servers.each { |s| s.lock! } begin return yield ensure @servers.each { |s| s.unlock! } end end
server_for_key(key)
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# File lib/dalli/ring.rb, line 30 def server_for_key(key) if @continuum hkey = hash_for(key) 20.times do |try| entryidx = binary_search(@continuum, hkey) server = @continuum[entryidx].server return server if server.alive? break unless @failover hkey = hash_for("#{try}#{key}") end else server = @servers.first return server if server && server.alive? end raise Dalli::RingError, "No server available" end
Private Instance Methods
binary_search(ary, value)
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# File lib/dalli/ring.rb, line 110 def binary_search(ary, value) upper = ary.size - 1 lower = 0 idx = 0 while (lower <= upper) do idx = (lower + upper) / 2 comp = ary[idx].value <=> value if comp == 0 return idx elsif comp > 0 upper = idx - 1 else lower = idx + 1 end end return upper end
entry_count_for(server, total_servers, total_weight)
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# File lib/dalli/ring.rb, line 69 def entry_count_for(server, total_servers, total_weight) ((total_servers * POINTS_PER_SERVER * server.weight) / Float(total_weight)).floor end
hash_for(key)
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# File lib/dalli/ring.rb, line 65 def hash_for(key) Zlib.crc32(key) end
threadsafe!()
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# File lib/dalli/ring.rb, line 59 def threadsafe! @servers.each do |s| s.extend(Dalli::Threadsafe) end end