94 lines
1.9 KiB
Ruby
Executable file
94 lines
1.9 KiB
Ruby
Executable file
#
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# A dictionary server using Distributed Ruby (DRb).
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#
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# All modifications to the dictionary are done as commands,
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# while read-only queries (i.e 'lookup') are done directly.
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#
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# First launch this server in the background, then use
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# dictionary_client.rb to look up and add items to the
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# dictionary.
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# You can kill the server at any time. The contents of the
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# dictionary will still be there when you restart it.
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#
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# DRb is available at http://raa.ruby-lang.org/list.rhtml?name=druby
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#
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$LOAD_PATH.unshift(".." + File::SEPARATOR + "lib")
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require 'madeleine'
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require 'drb'
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class Dictionary
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def initialize
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@data = {}
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end
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def add(key, value)
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@data[key] = value
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end
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def lookup(key)
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@data[key]
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end
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end
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class Addition
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def initialize(key, value)
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@key, @value = key, value
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end
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def execute(system)
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system.add(@key, @value)
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end
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end
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class Lookup
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def initialize(key)
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@key = key
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end
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def execute(system)
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system.lookup(@key)
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end
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end
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class DictionaryServer
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def initialize(madeleine)
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@madeleine = madeleine
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@dictionary = madeleine.system
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end
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def add(key, value)
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# When adding a new key-value pair we modify the system, so
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# this operation has to be done through a command.
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@madeleine.execute_command(Addition.new(key, value))
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end
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def lookup(key)
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# A lookup is a read-only operation, so we can do it as a non-logged
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# query. If we weren't worried about concurrency problems we could
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# have just called @dictionary.lookup(key) directly instead.
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@madeleine.execute_query(Lookup.new(key))
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end
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end
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madeleine = SnapshotMadeleine.new("dictionary-base") { Dictionary.new }
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Thread.new(madeleine) {
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puts "Taking snapshot every 30 seconds."
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while true
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sleep(30)
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madeleine.take_snapshot
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end
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}
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DRb.start_service("druby://localhost:1234",
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DictionaryServer.new(madeleine))
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DRb.thread.join
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