Class: Nanite::State

Inherits:
Object show all
Includes:
Enumerable
Defined in:
lib/nanite/state.rb

Instance Method Summary collapse

Constructor Details

#initialize(redis) ⇒ State

this class encapsulates the state of a nanite system using redis as the data store. here is the schema, for each agent we store a number of items, for a nanite with the identity: nanite-foobar we store the following things:

nanite-foobar: 0.72 # load average or ‘status’ s-nanite-foobar: { /foo/bar, /foo/nik } # a SET of the provided services tg-nanite-foobar: { foo-42, customer-12 } # a SET of the tags for this agent t-nanite-foobar: 123456789 # unix timestamp of the last state update

also we do an inverted index for quick lookup of agents providing a certain service, so for each service the agent provides, we add the nanite to a SET of all the nanites that provide said service:

foo/bar: { nanite-foobar, nanite-nickelbag, nanite-another } # redis SET

we do that same thing for tags: some-tag: { nanite-foobar, nanite-nickelbag, nanite-another } # redis SET

This way we can do a lookup of what nanites provide a set of services and tags based on redis SET intersection:

nanites_for(‘/gems/list’, ‘some-tag’)

> returns a nested array of nanites and their state that provide the intersection

of these two service tags



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# File 'lib/nanite/state.rb', line 32

def initialize(redis)
  Nanite::Log.info("[setup] initializing redis state: #{redis}")
  host, port = redis.split(':')
  host ||= '127.0.0.1'
  port ||= '6379'
  @redis = Redis.new :host => host, :port => port
end

Instance Method Details

#[](nanite) ⇒ Object 



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# File 'lib/nanite/state.rb', line 47

def [](nanite)
  log_redis_error("[]") do
    status = @redis[nanite]
    timestamp = @redis["t-#{nanite}"]
    services = @redis.smembers("s-#{nanite}")
    tags = @redis.smembers("tg-#{nanite}")
    return nil unless status && timestamp && services
    {:services => services, :status => status, :timestamp => timestamp.to_i, :tags => tags}
  end
end

#[]=(nanite, attributes) ⇒ Object 



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# File 'lib/nanite/state.rb', line 58

def []=(nanite, attributes)
  log_redis_error("[]=") do
    update_state(nanite, attributes[:status], attributes[:services], attributes[:tags])
  end
end

#all_services ⇒ Object 



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# File 'lib/nanite/state.rb', line 87

def all_services
  log_redis_error("all_services") do
    @redis.smembers("naniteservices")
  end
end

#all_tags ⇒ Object 



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# File 'lib/nanite/state.rb', line 93

def all_tags
  log_redis_error("all_tags") do
    @redis.smembers("nanitetags")
  end
end

#clear_state ⇒ Object 



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# File 'lib/nanite/state.rb', line 145

def clear_state
  log_redis_error("clear_state") do
    @redis.keys("*").each {|k| @redis.delete k}
  end
end

#delete(nanite) ⇒ Object 



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# File 'lib/nanite/state.rb', line 64

def delete(nanite)
  log_redis_error("delete") do
    (@redis.smembers("s-#{nanite}")||[]).each do |srv|
      @redis.srem(srv, nanite)
      if @redis.scard(srv) == 0
        @redis.del(srv)
        @redis.srem("naniteservices", srv)
      end
    end
    (@redis.smembers("tg-#{nanite}")||[]).each do |tag|
      @redis.srem(tag, nanite)
      if @redis.scard(tag) == 0
        @redis.del(tag)
        @redis.sdelete("nanitetags", tag)
      end
    end
    @redis.del nanite
    @redis.del "s-#{nanite}"
    @redis.del "t-#{nanite}"
    @redis.del "tg-#{nanite}"
  end
end

#each ⇒ Object 



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# File 'lib/nanite/state.rb', line 151

def each
  list_nanites.each do |nan|
    yield nan, self[nan]
  end
end

#list_nanites ⇒ Object 



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# File 'lib/nanite/state.rb', line 135

def list_nanites
  log_redis_error("list_nanites") do
    @redis.keys("nanite-*")
  end
end

#log_redis_error(meth, &blk) ⇒ Object 



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# File 'lib/nanite/state.rb', line 40

def log_redis_error(meth,&blk)
  blk.call
rescue Exception => e
  Nanite::Log.info("redis error in method: #{meth}")
  raise e
end

#nanites_for(service, *tags) ⇒ Object 



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# File 'lib/nanite/state.rb', line 157

def nanites_for(service, *tags)
  keys = tags.dup << service
  log_redis_error("nanites_for") do
    res = []
    (@redis.sinter(keys)||[]).each do |nan|
      res << [nan, self[nan]]
    end
    res
  end
end

#size ⇒ Object 



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# File 'lib/nanite/state.rb', line 141

def size
  list_nanites.size
end

#update_state(name, status, services, tags) ⇒ Object 



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# File 'lib/nanite/state.rb', line 99

def update_state(name, status, services, tags)
  old_services = @redis.smembers("s-#{name}")
  if old_services
    (old_services - services).each do |s|
      @redis.srem(s, name)
      @redis.srem("naniteservices", s)
    end
  end
  old_tags = @redis.smembers("tg-#{name}")
  if old_tags
    (old_tags - tags).each do |t|
      @redis.srem(t, name)
      @redis.srem("nanitetags", t)
    end
  end
  @redis.del("s-#{name}")
  services.each do |srv|
    @redis.sadd(srv, name)
    @redis.sadd("s-#{name}", srv)
    @redis.sadd("naniteservices", srv)
  end
  @redis.del("tg-#{name}")
  tags.each do |tag|
    next if tag.nil?
    @redis.sadd(tag, name)
    @redis.sadd("tg-#{name}", tag)
    @redis.sadd("nanitetags", tag)
  end
  update_status(name, status)
end

#update_status(name, status) ⇒ Object 



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# File 'lib/nanite/state.rb', line 130

def update_status(name, status)
  @redis[name] = status
  @redis["t-#{name}"] = Time.now.utc.to_i
end