module PgsqlStats
  class Database
    attr_accessor :oid, :name, :commits, :rollbacks, :blocks_read, :cache_hits

    def initialize(row)
      load(row)
    end
    
    def refresh
      load(Collector.connection.select_one("SELECT * FROM pg_stat_database WHERE datid = #{oid}"))
    end
    
    def server_processes
      Collector.server_activity(self.oid)
    end
    
    def total_transactions
      commits + rollbacks
    end
    
    def cache_hit_rate
      cache_hits.to_f / (blocks_read + cache_hits) * 100
    end
    
    private
    
    def load(row)
      self.oid = row["datid"].to_i
      self.name = row["datname"]
      self.commits = row["xact_commit"].to_i
      self.rollbacks = row["xact_rollback"].to_i
      self.blocks_read = row["blks_read"].to_i
      self.cache_hits = row["blks_hit"].to_i
    end
  end
end