Module: PG::Instrumentation

Defined in:
lib/pg/instrumentation.rb,
lib/pg/instrumentation/version.rb

Constant Summary collapse

VERSION =
"0.1.0"

Class Attribute Summary collapse

Class Method Summary collapse

Class Attribute Details

.tracerObject

Returns the value of attribute tracer.



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# File 'lib/pg/instrumentation.rb', line 8

def tracer
  @tracer
end

Class Method Details

.instrument(tracer: OpenTracing.global_tracer) ⇒ Object



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# File 'lib/pg/instrumentation.rb', line 10

def instrument(tracer: OpenTracing.global_tracer)
  begin
    require 'pg'
  rescue LoadError
    return
  end

  @tracer = tracer

  patch_methods unless @instrumented
  @instrumented = true
end

.patch_methodsObject



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# File 'lib/pg/instrumentation.rb', line 23

def patch_methods
  ::PG::Connection.class_eval do

    alias_method :initialize_original, :initialize
    alias_method :async_exec_original, :async_exec
    alias_method :exec_original, :exec
    alias_method :exec_params_original, :exec_params
    alias_method :prepare_original, :prepare
    alias_method :exec_prepared_original, :exec_prepared

    def initialize(*args)
      return initialize_original(*args) if args.empty?

      hash_arg = args.first.is_a?( Hash ) ? args.first : {}
      db_name = hash_arg.fetch(:dbname, nil)
      db_user = hash_arg.fetch(:user, nil)
      host = hash_arg.fetch(:host, nil)
      port = hash_arg.fetch(:port, nil)

      @shared_tags = {
        'span.kind' => 'client',
        'component' => 'pg',
        'db.type' => 'pg'}

      @shared_tags['db.instance'] = db_name if db_name
      @shared_tags['db.user'] = db_user if db_user
      @shared_tags['peer.hostname'] = host if host
      @shared_tags['peer.port'] = port if port
      @shared_tags['peer.address'] = "pg://#{host}:#{port}" if host && port

      operation_name = 'pg.initialize'
      scope = ::PG::Instrumentation.tracer.start_active_span(operation_name, tags: @shared_tags)

      initialize_original(*args)

    rescue => e
      log_error(scope.span, e) if scope
    ensure
      scope.close if scope
    end

    def async_exec(*args)
      tags = @shared_tags.dup

      sql = args.first.to_s[0, 1024]
      tags['db.statement'] = sql

      default_op_name = 'pg.query'
      operation_name = get_operation_name(sql, default_op_name)

      scope = ::PG::Instrumentation.tracer.start_active_span(operation_name, tags: tags)

      async_exec_original(*args)

    rescue => e
      log_error(scope.span, e) if scope
    ensure
      scope.close if scope
    end

    def exec(*args)
      tags = @shared_tags.dup

      sql = args.first.to_s[0, 1024]
      tags['db.statement'] = sql

      default_op_name = 'pg.query'
      operation_name = get_operation_name(sql, default_op_name)
      scope = ::PG::Instrumentation.tracer.start_active_span(operation_name, tags: tags)

      exec_original(*args)

    rescue => e
      log_error(scope.span, e) if scope
    ensure
      scope.close if scope
    end

    def exec_params(*args)
      tags = @shared_tags.dup

      sql = args.first.to_s[0, 1024]
      tags['db.statement'] = sql

      default_op_name = 'pg.query'
      operation_name = get_operation_name(sql, default_op_name)

      scope = ::PG::Instrumentation.tracer.start_active_span(operation_name, tags: tags)

      exec_params_original(*args)

    rescue => e
      log_error(scope.span, e) if scope
    ensure
      scope.close if scope
    end

    def prepare(*args)
      tags = @shared_tags.dup

      sql = args[1].to_str[0, 1024]
      tags['db.statement'] = sql
      tags['prepared.statement.name'] = args.first

      default_op_name = 'pg.prepare'
      operation_name = get_operation_name(sql, default_op_name)

      scope = ::PG::Instrumentation.tracer.start_active_span(operation_name, tags: tags)

      prepare_original(*args)

      rescue => e
        log_error(scope.span, e) if scope
      ensure
        scope.close if scope
      end

    def exec_prepared(*args)
      tags = @shared_tags.dup

      tags['prepared.statement.name'] = args.first
      tags['prepared.statement.input'] = args[1][0, 21]
      operation_name = 'pg.exec_prepared'
      scope = ::PG::Instrumentation.tracer.start_active_span(operation_name, tags: tags)

      exec_prepared_original(*args)

    rescue => e
      log_error(scope.span, e) if scope
    ensure
      scope.close if scope
    end

    # Helper functions
    def get_operation_name(sql, default)
      sql_split = sql.split(' ')
      candidate = sql_split[0].upcase if sql_split.length > 1
      return candidate if !candidate.nil? && !candidate.empty?

      return default
    rescue
    end

    def log_error(span, error)
      span.set_tag('error', true)
      span.log_kv(key: 'message',
                  value: error.message,
                  :error_kind => error.class.to_s,
                  :error_object => error,
                  :error_stack =>  error.backtrace.join("\n"))

      raise error
    end
  end # class_eval
end