Module: Redis::Instrumentation

Defined in:
lib/redis/instrumentation.rb

Constant Summary collapse

COMMON_TAGS = 
{
  'span.kind' => 'client',
  'component' => 'ruby-redis',
  'db.type' => 'redis',
}.freeze

Class Attribute Summary collapse

Class Method Summary collapse

Class Attribute Details

.db_statement_length ⇒ Object

Returns the value of attribute db_statement_length.



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# File 'lib/redis/instrumentation.rb', line 17

def db_statement_length
  @db_statement_length
end

.tracer ⇒ Object

Returns the value of attribute tracer.



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# File 'lib/redis/instrumentation.rb', line 16

def tracer
  @tracer
end

Class Method Details

.instrument(tracer: OpenTracing.global_tracer, db_statement_length: nil) ⇒ Object 



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# File 'lib/redis/instrumentation.rb', line 19

def instrument(tracer: OpenTracing.global_tracer,
               db_statement_length: nil)
  begin
    require 'redis'
  rescue LoadError => e
    return
  end

  @tracer = tracer
  @db_statement_length = db_statement_length

  patch_client if !@patched_client
  @patched_client = true
end

.patch_client ⇒ Object 



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# File 'lib/redis/instrumentation.rb', line 34

def patch_client
  ::Redis::Client.class_eval do
    alias_method :call_original, :call
    alias_method :call_pipeline_original, :call_pipeline

    def call(command, trace: true, &block)
      tags = ::Redis::Instrumentation::COMMON_TAGS.dup
      statement = command.join(' ')
      statement = statement.to_s[0, ::Redis::Instrumentation::db_statement_length] if ::Redis::Instrumentation::db_statement_length
      tags['db.statement'] = statement
      tags['db.instance'] = db
      tags['peer.address'] = "redis://#{host}:#{port}"

      # command[0] is usually the actual command name
      scope = ::Redis::Instrumentation.tracer.start_active_span("redis.#{command[0]}", tags: tags)

      call_original(command, &block)
    rescue => e
      if scope
        scope.span.record_exception(e)
      end
      raise e
    ensure
      scope.close if scope
    end

    def call_pipeline(pipeline)
      commands = pipeline.commands
      tags = ::Redis::Instrumentation::COMMON_TAGS.dup
      statement = commands.empty? ? "" : commands.map{ |arr| arr.join(' ') }.join(', ')
      statement = statement.to_s[0, ::Redis::Instrumentation::db_statement_length] if ::Redis::Instrumentation::db_statement_length
      tags['db.statement'] = statement
      tags['db.instance'] = db
      tags['peer.address'] = "redis://#{host}:#{port}"

      scope = ::Redis::Instrumentation.tracer.start_active_span("redis.pipelined", tags: tags)

      call_pipeline_original(pipeline)
    rescue => e
      if scope
        scope.span.set_tag("error", true)
        scope.span.log_kv("error.kind": e.class.name, message: e.message, "error.object": e)
      end
      raise e
    ensure
      scope.close if scope
    end
  end
end