Class: Datadog::Span

Inherits:
Object
  • Object
show all
Includes:
Analytics::Span, ForcedTracing::Span
Defined in:
lib/ddtrace/span.rb

Overview

Represents a logical unit of work in the system. Each trace consists of one or more spans. Each span consists of a start time and a duration. For example, a span can describe the time spent on a distributed call on a separate machine, or the time spent in a small component within a larger operation. Spans can be nested within each other, and in those instances will have a parent-child relationship.

rubocop:disable Metrics/ClassLength

Constant Summary collapse

MAX_ID =

The max value for a Span identifier. Span and trace identifiers should be strictly positive and strictly inferior to this limit.

Limited to 63-bit positive integers, as some other languages might be limited to this, and IDs need to be easy to port across various languages and platforms.

2**63
EXTERNAL_MAX_ID =

While we only generate 63-bit integers due to limitations in other languages, we support parsing 64-bit integers for distributed tracing since an upstream system may generate one

2**64
NUMERIC_TAG_SIZE_RANGE =

This limit is for numeric tags because uint64 could end up rounded.

(-2**53..2**53)

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(tracer, name, options = {}) ⇒ Span

Create a new span linked to the given tracer. Call the Tracer method start_span() and then finish() once the tracer operation is over.

  • service: the service name for this span

  • resource: the resource this span refers, or name if it’s missing

  • span_type: the type of the span (such as http, db and so on)

  • parent_id: the identifier of the parent span

  • trace_id: the identifier of the root span for this trace

  • context: the context of the span



54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
 
# File 'lib/ddtrace/span.rb', line 54

def initialize(tracer, name, options = {})
  @tracer = tracer

  @name = name
  @service = options.fetch(:service, nil)
  @resource = options.fetch(:resource, name)
  @span_type = options.fetch(:span_type, nil)

  @span_id = Datadog::Utils.next_id
  @parent_id = options.fetch(:parent_id, 0)
  @trace_id = options.fetch(:trace_id, Datadog::Utils.next_id)

  @context = options.fetch(:context, nil)

  @meta = {}
  @metrics = {}
  @status = 0

  @parent = nil
  @sampled = true

  @start_time = nil # set by Tracer.start_span
  @end_time = nil # set by Span.finish

  @allocation_count_start = now_allocations
  @allocation_count_finish = @allocation_count_start
end

Instance Attribute Details

#context ⇒ Object

Returns the value of attribute context.



38
39
40
 
# File 'lib/ddtrace/span.rb', line 38

def context
  @context
end

#end_time ⇒ Object

Returns the value of attribute end_time.



38
39
40
 
# File 'lib/ddtrace/span.rb', line 38

def end_time
  @end_time
end

#name ⇒ Object

Returns the value of attribute name.



38
39
40
 
# File 'lib/ddtrace/span.rb', line 38

def name
  @name
end

#parent ⇒ Object

Returns the value of attribute parent.



44
45
46
 
# File 'lib/ddtrace/span.rb', line 44

def parent
  @parent
end

#parent_id ⇒ Object

Returns the value of attribute parent_id.



38
39
40
 
# File 'lib/ddtrace/span.rb', line 38

def parent_id
  @parent_id
end

#resource ⇒ Object

Returns the value of attribute resource.



38
39
40
 
# File 'lib/ddtrace/span.rb', line 38

def resource
  @resource
end

#sampled ⇒ Object

Returns the value of attribute sampled.



38
39
40
 
# File 'lib/ddtrace/span.rb', line 38

def sampled
  @sampled
end

#service ⇒ Object

Returns the value of attribute service.



38
39
40
 
# File 'lib/ddtrace/span.rb', line 38

def service
  @service
end

#span_id ⇒ Object

Returns the value of attribute span_id.



38
39
40
 
# File 'lib/ddtrace/span.rb', line 38

def span_id
  @span_id
end

#span_type ⇒ Object

Returns the value of attribute span_type.



38
39
40
 
# File 'lib/ddtrace/span.rb', line 38

def span_type
  @span_type
end

#start_time ⇒ Object

Returns the value of attribute start_time.



38
39
40
 
# File 'lib/ddtrace/span.rb', line 38

def start_time
  @start_time
end

#status ⇒ Object

Returns the value of attribute status.



38
39
40
 
# File 'lib/ddtrace/span.rb', line 38

def status
  @status
end

#trace_id ⇒ Object

Returns the value of attribute trace_id.



38
39
40
 
# File 'lib/ddtrace/span.rb', line 38

def trace_id
  @trace_id
end

#tracer ⇒ Object

Returns the value of attribute tracer.



38
39
40
 
# File 'lib/ddtrace/span.rb', line 38

def tracer
  @tracer
end

Instance Method Details

#allocations ⇒ Object 



219
220
221
 
# File 'lib/ddtrace/span.rb', line 219

def allocations
  @allocation_count_finish - @allocation_count_start
end

#clear_metric(key) ⇒ Object

This method removes a metric for the given key. It acts like #remove_tag.



134
135
136
 
# File 'lib/ddtrace/span.rb', line 134

def clear_metric(key)
  @metrics.delete(key)
end

#clear_tag(key) ⇒ Object

This method removes a tag for the given key.



111
112
113
 
# File 'lib/ddtrace/span.rb', line 111

def clear_tag(key)
  @meta.delete(key)
end

#finish(finish_time = nil) ⇒ Object

Mark the span finished at the current time and submit it.



154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
 
# File 'lib/ddtrace/span.rb', line 154

def finish(finish_time = nil)
  # A span should not be finished twice. Note that this is not thread-safe,
  # finish is called from multiple threads, a given span might be finished
  # several times. Again, one should not do this, so this test is more a
  # fallback to avoid very bad things and protect you in most common cases.
  return if finished?

  @allocation_count_finish = now_allocations

  # Provide a default start_time if unset, but this should have been set by start_span.
  # Using now here causes 0-duration spans, still, this is expected, as we never
  # explicitely say when it started.
  @start_time ||= Time.now.utc

  @end_time = finish_time.nil? ? Time.now.utc : finish_time # finish this

  # Finish does not really do anything if the span is not bound to a tracer and a context.
  return self if @tracer.nil? || @context.nil?

  # spans without a service would be dropped, so here we provide a default.
  # This should really never happen with integrations in contrib, as a default
  # service is always set. It's only for custom instrumentation.
  @service ||= (@tracer && @tracer.default_service)

  begin
    @context.close_span(self)
    @tracer.record(self)
  rescue StandardError => e
    Datadog::Logger.log.debug("error recording finished trace: #{e}")
    Diagnostics::Health.metrics.error_span_finish(1, tags: ["error:#{e.class.name}"])
  end
  self
end

#finished? ⇒ Boolean

Return whether the span is finished or not.

Returns:

  • (Boolean) 


189
190
191
 
# File 'lib/ddtrace/span.rb', line 189

def finished?
  !@end_time.nil?
end

#get_metric(key) ⇒ Object

Return the metric with the given key, nil if it doesn’t exist.



139
140
141
 
# File 'lib/ddtrace/span.rb', line 139

def get_metric(key)
  @metrics[key] || @meta[key]
end

#get_tag(key) ⇒ Object

Return the tag with the given key, nil if it doesn’t exist.



116
117
118
 
# File 'lib/ddtrace/span.rb', line 116

def get_tag(key)
  @meta[key] || @metrics[key]
end

#pretty_print(q) ⇒ Object

Return a human readable version of the span



248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
 
# File 'lib/ddtrace/span.rb', line 248

def pretty_print(q)
  start_time = (@start_time.to_f * 1e9).to_i rescue '-'
  end_time = (@end_time.to_f * 1e9).to_i rescue '-'
  duration = ((@end_time - @start_time) * 1e9).to_i rescue 0
  q.group 0 do
    q.breakable
    q.text "Name: #{@name}\n"
    q.text "Span ID: #{@span_id}\n"
    q.text "Parent ID: #{@parent_id}\n"
    q.text "Trace ID: #{@trace_id}\n"
    q.text "Type: #{@span_type}\n"
    q.text "Service: #{@service}\n"
    q.text "Resource: #{@resource}\n"
    q.text "Error: #{@status}\n"
    q.text "Start: #{start_time}\n"
    q.text "End: #{end_time}\n"
    q.text "Duration: #{duration}\n"
    q.text "Allocations: #{allocations}\n"
    q.group(2, 'Tags: [', "]\n") do
      q.breakable
      q.seplist @meta.each do |key, value|
        q.text "#{key} => #{value}"
      end
    end
    q.group(2, 'Metrics: [', ']') do
      q.breakable
      q.seplist @metrics.each do |key, value|
        q.text "#{key} => #{value}"
      end
    end
  end
end

#set_error(e) ⇒ Object

Mark the span with the given error.



144
145
146
147
148
149
150
151
 
# File 'lib/ddtrace/span.rb', line 144

def set_error(e)
  e = Error.build_from(e)

  @status = Ext::Errors::STATUS
  set_tag(Ext::Errors::TYPE, e.type) unless e.type.empty?
  set_tag(Ext::Errors::MSG, e.message) unless e.message.empty?
  set_tag(Ext::Errors::STACK, e.backtrace) unless e.backtrace.empty?
end

#set_metric(key, value) ⇒ Object

This method sets a tag with a floating point value for the given key. It acts like ‘set_tag()` and it simply add a tag without further processing.



122
123
124
125
126
127
128
129
130
131
 
# File 'lib/ddtrace/span.rb', line 122

def set_metric(key, value)
  # Keys must be unique between tags and metrics
  @meta.delete(key)

  # enforce that the value is a floating point number
  value = Float(value)
  @metrics[key] = value
rescue StandardError => e
  Datadog::Logger.log.debug("Unable to set the metric #{key}, ignoring it. Caused by: #{e}")
end

#set_parent(parent) ⇒ Object

DEPRECATED: remove this function in the next release, replaced by “parent=“



199
200
201
 
# File 'lib/ddtrace/span.rb', line 199

def set_parent(parent)
  self.parent = parent
end

#set_tag(key, value = nil) ⇒ Object

Set the given key / value tag pair on the span. Keys and values must be strings. A valid example is:

span.set_tag('http.method', request.method)



86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
 
# File 'lib/ddtrace/span.rb', line 86

def set_tag(key, value = nil)
  # Keys must be unique between tags and metrics
  @metrics.delete(key)

  # Ensure `http.status_code` is always a string so it is added to
  #   @meta instead of @metrics
  # DEV: This is necessary because the agent looks to `meta['http.status_code']` for
  #   tagging necessary metrics
  value = value.to_s if key == Ext::HTTP::STATUS_CODE

  # NOTE: Adding numeric tags as metrics is stop-gap support
  #       for numeric typed tags. Eventually they will become
  #       tags again.
  # Any numeric that is not an integer greater than max size is logged as a metric.
  # Everything else gets logged as a tag.
  if value.is_a?(Numeric) && !(value.is_a?(Integer) && !NUMERIC_TAG_SIZE_RANGE.cover?(value))
    set_metric(key, value)
  else
    @meta[key] = value.to_s
  end
rescue StandardError => e
  Datadog::Logger.log.debug("Unable to set the tag #{key}, ignoring it. Caused by: #{e}")
end

#to_hash ⇒ Object

Return the hash representation of the current span.



224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
 
# File 'lib/ddtrace/span.rb', line 224

def to_hash
  h = {
    span_id: @span_id,
    parent_id: @parent_id,
    trace_id: @trace_id,
    name: @name,
    service: @service,
    resource: @resource,
    type: @span_type,
    meta: @meta,
    metrics: @metrics,
    allocations: allocations,
    error: @status
  }

  if !@start_time.nil? && !@end_time.nil?
    h[:start] = (@start_time.to_f * 1e9).to_i
    h[:duration] = ((@end_time - @start_time) * 1e9).to_i
  end

  h
end

#to_s ⇒ Object

Return a string representation of the span.



194
195
196
 
# File 'lib/ddtrace/span.rb', line 194

def to_s
  "Span(name:#{@name},sid:#{@span_id},tid:#{@trace_id},pid:#{@parent_id})"
end