Merge pull request #1694 from ruby-agent/RUBY-1530_truncate_stack_traces

Add truncate_trace method and tests
newrelic · Apr 12, 2018 · 89a6423 · 89a6423
2 parents ecb7497 + b049ce8
commit 89a6423
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Showing 2 changed files with 37 additions and 1 deletion.
diff --git a/lib/new_relic/agent/error_collector.rb b/lib/new_relic/agent/error_collector.rb
@@ -13,6 +13,9 @@ class ErrorCollector
       # made configurable in the future. This is a tradeoff between
       # memory and data retention
       MAX_ERROR_QUEUE_LENGTH = 20
+      # Maximum number of frames in backtraces. May be made configurable
+      # in the future.
+      MAX_BACKTRACE_FRAMES = 50
       EXCEPTION_TAG_IVAR = :'@__nr_seen_exception'
 
       attr_reader :error_trace_aggregator, :error_event_aggregator
@@ -213,6 +216,19 @@ def notice_error(exception, options={}) #THREAD_LOCAL_ACCESS
         nil
       end
 
+      def truncate_trace(trace, keep_frames=MAX_BACKTRACE_FRAMES)
+        return trace if trace.length < keep_frames || trace.length == 0
+
+        # If keep_frames is odd, we will split things up favoring the top of the trace
+        keep_top = (keep_frames / 2.0).ceil
+        keep_bottom = (keep_frames / 2.0).floor
+
+        truncate_frames = trace.length - keep_frames
+
+        truncated_trace = trace[0...keep_top].concat(["<truncated #{truncate_frames.to_s} additional frames>"]).concat(trace[-keep_bottom..-1])
+        truncated_trace
+      end
+
       EMPTY_STRING = ''.freeze
 
       def create_noticed_error(exception, options)
@@ -225,7 +241,7 @@ def create_noticed_error(exception, options)
 
         noticed_error.file_name   = sense_method(exception, :file_name)
         noticed_error.line_number = sense_method(exception, :line_number)
-        noticed_error.stack_trace = extract_stack_trace(exception)
+        noticed_error.stack_trace = truncate_trace(extract_stack_trace(exception))
 
         noticed_error.expected = !! options.delete(:expected)
 

diff --git a/test/new_relic/agent/error_collector_test.rb b/test/new_relic/agent/error_collector_test.rb
@@ -248,6 +248,26 @@ def test_extract_stack_trace
     assert_equal('<no stack trace>', @error_collector.extract_stack_trace(Exception.new))
   end
 
+  def test_short_trace_not_truncated
+    trace = @error_collector.truncate_trace(['error', 'error', 'error'], 6)
+    assert_equal trace.length, 3
+  end
+
+  def test_empty_trace_not_truncated
+    trace = @error_collector.truncate_trace([], 7)
+    assert_equal trace.length, 0
+  end
+
+  def test_keeps_correct_frames_if_keep_frames_is_even
+    trace = @error_collector.truncate_trace(['error1', 'error2', 'error3', 'error4'], 2)
+    assert_equal ['error1', '<truncated 2 additional frames>', 'error4'], trace
+  end
+
+  def test_keeps_correct_frames_if_keep_frames_is_odd
+    trace = @error_collector.truncate_trace(['error1', 'error2', 'error3', 'error4'], 3)
+    assert_equal ['error1', 'error2', '<truncated 1 additional frames>', 'error4'], trace
+  end
+
   if defined?(Rails::VERSION::MAJOR) && Rails::VERSION::MAJOR < 5
     def test_extract_stack_trace_from_original_exception
       orig = mock('original', :backtrace => "STACK STACK STACK")