DEBUG-2334 Ruby 2 compatibility for dynamic instrumentation (#4120)

Author: p-datadog

lib/datadog/di/instrumenter.rb

@@ -105,8 +105,19 @@ def hook_method(probe, &block)
                 serializer.serialize_args(args, kwargs)
               end
               rv = nil
+              # Under Ruby 2.6 we cannot just call super(*args, **kwargs)
               duration = Benchmark.realtime do # steep:ignore
-                rv = super(*args, **kwargs)
+                rv = if args.any?
+                  if kwargs.any?
+                    super(*args, **kwargs)
+                  else
+                    super(*args)
+                  end
+                elsif kwargs.any?
+                  super(**kwargs)
+                else
+                  super()
+                end
               end
               # The method itself is not part of the stack trace because
               # we are getting the stack trace from outside of the method.

spec/datadog/di/hook_method.rb

@@ -11,6 +11,10 @@ def hook_test_method_with_kwarg(kwarg:)
     kwarg
   end
 
+  def hook_test_method_with_pos_and_kwarg(arg, kwarg:)
+    [arg, kwarg]
+  end
+
   def recursive(depth)
     if depth > 0
       recursive(depth - 1) + '-'

spec/datadog/di/instrumenter_spec.rb

@@ -102,19 +102,124 @@
            capture_snapshot: true}
         end
 
-        it 'invokes callback and captures parameters' do
-          instrumenter.hook_method(probe) do |payload|
-            observed_calls << payload
+        let(:target_call) do
+          expect(HookTestClass.new.hook_test_method_with_arg(2)).to eq 2
+        end
+
+        shared_examples 'invokes callback and captures parameters' do
+          it 'invokes callback and captures parameters' do
+            instrumenter.hook_method(probe) do |payload|
+              observed_calls << payload
+            end
+
+            target_call
+
+            expect(observed_calls.length).to eq 1
+            expect(observed_calls.first.keys.sort).to eq call_keys
+            expect(observed_calls.first[:rv]).to eq 2
+            expect(observed_calls.first[:duration]).to be_a(Float)
+
+            expect(observed_calls.first[:serialized_entry_args]).to eq(arg1: {type: 'Integer', value: '2'})
           end
+        end
 
-          expect(HookTestClass.new.hook_test_method_with_arg(2)).to eq 2
+        include_examples 'invokes callback and captures parameters'
 
-          expect(observed_calls.length).to eq 1
-          expect(observed_calls.first.keys.sort).to eq call_keys
-          expect(observed_calls.first[:rv]).to eq 2
-          expect(observed_calls.first[:duration]).to be_a(Float)
+        context 'when passed via a splat' do
+          let(:target_call) do
+            args = [2]
+            expect(HookTestClass.new.hook_test_method_with_arg(*args)).to eq 2
+          end
+
+          include_examples 'invokes callback and captures parameters'
+        end
+      end
+    end
+
+    context 'keyword args' do
+      context 'with snapshot capture' do
+        let(:probe_args) do
+          {type_name: 'HookTestClass', method_name: 'hook_test_method_with_kwarg',
+           capture_snapshot: true}
+        end
+
+        let(:target_call) do
+          expect(HookTestClass.new.hook_test_method_with_kwarg(kwarg: 42)).to eq 42
+        end
+
+        shared_examples 'invokes callback and captures parameters' do
+          it 'invokes callback and captures parameters' do
+            instrumenter.hook_method(probe) do |payload|
+              observed_calls << payload
+            end
+
+            target_call
+
+            expect(observed_calls.length).to eq 1
+            expect(observed_calls.first.keys.sort).to eq call_keys
+            expect(observed_calls.first[:rv]).to eq 42
+            expect(observed_calls.first[:duration]).to be_a(Float)
+
+            expect(observed_calls.first[:serialized_entry_args]).to eq(kwarg: {type: 'Integer', value: '42'})
+          end
+        end
+
+        include_examples 'invokes callback and captures parameters'
+
+        context 'when passed via a splat' do
+          let(:target_call) do
+            kwargs = {kwarg: 42}
+            expect(HookTestClass.new.hook_test_method_with_kwarg(**kwargs)).to eq 42
+          end
+
+          include_examples 'invokes callback and captures parameters'
+        end
+      end
+    end
+
+    context 'positional and keyword args' do
+      context 'with snapshot capture' do
+        let(:probe_args) do
+          {type_name: 'HookTestClass', method_name: 'hook_test_method_with_pos_and_kwarg',
+           capture_snapshot: true}
+        end
+
+        let(:target_call) do
+          expect(HookTestClass.new.hook_test_method_with_pos_and_kwarg(41, kwarg: 42)).to eq [41, 42]
+        end
+
+        shared_examples 'invokes callback and captures parameters' do
+          it 'invokes callback and captures parameters' do
+            instrumenter.hook_method(probe) do |payload|
+              observed_calls << payload
+            end
+
+            target_call
+
+            expect(observed_calls.length).to eq 1
+            expect(observed_calls.first.keys.sort).to eq call_keys
+            expect(observed_calls.first[:rv]).to eq [41, 42]
+            expect(observed_calls.first[:duration]).to be_a(Float)
+
+            expect(observed_calls.first[:serialized_entry_args]).to eq(
+              # TODO actual argument name not captured yet,
+              # requires method call trace point.
+              arg1: {type: 'Integer', value: '41'},
+              kwarg: {type: 'Integer', value: '42'}
+            )
+          end
+        end
+
+        include_examples 'invokes callback and captures parameters'
+
+        context 'when passed via a splat' do
+          let(:target_call) do
+            args = [41]
+            kwargs = {kwarg: 42}
+            expect(HookTestClass.new.hook_test_method_with_pos_and_kwarg(*args, **kwargs)).to eq [41, 42]
+          end
 
-          expect(observed_calls.first[:serialized_entry_args]).to eq(arg1: {type: 'Integer', value: '2'})
+          include_examples 'invokes callback and captures parameters'
         end
       end
     end