DAP: introduce rdbg trace inspector

lib/debug/server_dap.rb

@@ -463,6 +463,10 @@ def process
       send_event :terminated unless @sock.closed?
     end
 
+    def request_rdbgTraceInspector req
+      @q_msg << req
+    end
+
     ## called by the SESSION thread
 
     def respond req, res
@@ -655,6 +659,53 @@ def process_protocol_request req
       end
     end
 
+    def request_rdbgTraceInspector(req)
+      cmd = req.dig('arguments', 'command')
+      case cmd
+      when 'enable'
+        events = req.dig('arguments', 'events')
+        evts = []
+        events.each{|evt|
+          case evt
+          when 'line'
+            evts << :line
+          when 'call'
+            evts << :call
+            evts << :c_call
+            evts << :b_call
+          when 'return'
+            evts << :return
+            evts << :c_return
+            evts << :b_return
+          else
+            raise "unknown trace type #{evt}"
+          end
+        }
+        add_tracer MultiTracer.new @ui, evts
+        @ui.respond req, {}
+      when 'disable'
+        @tracers.values.each{|t|
+          if t.type == 'multi'
+            t.disable
+            break
+          end
+        }
+        @ui.respond req, {}
+      when 'collect'
+        logs = []
+        @tracers.values.each{|t|
+          if t.type == 'multi'
+            logs = t.log
+            break
+          end
+        }
+        @ui.respond req, logs: logs
+      else
+        raise "unknown command #{cmd}"
+      end
+      return :retry
+    end
+
     def dap_event args
       # puts({dap_event: args}.inspect)
       type, req, result = args

lib/debug/tracer.rb

@@ -148,6 +148,78 @@ def skip_with_pattern?(tp)
     end
   end
 
+  # MultiTracer is designated for DAP.
+  class MultiTracer < Tracer
+    MAX_LOG_SIZE = 4000
+    def initialize ui, evts, **kw
+      super(ui, **kw)
+      @log = []
+      @evts = evts
+    end
+
+    attr_reader :log
+
+    def setup
+      @tracer = TracePoint.new(*@evts){|tp|
+        next if skip?(tp)
+
+        case tp.event
+        when :call, :c_call, :b_call
+          append(call_trace_log(tp))
+        when :return, :c_return, :b_return
+          return_str = DEBUGGER__.safe_inspect(tp.return_value, short: true, max_length: 120)
+          append(call_trace_log(tp, return_str: return_str))
+        when :line
+          append(line_trace_log(tp))
+        end
+      }
+    end
+
+    def call_identifier_str tp
+      if tp.defined_class
+        minfo(tp)
+      else
+        "block"
+      end
+    end
+
+    def append log
+      if @log.size >= MAX_LOG_SIZE
+        @log.shift
+      end
+      @log << log
+    end
+
+    def call_trace_log tp, return_str: nil
+      log = {
+        depth: DEBUGGER__.frame_depth,
+        name: call_identifier_str(tp),
+        threadId: Thread.current.instance_variable_get(:@__thread_client_id),
+        location: {
+          path: tp.path,
+          line: tp.lineno
+        }
+      }
+      log[:returnValue] = return_str if return_str
+      log
+    end
+
+    def line_trace_log tp
+      {
+        depth: DEBUGGER__.frame_depth,
+        threadId: Thread.current.instance_variable_get(:@__thread_client_id),
+        location: {
+          path: tp.path,
+          line: tp.lineno
+        }
+      }
+    end
+
+    def skip? tp
+      super || !@evts.include?(tp.event)
+    end
+  end
+
   class ExceptionTracer < Tracer
     def setup
       @tracer = TracePoint.new(:raise) do |tp|