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Debugging

Powered by Delve Debugger.

Introduction​

Gont can manage Delve debugger instances attached to spawned sub-processes. These Delve instances can be used to debug or trace multiple applications in a distributed system simultaneously. Users can either use DAP-compatible IDEs like VScode to attach to those processes, or record tracepoint data generated by Delve break- & watchpoints to a PCAPng file.

Its integration with the packet capture and event tracing feature of Gont allows the user to even streaming tracepoint data interleaved with packet and other tracing data in real-time to Wireshark.

Create a debugger​

import dopt "cunicu.li/gont/v2/pkt/options/debug"

t := gont.NewTracer(...)

d := gont.NewDebugger(
  // ... Tracepoints are defined here
  dopt.BreakOnEntry(true),
  dopt.ToTracer(t),

  // Listening socket for connection of external DAP client
  dopt.ListenAddr("tcp:[::]:1234"))

Attach a debugger​

Debug all processes started by nodes of this network:

network, _ := gont.NewNetwork("", d)

Debug all processes started by a node:

host1 := network.NewHost("host1", d)

Debug a single process:

host1.RunGo("test/main.go", d)

(Like for the event tracing)

Define tracepoints​

Break-, watchpoint location​

import "github.com/go-delve/delve/service/api"
import dopt "cunicu.li/gont/v2/pkg/options/debug"

d := gont.NewDebugger(
  gont.NewTracepoint(
    dopt.Disabled(false),
    dopt.Name("tp1"),
    dopt.Message("A trace message with evaluated {placeholders}"),
    dopt.Location(...), // A Delve locspec
    dopt.Address(0x12312321),
    dopt.File("main.go"),
    dopt.Line(12),
    dopt.FunctionName("main.main"),
    dopt.FunctionNameRegex("main\.(main|setupLogger)"),
    dopt.Condition("i % 100 == 0"),
    dopt.HitCondition("> 100"),
    dopt.HitConditionPerGoroutine(true),
    dopt.Watch("p", api.WatchRead|api.WatchWrite)),
  ...
)

Define tracepoints​

Gathering of breakpoint information​

import dopt "cunicu.li/gont/v2/pkt/options/debug"

d := gont.NewDebugger(
  gont.NewTracepoint(
    ...
    dopt.Variable("j"),
    dopt.Goroutine(true),
    dopt.Stacktrace(10),
    dopt.LoadLocals(...),
    dopt.LoadArguments(
      dopt.FollowPointers(true),
      dopt.MaxVariableRecurse(3),
      dopt.MaxStringLen(128),
      dopt.MaxArrayValues(128),
      dopt.MaxStructFields(32))))

VSCode Integration​

Gont generates VS Code launch compound configurations based on the active debugging sessions.

d.WriteVSCodeConfigs("", false)