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Merged
tonistiigi merged 1 commit into from
Jul 4, 2025
Merged

dap: add stack traces with next and continue functionality #3279

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4 changes: 2 additions & 2 deletions build/build.go
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Original file line number Diff line number Diff line change
Expand Up @@ -314,7 +314,7 @@ func toRepoOnly(in string) (string, error) {
}

type (
EvaluateFunc func(ctx context.Context, name string, c gateway.Client, res *gateway.Result) error
EvaluateFunc func(ctx context.Context, name string, c gateway.Client, res *gateway.Result, opt Options) error
Handler struct {
Evaluate EvaluateFunc
}
Expand Down Expand Up @@ -525,7 +525,7 @@ func BuildWithResultHandler(ctx context.Context, nodes []builder.Node, opts map[

// invoke custom evaluate handler if it is present
if bh != nil && bh.Evaluate != nil {
if err := bh.Evaluate(ctx, k, c, res); err != nil {
if err := bh.Evaluate(ctx, k, c, res, opt); err != nil {
return nil, err
}
} else if forceEval {
Expand Down
215 changes: 115 additions & 100 deletions dap/adapter.go
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Original file line number Diff line number Diff line change
@@ -1,11 +1,14 @@
package dap

import (
"bytes"
"context"
"encoding/json"
"fmt"
"io"
"path"
"sync"
"sync/atomic"

"github.com/docker/buildx/build"
"github.com/google/go-dap"
Expand All @@ -28,6 +31,9 @@ type Adapter[T any] struct {
threads map[int]*thread
threadsMu sync.RWMutex
nextThreadID int

sourceMap sourceMap
idPool *idPool
}

func New[T any](cfg *build.InvokeConfig) *Adapter[T] {
Expand All @@ -38,6 +44,7 @@ func New[T any](cfg *build.InvokeConfig) *Adapter[T] {
evaluateReqCh: make(chan *evaluateRequest),
threads: make(map[int]*thread),
nextThreadID: 1,
idPool: new(idPool),
}
if cfg != nil {
d.cfg = *cfg
Expand Down Expand Up @@ -131,7 +138,16 @@ func (d *Adapter[T]) Continue(c Context, req *dap.ContinueRequest, resp *dap.Con
t := d.threads[req.Arguments.ThreadId]
d.threadsMu.RUnlock()

t.Resume(c)
t.Continue()
return nil
}

func (d *Adapter[T]) Next(c Context, req *dap.NextRequest, resp *dap.NextResponse) error {
d.threadsMu.RLock()
t := d.threads[req.Arguments.ThreadId]
d.threadsMu.RUnlock()

t.Next()
return nil
}

Expand Down Expand Up @@ -182,7 +198,7 @@ func (d *Adapter[T]) launch(c Context) {
started := c.Go(func(c Context) {
defer d.deleteThread(c, t)
defer close(req.errCh)
req.errCh <- t.Evaluate(c, req.c, req.ref, req.meta, d.cfg)
req.errCh <- t.Evaluate(c, req.c, req.ref, req.meta, req.inputs)
})

if !started {
Expand All @@ -197,8 +213,10 @@ func (d *Adapter[T]) newThread(ctx Context, name string) (t *thread) {
d.threadsMu.Lock()
id := d.nextThreadID
t = &thread{
id: id,
name: name,
id: id,
name: name,
sourceMap: &d.sourceMap,
idPool: d.idPool,
}
d.threads[t.id] = t
d.nextThreadID++
Expand Down Expand Up @@ -236,41 +254,43 @@ func (d *Adapter[T]) deleteThread(ctx Context, t *thread) {
}

type evaluateRequest struct {
name string
c gateway.Client
ref gateway.Reference
meta map[string][]byte
errCh chan<- error
name string
c gateway.Client
ref gateway.Reference
meta map[string][]byte
inputs build.Inputs
errCh chan<- error
}

func (d *Adapter[T]) EvaluateResult(ctx context.Context, name string, c gateway.Client, res *gateway.Result) error {
func (d *Adapter[T]) EvaluateResult(ctx context.Context, name string, c gateway.Client, res *gateway.Result, inputs build.Inputs) error {
eg, _ := errgroup.WithContext(ctx)
if res.Ref != nil {
eg.Go(func() error {
return d.evaluateRef(ctx, name, c, res.Ref, res.Metadata)
return d.evaluateRef(ctx, name, c, res.Ref, res.Metadata, inputs)
})
}

for k, ref := range res.Refs {
refName := fmt.Sprintf("%s (%s)", name, k)
eg.Go(func() error {
return d.evaluateRef(ctx, refName, c, ref, res.Metadata)
return d.evaluateRef(ctx, refName, c, ref, res.Metadata, inputs)
})
}
return eg.Wait()
}

func (d *Adapter[T]) evaluateRef(ctx context.Context, name string, c gateway.Client, ref gateway.Reference, meta map[string][]byte) error {
func (d *Adapter[T]) evaluateRef(ctx context.Context, name string, c gateway.Client, ref gateway.Reference, meta map[string][]byte, inputs build.Inputs) error {
errCh := make(chan error, 1)

// Send a solve request to the launch routine
// which will perform the solve in the context of the server.
ereq := &evaluateRequest{
name: name,
c: c,
ref: ref,
meta: meta,
errCh: errCh,
name: name,
c: c,
ref: ref,
meta: meta,
inputs: inputs,
errCh: errCh,
}
select {
case d.evaluateReqCh <- ereq:
Expand Down Expand Up @@ -307,16 +327,28 @@ func (d *Adapter[T]) StackTrace(c Context, req *dap.StackTraceRequest, resp *dap
return errors.Errorf("no such thread: %d", req.Arguments.ThreadId)
}

resp.Body.StackFrames = t.StackFrames()
resp.Body.StackFrames = t.StackTrace()
return nil
}

func (d *Adapter[T]) Source(c Context, req *dap.SourceRequest, resp *dap.SourceResponse) error {
fname := req.Arguments.Source.Path

dt, ok := d.sourceMap.Get(fname)
if !ok {
return errors.Errorf("file not found: %s", fname)
}

resp.Body.Content = string(dt)
return nil
}

func (d *Adapter[T]) evaluate(ctx context.Context, name string, c gateway.Client, res *gateway.Result) error {
func (d *Adapter[T]) evaluate(ctx context.Context, name string, c gateway.Client, res *gateway.Result, opt build.Options) error {
errCh := make(chan error, 1)

started := d.srv.Go(func(ctx Context) {
defer close(errCh)
errCh <- d.EvaluateResult(ctx, name, c, res)
errCh <- d.EvaluateResult(ctx, name, c, res, opt.Inputs)
})
if !started {
return context.Canceled
Expand All @@ -341,93 +373,16 @@ func (d *Adapter[T]) dapHandler() Handler {
Initialize: d.Initialize,
Launch: d.Launch,
Continue: d.Continue,
Next: d.Next,
SetBreakpoints: d.SetBreakpoints,
ConfigurationDone: d.ConfigurationDone,
Disconnect: d.Disconnect,
Threads: d.Threads,
StackTrace: d.StackTrace,
Source: d.Source,
}
}

type thread struct {
id int
name string

paused chan struct{}
rCtx *build.ResultHandle
mu sync.Mutex
}

func (t *thread) Evaluate(ctx Context, c gateway.Client, ref gateway.Reference, meta map[string][]byte, cfg build.InvokeConfig) error {
err := ref.Evaluate(ctx)
if reason, desc := t.needsDebug(cfg, err); reason != "" {
rCtx := build.NewResultHandle(ctx, c, ref, meta, err)

select {
case <-t.pause(ctx, rCtx, reason, desc):
case <-ctx.Done():
t.Resume(ctx)
return context.Cause(ctx)
}
}
return err
}

func (t *thread) needsDebug(cfg build.InvokeConfig, err error) (reason, desc string) {
if !cfg.NeedsDebug(err) {
return
}

if err != nil {
reason = "exception"
desc = "Encountered an error during result evaluation"
} else {
reason = "pause"
desc = "Result evaluation completed"
}
return
}

func (t *thread) pause(c Context, rCtx *build.ResultHandle, reason, desc string) <-chan struct{} {
if t.paused == nil {
t.paused = make(chan struct{})
}
t.rCtx = rCtx

c.C() <- &dap.StoppedEvent{
Event: dap.Event{Event: "stopped"},
Body: dap.StoppedEventBody{
Reason: reason,
Description: desc,
ThreadId: t.id,
},
}
return t.paused
}

func (t *thread) Resume(c Context) {
t.mu.Lock()
defer t.mu.Unlock()

if t.paused == nil {
return
}

if t.rCtx != nil {
t.rCtx.Done()
t.rCtx = nil
}

close(t.paused)
t.paused = nil
}

// TODO: return a suitable stack frame for the thread.
// For now, just returns nothing.
func (t *thread) StackFrames() []dap.StackFrame {
return []dap.StackFrame{}
}

func (d *Adapter[T]) Out() io.Writer {
return &adapterWriter[T]{d}
}
Expand All @@ -454,3 +409,63 @@ func (d *adapterWriter[T]) Write(p []byte) (n int, err error) {
}
return n, nil
}

type idPool struct {
next atomic.Int64
}

func (p *idPool) Get() int64 {
return p.next.Add(1)
}

func (p *idPool) Put(x int64) {
// noop
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Collaborator

@ktock ktock Jul 3, 2025

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nit: It's unlikely happen but it's safe to return an error or panic if the id is exhausted.

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@jsternberg jsternberg Jul 3, 2025

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I was mostly just adding this struct in case we ever wanted to reuse ids for some reason. That's the main reason why this function exists. I can also just remove this entirely and we can add that later if it's ever used.

}

type sourceMap struct {
m sync.Map
}

func (s *sourceMap) Put(c Context, fname string, dt []byte) {
for {
old, loaded := s.m.LoadOrStore(fname, dt)
if !loaded {
c.C() <- &dap.LoadedSourceEvent{
Event: dap.Event{Event: "loadedSource"},
Body: dap.LoadedSourceEventBody{
Reason: "new",
Source: dap.Source{
Name: path.Base(fname),
Path: fname,
},
},
}
}

if bytes.Equal(old.([]byte), dt) {
// Nothing to do.
return
}

if s.m.CompareAndSwap(fname, old, dt) {
c.C() <- &dap.LoadedSourceEvent{
Event: dap.Event{Event: "loadedSource"},
Body: dap.LoadedSourceEventBody{
Reason: "changed",
Source: dap.Source{
Name: path.Base(fname),
Path: fname,
},
},
}
}
}
}

func (s *sourceMap) Get(fname string) ([]byte, bool) {
v, ok := s.m.Load(fname)
if !ok {
return nil, false
}
return v.([]byte), true
}
2 changes: 2 additions & 0 deletions dap/handler.go
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Original file line number Diff line number Diff line change
Expand Up @@ -51,8 +51,10 @@ type Handler struct {
Disconnect HandlerFunc[*dap.DisconnectRequest, *dap.DisconnectResponse]
Terminate HandlerFunc[*dap.TerminateRequest, *dap.TerminateResponse]
Continue HandlerFunc[*dap.ContinueRequest, *dap.ContinueResponse]
Next HandlerFunc[*dap.NextRequest, *dap.NextResponse]
Restart HandlerFunc[*dap.RestartRequest, *dap.RestartResponse]
Threads HandlerFunc[*dap.ThreadsRequest, *dap.ThreadsResponse]
StackTrace HandlerFunc[*dap.StackTraceRequest, *dap.StackTraceResponse]
Evaluate HandlerFunc[*dap.EvaluateRequest, *dap.EvaluateResponse]
Source HandlerFunc[*dap.SourceRequest, *dap.SourceResponse]
}
4 changes: 4 additions & 0 deletions dap/server.go
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Original file line number Diff line number Diff line change
Expand Up @@ -117,6 +117,8 @@ func (s *Server) handleMessage(c Context, m dap.Message) (dap.ResponseMessage, e
return s.h.Terminate.Do(c, req)
case *dap.ContinueRequest:
return s.h.Continue.Do(c, req)
case *dap.NextRequest:
return s.h.Next.Do(c, req)
case *dap.RestartRequest:
return s.h.Restart.Do(c, req)
case *dap.ThreadsRequest:
Expand All @@ -125,6 +127,8 @@ func (s *Server) handleMessage(c Context, m dap.Message) (dap.ResponseMessage, e
return s.h.StackTrace.Do(c, req)
case *dap.EvaluateRequest:
return s.h.Evaluate.Do(c, req)
case *dap.SourceRequest:
return s.h.Source.Do(c, req)
default:
return nil, errors.New("not implemented")
}
Expand Down
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