Add runner context interrupting

Author: Тимофей Шкредов

main.go

@@ -11,8 +11,10 @@ import (
 	"fmt"
 	"log"
 	"os"
+	"os/signal"
 	"runtime"
 	"runtime/pprof"
+	"syscall"
 
 	"github.com/go-python/gpython/py"
 	"github.com/go-python/gpython/repl"
@@ -48,6 +50,14 @@ func xmain(args []string) {
 	ctx := py.NewContext(opts)
 	defer ctx.Close()
 
+	sigCh := make(chan os.Signal, 1)
+	signal.Notify(sigCh, os.Interrupt, syscall.SIGINT, syscall.SIGTERM)
+	go func() {
+		for range sigCh {
+			ctx.SetInterrupt()
+		}
+	}()
+
 	if *cpuprofile != "" {
 		f, err := os.Create(*cpuprofile)
 		if err != nil {

py/run.go

@@ -42,6 +42,14 @@ type Context interface {
 	// Gereric access to this context's modules / state.
 	Store() *ModuleStore
 
+	// SetInterrupt signals the VM to raise KeyboardInterrupt at the next opcode boundary.
+	// Safe to call from any goroutine (e.g. a signal handler).
+	SetInterrupt()
+
+	// CheckInterrupt atomically checks and clears the interrupt flag.
+	// Returns true if an interrupt was pending.
+	CheckInterrupt() bool
+
 	// Close signals this context is about to go out of scope and any internal resources should be released.
 	// Code execution on a py.Context that has been closed will result in an error.
 	Close() error

repl/cli/cli.go

@@ -51,6 +51,7 @@ func newReadline(repl *repl.REPL) *readline {
 	}
 	rl.SetTabCompletionStyle(liner.TabPrints)
 	rl.SetWordCompleter(rl.Completer)
+	rl.SetCtrlCAborts(true)
 	return rl
 }
 
@@ -146,6 +147,11 @@ func RunREPL(replCtx *repl.REPL) error {
 				fmt.Printf("\n")
 				break
 			}
+			if err == liner.ErrPromptAborted {
+				fmt.Println("KeyboardInterrupt")
+				rl.repl.ResetContinuation()
+				continue
+			}
 			fmt.Printf("Problem reading line: %v\n", err)
 			continue
 		}

repl/repl.go

@@ -65,6 +65,14 @@ func (r *REPL) SetUI(term UI) {
 	r.term.SetPrompt(NormalPrompt)
 }
 
+// ResetContinuation cancels any multi-line input in progress,
+// restoring the REPL to a clean prompt state (e.g. after Ctrl+C).
+func (r *REPL) ResetContinuation() {
+	r.continuation = false
+	r.previous = ""
+	r.term.SetPrompt(NormalPrompt)
+}
+
 // Run runs a single line of the REPL
 func (r *REPL) Run(line string) error {
 	// Override the PrintExpr output temporarily
@@ -112,6 +120,10 @@ func (r *REPL) Run(line string) error {
 		if py.IsException(py.SystemExit, err) {
 			return err
 		}
+		if py.IsException(py.KeyboardInterrupt, err) {
+			r.term.Print("KeyboardInterrupt")
+			return nil
+		}
 		py.TracebackDump(err)
 	}
 	return nil

stdlib/stdlib.go

@@ -13,6 +13,7 @@ import (
 	"path/filepath"
 	"strings"
 	"sync"
+	"sync/atomic"
 
 	"github.com/go-python/gpython/py"
 	"github.com/go-python/gpython/stdlib/marshal"
@@ -44,6 +45,7 @@ type context struct {
 	closed    bool
 	running   sync.WaitGroup
 	done      chan struct{}
+	interrupt int32 // atomic; non-zero means KeyboardInterrupt pending
 }
 
 // NewContext creates a new gpython interpreter instance context.
@@ -192,6 +194,16 @@ func (ctx *context) ResolveAndCompile(pathname string, opts py.CompileOpts) (py.
 	return out, nil
 }
 
+// See interface py.Context defined in py/run.go
+func (ctx *context) SetInterrupt() {
+	atomic.StoreInt32(&ctx.interrupt, 1)
+}
+
+// See interface py.Context defined in py/run.go
+func (ctx *context) CheckInterrupt() bool {
+	return atomic.SwapInt32(&ctx.interrupt, 0) != 0
+}
+
 func (ctx *context) pushBusy() error {
 	if ctx.closed {
 		return py.ExceptionNewf(py.RuntimeError, "Context closed")
@@ -208,6 +220,7 @@ func (ctx *context) popBusy() {
 func (ctx *context) Close() error {
 	ctx.closeOnce.Do(func() {
 		ctx.closing = true
+		ctx.SetInterrupt()
 		ctx.running.Wait()
 		ctx.closed = true
 

vm/eval.go

@@ -1751,7 +1751,6 @@ func RunFrame(frame *py.Frame) (res py.Object, err error) {
 		frame:   frame,
 		context: frame.Context,
 	}
-
 	// FIXME need to do this to save the old exeption when we
 	// yield from a generator.  Should save it in the Frame though
 	// (see slots in the frame)
@@ -1778,6 +1777,13 @@ func RunFrame(frame *py.Frame) (res py.Object, err error) {
 	var arg int32
 	opcodes := frame.Code.Code
 	for vm.why == whyNot {
+		// Check for pending interrupt (e.g. SIGINT / Context.SetInterrupt).
+		// Routed through the normal exception mechanism so that
+		// try/except/finally blocks are honored.
+		if vm.context != nil && vm.context.CheckInterrupt() {
+			vm.SetException(py.MakeException(py.ExceptionNewf(py.KeyboardInterrupt, "KeyboardInterrupt")))
+			goto handleException
+		}
 		if debugging {
 			debugf("* %4d:", frame.Lasti)
 		}
@@ -1822,7 +1828,7 @@ func RunFrame(frame *py.Frame) (res py.Object, err error) {
 		if vm.why == whyYield {
 			goto fast_yield
 		}
-
+	handleException:
 		// Something exceptional has happened - unwind the block stack
 		// and find out what
 		for vm.why != whyNot && frame.Block != nil {