From 71d9d4e12b2a83e8c98be6f53082d2e9d5acd962 Mon Sep 17 00:00:00 2001
From: siyul-park <siyual.bak@gmail.com>
Date: Fri, 27 Sep 2024 20:00:07 -0400
Subject: [PATCH] fix: escape deathlock in agent

---
 pkg/agent/agent.go     | 25 +++++++++++++++++--------
 pkg/debug/debugger.go  | 13 +++++--------
 pkg/process/process.go |  6 +++---
 3 files changed, 25 insertions(+), 19 deletions(-)

diff --git a/pkg/agent/agent.go b/pkg/agent/agent.go
index 5275686b..49037c5d 100644
--- a/pkg/agent/agent.go
+++ b/pkg/agent/agent.go
@@ -22,7 +22,6 @@ type Agent struct {
 	mu        sync.RWMutex
 }
 
-// Ensure Agent implements LoadHook and UnloadHook interfaces.
 var _ symbol.LoadHook = (*Agent)(nil)
 var _ symbol.UnloadHook = (*Agent)(nil)
 
@@ -117,7 +116,7 @@ func (a *Agent) Frames(id uuid.UUID) ([]*Frame, bool) {
 	if !exists {
 		return nil, false
 	}
-	return append([]*Frame(nil), frames...), true
+	return frames[:], true
 }
 
 // Load adds a symbol and its hooks to the agent.
@@ -202,9 +201,10 @@ func (a *Agent) Close() {
 // accept registers a process and notifies watchers.
 func (a *Agent) accept(proc *process.Process) {
 	a.mu.Lock()
-	defer a.mu.Unlock()
 
-	if _, exists := a.processes[proc.ID()]; !exists {
+	_, exists := a.processes[proc.ID()]
+
+	if !exists {
 		a.processes[proc.ID()] = proc
 
 		proc.AddExitHook(process.ExitFunc(func(err error) {
@@ -215,14 +215,21 @@ func (a *Agent) accept(proc *process.Process) {
 			delete(a.frames, proc.ID())
 		}))
 
-		for _, watcher := range a.watchers {
-			watcher.OnProcess(proc)
-		}
-
 		if _, exists := a.frames[proc.ID()]; !exists {
 			a.frames[proc.ID()] = nil
 		}
 	}
+
+	watchers := a.watchers[:]
+
+	a.mu.Unlock()
+
+	if !exists {
+		for i := len(watchers) - 1; i >= 0; i-- {
+			watcher := watchers[i]
+			watcher.OnProcess(proc)
+		}
+	}
 }
 
 func (a *Agent) hooks(proc *process.Process, sym *symbol.Symbol, in *port.InPort, out *port.OutPort) (packet.Hook, packet.Hook) {
@@ -251,6 +258,7 @@ func (a *Agent) hooks(proc *process.Process, sym *symbol.Symbol, in *port.InPort
 		}
 
 		watchers := a.watchers[:]
+
 		a.mu.Unlock()
 
 		for i := len(watchers) - 1; i >= 0; i-- {
@@ -284,6 +292,7 @@ func (a *Agent) hooks(proc *process.Process, sym *symbol.Symbol, in *port.InPort
 		}
 
 		watchers := a.watchers[:]
+
 		a.mu.Unlock()
 
 		for i := len(watchers) - 1; i >= 0; i-- {
diff --git a/pkg/debug/debugger.go b/pkg/debug/debugger.go
index ef36fde8..8f13d307 100644
--- a/pkg/debug/debugger.go
+++ b/pkg/debug/debugger.go
@@ -68,16 +68,13 @@ func (d *Debugger) Breakpoints() []*Breakpoint {
 	d.mu.RLock()
 	defer d.mu.RUnlock()
 
-	if len(d.breakpoints) == 0 {
-		return nil
-	}
-	return append([]*Breakpoint(nil), d.breakpoints...)
+	return d.breakpoints[:]
 }
 
 // Pause blocks until a breakpoint is hit or monitoring is done.
 func (d *Debugger) Pause(ctx context.Context) bool {
-	d.mu.RLock()
-	defer d.mu.RUnlock()
+	d.mu.Lock()
+	defer d.mu.Unlock()
 
 	if d.current != nil {
 		return true
@@ -95,8 +92,8 @@ func (d *Debugger) Pause(ctx context.Context) bool {
 
 // Step continues execution until the next breakpoint is hit.
 func (d *Debugger) Step(ctx context.Context) bool {
-	d.mu.RLock()
-	defer d.mu.RUnlock()
+	d.mu.Lock()
+	defer d.mu.Unlock()
 
 	if d.current != nil {
 		go d.next(d.current)
diff --git a/pkg/process/process.go b/pkg/process/process.go
index decc9f64..cb793852 100644
--- a/pkg/process/process.go
+++ b/pkg/process/process.go
@@ -50,7 +50,7 @@ func (p *Process) ID() uuid.UUID {
 func (p *Process) Load(key string) any {
 	p.mu.RLock()
 	defer p.mu.RUnlock()
-	
+
 	return p.data[key]
 }
 
@@ -58,7 +58,7 @@ func (p *Process) Load(key string) any {
 func (p *Process) Store(key string, val any) {
 	p.mu.Lock()
 	defer p.mu.Unlock()
-	
+
 	p.data[key] = val
 }
 
@@ -66,7 +66,7 @@ func (p *Process) Store(key string, val any) {
 func (p *Process) Delete(key string) bool {
 	p.mu.Lock()
 	defer p.mu.Unlock()
-	
+
 	if _, ok := p.data[key]; ok {
 		delete(p.data, key)
 		return true