# 🚨 SocketBox Method Call Deadlock - Critical System Failure

**Status**: 🔥 **CRITICAL** - Complete SocketBox functionality failure  
**Impact**: Phase 9 HTTP server implementation completely blocked  
**Priority**: Immediate investigation required  

## 📋 Problem Summary

All SocketBox methods (`bind()`, `listen()`, `isServer()`, `toString()`) cause infinite blocking/deadlock. Other Box types (StringBox, ArrayBox, MapBox) work normally.

## 🎯 Root Cause Analysis Completed

### ✅ **Confirmed Working Components**
- SocketBox creation: `new SocketBox()` ✅
- Arc reference sharing: `Arc addresses match = true` ✅  
- Clone functionality: Proper Arc<Mutex> sharing ✅

### ❌ **Identified Problem Location**
```rust
// src/interpreter/expressions.rs:462-464
if let Some(socket_box) = obj_value.as_any().downcast_ref::<SocketBox>() {
    let result = self.execute_socket_method(socket_box, method, arguments)?;
    // ↑ Never reaches this line - execute_socket_method is never called
}
```

**Core Issue**: Deadlock occurs in method resolution pipeline BEFORE execute_socket_method is reached.

## 📊 Evidence from Execution Logs

### 🔥 **Deadlock Reproduction Log**
```bash
[Console LOG] SocketBox作成完了
[Console LOG] bind実行開始...
🔥 SOCKETBOX CLONE DEBUG: Arc addresses match = true  # ← Clone works fine
# Infinite block here - 🔥 SOCKET_METHOD: bind() called never appears
```

### ✅ **Normal Box Comparison (ArrayBox)**
```bash
[Console LOG] ArrayBox作成完了  
[Console LOG] push実行開始...
✅ ARRAY_METHOD: push() called    # ← Method reached normally
✅ ArrayBox push completed        # ← Completes successfully
```

## 🧪 **Reproduction Test Cases**

### **Test 1: Minimal Deadlock Reproduction**
```bash
# Command
timeout 10s ./target/release/nyash test_socket_deadlock_minimal.nyash

# Expected: Timeout (deadlock)
# Actual Output:
# [Console LOG] SocketBox作成成功
# [Console LOG] bind()実行開始...
# (infinite block)
```

### **Test 2: Other Boxes Normal Operation**
```bash  
# Command
./target/release/nyash test_other_boxes_working.nyash

# Expected: Normal completion
# Actual Output:
# [Console LOG] ✅ ArrayBox正常: size=1
# [Console LOG] ✅ MapBox正常: value=test_value
# [Console LOG] 🎉 他のBox全て正常動作: 4件成功
```

### **Test 3: All SocketBox Methods**
```bash
# Command  
timeout 30s ./target/release/nyash test_socket_methods_comprehensive.nyash

# Expected: Deadlock on first method call
# All methods (toString, isServer, bind, close) should deadlock
```

## 🔍 **Technical Investigation Required**

### **Primary Hypothesis**
SocketBox's unique **multiple Arc<Mutex> combination** causing circular deadlock:

```rust
// SocketBox structure (PROBLEMATIC)
pub struct SocketBox {
    listener: Arc<Mutex<Option<TcpListener>>>,     // Mutex 1
    stream: Arc<Mutex<Option<TcpStream>>>,         // Mutex 2  
    is_server: Arc<Mutex<bool>>,                   // Mutex 3
    is_connected: Arc<Mutex<bool>>,                // Mutex 4
}

// vs Other Boxes (WORKING)
StringBox: Arc<String> only                       // No Mutex
ArrayBox: Arc<Mutex<Vec<T>>> only                 // Single Mutex  
MapBox: Arc<Mutex<HashMap<K,V>>> only             // Single Mutex
```

### **Investigation Areas**
1. **Lock ordering**: Multiple mutex acquisition sequence
2. **Recursive locking**: Same mutex re-entry during method resolution
3. **Cross-reference deadlock**: Arc reference cycles
4. **Interpreter pipeline**: Method resolution vs execution stage bottleneck

## 🎯 **Required Analysis**

### **Systematic Approach Required**
- **NO band-aid fixes** - Root cause identification essential
- **NO guesswork solutions** - Evidence-based analysis only
- **Complete validation** - All test cases must pass

### **Investigation Phases**
1. **Architecture Level**: Compare SocketBox vs other Box memory/locking patterns
2. **Runtime Level**: Method resolution pipeline analysis  
3. **Concurrency Level**: Arc<Mutex> deadlock detection
4. **Parser/AST Level**: If needed, verify AST generation differences

## 🧪 **Test Files Provided**

All test files are ready for immediate execution:
- `test_socket_deadlock_minimal.nyash` - Minimal reproduction
- `test_socket_methods_comprehensive.nyash` - All methods test  
- `test_other_boxes_working.nyash` - Normal Box operation verification
- `SOCKETBOX_ISSUE_REPRODUCTION.md` - Complete reproduction guide

## ✅ **Success Criteria**

### **Must Achieve**
```bash
# Basic functionality  
./target/release/nyash test_socket_deadlock_minimal.nyash
# Expected: Normal completion, no deadlock

# State management
socket.bind("127.0.0.1", 8080)
socket.isServer()  # Must return true

# All methods working
./target/release/nyash test_socket_methods_comprehensive.nyash  
# Expected: All methods complete successfully
```

### **Validation Required**
- **Before/After comparison**: Detailed behavior analysis
- **Performance impact**: Ensure fix doesn't degrade other functionality
- **Memory safety**: Maintain Rust safety guarantees
- **Architecture consistency**: Solution aligns with "Everything is Box" philosophy

---

**🚨 This issue completely blocks Phase 9 HTTP server implementation. Immediate resolution critical.**