Fixing debugger startup race.

src/xenia/debug/debug_server.h

@@ -10,6 +10,8 @@
 #ifndef XENIA_DEBUG_DEBUG_SERVER_H_
 #define XENIA_DEBUG_DEBUG_SERVER_H_
 
+#include <functional>
+
 #include "xenia/cpu/function.h"
 #include "xenia/cpu/processor.h"
 #include "xenia/debug/breakpoint.h"
@@ -27,6 +29,8 @@ class DebugServer {
 
   virtual bool Initialize() = 0;
 
+  virtual void PostSynchronous(std::function<void()> fn) = 0;
+
   // TODO(benvanik): better thread type (XThread?)
   // virtual void OnThreadCreated(ThreadState* thread_state) = 0;
   // virtual void OnThreadDestroyed(ThreadState* thread_state) = 0;

src/xenia/debug/debugger.cc

@@ -123,7 +123,7 @@ void Debugger::PreLaunch() {
 
     // Start paused.
     execution_state_ = ExecutionState::kRunning;
-    Interrupt();
+    server_->PostSynchronous([this]() { Interrupt(); });
   } else {
     // Start running.
     execution_state_ = ExecutionState::kRunning;

src/xenia/debug/server/gdb/gdb_server.cc

@@ -44,6 +44,8 @@ bool GdbServer::Initialize() {
   return true;
 }
 
+void GdbServer::PostSynchronous(std::function<void()> fn) { assert_always(); }
+
 void GdbServer::AcceptClient(std::unique_ptr<Socket> client) {
   // If we have an existing client, kill it and join its thread.
   if (client_) {

src/xenia/debug/server/gdb/gdb_server.h

@@ -32,6 +32,8 @@ class GdbServer : public DebugServer {
 
   bool Initialize() override;
 
+  void PostSynchronous(std::function<void()> fn) override;
+
  private:
   void AcceptClient(std::unique_ptr<Socket> client);
   bool HandleClientEvent();

src/xenia/debug/server/mi/mi_server.cc

@@ -44,6 +44,8 @@ bool MIServer::Initialize() {
   return true;
 }
 
+void MIServer::PostSynchronous(std::function<void()> fn) { assert_always(); }
+
 void MIServer::AcceptClient(std::unique_ptr<Socket> client) {
   // If we have an existing client, kill it and join its thread.
   if (client_) {

src/xenia/debug/server/mi/mi_server.h

@@ -32,6 +32,8 @@ class MIServer : public DebugServer {
 
   bool Initialize() override;
 
+  void PostSynchronous(std::function<void()> fn) override;
+
  private:
   void AcceptClient(std::unique_ptr<Socket> client);
   bool HandleClientEvent();

src/xenia/debug/server/xdp/xdp_server.cc

@@ -42,6 +42,8 @@ XdpServer::XdpServer(Debugger* debugger)
 XdpServer::~XdpServer() = default;
 
 bool XdpServer::Initialize() {
+  post_event_ = xe::threading::Event::CreateAutoResetEvent(false);
+
   socket_server_ = SocketServer::Create(uint16_t(FLAGS_xdp_server_port),
                                         [this](std::unique_ptr<Socket> client) {
                                           AcceptClient(std::move(client));
@@ -54,6 +56,19 @@ bool XdpServer::Initialize() {
   return true;
 }
 
+void XdpServer::PostSynchronous(std::function<void()> fn) {
+  xe::threading::Fence fence;
+  {
+    std::lock_guard<std::mutex> lock(post_mutex_);
+    post_queue_.push_back([&fence, fn]() {
+      fn();
+      fence.Signal();
+    });
+  }
+  post_event_->Set();
+  fence.Wait();
+}
+
 void XdpServer::AcceptClient(std::unique_ptr<Socket> client) {
   // If we have an existing client, kill it and join its thread.
   if (client_) {
@@ -85,11 +100,35 @@ void XdpServer::AcceptClient(std::unique_ptr<Socket> client) {
     // Main loop.
     bool running = true;
     while (running) {
-      auto wait_result = xe::threading::Wait(client_->wait_handle(), true);
-      switch (wait_result) {
+      xe::threading::WaitHandle* wait_handles[] = {
+          client_->wait_handle(), post_event_.get(),
+      };
+      auto wait_result = xe::threading::WaitMultiple(
+          wait_handles, xe::countof(wait_handles), false, true);
+      switch (wait_result.first) {
         case xe::threading::WaitResult::kSuccess:
           // Event (read or close).
-          running = HandleClientEvent();
+          switch (wait_result.second) {
+            case 0: {
+              running = HandleClientEvent();
+            } break;
+            case 1: {
+              bool has_remaining = true;
+              while (has_remaining) {
+                std::function<void()> fn;
+                {
+                  std::lock_guard<std::mutex> lock(post_mutex_);
+                  fn = std::move(post_queue_.front());
+                  post_queue_.pop_front();
+                  has_remaining = !post_queue_.empty();
+                  if (!has_remaining) {
+                    post_event_->Reset();
+                  }
+                }
+                fn();
+              }
+            } break;
+          }
           continue;
         case xe::threading::WaitResult::kAbandoned:
         case xe::threading::WaitResult::kFailed:

src/xenia/debug/server/xdp/xdp_server.h

@@ -10,7 +10,9 @@
 #ifndef XENIA_DEBUG_SERVER_XDP_XDP_SERVER_H_
 #define XENIA_DEBUG_SERVER_XDP_XDP_SERVER_H_
 
+#include <list>
 #include <memory>
+#include <mutex>
 
 #include "xenia/base/socket.h"
 #include "xenia/base/threading.h"
@@ -33,6 +35,8 @@ class XdpServer : public DebugServer {
 
   bool Initialize() override;
 
+  void PostSynchronous(std::function<void()> fn) override;
+
   void OnExecutionContinued() override;
   void OnExecutionInterrupted() override;
 
@@ -54,6 +58,11 @@ class XdpServer : public DebugServer {
 
   std::unique_ptr<Socket> client_;
   std::unique_ptr<xe::threading::Thread> client_thread_;
+
+  std::mutex post_mutex_;
+  std::unique_ptr<xe::threading::Event> post_event_;
+  std::list<std::function<void()>> post_queue_;
+
   std::vector<uint8_t> receive_buffer_;
   proto::PacketReader packet_reader_;
   proto::PacketWriter packet_writer_;