1 files changed, 25 insertions, 13 deletions

diff --git a/lldb/source/Core/Communication.cpp b/lldb/source/Core/Communication.cpp
index 0afd897a2093..b358e70b1a91 100644
--- a/lldb/source/Core/Communication.cpp
+++ b/lldb/source/Core/Communication.cpp
@@ -1,4 +1,4 @@
-//===-- Communication.cpp ---------------------------------------*- C++ -*-===//
+//===-- Communication.cpp -------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
@@ -71,8 +71,8 @@ Communication::~Communication() {
 
 void Communication::Clear() {
   SetReadThreadBytesReceivedCallback(nullptr, nullptr);
-  Disconnect(nullptr);
   StopReadThread(nullptr);
+  Disconnect(nullptr);
 }
 
 ConnectionStatus Communication::Connect(const char *url, Status *error_ptr) {
@@ -93,6 +93,8 @@ ConnectionStatus Communication::Disconnect(Status *error_ptr) {
   LLDB_LOG(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_COMMUNICATION),
            "{0} Communication::Disconnect ()", this);
 
+  assert((!m_read_thread_enabled || m_read_thread_did_exit) &&
+         "Disconnecting while the read thread is running is racy!");
   lldb::ConnectionSP connection_sp(m_connection_sp);
   if (connection_sp) {
     ConnectionStatus status = connection_sp->Disconnect(error_ptr);
@@ -315,16 +317,12 @@ lldb::thread_result_t Communication::ReadThread(lldb::thread_arg_t p) {
   Status error;
   ConnectionStatus status = eConnectionStatusSuccess;
   bool done = false;
+  bool disconnect = false;
   while (!done && comm->m_read_thread_enabled) {
     size_t bytes_read = comm->ReadFromConnection(
         buf, sizeof(buf), std::chrono::seconds(5), status, &error);
-    if (bytes_read > 0)
+    if (bytes_read > 0 || status == eConnectionStatusEndOfFile)
       comm->AppendBytesToCache(buf, bytes_read, true, status);
-    else if ((bytes_read == 0) && status == eConnectionStatusEndOfFile) {
-      if (comm->GetCloseOnEOF())
-        comm->Disconnect();
-      comm->AppendBytesToCache(buf, bytes_read, true, status);
-    }
 
     switch (status) {
     case eConnectionStatusSuccess:
@@ -332,11 +330,12 @@ lldb::thread_result_t Communication::ReadThread(lldb::thread_arg_t p) {
 
     case eConnectionStatusEndOfFile:
       done = true;
+      disconnect = comm->GetCloseOnEOF();
       break;
     case eConnectionStatusError: // Check GetError() for details
       if (error.GetType() == eErrorTypePOSIX && error.GetError() == EIO) {
         // EIO on a pipe is usually caused by remote shutdown
-        comm->Disconnect();
+        disconnect = comm->GetCloseOnEOF();
         done = true;
       }
       if (error.Fail())
@@ -365,9 +364,22 @@ lldb::thread_result_t Communication::ReadThread(lldb::thread_arg_t p) {
   if (log)
     LLDB_LOGF(log, "%p Communication::ReadThread () thread exiting...", p);
 
-  comm->m_read_thread_did_exit = true;
+  // Handle threads wishing to synchronize with us.
+  {
+    // Prevent new ones from showing up.
+    comm->m_read_thread_did_exit = true;
+
+    // Unblock any existing thread waiting for the synchronization signal.
+    comm->BroadcastEvent(eBroadcastBitNoMorePendingInput);
+
+    // Wait for the thread to finish...
+    std::lock_guard<std::mutex> guard(comm->m_synchronize_mutex);
+    // ... and disconnect.
+    if (disconnect)
+      comm->Disconnect();
+  }
+
   // Let clients know that this thread is exiting
-  comm->BroadcastEvent(eBroadcastBitNoMorePendingInput);
   comm->BroadcastEvent(eBroadcastBitReadThreadDidExit);
   return {};
 }
@@ -399,10 +411,10 @@ void Communication::SynchronizeWithReadThread() {
   listener_sp->GetEvent(event_sp, llvm::None);
 }
 
-void Communication::SetConnection(Connection *connection) {
+void Communication::SetConnection(std::unique_ptr<Connection> connection) {
   Disconnect(nullptr);
   StopReadThread(nullptr);
-  m_connection_sp.reset(connection);
+  m_connection_sp = std::move(connection);
 }
 
 const char *