Vendor import of lldb trunk r321017:vendor/lldb/lldb-trunk-r321017

https://llvm.org/svn/llvm-project/lldb/trunk@321017

1 files changed, 17 insertions, 2 deletions

diff --git a/source/Utility/Log.cpp b/source/Utility/Log.cpp
index a80b106838bc..f247124f8d63 100644
--- a/source/Utility/Log.cpp
+++ b/source/Utility/Log.cpp
@@ -32,6 +32,7 @@
 #include <process.h> // for getpid
 #else
 #include <unistd.h>
+#include <pthread.h>
 #endif
 
 using namespace lldb_private;
@@ -181,6 +182,13 @@ void Log::Warning(const char *format, ...) {
   Printf("warning: %s", Content.c_str());
 }
 
+void Log::Initialize() {
+#ifdef LLVM_ON_UNIX
+  pthread_atfork(nullptr, nullptr, &Log::DisableLoggingChild);
+#endif
+  InitializeLldbChannel();
+}
+
 void Log::Register(llvm::StringRef name, Channel &channel) {
   auto iter = g_channel_map->try_emplace(name, channel);
   assert(iter.second == true);
@@ -279,8 +287,7 @@ void Log::WriteHeader(llvm::raw_ostream &OS, llvm::StringRef file,
   if (options.Test(LLDB_LOG_OPTION_PREPEND_THREAD_NAME)) {
     llvm::SmallString<32> thread_name;
     llvm::get_thread_name(thread_name);
-    if (!thread_name.empty())
-      OS << thread_name;
+    OS << llvm::formatv("{0,-16} ", thread_name);
   }
 
   if (options.Test(LLDB_LOG_OPTION_BACKTRACE))
@@ -321,3 +328,11 @@ void Log::Format(llvm::StringRef file, llvm::StringRef function,
   message << payload << "\n";
   WriteMessage(message.str());
 }
+
+void Log::DisableLoggingChild() {
+  // Disable logging by clearing out the atomic variable after forking -- if we
+  // forked while another thread held the channel mutex, we would deadlock when
+  // trying to write to the log.
+  for (auto &c: *g_channel_map)
+    c.second.m_channel.log_ptr.store(nullptr, std::memory_order_relaxed);
+}