made sure everything's thread safe
Pretty much everything already was, but I tweaked a few things to make
sure they stay that way and added various comments about that fact. Also
cleaned up a few things along the way and removed SafeMessageBuilder
because it wasn't.
diff --git a/aos/common/logging/logging_impl.cc b/aos/common/logging/logging_impl.cc
index f520b35..969c0ee 100644
--- a/aos/common/logging/logging_impl.cc
+++ b/aos/common/logging/logging_impl.cc
@@ -38,7 +38,7 @@
Context *context = Context::Get();
context->implementation = implementation;
- global_top_implementation = implementation;
+ global_top_implementation.store(implementation);
}
void NewContext() {
diff --git a/aos/common/logging/logging_impl.h b/aos/common/logging/logging_impl.h
index a55e768..f24ce6a 100644
--- a/aos/common/logging/logging_impl.h
+++ b/aos/common/logging/logging_impl.h
@@ -11,6 +11,7 @@
#include <string>
#include <functional>
+#include <atomic>
#include "aos/common/logging/logging.h"
#include "aos/common/type_traits.h"
@@ -30,7 +31,8 @@
//
// It is implemented in logging_impl.cc and logging_interface.cc. They are
// separate so that code used by logging_impl.cc can link in
-// logging_interface.cc to use logging.
+// logging_interface.cc to use logging without creating a circular dependency.
+// However, any executables with such code still need logging_impl.cc linked in.
namespace aos {
namespace logging {
@@ -250,10 +252,13 @@
// goes.
namespace internal {
-extern LogImplementation *global_top_implementation;
+extern ::std::atomic<LogImplementation *> global_top_implementation;
// An separate instance of this class is accessible from each task/thread.
// NOTE: It will get deleted in the child of a fork.
+//
+// Get() and Delete() are implemented in the platform-specific interface.cc
+// file.
struct Context {
Context();
@@ -267,6 +272,8 @@
// Deletes the Context object for this task/thread so that the next Get() is
// called it will create a new one.
// It is valid to call this when Get() has never been called.
+ // This also gets called after a fork(2) in the new process, where it should
+ // still work to clean up any state.
static void Delete();
// Which one to log to right now.
diff --git a/aos/common/logging/logging_interface.cc b/aos/common/logging/logging_interface.cc
index 8c45afd..e4c6fcd 100644
--- a/aos/common/logging/logging_interface.cc
+++ b/aos/common/logging/logging_interface.cc
@@ -15,10 +15,10 @@
namespace logging {
namespace internal {
-LogImplementation *global_top_implementation(NULL);
+::std::atomic<LogImplementation *> global_top_implementation(NULL);
Context::Context()
- : implementation(global_top_implementation),
+ : implementation(global_top_implementation.load()),
sequence(0) {
cork_data.Reset();
}