init: Handle properties in the background of calling fs_mgr
It's been a long standing problem that init calls fs_mgr functions
synchronously and therefore stops handling properties, which causes
deadlocks if either fs_mgr, or vdc, or vold attempt to set
properties.
Previous work, b/21904461, shows that there is a large performance
penalty for adding any amount of locking to properties, so moving
property service into its own thread generically is not a viable
option. However, we can be sure that init is not setting properties
while the fs_mgr functions are running, so we can poll the property
socket in a thread while we call these functions.
The other alternative would have been to separate the fs_mgr functions
into smaller pieces and revisit the main init loop between each
piece. Unfortunately, this would be difficult, since
fs_mgr_mount_all() calls out to different processes via logwrapper,
which synchronously polls on a logging FD from the child, among other
complexities that would make this strategy much more difficult than it
would be worth.
Bug: 21904461
Test: device boots, including when setting property in
fs_mgr_mount_all()
Change-Id: Ib0b7123024035884f9d90f9b489c1e2f5a2e1707
diff --git a/init/property_service.h b/init/property_service.h
index 7f9f844..dc47b4d 100644
--- a/init/property_service.h
+++ b/init/property_service.h
@@ -18,9 +18,11 @@
#include <sys/socket.h>
+#include <functional>
#include <string>
#include "epoll.h"
+#include "result.h"
namespace android {
namespace init {
@@ -37,5 +39,13 @@
void load_persist_props();
void StartPropertyService(Epoll* epoll);
+template <typename F, typename... Args>
+Result<int> CallFunctionAndHandleProperties(F&& f, Args&&... args) {
+ Result<int> CallFunctionAndHandlePropertiesImpl(const std::function<int()>& f);
+
+ auto func = [&] { return f(args...); };
+ return CallFunctionAndHandlePropertiesImpl(func);
+}
+
} // namespace init
} // namespace android