Team2890/allwpilib
4
0
Fork 0
mirror of https://github.com/wpilibsuite/allwpilib synced 2026-06-21 01:01:43 +00:00
Code Issues Packages Projects Releases Wiki Activity

Add SafeThread to fix thread JNI shutdown races.

Browse Source 
During JVM shutdown, some JNI calls may not return, so it's not possible to
reliably perform a join() during static variable destruction (which occurs
as the JVM unloads the JNI module).

Also, due to static variable destruction, it's not safe to use any members
of a static class instance from a separate thread of execution.

SafeThread is a templated thread class and a related owner class that's
designed for safe operation and shutdown of threads in the presence of
callbacks that may not return.  It also passes ownership of variables from
the static instance to the thread, so the thread can safely operate until
it exits (the last operation of the thread being to destroy its instance).

Notifiers, RpcServer, and Logger now use SafeThread to ensure race-free
destruction in both C++ and Java.

All Java callback threads are now marked as Java daemon threads so they
don't keep the JVM running after main() terminates.

All Java callback threads are now named so their purpose is more easily
identified in a debugger.

Add SetRpcServerOnStart and SetRpcServerOnExit (similar to Listener).
This commit is contained in:
Peter Johnson
2015-12-28 08:28:24 -08:00
parent d8de5e4f19
commit fef8f933d9
13 changed files with 343 additions and 287 deletions
Download Patch File Download Diff File Expand all files Collapse all files

17
src/ntcore_cpp.cpp
View File

@@ -75,9 +75,8 @@ void SetListenerOnExit(std::function<void()> on_exit) {
unsigned int AddEntryListener(StringRef prefix, EntryListenerCallback callback,
unsigned int flags) {
Notifier& notifier = Notifier::GetInstance();
unsigned int uid = notifier.AddEntryListener(prefix, callback, flags);
notifier.Start();
unsigned int uid =
Notifier::GetInstance().AddEntryListener(prefix, callback, flags);
if ((flags & NT_NOTIFY_IMMEDIATE) != 0)
Storage::GetInstance().NotifyEntries(prefix, callback);
return uid;
@@ -89,9 +88,7 @@ void RemoveEntryListener(unsigned int entry_listener_uid) {
unsigned int AddConnectionListener(ConnectionListenerCallback callback,
bool immediate_notify) {
Notifier& notifier = Notifier::GetInstance();
unsigned int uid = notifier.AddConnectionListener(callback);
Notifier::GetInstance().Start();
unsigned int uid = Notifier::GetInstance().AddConnectionListener(callback);
if (immediate_notify) Dispatcher::GetInstance().NotifyConnections(callback);
return uid;
}
@@ -106,6 +103,14 @@ bool NotifierDestroyed() { return Notifier::destroyed(); }
* Remote Procedure Call Functions
*/
void SetRpcServerOnStart(std::function<void()> on_start) {
RpcServer::GetInstance().SetOnStart(on_start);
}
void SetRpcServerOnExit(std::function<void()> on_exit) {
RpcServer::GetInstance().SetOnExit(on_exit);
}
void CreateRpc(StringRef name, StringRef def, RpcCallback callback) {
Storage::GetInstance().CreateRpc(name, def, callback);
}