cache RPC recorder threading fixes (#617)

* ensure all access to m_Entries is done while holding lock
* RPC recorder concurrency fixes - setup/teardown of recorder needs to be done while holding an exclusive lock. Calls into recorder should be done while holding a shared lock.

1 files changed, 6 insertions, 0 deletions

diff --git a/src/zenserver/cache/httpstructuredcache.h b/src/zenserver/cache/httpstructuredcache.h
index 57a533029..2feaaead8 100644
--- a/src/zenserver/cache/httpstructuredcache.h
+++ b/src/zenserver/cache/httpstructuredcache.h
@@ -190,6 +190,12 @@ private:
 
 	void ReplayRequestRecorder(const CacheRequestContext& Context, cache::IRpcRequestReplayer& Replayer, uint32_t ThreadCount);
 
+	// This exists to avoid taking locks when recording is not enabled
+	std::atomic_bool m_RequestRecordingEnabled{false};
+
+	// This lock should be taken in SHARED mode when calling into the recorder,
+	// and taken in EXCLUSIVE mode whenever the recorder is created or destroyed
+	RwLock										m_RequestRecordingLock;
 	std::unique_ptr<cache::IRpcRequestRecorder> m_RequestRecorder;
 };