utils: ipc: proxy: Track IPA with a state machine

Asynchronous tasks can only be submitted while the IPA is running.

Further more, the shutdown sequence can not be tracked with a simple
running flag. We can also be in the state 'Stopping' where we have not
yet completed all events, but we must not commence anything new.

Refactor the running_ boolean into a stateful enum to track this.

Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

include/libcamera/internal/ipa_proxy.h

@@ -17,6 +17,12 @@ namespace libcamera {
 
 class IPAModule;
 
+enum ProxyState {
+	ProxyStopped,
+	ProxyStopping,
+	ProxyRunning,
+};
+
 class IPAProxy : public IPAInterface
 {
 public:
@@ -31,6 +37,7 @@ protected:
 	std::string resolvePath(const std::string &file) const;
 
 	bool valid_;
+	ProxyState state_;
 
 private:
 	IPAModule *ipam_;