Rearrange encoder threading.

Soon we'll add a new encoder type, and the existing structure was
already creaking a bit at the seams while handling local and remote
encodes.  Here we split out an encoder thread and introduce the concept
of a "sync" thread (which blocks while the encoding is happening).
Later we'll have another type which submits the encode request to a
GPU and receives the reply back later.

1 files changed, 9 insertions, 1 deletions

diff --git a/src/lib/scope_guard.h b/src/lib/scope_guard.h
index ac60f9fea..e0d1e81fc 100644
--- a/src/lib/scope_guard.h
+++ b/src/lib/scope_guard.h
@@ -45,11 +45,19 @@ public:
 
 	~ScopeGuard ()
 	{
-		_function();
+		if (!_cancelled) {
+			_function();
+		}
+	}
+
+	void cancel()
+	{
+		_cancelled = true;
 	}
 
 private:
 	std::function<void()> _function;
+	bool _cancelled = false;
 };