From review:

* Document new parameter
* In BatchSpanProcessor use the lower of the timeout values

Author: Ignacio Bonafonte

Sources/OpenTelemetrySdk/Trace/SpanProcessor.swift

@@ -18,6 +18,7 @@ public protocol SpanProcessor {
     /// Called when a Span is started, if the Span.isRecording is true.
     /// This method is called synchronously on the execution thread, should not throw or block the
     /// execution thread.
+    /// - Parameter parentContext: the context of the span parent, if exists
     /// - Parameter span: the ReadableSpan that just started
     func onStart(parentContext: SpanContext?, span: ReadableSpan)
 
@@ -33,6 +34,7 @@ public protocol SpanProcessor {
 
     /// Processes all span events that have not yet been processed.
     /// This method is executed synchronously on the calling thread
+    /// - Parameter timeout: Maximum time the flush complete or abort. If nil, it will wait indefinitely
     func forceFlush(timeout: TimeInterval?)
 }
 

Sources/OpenTelemetrySdk/Trace/SpanProcessors/BatchSpanProcessor.swift

@@ -135,7 +135,8 @@ private class BatchWorker: Thread {
         }
         let timeoutTimer = DispatchSource.makeTimerSource(queue: DispatchQueue.global())
         timeoutTimer.setEventHandler { exportOperation.cancel() }
-        timeoutTimer.schedule(deadline: .now() + .milliseconds(Int(explicitTimeout?.toMilliseconds ?? exportTimeout.toMilliseconds)), leeway: .milliseconds(1))
+        let maxTimeOut = min(explicitTimeout ?? TimeInterval.greatestFiniteMagnitude, exportTimeout)
+        timeoutTimer.schedule(deadline: .now() + .milliseconds(Int(maxTimeOut.toMilliseconds)), leeway: .milliseconds(1))
         timeoutTimer.activate()
         queue.addOperation(exportOperation)
         queue.waitUntilAllOperationsAreFinished()