DPL: avoid busy looping when in Idle state (#4481)

ktf · web-flow · commit eb686b0df3f6 · 2020-10-01T13:53:45.000+02:00
Under certain conditions (most notably when an enumeration was provided and
the device switched to "Idle" state) the libuv integration mistaken ly
considered as activity any further enumeration, resulting in a busy loop. This
makes sure we always UV_ONCE (i.e. wait for an external event) when in
StreamingState::Idle.
diff --git a/Framework/Core/src/DataProcessingDevice.cxx b/Framework/Core/src/DataProcessingDevice.cxx
@@ -427,7 +427,7 @@ bool DataProcessingDevice::ConditionalRun()
   if (mState.loop) {
     ZoneScopedN("uv idle");
     TracyPlot("past activity", (int64_t)mWasActive);
-    uv_run(mState.loop, mWasActive ? UV_RUN_NOWAIT : UV_RUN_ONCE);
+    uv_run(mState.loop, mWasActive && (mDataProcessorContexes.at(0).state->streaming != StreamingState::Idle) ? UV_RUN_NOWAIT : UV_RUN_ONCE);
   }
 
   // Notify on the main thread the new region callbacks, making sure

Original file line number	Diff line number	Diff line change
`@@ -427,7 +427,7 @@ bool DataProcessingDevice::ConditionalRun()`
`427`	`427`	`if (mState.loop) {`
`428`	`428`	`ZoneScopedN("uv idle");`
`429`	`429`	`TracyPlot("past activity", (int64_t)mWasActive);`
`430`		`- uv_run(mState.loop, mWasActive ? UV_RUN_NOWAIT : UV_RUN_ONCE);`
	`430`	`+ uv_run(mState.loop, mWasActive && (mDataProcessorContexes.at(0).state->streaming != StreamingState::Idle) ? UV_RUN_NOWAIT : UV_RUN_ONCE);`
`431`	`431`	`}`
`432`	`432`
`433`	`433`	`// Notify on the main thread the new region callbacks, making sure`