Race condition in DataFeedHandler::sendDataFeedUpdate #1620
Description
When the GUI starts up and sends the StartDataFeed packet, sendDataFeedUpdate might run while onStartDataFeed is setting up the ConnectionContext's dataFeedConfigList and dataFeedTimers lists, which may result in a server crash.
19:10:11 [INFO] [WebSocketAPI] New connection from: 0:0:0:0:0:0:0:1
19:10:11 [SEVERE] Exception in thread "VRServer" java.lang.IndexOutOfBoundsException: Index 0 out of bounds for length 0
19:10:11 [SEVERE] at java.base/jdk.internal.util.Preconditions.outOfBounds(Preconditions.java:64)
19:10:11 [SEVERE] at java.base/jdk.internal.util.Preconditions.outOfBoundsCheckIndex(Preconditions.java:70)
19:10:11 [SEVERE] at java.base/jdk.internal.util.Preconditions.checkIndex(Preconditions.java:266)
19:10:11 [SEVERE] at java.base/java.util.Objects.checkIndex(Objects.java:361)
19:10:11 [SEVERE] at java.base/java.util.ArrayList.get(ArrayList.java:427)
19:10:11 [SEVERE] at dev.slimevr.protocol.datafeed.DataFeedHandler.lambda$sendDataFeedUpdate$0(DataFeedHandler.java:129)
19:10:11 [SEVERE] at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183)
19:10:11 [SEVERE] at java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:179)
19:10:11 [SEVERE] at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197)
19:10:11 [SEVERE] at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1625)
19:10:11 [SEVERE] at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509)
19:10:11 [SEVERE] at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499)
19:10:11 [SEVERE] at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150)
19:10:11 [SEVERE] at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173)
19:10:11 [SEVERE] at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
19:10:11 [SEVERE] at java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:596)
19:10:11 [SEVERE] at dev.slimevr.protocol.datafeed.DataFeedHandler.lambda$sendDataFeedUpdate$1(DataFeedHandler.java:121)
19:10:11 [SEVERE] at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
19:10:11 [SEVERE] at dev.slimevr.protocol.datafeed.DataFeedHandler.sendDataFeedUpdate(DataFeedHandler.java:121)
19:10:11 [SEVERE] at dev.slimevr.VRServer.run(VRServer.kt:233)
19:22:23 [INFO] [WebSocketAPI] New connection from: 0:0:0:0:0:0:0:1
19:22:24 [INFO] [WebSocketAPI] Disconnected: 0:0:0:0:0:0:0:1, (1006) Connection reset by peer. Remote: false
19:22:25 [INFO] [WebSocketAPI] New connection from: 0:0:0:0:0:0:0:1
19:22:25 [INFO] [WebSocketAPI] Disconnected: 0:0:0:0:0:0:0:1, (1006) Connection reset. Remote: false
19:22:26 [INFO] [WebSocketAPI] New connection from: 0:0:0:0:0:0:0:1
19:22:26 [INFO] [WebSocketAPI] Disconnected: 0:0:0:0:0:0:0:1, (1006) . Remote: true
19:22:27 [INFO] [WebSocketAPI] New connection from: 0:0:0:0:0:0:0:1
19:22:27 [SEVERE] Exception in thread "VRServer" java.lang.IndexOutOfBoundsException: Index 0 out of bounds for length 0
19:22:27 [SEVERE] at java.base/jdk.internal.util.Preconditions.outOfBounds(Preconditions.java:64)
19:22:27 [SEVERE] at java.base/jdk.internal.util.Preconditions.outOfBoundsCheckIndex(Preconditions.java:70)
19:22:27 [SEVERE] at java.base/jdk.internal.util.Preconditions.checkIndex(Preconditions.java:266)
19:22:27 [SEVERE] at java.base/java.util.Objects.checkIndex(Objects.java:361)
19:22:27 [SEVERE] at java.base/java.util.ArrayList.get(ArrayList.java:427)
19:22:27 [SEVERE] at dev.slimevr.protocol.datafeed.DataFeedHandler.lambda$sendDataFeedUpdate$0(DataFeedHandler.java:129)