Efficiency of Network Tables

[virtuald]

Originally Posted by Jaci

GetJoystickName and GetJoystickIsXbox both retrieve values from the HALJoystickDescriptor, which stores values in memory (source 1 source 2). The Joystick Descriptor is updated each control packet as defined by DriverStation::GetData(). This code appears to be common between Java and C++ variants of the library.

A state retrieval doesn't affect the inner loop at all, since state ticking is done by WPILib before user code, and therefore should not cause a loop to slow..

Not true for Java... if you look at the Java code most of the methods are marked as 'synchronized'. The DriverStation thread task calls getData() which goes into HAL a bunch so it's probably not particularly fast (JNI overhead) -- and it's also marked as synchronized, so they'll all block each other in various ways.

I didn't realize that C++ did this differently though, very interesting.