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Fix battery drain from busy-polling the incoming packet queue - #11
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Summary
writeIncomingPackets polled Mobile.read() with a 2 ms sleep, so the tunnel woke the CPU about 500 times a second even with no traffic. With the tunnel on, the phone lost about 30% battery in two hours. The loop now uses Mobile.readTimeout(1000), which blocks on the core's arrived channel and returns as soon as a packet is queued. The 2 ms sleep stays as a fallback for the case where readTimeout returns at once before the core starts.
After the fix, the same phone with the tunnel on and the screen off went from 95% to 85% in about 6 hours.
Verification
go test ./...go vet ./...git diff --checkProtocol and security impact
None. Packet latency stays the same since readTimeout wakes on arrival.