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Lua in Redis: RateLimiter Example

Use Lua in Redis, how and why, with an example of token bucket rate limiter.

Command Semantics over MQTT

The hardest problem in device communication over MQTT is not delivery. It is semantic consistency under concurrency. Once you scale beyond a single service instance and a single stable device connection, three things become unavoidable: Messages are duplicated; they arrive late; state transitions race.

Most designs fail not because MQTT misbehaves, but because command progression is modeled implicitly instead of...

Why Cannot Close a Go Channel Twice

Every time someone asks why closing a channel twice panics, the real question is usually about ownership.