Maybe you have a big ol' monorepo, and git operations are pretty slow in it. For those of us who like to show information about the repository's dirty status in our prompt, that means a slow prompt. Waiting 1s every time you hit the return key can really add up! Instead of just giving up and eschewing the dirty status entirely, why not just cache it in the background have your prompt read from the cache?
First, install fswatch:
brew install fswatch
| var LUA_GETS = | |
| 'return {' | |
| + 'redis.call(\'get\', KEYS[1]),' | |
| + 'redis.call(\'get\', KEYS[1]..\'_ver\')' | |
| + '}'; | |
| var LUA_CAS = | |
| 'local ver = redis.call(\'get\', KEYS[1]..\'_ver\') ' | |
| + 'if not ver or ver == KEYS[3] ' | |
| + 'then ' |
| Latency Comparison Numbers (~2012) | |
| ---------------------------------- | |
| L1 cache reference 0.5 ns | |
| Branch mispredict 5 ns | |
| L2 cache reference 7 ns 14x L1 cache | |
| Mutex lock/unlock 25 ns | |
| Main memory reference 100 ns 20x L2 cache, 200x L1 cache | |
| Compress 1K bytes with Zippy 3,000 ns 3 us | |
| Send 1K bytes over 1 Gbps network 10,000 ns 10 us | |
| Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD |