locks.go

package main

import "fmt"

// Locks request channel and data structure
var lock_channel = make(chan lock_request, 8192)
var locks = map[string]string{}

func mind_locks() {
	var response string
	for true {
		// Block this specific goroutine until we get a request
		req := <-lock_channel
		// Immediately check to see if the lock exists in the global state
		// since literally everything else in the function depends on this
		// information
		_, present := locks[req.lock]
		switch req.action {
		case -1:
			// The client wants to rellease the lock
			if present {
				// Cool. Done
				delete(locks, req.lock)
				response = fmt.Sprintf("1 Lock Release Success: %s\n", req.lock)
				// Bump
				stats_channel <- stat_bump{stat: "locks", val: -1}
			} else {
				// No dice
				response = fmt.Sprintf("0 Lock Release Failure: %s\n", req.lock)
			}
		case 0:
			// The client is checking on a lock
			if present {
				// Yep, locked
				response = fmt.Sprintf("1 Lock Is Locked: %s\r\n", req.lock)
			} else {
				// Nope, not locked
				response = fmt.Sprintf("0 Lock Not Locked: %s\r\n", req.lock)
			}
			break
		case 1:
			// The client wants to obtain a lock
			if present {
				// But can't because it's already locked
				response = fmt.Sprintf("0 Lock Get Failure: %s\r\n", req.lock)
			} else {
				// Cool, done.
				locks[req.lock] = req.client
				response = fmt.Sprintf("1 Lock Get Success: %s\r\n", req.lock)
				// Bump
				stats_channel <- stat_bump{stat: "locks", val: 1}
			}
			break
		}
		// Reply back to the client on the channel it provided us with in the request
		req.reply <- lock_reply{lock: req.lock, response: response}
	}
}