Generated by XState Viz: https://xstate.js.org/viz

machine.js

// Available variables:
// - Machine
// - interpret
// - assign
// - send
// - sendParent
// - spawn
// - raise
// - actions
// - XState (all XState exports)

const randomInt = (min, max) => Math.floor(Math.random() * (max - min)) + min;

const lockConfig = {
	createDelayMs: 1000, // 1s
	minHoldTimeMs: 2500, // 2.5s
	checkDelayMs: 500, // 0.5s
	minWaitTimeMs: 1000, // 1s
	maxWaitTimeMs: 3000, // 3s
	waitTimeoutMs: 60 * 1000, // 1 minute
};
  
const lockMachine = Machine({
	id: "AcquireLockMachine",
	initial: "initialRead",
	context: {
		wait_time: 0,
		total_wait_time: 0,
		total_held_time: 0,
	},
	states: {
	  initialRead: {
	    on: {
	      // comment doesn't exist
	      CREATE: 'delayingCreate',
	      // comment exists, locked
	      ACQUIRE: 'delayingAcquire',
	      // comment exists, have hold
	      HOLD: 'holding',
	      // comment exists, no lock
	      WRITE: 'writing'
	    }
	  },
	  attemptingCreate: {
	    on: {
	      // comment doens't exist, done waiting
	      CREATE: "creating",
	      // comment exists, try to acquire
	      ACQUIRE: "acquiring",
	      // comment doesn't exist, need to wait
	      DELAY: "delayingCreate",
	      // wait time exceeded time out
	      TIMEOUT: "timed_out",
	    },
	  },
	  delayingCreate: {
	    on: {
	      COMPLETE_WAIT: "attemptingCreate",
	    },
	  },
	  creating: {
	    on: {
	      ACQUIRED: "acquired",
	    },
	  },
		acquiring: {
			on: {
			  // Comment exists, no one has lock
			  WRITE: "writing",
			  // comment exists, is locked
				WAIT: "delayingAcquire",
				// comment exists, wait timeout exceeded
				TIMEOUT: "timed_out",
			},
		},
		// Wait random time before attempting to acquire again
		delayingAcquire: {
			entry: ["resetTotalHeldTime", "setWaitTime"],
			exit: "updateTotalWaitTime",
			on: {
				COMPLETE_WAIT: "acquiring",
			},
		},
	  writing: {
	    on: {
	      HOLD: 'holding',
	    },
	  },
		// Wait deterministic time before reading lock
		holding: {
			entry: "resetTotalWaitTime",
			exit: "updateTotalHeldTime",
			on: {
				CHECK_HOLD: "checking",
			},
		},
		// read lock to see if we still have it
		checking: {
			on: {
				ACQUIRED: "acquired",
				HOLD: "holding",
				WAIT: "delayingAcquire",
			},
		},
		// final states
		acquired: {
		  type: "final"
		},
		timed_out: {
		  type: "final"
		},
	},
},
{
	actions: {
		resetTotalHeldTime: assign({
			total_held_time: 0,
		}),
		updateTotalHeldTime: assign({
			total_held_time: (ctx, evt) => {
				return ctx.total_held_time + lockConfig.checkDelayMs;
			},
		}),
		setWaitTime: assign({
			wait_time: (ctx, evt) => {
			  console.log(evt);
				return randomInt(
					lockConfig.minWaitTimeMs,
					lockConfig.maxWaitTimeMs
				);
			},
		}),
		resetTotalWaitTime: assign({
			total_wait_time: 0,
		}),
		updateTotalWaitTime: assign({
			wait_time: 0,
			total_wait_time: (ctx, evt) => {
				return ctx.total_wait_time + ctx.wait_time;
			},
		}),
	},
});