function handleError(event, err) {
nextTick(() => {
stateProviderEmitter.emit(event, err)
console.error(`${event} - ${err.message}`)
if (throwOnError) {
throw err
}
})
}
return stateNames.map(prototypalStateHolder.get).forEach(state => {
const emitter = new EventEmitter()
const context = Object.create(emitter)
context.domApi = activeDomApis[state.name]
context.data = state.data
context.parameters = parameters
context.content = getContentObject(activeStateResolveContent, state.name)
activeEmitters[state.name] = emitter
try {
state.activate && state.activate(context)
} catch (e) {
nextTick(() => {
throw e
})
}
})
module.exports = function Expirer({ timeoutMs, db, checkIntervalMs = 1000, repeatExpirations = false }) {
const forgotten = new Set()
function filterForgotten(keys) {
return keys.filter(key => !forgotten.has(key))
}
const checkForExpiredKeys = onlyLetOneTaskRunAtATime(async() => {
const now = new Date().getTime()
const batchKeys = await new Promise(resolve => {
const batchKeys = []
db.createReadStream().on('data', function(data) {
if (parseInt(data.value) + timeoutMs < now) {
batchKeys.push(data.key)
}
}).on('end', () => resolve(batchKeys))
})
// Need to make sure that none of these keys were "forgotten" since we opened the read stream
const expiringNow = filterForgotten(batchKeys)
const batchObjects = expiringNow.map(key => {
return repeatExpirations
? { type: 'put', key: key, value: new Date().getTime() }
: { type: 'del', key: key }
})
try {
await db.batch(batchObjects)
filterForgotten(expiringNow)
.forEach(key => expirer.emit('expire', key))
forgotten.clear()
} catch (err) {
forgotten.clear()
throw err
}
})
async function touch(key) {
await db.put(key, new Date().getTime())
expirer.emit('touch', key)
}
async function forget(key) {
forgotten.add(key)
await db.del(key)
expirer.emit('forget', key)
}
const interval = setInterval(checkForExpiredKeys, checkIntervalMs)
interval.unref && interval.unref()
const expirer = makeEmitter({
touch,
forget,
async createIfNotExists(key) {
try {
await db.get(key)
} catch (err) {
if (err.notFound) {
touch(key)
} else {
throw err
}
}
},
stop() {
clearInterval(interval)
},
})
nextTick(checkForExpiredKeys)
return expirer
}