semaphore/routes/_utils/sync.js

34 lines
1.2 KiB
JavaScript
Raw Normal View History

// Hit both the cache and the network, setting state for the cached version first,
// then the network version (as it's assumed to be fresher). Also update the db afterwards.
2018-02-09 06:29:29 +00:00
export async function cacheFirstUpdateAfter (networkFetcher, dbFetcher, dbUpdater, stateSetter) {
let networkPromise = networkFetcher() // kick off network request immediately
let dbResponse
try {
dbResponse = await dbFetcher()
stateSetter(dbResponse)
} finally {
let fetchAndUpdatePromise = networkPromise.then(networkResponse => {
/* no await */ dbUpdater(networkResponse)
stateSetter(networkResponse)
})
if (!dbResponse) { // no cached result available, await the network
await fetchAndUpdatePromise
}
}
2018-02-09 06:29:29 +00:00
}
2018-03-21 00:41:39 +00:00
// Make a change that we optimistically show to the user as successful, but which
// actually depends on a network operation. In the unlikely event that the network
// operation fails, revert the changes
export async function optimisticUpdate (doImmediately, networkUpdater, onSuccess, onFailure) {
let networkPromise = networkUpdater()
doImmediately()
try {
let response = await networkPromise
onSuccess(response)
} catch (e) {
console.error(e)
onFailure(e)
}
}