Rework caching expiration handling
Check expiration of cached items when serving them instead of computing an expiration date when first caching them. If the user changes the caching duration after a request was cached, the new setting will be used now.
This commit is contained in:
parent
07ab80542d
commit
cecf1fd8a5
203
src/sw.js
203
src/sw.js
@ -45,7 +45,7 @@ Object.keys(TILE_SERVERS).forEach((tileServer) => {
|
||||
|
||||
// Get duration (in s) before (cache) expiration from headers of a fetch
|
||||
// request.
|
||||
function getExpiresFromHeaders(headers) {
|
||||
function _getExpiresFromHeaders(headers) {
|
||||
// Try to use the Cache-Control header (and max-age)
|
||||
if (headers.get('cache-control')) {
|
||||
const maxAge = headers.get('cache-control').match(/max-age=(\d+)/);
|
||||
@ -65,6 +65,60 @@ function getExpiresFromHeaders(headers) {
|
||||
return null;
|
||||
}
|
||||
|
||||
// Get tile caching duration from config
|
||||
function _getTileCachingDurationPromise() {
|
||||
// Get tile caching duration from settings
|
||||
let tileCachingDurationPromise = (
|
||||
Promise.resolve(0) // no caching by default
|
||||
);
|
||||
if (
|
||||
localforage.driver() === localforage.INDEXEDDB
|
||||
) {
|
||||
tileCachingDurationPromise = loadDataFromStorage(
|
||||
'settings', 'tileCachingDuration',
|
||||
);
|
||||
}
|
||||
return tileCachingDurationPromise;
|
||||
}
|
||||
|
||||
// Check expiration of an item in cache
|
||||
// Return the response is not expired. Deletes it from cache and returns null
|
||||
// otherwise.
|
||||
function _checkExpiration(cache, request, response) {
|
||||
return _getTileCachingDurationPromise().then((cachingDurationFromConfig) => {
|
||||
const cachedDate = Date.parse(response.headers.get('sw-cached-date'));
|
||||
const now = new Date();
|
||||
|
||||
// Check wether it is expired according to config
|
||||
if (cachingDurationFromConfig > 0) {
|
||||
const expirationDateFromConfig = new Date(cachedDate.valueOf());
|
||||
expirationDateFromConfig.setSeconds(
|
||||
expirationDateFromConfig.getSeconds() + cachingDurationFromConfig,
|
||||
);
|
||||
if (expirationDateFromConfig > now) {
|
||||
DEBUG && console.log(`SW: Found ${request.url} in cache.`);
|
||||
return response;
|
||||
}
|
||||
DEBUG && console.log(`SW: Deleting expired ${request.url} from cache.`);
|
||||
cache.delete(request);
|
||||
}
|
||||
|
||||
// If no special caching from config or not expired from config, check
|
||||
// whether it is expired from HTTP headers.
|
||||
const cachingDurationFromHeaders = response.headers.get('sw-http-cache-duration');
|
||||
const expirationDateFromHeaders = new Date(cachedDate.valueOf());
|
||||
expirationDateFromHeaders.setSeconds(
|
||||
expirationDateFromHeaders.getSeconds() + cachingDurationFromHeaders,
|
||||
);
|
||||
if (expirationDateFromHeaders > now) {
|
||||
return response;
|
||||
}
|
||||
DEBUG && console.log(`SW: Deleting expired ${request.url} from cache.`);
|
||||
cache.delete(request);
|
||||
return null;
|
||||
});
|
||||
}
|
||||
|
||||
global.self.addEventListener('install', (event) => {
|
||||
DEBUG && console.log('SW: installing…');
|
||||
event.waitUntil(
|
||||
@ -135,81 +189,80 @@ global.self.addEventListener('fetch', (event) => {
|
||||
event.respondWith(global.caches.open(`${CACHE_NAME}-tiles`).then(
|
||||
cache => cache.match(request).then(
|
||||
(response) => {
|
||||
// Helper function to fetch data from the network
|
||||
const _fetchFromNetwork = (
|
||||
// Note: We HAVE to use fetch(request.url) here to ensure we
|
||||
// have a CORS-compliant request. Otherwise, we could get back
|
||||
// an opaque response which we cannot inspect
|
||||
// (https://developer.mozilla.org/en-US/docs/Web/API/Response/type).
|
||||
() => fetch(request.url).then(
|
||||
liveResponse => _getTileCachingDurationPromise().then(
|
||||
(cachingDurationFromConfig) => {
|
||||
// This is caching duration specified in HTTP headers
|
||||
const cachingDurationFromHeaders = _getExpiresFromHeaders(
|
||||
liveResponse.headers,
|
||||
) || 0;
|
||||
|
||||
// If any form of caching is possible, do it
|
||||
if (
|
||||
cachingDurationFromConfig > 0
|
||||
|| cachingDurationFromHeaders > 0
|
||||
) {
|
||||
// Recreate a Response object from scratch to put
|
||||
// it in the cache, with the extra header for
|
||||
// managing cache expiration.
|
||||
const cachedResponseFields = {
|
||||
status: liveResponse.status,
|
||||
statusText: liveResponse.statusText,
|
||||
headers: {
|
||||
'SW-Cached-Date': (new Date()).toUTCString(),
|
||||
'SW-HTTP-Cache-Duration': cachingDurationFromHeaders,
|
||||
},
|
||||
};
|
||||
liveResponse.headers.forEach((v, k) => {
|
||||
cachedResponseFields.headers[k] = v;
|
||||
});
|
||||
// We will consume body of the live response, so
|
||||
// clone it before to be able to return it
|
||||
// afterwards.
|
||||
const returnedResponse = liveResponse.clone();
|
||||
return liveResponse.blob().then((body) => {
|
||||
DEBUG && console.log(
|
||||
`SW: caching tiles ${request.url}.`,
|
||||
);
|
||||
// Put the duplicated Response in the cache
|
||||
cache.put(
|
||||
request, new Response(body, cachedResponseFields),
|
||||
);
|
||||
// Return the live response from the network
|
||||
return returnedResponse;
|
||||
});
|
||||
}
|
||||
// Otherwise, just return the live result from the network
|
||||
return liveResponse;
|
||||
},
|
||||
),
|
||||
)
|
||||
);
|
||||
|
||||
// If there is a match from the cache
|
||||
if (response) {
|
||||
DEBUG && console.log(`SW: serving ${request.url} from cache.`);
|
||||
const expirationDate = Date.parse(response.headers.get('sw-cache-expires'));
|
||||
const now = new Date();
|
||||
// Check it is not already expired and return from the
|
||||
// cache
|
||||
if (expirationDate > now) {
|
||||
return response;
|
||||
}
|
||||
}
|
||||
DEBUG && console.log(`SW: Found ${request.url} in cache.`);
|
||||
|
||||
return _checkExpiration(cache, request, response).then(
|
||||
(notExpiredResponse) => {
|
||||
if (notExpiredResponse) {
|
||||
DEBUG && console.log(`SW: Serving ${request.url} from cache.`);
|
||||
return notExpiredResponse;
|
||||
}
|
||||
DEBUG && console.log(`SW: Serving ${request.url} from network, expired in cache.`);
|
||||
return _fetchFromNetwork();
|
||||
},
|
||||
);
|
||||
}
|
||||
// Otherwise, let's fetch it from the network
|
||||
DEBUG && console.log(`SW: no match in cache for ${request.url}, using network.`);
|
||||
return fetch(request.url).then((liveResponse) => {
|
||||
// Get tile caching duration from settings
|
||||
let tileCachingDurationPromise = (
|
||||
Promise.resolve(0) // no caching by default
|
||||
);
|
||||
if (
|
||||
localforage.driver() === localforage.INDEXEDDB
|
||||
) {
|
||||
tileCachingDurationPromise = loadDataFromStorage(
|
||||
'settings', 'tileCachingDuration',
|
||||
);
|
||||
}
|
||||
return tileCachingDurationPromise.then((tileCachingDuration) => {
|
||||
// This is caching duration from settings
|
||||
const cachingDuration = (
|
||||
tileCachingDuration || 0
|
||||
);
|
||||
// This is caching duration specified in HTTP headers
|
||||
const cachingDurationFromHeaders = getExpiresFromHeaders(
|
||||
liveResponse.headers,
|
||||
) || 0;
|
||||
|
||||
// If any form of caching is possible, do it
|
||||
if (tileCachingDuration > 0 || cachingDurationFromHeaders > 0) {
|
||||
// Compute expires date from caching duration
|
||||
const expires = new Date();
|
||||
expires.setSeconds(
|
||||
expires.getSeconds()
|
||||
// Caching duration cannot be less than
|
||||
// specified by HTTP headers.
|
||||
+ Math.max(cachingDuration, cachingDurationFromHeaders),
|
||||
);
|
||||
// Recreate a Response object from scratch to put
|
||||
// it in the cache, with the extra header for
|
||||
// managing cache expiration.
|
||||
const cachedResponseFields = {
|
||||
status: liveResponse.status,
|
||||
statusText: liveResponse.statusText,
|
||||
headers: { 'SW-Cache-Expires': expires.toUTCString() },
|
||||
};
|
||||
liveResponse.headers.forEach((v, k) => {
|
||||
cachedResponseFields.headers[k] = v;
|
||||
});
|
||||
// We will consume body of the live response, so
|
||||
// clone it before to be able to return it
|
||||
// afterwards.
|
||||
const returnedResponse = liveResponse.clone();
|
||||
return liveResponse.blob().then((body) => {
|
||||
DEBUG && console.log(
|
||||
`SW: caching tiles ${request.url} until ${expires.toUTCString()}.`,
|
||||
);
|
||||
// Put the duplicated Response in the cache
|
||||
cache.put(request, new Response(body, cachedResponseFields));
|
||||
// Return the live response from the network
|
||||
return returnedResponse;
|
||||
});
|
||||
}
|
||||
// Otherwise, just return the live result from the network
|
||||
return liveResponse;
|
||||
});
|
||||
});
|
||||
return _fetchFromNetwork();
|
||||
},
|
||||
),
|
||||
));
|
||||
@ -250,13 +303,7 @@ global.self.addEventListener('message', (event) => {
|
||||
cache => cache.keys().then(
|
||||
keys => keys.forEach(
|
||||
key => cache.match(key).then((cachedResponse) => {
|
||||
const expirationDate = Date.parse(cachedResponse.headers.get('sw-cache-expires'));
|
||||
const now = new Date();
|
||||
// Check it is not already expired
|
||||
if (expirationDate < now) {
|
||||
DEBUG && console.log(`SW: purging (expired) tile ${key.url} from cache.`);
|
||||
cache.delete(key);
|
||||
}
|
||||
_checkExpiration(cache, key, cachedResponse);
|
||||
}),
|
||||
),
|
||||
),
|
||||
|
||||
Loading…
Reference in New Issue
Block a user