phillip/ingress-intel-total-conversion
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cache improvements

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- min and max size - expire early if over max size, don't expire if below min size
- increase max cache age to an hour
This commit is contained in:
Jon Atkins 2013-06-26 15:13:14 +01:00
parent dfba994f4b
commit 7061f5f561
1 changed files with 20 additions and 5 deletions
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25
code/map_data.js
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@ -42,9 +42,17 @@ window._requestCache = {}
// cache entries older than the fresh age, and younger than the max age, are stale. they're used in the case of an error from the server
window.REQUEST_CACHE_FRESH_AGE = 60; // if younger than this, use data in the cache rather than fetching from the server
window.REQUEST_CACHE_MAX_AGE = 15*60; // maximum cache age. entries are deleted from the cache after this time
window.REQUEST_CACHE_MAX_AGE = 60*60; // maximum cache age. entries are deleted from the cache after this time
window.REQUEST_CACHE_MIN_SIZE = 200; // if fewer than this many entries, don't expire any
window.REQUEST_CACHE_MAX_SIZE = 2000; // if more than this many entries, expire early
window.storeDataCache = function(qk,data) {
// fixme? common behaviour for objects is that properties are kept in the order they're added
// this is handy, as it allows easy retrieval of the oldest entries for expiring
// however, this is not guaranteed by the standards, but all our supported browsers work this way
delete window._requestCache[qk];
var d = new Date();
window._requestCache[qk] = { time: d.getTime(), data: data };
}
@ -68,17 +76,24 @@ window.isDataCacheFresh = function(qk) {
}
window.expireDataCache = function() {
// TODO: add a limit on the maximum number of cache entries, and start expiring them sooner than the expiry time
// (might also make sense to approximate the size of cache entries, and have an overall size limit?)
var d = new Date();
var t = d.getTime()-window.REQUEST_CACHE_MAX_AGE*1000;
var cacheSize = Object.keys(window._requestCache).length;
for(var qk in window._requestCache) {
if (window._requestCache[qk].time < t) {
// stop processing once we hit the minimum size
if (cacheSize < window.REQUEST_CACHE_MIN_SIZE) break;
// fixme? our MAX_SIZE test here assumes we're processing the oldest first. this relies
// on looping over object properties in the order they were added. this is true in most browsers,
// but is not a requirement of the standards
if (cacheSize > window.REQUEST_CACHE_MAX_SIZE || window._requestCache[qk].time < t) {
delete window._requestCache[qk];
cacheSize--;
}
}
}