phillip/ingress-intel-total-conversion
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data cache:

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- reduce the expiry time (the niantic servers are no longer as unreliable as they were, so keeping old data is less useful than it once was)
- add upper size limit on cache, as well as item count limit
- add debug method to get cache size as a string
This commit is contained in:
Jon Atkins 2015-02-22 17:00:18 +00:00
parent 6ad6ee56cf
commit 46275956cf
1 changed files with 30 additions and 7 deletions
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37
code/data_cache.js
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@ -4,17 +4,22 @@
window.DataCache = function() {
this.REQUEST_CACHE_FRESH_AGE = 3*60; // if younger than this, use data in the cache rather than fetching from the server
this.REQUEST_CACHE_MAX_AGE = 15*60; // maximum cache age. entries are deleted from the cache after this time
this.REQUEST_CACHE_MAX_AGE = 5*60; // maximum cache age. entries are deleted from the cache after this time
//NOTE: characters are 16 bits (ECMAScript standard), so divide byte size by two for correct limit
if (L.Browser.mobile) {
// on mobile devices, smaller cache size
this.REQUEST_CACHE_MAX_SIZE = 300; // if more than this many entries, expire early
this.REQUEST_CACHE_MAX_ITEMS = 300; // if more than this many entries, expire early
this.REQUEST_CACHE_MAX_CHARS = 5000000/2; // or more than this total size
} else {
// but on desktop, allow more
this.REQUEST_CACHE_MAX_SIZE = 1000; // if more than this many entries, expire early
this.REQUEST_CACHE_MAX_ITEMS = 1000; // if more than this many entries, expire early
this.REQUEST_CACHE_MAX_CHARS = 20000000/2; // or more than this total size
}
this._cache = {};
this._cacheCharSize = 0;
this._interval = undefined;
}
@ -24,18 +29,29 @@ window.DataCache.prototype.store = function(qk,data,freshTime) {
// 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 this._cache[qk];
this.remove(qk);
var time = new Date().getTime();
if (freshTime===undefined) freshTime = this.REQUEST_CACHE_FRESH_AGE*1000;
var expire = time + freshTime;
this._cache[qk] = { time: time, expire: expire, data: JSON.stringify(data) };
var dataStr = JSON.stringify(data);
this._cacheCharSize += dataStr.length;
this._cache[qk] = { time: time, expire: expire, dataStr: dataStr };
}
window.DataCache.prototype.remove = function(qk) {
if (qk in this._cache) {
this._cacheCharSize -= this._cache[qk].dataStr.length;
delete this._cache[qk];
}
}
window.DataCache.prototype.get = function(qk) {
if (qk in this._cache) return JSON.parse(this._cache[qk].data);
if (qk in this._cache) return JSON.parse(this._cache[qk].dataStr);
else return undefined;
}
@ -82,9 +98,16 @@ window.DataCache.prototype.runExpire = function() {
// 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 > this.REQUEST_CACHE_MAX_SIZE || this._cache[qk].time < t) {
if (cacheSize > this.REQUEST_CACHE_MAX_ITEMS || this._cacheCharSize > this.REQUEST_CACHE_MAX_CHARS || this._cache[qk].time < t) {
this._cacheCharSize -= this._cache[qk].dataStr.length;
delete this._cache[qk];
cacheSize--;
}
}
}
window.DataCache.prototype.debug = function() {
//NOTE: ECMAScript strings use 16 bit chars (it's in the standard), so convert for bytes/Kb
return 'Cache: '+Object.keys(this._cache).length+' items, '+(this._cacheCharSize*2).toLocaleString()+' bytes ('+Math.ceil(this._cacheCharSize/512).toLocaleString()+'K)';
}