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Unity Engine

Cache behavior in Web

Customize the Web cache behavior.
Read time 3 minutesLast updated 12 days ago
In the Unity Web platform, the Cache API lets you store the asset data cached in .data files and AssetBundles within the browser cache. Storage limits for the browser cache such as maximum file size, maximum overall cache size, and eviction criteria are dependent on the browser and platform that you're using. For more information, refer to Browser storage limits and eviction criteria.

Data Caching

To access Data Caching, open the Publishing Settings for Web from File > Build Profiles >
Player Settings

?

. This enables the browser to cache the main data files into the IndexedDB database.
Using the default browser HTTP cache doesn't guarantee that the browser caches a particular response. This is because the browser HTTP cache has limited space, and the browser might not be able to cache files that are too large.
To improve your loading speed, 
IndexedDB
allows you to cache files above the browser limit. When you cache more files, you increase the chance that downloaded content is available on the user's machine during the next run of the build.
To allow the browser to cache the main data files (.data) in the 
IndexedDB
cache, enable Data Caching in Player settings (menu: Edit >
Project Settings

?

> Player). By default, the standard Web loader configuration also caches AssetBundles and revalidates them. You don't need to override the cache behavior unless you want to change this default (for example, to stop caching bundles or to cache other file types).
If you do want to customize cache control via the instance directly, make sure 
Module.cacheControl(url)
returns 
must-revalidate
for the requested AssetBundle URL to keep caching enabled. For example, you can override the 
unityInstance.Module.cacheControl()
function in the fulfillment callback of the Promise that 
createUnityInstance()
returns.
For further information on 
createUnityInstance()
, refer to Compressed builds and server configuration.

Customize Web Cache behavior

By default, the cache configuration stores the asset data file .data and AssetBundle files .bundle, and revalidates them before loading them from the cache. To change this behavior, add a new Web template that changes the 
UnityLoader
configuration.
The following example shows how to add a custom 
cacheControl
function to the 
UnityLoader
configuration within the 
index.html
file.
var config = {   // ...#if USE_DATA_CACHING   cacheControl: function (url) {     // Caching enabled for .data and .bundle files.     // Revalidate if file is up to date before loading from cache     if (url.match(/\.data/) || url.match(/\.bundle/)) {         return "must-revalidate";     }     // Caching enabled for .mp4 and .custom files     // Load file from cache without revalidation.     if (url.match(/\.mp4/) || url.match(/\.custom/)) {         return "immutable";     }     // Disable explicit caching for all other files.     // Note: the default browser cache may cache them anyway.     return "no-store";   },#endif   // ...}
The 
cacheControl
function takes the url of a request as a parameter and returns one of the following:
  • must-revalidate
    - If the function returns must-revalidate, the cache returns to an enabled state and the file is revalidated before being loaded from the cache.
  • immutable
    - If the function returns immutable, the cache is enabled and the file is loaded from the cache without revalidation.
  • no-store
    - If the function returns no-store, the cache is disabled.
The browser automatically stores (caches) certain file types such as .html, .js, .css, .json, .jpg, .png, so they don't need to be explicitly stored in the Web Cache. Typical candidates for the Web cache include large files and files that use a custom file format.