BastionCache

Bastion.Cache — ETag, response caching, fragment caching, and Cache-Control helpers.

Provides caching middleware that composes into the HttpServer Conn pipeline.

Typical usage:

conn
|> MyApp.Router.route()
|> Bastion.Cache.etag()

-- Full-response cache:
Bastion.Cache.cached(conn, "posts:index", 60, fn c ->
  HttpServer.send_resp(c, 200, posts_html())
end)

-- Fragment cache:
Bastion.Cache.fragment("stats:global", 300, fn ->
  IOList.from_string("<div>" ++ compute_stats() ++ "</div>")
end)

Functions

fncache_controlcache_control(conn, directives)#

Set an arbitrary Cache-Control header value on the response.

fncachedcached(conn, key, ttl_secs, generator)#

Full-response cache middleware. On a cache hit the stored status and body are restored onto conn and the generator is skipped. On a miss the generator runs, its result is stored in Vault with the given TTL, and then returned.

`key`       — string cache key, e.g. `"posts:index"`
`ttl_secs`  — time-to-live in seconds; `0` caches forever
`generator` — `fn(Conn) -> Conn` that builds the response

    BastionCache.cached(conn, "posts:index", 60, fn c ->
      HttpServer.send_resp(c, 200, posts_html())
    end)

fnetagetag(conn)#

ETag middleware. Computes a weak ETag from the response body hash, sets the ETag response header, and short-circuits to 304 Not Modified when the client's If-None-Match header matches.

Call after the response body has been set but before sending.

    conn
    |> MyApp.Router.route()
    |> BastionCache.etag()

fnfragmentfragment(key, ttl_secs, generator)#

Fragment cache. On a hit returns the cached IOList directly. On a miss calls the generator, stores with ttl_secs, and returns it.

`key`       — string cache key, e.g. `"stats:global"`
`ttl_secs`  — TTL in seconds; `0` caches forever
`generator` — `fn() -> IOList`

    BastionCache.fragment("stats:global", 300, fn () ->
      IOList.from_string("<div>" ++ compute_stats() ++ "</div>")
    end)

fninvalidateinvalidate(table_name, key)#

Delete a single entry from the named Vault table by key. No-op if the key does not exist.

    BastionCache.invalidate("response_cache", "posts:index")

fninvalidate_prefixinvalidate_prefix(table_name, prefix)#

Delete all entries whose string key starts with prefix from the named Vault table. O(n) scan — avoid on very large tables.

    BastionCache.invalidate_prefix("fragment_cache", "user:42:")

fnno_cacheno_cache(conn)#

Set Cache-Control: no-store, no-cache, must-revalidate — no caching.

fnpublic_cachepublic_cache(conn, max_age_secs)#

Set Cache-Control: public, max-age=<seconds>.