https://nalar.dev/tags/caching/ Recent content in Caching on Nalar Hugo en-us Wed, 02 Sep 2026 00:00:00 +0700 https://nalar.dev/cache-pure-work-with-functools-cache-and-lru-cache/ Wed, 02 Sep 2026 00:00:00 +0700 https://nalar.dev/cache-pure-work-with-functools-cache-and-lru-cache/ <p>Caching can turn repeated expensive work into a dictionary lookup, but it can also return stale data or grow memory without bound. Python&rsquo;s <code>functools</code> module provides two convenient memoization decorators: <code>lru_cache</code> and <code>cache</code>.</p> <p><code>functools.cache</code> has been available since Python 3.9. It is effectively an unbounded memoization cache. <code>lru_cache</code> adds a configurable size limit and eviction behavior.</p> <h2 id="cache-functions-not-arbitrary-side-effects">Cache functions, not arbitrary side effects</h2> <p>Memoization works best when a function behaves like a pure function: the result depends only on its arguments.</p> https://nalar.dev/http-content-negotiation-and-correct-vary-headers/ Wed, 02 Sep 2026 00:00:00 +0700 https://nalar.dev/http-content-negotiation-and-correct-vary-headers/ <p>One URL can sometimes represent the same resource in several formats. An API might return JSON or CSV, while a documentation endpoint might return HTML or plain text.</p> <p>HTTP content negotiation lets a client express which representation it can accept. The server chooses a response and tells caches which request headers influenced that choice.</p> <p>The second part is easy to miss: if the response changes based on a request header, shared caches need the correct <code>Vary</code> metadata.</p> https://nalar.dev/http-conditional-requests-with-etag-and-last-modified/ Tue, 01 Sep 2026 00:00:00 +0700 https://nalar.dev/http-conditional-requests-with-etag-and-last-modified/ <p>HTTP caching is not only about choosing a long <code>max-age</code>. Applications often need clients to revalidate data because a resource can change, while still avoiding retransmitting the full representation when it has not changed.</p> <p>HTTP validators solve that problem. The two common validators are <code>ETag</code> and <code>Last-Modified</code>.</p> <h2 id="freshness-and-validation-are-different">Freshness and validation are different</h2> <p>A freshness directive can tell a cache that a response may be reused without contacting the server for a period:</p>