# Cache

### refresh vs expire

* Refresh and expire can exist at the same time. Entries queried with longer life than expire limit would trigger `load()` , and entries queried with longer life than refresh limit would trigger `reload()` accordingly.
* When entry is expired, `get()` would trigger `load()` and block until `load()` is complete.
* Entry runs `reload()` when its life is longer than refresh limit and gets invoked of `call()` .
* Event entry gets `load()` or `reload()`, the time they get into cache would not be updated.

```
public static void main(String[] args) throws InterruptedException {
    LoadingCache<String, String> ca = Caffeine.newBuilder()
            .expireAfterWrite(Duration.ofMillis(1000)) // Set to 800 to trigger load()
            .refreshAfterWrite(Duration.ofMillis(800))
            .build(new CacheLoader<String, String>() {
        @Override
        public @Nullable String load(String key) throws Exception {
            return "load_" + key;
        }

        @Override
        public @Nullable String reload(String key, String oldValue) throws Exception {
            return "reload_" + key;
        }
    });
    ca.put("a", "A");
    int millisSleep = 300;
    System.out.println("ca.get(\"a\") = " + ca.get("a"));
    for (int i = 1; i <= 5; i++) {
        System.out.println("millis: " + i * millisSleep);
        Thread.sleep(millisSleep);
        System.out.println("ca.get(\"a\") = " + ca.get("a"));
        System.out.println("ca.get(\"a\") = " + ca.get("a"));
    }
}
```


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# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://ysfang82.gitbook.io/development-notes/programming-langauges/java/cache.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.