Cache

Simpesys supports incremental rendering by reusing previously generated document HTML. Caching improves build performance by skipping rendering for documents whose content and settings have not changed. Caching is disabled by default. Call init({ cache: true }) to enable it.

To share a cache between two or more Simpesys instances in the same process, pass the previous instance’s cache to the next instance.

import { Simpesys } from "@simpesys/core";

const first = await new Simpesys().init({ cache: true });

const second = await new Simpesys().init({
  cache: {
    previous: first.getCache(),
  },
});

This example retrieves the first instance’s cache with getCache() and passes it to the second instance through cache.previous.

Option	Type	Description
cache.version	string	Version used to distinguish caches.
cache.previous	Cache	Cache to reuse.

If you supply rendering hooks such as renderInternalLink or configureMarkdownConverter, explicitly set cache.version when reusing a previous cache. Update the version when the hook implementation changes.

await new Simpesys(config).init({
  cache: { previous, version: "v2" },
});

The in-memory cache is lost when the process restarts. The application can save the cache to the filesystem so that instances in another process can reuse it.

import { type Cache, Simpesys } from "@simpesys/core";

const cacheDirectory = ".simpesys";
const cachePath = `${cacheDirectory}/cache.json`;

let previous: Cache | undefined;

try {
  previous = JSON.parse(await Deno.readTextFile(cachePath));
} catch (error) {
  if (!(error instanceof Deno.errors.NotFound || error instanceof SyntaxError)) {
    throw error;
  }
}

const simpesys = await new Simpesys().init({
  cache: { previous },
});

const next = simpesys.getCache();

if (next) {
  await Deno.mkdir(cacheDirectory, { recursive: true });
  await Deno.writeTextFile(cachePath, JSON.stringify(next));
}

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