Incremental Building

tip

Farm supports incremental build by persistent cache since v0.14.0

Since v0.14.0, Farm supports cache the compiled result to disk, which can greatly speed up the compilation for hot start/hot build. When persistentCache is enabled, the compilation time can reduce up to 80%.

Performance compare between cold start(without cache) and hot start(with cache) using examples/argo-pro:

	Cold(without cache)	Hot(with cache)	diff
start	1519ms	371ms	reduced 75%
build	3582ms	562ms	reduced 84%

Using Cache

Using compilation.persistentCache to enable/disable Cache:

import { defineConfig } from "@farmfe/core";

export default defineConfig({
  compilation: {
    persistentCache: true,
  },
});

note

persistentCache: true is equal to:

({
  persistentCache: {
    // Directory that cache is stored
    cacheDir: "node_modules/.farm/cache",
    // namespace of the cache
    namespace: "farm-cache",
    buildDependencies: [
      "farm.config.ts",
      "@farmfe/core",
      "@farmfe/plugin-react",
      // ... all other dependencies
    ],
    moduleCacheKeyStrategy: {
      timestamp: true,
      hash: true,
    },
  },
});

Configuring persistentCache to false to disable cache.

Cache Validation

Cache will be validated when trying to reuse it by following conditions, if any of following conditions changed, all cache will be invalidated:

• Env Object: configured by persistentCache.envs, default to Farm Env Mode(process.env.NODE_ENV, process.env.DEV, process.env.PROD), see Environment Variables and Modes.
• lockfile: If your lockfile changed, means there are dependencies changes, the cache will be invalidated.

• Build Dependencies: configured by persistentCache.buildDependencies, if any of the buildDependencies changed, all cache will be invalidated.
• Cache Namespace: configured by persistentCache.namespace, cache under different namespaces won't be reused. If you want to invalidate all cache, you can configure a different namespace.
• Internal Cache Version: Farm maintains a cache version internally, if Farm itself changed, for example, render optimization that affects the output between versions of Farm, Farm will bump the cache version and all cache will be invalidated.

If your cache does not work, check out above conditions to figure out the reason. If the cache is broken, you can also delete node_modules/.farm/cache to remove cache manually.

Build Dependencies

Build dependencies is dependencies that can affect the compilation process or compiled output, for examples, plugins or config files. If any of these dependencies changed, all cache will be invalidated.

Build dependencies can be a file path for a package name, for example:

import { defineConfig } from "@farmfe/core";
import path from "node:path";

export default defineConfig({
  persistentCache: {
    buildDependencies: [
      // a file path
      path.resolve(process.cwd(), "./plugins/my-plugin.js"),
      // a package name, note that this package must expose package.json
      "farm-plugin-custom-xxx",
    ],
  },
});

note

By default, all config files and its dependencies are included. But if you want to add some additional files or dependencies to invalidate the cache, you can using buildDependencies once these files changed, all cache will be invalidated.

Module Cache Key Strategy

Farm provides 2 strategies to control how to generate module cache key:

• timestamp: whether check timestamp of the module, if the update timestamp does not change, the build of this module will be skipped, which has the best performance.
• hash: whether check content hash after load and transform, if the content does not change, the left build of this module will be skipped.

By default timestamp and hash are both enabled.

Caveats For Plugins

when timestamp is enabled, all build stages hooks like load and transform won't be called. So if the plugin relies load and transform and it does not implement plugin_cache_loaded and write_plugin_cache hook, it may not work as expected. For example, if a plugin collect information in load and transform, all emit them at finish hook, it should implement plugin_cache_loaded and write_plugin_cache hook to load and write cache, otherwise it will not work as expected.

Farm will set timestamp to false when output.targetEnv is node.