Allow creation of a CacheConfig without loading from a file (#10665)

* cache: Add builder pattern for CacheConfig

* wasmtime: Add cache_config method to wasmtime::Config

* Refactor test_builder_default to use test_prolog helper

* Remove enabled option from CacheConfigBuilder and always set to true

* Change builder methods to take &mut self and return &mut Self

* Simplify cache configuration API

A new `cache_config(Option<CacheConfig>)` method replaces multiple methods
for controlling module caching. Now `None` disables caching, and users can
directly provide a cache config or load one from a file.

* Make cache configuration optional

* Add Cache struct to separate configuration from runtime (wip)

* Ensure default values earlier

* Consolidate CacheConfig and CacheConfigBuilder

* Set Cache directly on wastime::Config and make it easier to create one
from a file

* Validate after loading file again

* Move cache to top-level module

* Fix tests

Author: benbrandt

crates/bench-api/src/lib.rs

@@ -436,7 +436,7 @@ impl BenchState {
     ) -> Result<Self> {
         let mut config = options.config(None)?;
         // NB: always disable the compilation cache.
-        config.disable_cache();
+        config.cache(None);
         let engine = Engine::new(&config)?;
         let mut linker = Linker::<HostState>::new(&engine);
 

crates/c-api/src/config.rs

@@ -211,12 +211,18 @@ pub unsafe extern "C" fn wasmtime_config_cache_config_load(
     c: &mut wasm_config_t,
     filename: *const c_char,
 ) -> Option<Box<wasmtime_error_t>> {
+    use std::path::Path;
+
+    use wasmtime::Cache;
+
     handle_result(
         if filename.is_null() {
-            c.config.cache_config_load_default()
+            Cache::from_file(None).map(|cache| c.config.cache(Some(cache)))
         } else {
             match CStr::from_ptr(filename).to_str() {
-                Ok(s) => c.config.cache_config_load(s),
+                Ok(s) => {
+                    Cache::from_file(Some(&Path::new(s))).map(|cache| c.config.cache(Some(cache)))
+                }
                 Err(e) => Err(e.into()),
             }
         },