generate the hash at compile time

lib/runtime-core/Cargo.toml

@@ -46,3 +46,5 @@ field-offset = "0.1.1"
 [features]
 debug = []
 
+[build-dependencies]
+blake2b_simd = "0.4.1"

lib/runtime-core/build.rs

@@ -0,0 +1,26 @@
+use blake2b_simd::blake2bp;
+use std::{fs, io::Write, path::PathBuf};
+
+const WASMER_VERSION: &'static str = env!("CARGO_PKG_VERSION");
+
+fn main() {
+    let mut state = blake2bp::State::new();
+    state.update(WASMER_VERSION.as_bytes());
+
+    let hasher = state.finalize();
+    let hash_string = hasher.to_hex().as_str().to_owned();
+
+    let crate_dir = env!("CARGO_MANIFEST_DIR");
+    let wasmer_version_hash_file = {
+        let mut path = PathBuf::from(&crate_dir);
+        path.push("wasmer_version_hash.txt");
+        path
+    };
+
+    let mut f_out = fs::File::create(wasmer_version_hash_file)
+        .expect("Could not create file for wasmer hash value");
+
+    f_out
+        .write_all(hash_string.as_bytes())
+        .expect("Could not write to file for wasmer hash value");
+}

lib/runtime-core/src/cache.rs

@@ -208,13 +208,5 @@ pub trait Cache {
     fn store(&mut self, key: WasmHash, module: Module) -> Result<(), Self::StoreError>;
 }
 
-const WASMER_VERSION: &'static str = env!("CARGO_PKG_VERSION");
-
-/// Returns a unique ID generated from the version of Wasmer for use with cache versioning
-pub fn cache_versioned_sub_directory() -> String {
-    let mut state = blake2bp::State::new();
-    state.update(WASMER_VERSION.as_bytes());
-
-    let hasher = state.finalize();
-    hasher.to_hex().as_str().to_owned()
-}
+/// A unique ID generated from the version of Wasmer for use with cache versioning
+pub const WASMER_VERSION_HASH: &'static str = include_str!("../wasmer_version_hash.txt");

lib/runtime-core/wasmer_version_hash.txt

@@ -0,0 +1 @@
+beb6542931f7f7c823b8d1804b12639fd794711af1f90263c5ed7d338bf4429d1cbe69a531f18144f208c33c49ca01315ffa2b23c170e4c979b1114ffcfbba54

lib/runtime/src/cache.rs

@@ -7,7 +7,7 @@ use std::{
 };
 
 use wasmer_runtime_core::cache::Error as CacheError;
-pub use wasmer_runtime_core::cache::{cache_versioned_sub_directory, Artifact, Cache, WasmHash};
+pub use wasmer_runtime_core::cache::{Artifact, Cache, WasmHash, WASMER_VERSION_HASH};
 
 /// Representation of a directory that contains compiled wasm artifacts.
 ///
@@ -36,7 +36,6 @@ pub use wasmer_runtime_core::cache::{cache_versioned_sub_directory, Artifact, Ca
 /// ```
 pub struct FileSystemCache {
     path: PathBuf,
-    versioned_sub_directory: String,
 }
 
 impl FileSystemCache {
@@ -48,16 +47,12 @@ impl FileSystemCache {
     /// stored in this cache haven't been corrupted or tampered with.
     pub unsafe fn new<P: Into<PathBuf>>(path: P) -> io::Result<Self> {
         let path: PathBuf = path.into();
-        let versioned_sub_directory = cache_versioned_sub_directory();
 
         if path.exists() {
             let metadata = path.metadata()?;
             if metadata.is_dir() {
                 if !metadata.permissions().readonly() {
-                    Ok(Self {
-                        path,
-                        versioned_sub_directory,
-                    })
+                    Ok(Self { path })
                 } else {
                     // This directory is readonly.
                     Err(io::Error::new(
@@ -78,10 +73,7 @@ impl FileSystemCache {
         } else {
             // Create the directory and any parent directories if they don't yet exist.
             create_dir_all(&path)?;
-            Ok(Self {
-                path,
-                versioned_sub_directory,
-            })
+            Ok(Self { path })
         }
     }
 }
@@ -93,7 +85,7 @@ impl Cache for FileSystemCache {
     fn load(&self, key: WasmHash) -> Result<Module, CacheError> {
         let filename = key.encode();
         let mut new_path_buf = self.path.clone();
-        new_path_buf.push(&self.versioned_sub_directory);
+        new_path_buf.push(WASMER_VERSION_HASH);
         new_path_buf.push(filename);
         let file = File::open(new_path_buf)?;
         let mmap = unsafe { Mmap::map(&file)? };
@@ -105,7 +97,7 @@ impl Cache for FileSystemCache {
     fn store(&mut self, key: WasmHash, module: Module) -> Result<(), CacheError> {
         let filename = key.encode();
         let mut new_path_buf = self.path.clone();
-        new_path_buf.push(&self.versioned_sub_directory);
+        new_path_buf.push(WASMER_VERSION_HASH);
         new_path_buf.push(filename);
 
         let serialized_cache = module.cache()?;

src/bin/wasmer.rs

@@ -12,9 +12,7 @@ use structopt::StructOpt;
 use wasmer::webassembly::InstanceABI;
 use wasmer::*;
 use wasmer_emscripten;
-use wasmer_runtime::cache::{
-    cache_versioned_sub_directory, Cache as BaseCache, FileSystemCache, WasmHash,
-};
+use wasmer_runtime::cache::{Cache as BaseCache, FileSystemCache, WasmHash, WASMER_VERSION_HASH};
 
 #[derive(Debug, StructOpt)]
 #[structopt(name = "wasmer", about = "Wasm execution runtime.")]
@@ -73,7 +71,7 @@ fn get_cache_dir() -> PathBuf {
         Err(_) => {
             // We use a temporal directory for saving cache files
             let mut temp_dir = env::temp_dir();
-            temp_dir.push(cache_versioned_sub_directory());
+            temp_dir.push(WASMER_VERSION_HASH);
             temp_dir.push("wasmer");
             temp_dir
         }