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https://github.com/fluencelabs/wasmer
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Add documentation and make load safe
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@ -29,16 +29,34 @@ pub enum Error {
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InvalidatedCache,
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}
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impl From<io::Error> for Error {
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fn from(io_err: io::Error) -> Self {
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Error::IoError(io_err)
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}
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}
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/// The hash of a wasm module.
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///
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/// Used as a key when loading and storing modules in a [`Cache`].
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///
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/// [`Cache`]: trait.Cache.html
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#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
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pub struct WasmHash([u8; 32]);
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impl WasmHash {
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/// Hash a wasm module.
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///
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/// # Note:
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/// This does no verification that the supplied data
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/// is, in fact, a wasm module.
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pub fn generate(wasm: &[u8]) -> Self {
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let mut array = [0u8; 32];
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array.copy_from_slice(Sha256::digest(wasm).as_slice());
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WasmHash(array)
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}
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/// Create the hexadecimal representation of the
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/// stored hash.
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pub fn encode(self) -> String {
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hex::encode(self.0)
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}
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@ -183,10 +201,13 @@ impl SerializedCache {
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}
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}
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/// A generic cache for storing and loading compiled wasm modules.
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///
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/// The `wasmer-runtime` supplies a naive `FileSystemCache` api.
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pub trait Cache {
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type LoadError;
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type StoreError;
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unsafe fn load(&self, key: WasmHash) -> Result<Module, Self::LoadError>;
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fn load(&self, key: WasmHash) -> Result<Module, Self::LoadError>;
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fn store(&mut self, module: Module) -> Result<WasmHash, Self::StoreError>;
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}
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@ -91,12 +91,42 @@ use wasmer_runtime_core::cache::{Error as CacheError, SerializedCache};
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// }
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// }
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pub struct FSCache {
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/// Representation of a directory that contains compiled wasm artifacts.
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///
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/// The `FileSystemCache` type implements the [`Cache`] trait, which allows it to be used
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/// generically when some sort of cache is required.
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///
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/// [`Cache`]: trait.Cache.html
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///
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/// # Usage:
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///
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/// ```rust
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/// use wasmer_runtime::cache::{Cache, FileSystemCache};
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///
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/// # use wasmer_runtime::{Module, error::CacheError};
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/// fn store_and_load_module(module: Module) -> Result<Module, CacheError> {
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/// // Create a new file system cache.
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/// // This is unsafe because we can't ensure that the artifact wasn't
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/// // corrupted or tampered with.
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/// let mut fs_cache = unsafe { FileSystemCache::new("some/directory/goes/here")? };
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/// // Store a module into the cache.
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/// // The returned `key` is equivalent to `module.info().wasm_hash`.
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/// let key = fs_cache.store(module)?;
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/// // Load the module back from the cache with the `key`.
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/// fs_cache.load(key)
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/// }
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/// ```
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pub struct FileSystemCache {
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path: PathBuf,
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}
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impl FSCache {
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pub fn open<P: Into<PathBuf>>(path: P) -> io::Result<FSCache> {
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impl FileSystemCache {
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/// Construct a new `FileSystemCache` around the specified directory.
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///
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/// # Note:
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/// This method is unsafe because there's no way to ensure the artifacts
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/// stored in this cache haven't been corrupted or tampered with.
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pub unsafe fn new<P: Into<PathBuf>>(path: P) -> io::Result<Self> {
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let path: PathBuf = path.into();
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if path.exists() {
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@ -129,17 +159,17 @@ impl FSCache {
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}
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}
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impl Cache for FSCache {
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impl Cache for FileSystemCache {
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type LoadError = CacheError;
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type StoreError = CacheError;
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unsafe fn load(&self, key: WasmHash) -> Result<Module, CacheError> {
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fn load(&self, key: WasmHash) -> Result<Module, CacheError> {
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let filename = key.encode();
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let mut new_path_buf = self.path.clone();
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new_path_buf.push(filename);
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let serialized_cache = SerializedCache::open(new_path_buf)?;
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wasmer_runtime_core::load_cache_with(serialized_cache, super::default_compiler())
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unsafe { wasmer_runtime_core::load_cache_with(serialized_cache, super::default_compiler()) }
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}
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fn store(&mut self, module: Module) -> Result<WasmHash, CacheError> {
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