1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298
use std::{ error::Error, path::PathBuf, sync::{ atomic::{AtomicU64, Ordering}, Arc, }, }; use crossbeam_channel::Sender; use dashmap::DashMap; use distill_core::{AssetMetadata, AssetRef, AssetTypeId, AssetUuid}; /// Loading ID allocated by [`Loader`](crate::loader::Loader) to track loading of a particular asset /// or an indirect reference to an asset. #[derive(Copy, Clone, PartialEq, Eq, Debug, Hash)] pub struct LoadHandle(pub u64); impl LoadHandle { /// Returns true if the handle needs to be resolved through the [`IndirectionTable`] before use. /// An "indirect" LoadHandle represents a load operation for an identifier that is late-bound, /// meaning the identifier may change which [`AssetUuid`] it resolves to. /// An example of an indirect LoadHandle would be one that loads by filesystem path. /// The specific asset at a path may change as files change, move or are deleted, while a direct /// LoadHandle (one that addresses by AssetUuid) is guaranteed to refer to an AssetUuid for its /// whole lifetime. pub fn is_indirect(&self) -> bool { (self.0 & (1 << 63)) == 1 << 63 } pub(crate) fn set_indirect(self) -> LoadHandle { LoadHandle(self.0 | (1 << 63)) } } pub(crate) enum HandleOp { Error(LoadHandle, u32, Box<dyn Error + Send>), Complete(LoadHandle, u32), Drop(LoadHandle, u32), } /// Type that allows the downstream asset storage implementation to signal that an asset update /// operation has completed. See [`AssetStorage::update_asset`]. pub struct AssetLoadOp { sender: Option<Sender<HandleOp>>, handle: LoadHandle, version: u32, } impl AssetLoadOp { pub(crate) fn new(sender: Sender<HandleOp>, handle: LoadHandle, version: u32) -> Self { Self { sender: Some(sender), handle, version, } } /// Returns the `LoadHandle` associated with the load operation pub fn load_handle(&self) -> LoadHandle { self.handle } /// Signals that this load operation has completed succesfully. pub fn complete(mut self) { let _ = self .sender .as_ref() .unwrap() .send(HandleOp::Complete(self.handle, self.version)); self.sender = None; } /// Signals that this load operation has completed with an error. pub fn error<E: Error + 'static + Send>(mut self, error: E) { let _ = self.sender.as_ref().unwrap().send(HandleOp::Error( self.handle, self.version, Box::new(error), )); self.sender = None; } } impl Drop for AssetLoadOp { fn drop(&mut self) { if let Some(ref sender) = self.sender { let _ = sender.send(HandleOp::Drop(self.handle, self.version)); } } } /// Storage for all assets of all asset types. /// /// Consumers are expected to provide the implementation for this, as this is the bridge between /// [`Loader`](crate::loader::Loader) and the application. pub trait AssetStorage { /// Updates the backing data of an asset. /// /// An example usage of this is when a texture such as "player.png" changes while the /// application is running. The asset ID is the same, but the underlying pixel data can differ. /// /// # Parameters /// /// * `loader`: Loader implementation calling this function. /// * `asset_type_id`: UUID of the asset type. /// * `data`: The updated asset byte data. /// * `load_handle`: ID allocated by [`Loader`](crate::loader::Loader) to track loading of a particular asset. /// * `load_op`: Allows the loading implementation to signal when loading is done / errors. /// * `version`: Runtime load version of this asset, increments each time the asset is updated. fn update_asset( &self, loader_info: &dyn LoaderInfoProvider, asset_type_id: &AssetTypeId, data: Vec<u8>, load_handle: LoadHandle, load_op: AssetLoadOp, version: u32, ) -> Result<(), Box<dyn Error + Send + 'static>>; /// Commits the specified asset version as loaded and ready to use. /// /// # Parameters /// /// * `asset_type_id`: UUID of the asset type. /// * `load_handle`: ID allocated by [`Loader`](crate::loader::Loader) to track loading of a particular asset. /// * `version`: Runtime load version of this asset, increments each time the asset is updated. fn commit_asset_version(&self, asset_type: &AssetTypeId, load_handle: LoadHandle, version: u32); /// Frees the asset identified by the load handle. /// /// # Parameters /// /// * `asset_type_id`: UUID of the asset type. /// * `load_handle`: ID allocated by [`Loader`](crate::loader::Loader) to track loading of a particular asset. fn free(&self, asset_type_id: &AssetTypeId, load_handle: LoadHandle, version: u32); } /// Asset loading status. #[derive(Debug)] pub enum LoadStatus { /// There is no request for the asset to be loaded. NotRequested, /// The asset is an indirect reference which has not been resolved yet. Unresolved, /// The asset is being loaded. Loading, /// The asset is loaded. Loaded, /// The asset is being unloaded. Unloading, /// The asset does not exist. DoesNotExist, /// There was an error during loading / unloading of the asset. Error(Box<dyn Error>), } /// Information about an asset load operation. /// /// **Note:** The information is true at the time the `LoadInfo` is retrieved. The actual number of /// references may change. #[derive(Debug)] pub struct LoadInfo { /// UUID of the asset. pub asset_id: AssetUuid, /// Number of references to the asset. pub refs: u32, /// Path to asset's source file. Not guaranteed to always be available. pub path: Option<String>, /// Name of asset's source file. Not guaranteed to always be available. pub file_name: Option<String>, /// Asset name. Not guaranteed to always be available. pub asset_name: Option<String>, } /// Provides information about mappings between `AssetUuid` and `LoadHandle`. /// Intended to be used for `Handle` serde. pub trait LoaderInfoProvider: Send + Sync { /// Returns the load handle for the asset with the given UUID, if present. /// /// This will only return `Some(..)` if there has been a previous call to [`crate::loader::Loader::add_ref`]. /// /// # Parameters /// /// * `id`: UUID of the asset. fn get_load_handle(&self, asset_ref: &AssetRef) -> Option<LoadHandle>; /// Returns the AssetUUID for the given LoadHandle, if present. /// /// # Parameters /// /// * `load_handle`: ID allocated by [`Loader`](crate::loader::Loader) to track loading of the asset. fn get_asset_id(&self, load: LoadHandle) -> Option<AssetUuid>; } /// Allocates LoadHandles for [`Loader`](crate::loader::Loader) implementations. pub trait HandleAllocator: Send + Sync + 'static { /// Allocates a [`LoadHandle`] for use by a [`crate::loader::Loader`]. /// The same LoadHandle must not be returned by this function until it has been passed to `free`. /// NOTE: The most significant bit of the u64 in the LoadHandle returned MUST be unset, /// as it is reserved for indicating whether the handle is indirect or not. fn alloc(&self) -> LoadHandle; /// Frees a [`LoadHandle`], allowing the handle to be returned by a future `alloc` call. fn free(&self, handle: LoadHandle); } /// An implementation of [`HandleAllocator`] which uses an incrementing AtomicU64 internally to allocate LoadHandle IDs. pub struct AtomicHandleAllocator(AtomicU64); impl AtomicHandleAllocator { pub const fn new(starting_value: u64) -> Self { Self(AtomicU64::new(starting_value)) } } impl Default for AtomicHandleAllocator { fn default() -> Self { Self(AtomicU64::new(1)) } } impl HandleAllocator for AtomicHandleAllocator { fn alloc(&self) -> LoadHandle { LoadHandle(self.0.fetch_add(1, Ordering::Relaxed)) } fn free(&self, _handle: LoadHandle) {} } impl HandleAllocator for &'static AtomicHandleAllocator { fn alloc(&self) -> LoadHandle { LoadHandle(self.0.fetch_add(1, Ordering::Relaxed)) } fn free(&self, _handle: LoadHandle) {} } /// An indirect identifier that can be resolved to a specific [`AssetUuid`] by an [`IndirectionResolver`] impl. #[derive(Clone, PartialEq, Eq, Debug, Hash)] pub enum IndirectIdentifier { PathWithTagAndType(String, String, AssetTypeId), PathWithType(String, AssetTypeId), Path(String), } impl IndirectIdentifier { pub fn path(&self) -> &str { match self { IndirectIdentifier::PathWithTagAndType(path, _, _) => path.as_str(), IndirectIdentifier::PathWithType(path, _) => path.as_str(), IndirectIdentifier::Path(path) => path.as_str(), } } pub fn type_id(&self) -> Option<&AssetTypeId> { match self { IndirectIdentifier::PathWithTagAndType(_, _, ty) => Some(ty), IndirectIdentifier::PathWithType(_, ty) => Some(ty), IndirectIdentifier::Path(_) => None, } } } /// Resolves ambiguous [`IndirectIdentifier`]s to a single asset ID given a set of candidates. pub trait IndirectionResolver { fn resolve( &self, id: &IndirectIdentifier, candidates: Vec<(PathBuf, Vec<AssetMetadata>)>, ) -> Option<AssetUuid>; } /// Default implementation of [`IndirectionResolver`] which resolves to the first asset in the list of candidates /// of the appropriate type. pub struct DefaultIndirectionResolver; impl IndirectionResolver for DefaultIndirectionResolver { fn resolve( &self, id: &IndirectIdentifier, candidates: Vec<(PathBuf, Vec<AssetMetadata>)>, ) -> Option<AssetUuid> { let id_type = id.type_id(); for candidate in candidates { for asset in candidate.1 { if let Some(artifact) = asset.artifact { if id_type.is_none() || *id_type.unwrap() == artifact.type_id { return Some(asset.id); } } } } None } } /// Resolves indirect [`LoadHandle`]s. See [`LoadHandle::is_indirect`] for details. #[derive(Clone)] pub struct IndirectionTable(pub(crate) Arc<DashMap<LoadHandle, LoadHandle>>); impl IndirectionTable { pub fn resolve(&self, indirect_handle: LoadHandle) -> Option<LoadHandle> { self.0.get(&indirect_handle).map(|l| *l) } }