trine-kv 0.6.0

Embedded LSM MVCC key-value database.
Documentation 
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use std::sync::Arc;

use crate::{
    DurabilityMode,
    error::Result,
    object_store::ObjectStoreBackend,
    storage::{
        MemoryStorageBackend, NativeFileBackend, StorageObjectDeleteBackend, StorageObjectId,
        StorageObjectListBackend, StorageObjectListRequest, StorageObjectReadBackend,
        StorageObjectWriteBackend,
    },
};

use crate::db::DatabaseStorageRef;

use super::Db;

/// Narrow storage adapter for immutable-content objects.
///
/// Platform selection happens once when the adapter is created. Content state
/// machines call one semantic operation and do not duplicate native, memory,
/// object-store, and browser dispatch.
#[derive(Debug, Clone)]
pub(super) enum ContentObjectBackend {
    Memory(MemoryStorageBackend),
    Native(NativeFileBackend),
    ObjectStore(ObjectStoreBackend),
    #[cfg(all(target_arch = "wasm32", target_os = "unknown"))]
    Browser(crate::storage::BrowserStorageBackend),
}

impl ContentObjectBackend {
    pub(super) fn for_db(db: &Db) -> Self {
        match db.inner.storage.resources() {
            DatabaseStorageRef::Memory(resources) => Self::Memory(resources.content.clone()),
            DatabaseStorageRef::Filesystem(resources) => Self::Native(resources.files.clone()),
            DatabaseStorageRef::ObjectStore(resources) => {
                Self::ObjectStore(resources.objects.clone())
            }
            #[cfg(all(target_arch = "wasm32", target_os = "unknown"))]
            DatabaseStorageRef::Browser(resources) => Self::Browser(resources.files.clone()),
        }
    }

    pub(super) const fn requires_lease_fence(&self) -> bool {
        matches!(self, Self::ObjectStore(_))
    }

    pub(super) async fn read(&self, object: StorageObjectId) -> Result<Option<Arc<[u8]>>> {
        match self {
            Self::Memory(backend) => backend.read_object_bytes(object).await,
            Self::Native(backend) => backend.read_object_bytes(object).await,
            Self::ObjectStore(backend) => backend.read_object_bytes(object).await,
            #[cfg(all(target_arch = "wasm32", target_os = "unknown"))]
            Self::Browser(backend) => backend.read_object_bytes(object).await,
        }
    }

    pub(super) async fn write(
        &self,
        object: StorageObjectId,
        bytes: Arc<[u8]>,
        durability: DurabilityMode,
    ) -> Result<()> {
        match self {
            Self::Memory(backend) => backend.write_object(object, bytes, durability).await,
            Self::Native(backend) => backend.write_object(object, bytes, durability).await,
            Self::ObjectStore(backend) => backend.write_object(object, bytes, durability).await,
            #[cfg(all(target_arch = "wasm32", target_os = "unknown"))]
            Self::Browser(backend) => backend.write_object(object, bytes, durability).await,
        }
    }

    pub(super) async fn delete(
        &self,
        object: StorageObjectId,
        durability: DurabilityMode,
    ) -> Result<()> {
        match self {
            Self::Memory(backend) => backend.delete_object(object).await,
            Self::Native(backend) => backend.delete_object_durable(object, durability).await,
            Self::ObjectStore(backend) => backend.delete_unversioned_object_verified(object).await,
            #[cfg(all(target_arch = "wasm32", target_os = "unknown"))]
            Self::Browser(backend) => backend.delete_object(object).await,
        }
    }

    pub(super) async fn list(
        &self,
        request: StorageObjectListRequest,
    ) -> Result<Vec<StorageObjectId>> {
        match self {
            Self::Memory(backend) => backend.list_objects(request).await,
            Self::Native(backend) => backend.list_objects(request).await,
            Self::ObjectStore(backend) => backend.list_objects(request).await,
            #[cfg(all(target_arch = "wasm32", target_os = "unknown"))]
            Self::Browser(backend) => backend.list_objects(request).await,
        }
    }
}