storage/src/basic.ts

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import uuid1 from "uuid/v1";
/**
* Standard interface for the simplest key-value store
*/
export interface KeyValueStorage {
get(key: string): Promise<string | null>
set(key: string, value: string | null): Promise<void>
}
/**
* Basic memory implementation
*/
export class MemoryStorage implements KeyValueStorage {
private store: { [key: string]: string } = {}
async get(key: string): Promise<string | null> {
const result = this.store[key];
return (typeof result == "undefined") ? null : result;
}
async set(key: string, value: string | null): Promise<void> {
if (value === null) {
delete this.store[key];
} else {
this.store[key] = value;
}
}
}
type StorageDelegate = KeyValueStorage | (() => KeyValueStorage)
function fromDelegate(delegate: StorageDelegate): KeyValueStorage {
return (typeof delegate === "function") ? delegate() : delegate;
}
/**
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* Wrap a storage, scoping the keys using a suffix
*/
export class ScopedStorage implements KeyValueStorage {
private readonly target: KeyValueStorage
constructor(target: StorageDelegate, private readonly suffix: string) {
this.target = fromDelegate(target);
}
async get(key: string): Promise<string | null> {
return await this.target.get(`${key}#${this.suffix}`);
}
async set(key: string, value: string | null): Promise<void> {
return await this.target.set(`${key}#${this.suffix}`, value);
}
}
/**
* Use a target unscoped storage, scoping the keys in a virtual random namespace
*
* The namespace is persisted in a reference storage (used unscoped)
*/
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export class RefScopedStorage implements KeyValueStorage {
private readonly reference: KeyValueStorage
private readonly target: KeyValueStorage
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private inner?: KeyValueStorage
constructor(reference: StorageDelegate, target: StorageDelegate) {
this.reference = fromDelegate(reference);
this.target = fromDelegate(target);
}
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private async init(): Promise<KeyValueStorage> {
const refkey = "tk-storage-scope-ref";
const suffix = await this.reference.get(refkey);
if (suffix) {
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return new ScopedStorage(this.target, suffix);
} else {
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const suffix = uuid1();
await this.reference.set(refkey, suffix);
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return new ScopedStorage(this.target, suffix);
}
}
async get(key: string): Promise<string | null> {
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if (!this.inner) {
this.inner = await this.init();
}
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return await this.inner.get(key);
}
async set(key: string, value: string | null): Promise<void> {
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if (!this.inner) {
this.inner = await this.init();
}
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return await this.inner.set(key, value);
}
}