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/*
This file is part of GNU Taler
(C) 2019 GNUnet e.V.
GNU Taler is free software; you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation; either version 3, or (at your option) any later version.
GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with
GNU Taler; see the file COPYING. If not, see <http://www.gnu.org/licenses/>
*/
interface MemoEntry<T> {
p: Promise<T>;
t: number;
n: number;
}
export class AsyncOpMemoMap<T> {
private n = 0;
private memoMap: { [k: string]: MemoEntry<T> } = {};
private cleanUp(key: string, n: number): void {
const r = this.memoMap[key];
if (r && r.n === n) {
delete this.memoMap[key];
}
}
memo(key: string, pg: () => Promise<T>): Promise<T> {
const res = this.memoMap[key];
if (res) {
return res.p;
}
const n = this.n++;
// Wrap the operation in case it immediately throws
const p = Promise.resolve().then(() => pg());
this.memoMap[key] = {
p,
n,
t: new Date().getTime(),
};
return p.finally(() => {
this.cleanUp(key, n);
});
}
clear(): void {
this.memoMap = {};
}
}
export class AsyncOpMemoSingle<T> {
private n = 0;
private memoEntry: MemoEntry<T> | undefined;
private cleanUp(n: number): void {
if (this.memoEntry && this.memoEntry.n === n) {
this.memoEntry = undefined;
}
}
memo(pg: () => Promise<T>): Promise<T> {
const res = this.memoEntry;
if (res) {
return res.p;
}
const n = this.n++;
// Wrap the operation in case it immediately throws
const p = Promise.resolve().then(() => pg());
p.finally(() => {
this.cleanUp(n);
});
this.memoEntry = {
p,
n,
t: new Date().getTime(),
};
return p;
}
clear(): void {
this.memoEntry = undefined;
}
}
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