function decorator which ensures that calls do not run simultaneously
npm install decorator-synchronized   
> Function decorator which ensures that calls do not run simultaneously.
Requires _WeakMap_, it your system does not have it, use a polyfill.
Installation of the npm package:
``
> npm install --save decorator-synchronized
`js
import { synchronized } from "decorator-synchronized";
let i = 0;
const fn = synchronized(() => {
console.log(i);
return Promise.resolve().then(() => {
i++;
});
});
Promise.all([fn(), fn()]);
// => Prints 0 then 1
// Create a dedicated synchronizer which will be shared amongst
// multiple functions.
//
// Useful when functions work on the same resource.
const counterSynchronized = synchronized();
const increment = counterSynchronized(async () => {
const i = 1 + (await db.getCounter());
await db.setCounter(i);
return i;
});
const decrement = counterSynchronized(async () => {
const i = -1 + (await db.getCounter());
await db.setCounter(i);
return i;
});
increment().then(console.log); // prints 1
decrement().then(console.log); // prints 0
`
`js
import { synchronized } from "decorator-synchronized";
const updateUser = synchronized.withKey()(async (userId, props) => {
const user = await db.getUser(userId);
await db.setUser(userId, { ...user, ...props });
});
// will correctly update the user without race conditions
updaterUser("wq1567e", { foo: 3.14 });
updaterUser("wq1567e", { bar: 42 });
// different users are still updated in parallel
updateUser("ct356tv", { baz: 2.72 });
`
The key is deduced from the first argument, if you need something
else, just provide a key function:
`js`
const fn = synchronized.withKey((_, secondArg) => secondArg)(
(firstArg, secondArg) => {
// TODO
}
);
`Install dependencies
> yarn
Contributions are _very_ welcomed, either on the documentation or on
the code.
You may:
- report any issue
you've encountered;
- fork and create a pull request.
ISC © Pierre Donias