sequence-request
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A lightweight TypeScript library for handling request deduplication.
204 lines (201 loc) • 7.38 kB
JavaScript
;
/**
* RequestManager class for handling request deduplication.
* Only the latest request's result will be returned, previous requests' results will be ignored.
* Note: This does not actually cancel the underlying requests - they continue to execute.
*/ function asyncGeneratorStep(gen, resolve, reject, _next, _throw, key, arg) {
try {
var info = gen[key](arg);
var value = info.value;
} catch (error) {
reject(error);
return;
}
if (info.done) {
resolve(value);
} else {
Promise.resolve(value).then(_next, _throw);
}
}
function _async_to_generator(fn) {
return function() {
var self = this, args = arguments;
return new Promise(function(resolve, reject) {
var gen = fn.apply(self, args);
function _next(value) {
asyncGeneratorStep(gen, resolve, reject, _next, _throw, "next", value);
}
function _throw(err) {
asyncGeneratorStep(gen, resolve, reject, _next, _throw, "throw", err);
}
_next(undefined);
});
};
}
function _ts_generator(thisArg, body) {
var f, y, t, _ = {
label: 0,
sent: function() {
if (t[0] & 1) throw t[1];
return t[1];
},
trys: [],
ops: []
}, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() {
return this;
}), g;
function verb(n) {
return function(v) {
return step([
n,
v
]);
};
}
function step(op) {
if (f) throw new TypeError("Generator is already executing.");
while(g && (g = 0, op[0] && (_ = 0)), _)try {
if (f = 1, y && (t = op[0] & 2 ? y["return"] : op[0] ? y["throw"] || ((t = y["return"]) && t.call(y), 0) : y.next) && !(t = t.call(y, op[1])).done) return t;
if (y = 0, t) op = [
op[0] & 2,
t.value
];
switch(op[0]){
case 0:
case 1:
t = op;
break;
case 4:
_.label++;
return {
value: op[1],
done: false
};
case 5:
_.label++;
y = op[1];
op = [
0
];
continue;
case 7:
op = _.ops.pop();
_.trys.pop();
continue;
default:
if (!(t = _.trys, t = t.length > 0 && t[t.length - 1]) && (op[0] === 6 || op[0] === 2)) {
_ = 0;
continue;
}
if (op[0] === 3 && (!t || op[1] > t[0] && op[1] < t[3])) {
_.label = op[1];
break;
}
if (op[0] === 6 && _.label < t[1]) {
_.label = t[1];
t = op;
break;
}
if (t && _.label < t[2]) {
_.label = t[2];
_.ops.push(op);
break;
}
if (t[2]) _.ops.pop();
_.trys.pop();
continue;
}
op = body.call(thisArg, _);
} catch (e) {
op = [
6,
e
];
y = 0;
} finally{
f = t = 0;
}
if (op[0] & 5) throw op[1];
return {
value: op[0] ? op[1] : void 0,
done: true
};
}
}
var RequestManager = /*#__PURE__*/ function() {
function RequestManager() {
this.latestRequestId = 0;
}
var _proto = RequestManager.prototype;
/**
* Wraps a function to add request deduplication functionality.
* Only the most recent call to the wrapped function will return its result.
* Previous calls will return null (for successful requests) or be ignored (for failed requests).
* Note: The underlying requests are not cancelled - they continue to execute in the background.
* @param requestFn - The function to wrap
* @returns A wrapped function that ignores results from superseded requests
*/ _proto.wrap = function wrap(requestFn) {
var _this = this;
return function() {
for(var _len = arguments.length, args = new Array(_len), _key = 0; _key < _len; _key++){
args[_key] = arguments[_key];
}
return _async_to_generator(function() {
var currentRequestId, result, error;
return _ts_generator(this, function(_state) {
switch(_state.label){
case 0:
currentRequestId = ++this.latestRequestId;
_state.label = 1;
case 1:
_state.trys.push([
1,
3,
,
4
]);
return [
4,
requestFn.apply(void 0, [].concat(args))
];
case 2:
result = _state.sent();
// Only return result if this is still the latest request
if (currentRequestId === this.latestRequestId) {
return [
2,
result
];
} else {
// This request was superseded by a newer one, ignore the result
return [
2,
null
];
}
case 3:
error = _state.sent();
// Only throw error if this is still the latest request
if (currentRequestId === this.latestRequestId) {
throw error;
} else {
// This request was superseded by a newer one, ignore the error
return [
2,
null
];
}
case 4:
return [
2
];
}
});
}).call(_this);
};
};
return RequestManager;
}();
exports.RequestManager = RequestManager;
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