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let Status = {
SUCCESS_HEADER: -1,
SUCCESS_EOF: -2,
ERROR_TIMEOUT: -3,
ERROR_EXCEPTION: -4,
};
let connections = {};
let nextConnectionID = 1;
const encoder = new TextEncoder();
self.addEventListener("message", async function (event) {
if (event.data.close) {
let connectionID = event.data.close;
delete connections[connectionID];
return;
} else if (event.data.getMore) {
let connectionID = event.data.getMore;
let { curOffset, value, reader, intBuffer, byteBuffer } =
connections[connectionID];
// if we still have some in buffer, then just send it back straight away
if (!value || curOffset >= value.length) {
// read another buffer if required
try {
let readResponse = await reader.read();
if (readResponse.done) {
// read everything - clear connection and return
delete connections[connectionID];
Atomics.store(intBuffer, 0, Status.SUCCESS_EOF);
Atomics.notify(intBuffer, 0);
// finished reading successfully
// return from event handler
return;
}
curOffset = 0;
connections[connectionID].value = readResponse.value;
value = readResponse.value;
} catch (error) {
console.log("Request exception:", error);
let errorBytes = encoder.encode(error.message);
let written = errorBytes.length;
byteBuffer.set(errorBytes);
intBuffer[1] = written;
Atomics.store(intBuffer, 0, Status.ERROR_EXCEPTION);
Atomics.notify(intBuffer, 0);
}
}
// send as much buffer as we can
let curLen = value.length - curOffset;
if (curLen > byteBuffer.length) {
curLen = byteBuffer.length;
}
byteBuffer.set(value.subarray(curOffset, curOffset + curLen), 0);
Atomics.store(intBuffer, 0, curLen); // store current length in bytes
Atomics.notify(intBuffer, 0);
curOffset += curLen;
connections[connectionID].curOffset = curOffset;
return;
} else {
// start fetch
let connectionID = nextConnectionID;
nextConnectionID += 1;
const intBuffer = new Int32Array(event.data.buffer);
const byteBuffer = new Uint8Array(event.data.buffer, 8);
try {
const response = await fetch(event.data.url, event.data.fetchParams);
// return the headers first via textencoder
var headers = [];
for (const pair of response.headers.entries()) {
headers.push([pair[0], pair[1]]);
}
let headerObj = {
headers: headers,
status: response.status,
connectionID,
};
const headerText = JSON.stringify(headerObj);
let headerBytes = encoder.encode(headerText);
let written = headerBytes.length;
byteBuffer.set(headerBytes);
intBuffer[1] = written;
// make a connection
connections[connectionID] = {
reader: response.body.getReader(),
intBuffer: intBuffer,
byteBuffer: byteBuffer,
value: undefined,
curOffset: 0,
};
// set header ready
Atomics.store(intBuffer, 0, Status.SUCCESS_HEADER);
Atomics.notify(intBuffer, 0);
// all fetching after this goes through a new postmessage call with getMore
// this allows for parallel requests
} catch (error) {
console.log("Request exception:", error);
let errorBytes = encoder.encode(error.message);
let written = errorBytes.length;
byteBuffer.set(errorBytes);
intBuffer[1] = written;
Atomics.store(intBuffer, 0, Status.ERROR_EXCEPTION);
Atomics.notify(intBuffer, 0);
}
}
});
self.postMessage({ inited: true });

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