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