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| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 | import formatError from "../Core/formatError.js";
/**
* Creates an adapter function to allow a calculation function to operate as a Web Worker,
* paired with TaskProcessor, to receive tasks and return results.
*
* @function createTaskProcessorWorker
*
* @param {createTaskProcessorWorker.WorkerFunction} workerFunction The calculation function,
* which takes parameters and returns a result.
* @returns {createTaskProcessorWorker.TaskProcessorWorkerFunction} A function that adapts the
* calculation function to work as a Web Worker onmessage listener with TaskProcessor.
*
*
* @example
* function doCalculation(parameters, transferableObjects) {
* // calculate some result using the inputs in parameters
* return result;
* }
*
* return Cesium.createTaskProcessorWorker(doCalculation);
* // the resulting function is compatible with TaskProcessor
*
* @see TaskProcessor
* @see {@link http://www.w3.org/TR/workers/|Web Workers}
* @see {@link http://www.w3.org/TR/html5/common-dom-interfaces.html#transferable-objects|Transferable objects}
*/
function createTaskProcessorWorker(workerFunction) {
async function onMessageHandler({ data }) {
const transferableObjects = [];
const responseMessage = {
id: data.id,
result: undefined,
error: undefined,
};
self.CESIUM_BASE_URL = data.baseUrl;
try {
const result = await workerFunction(data.parameters, transferableObjects);
responseMessage.result = result;
} catch (error) {
if (error instanceof Error) {
responseMessage.error = {
name: error.name,
message: error.message,
stack: error.stack,
};
} else {
responseMessage.error = error;
}
}
if (!data.canTransferArrayBuffer) {
transferableObjects.length = 0;
}
try {
postMessage(responseMessage, transferableObjects);
} catch (error) {
// something went wrong trying to post the message, post a simpler
// error that we can be sure will be cloneable
responseMessage.result = undefined;
responseMessage.error = `postMessage failed with error: ${formatError(
error,
)}\n with responseMessage: ${JSON.stringify(responseMessage)}`;
postMessage(responseMessage);
}
}
function onMessageErrorHandler(event) {
postMessage({
id: event.data?.id,
error: `postMessage failed with error: ${JSON.stringify(event)}`,
});
}
self.onmessage = onMessageHandler;
self.onmessageerror = onMessageErrorHandler;
return self;
}
/**
* A function that performs a calculation in a Web Worker.
* @callback createTaskProcessorWorker.WorkerFunction
*
* @param {object} parameters Parameters to the calculation.
* @param {Array} transferableObjects An array that should be filled with references to objects inside
* the result that should be transferred back to the main document instead of copied.
* @returns {object} The result of the calculation.
*
* @example
* function calculate(parameters, transferableObjects) {
* // perform whatever calculation is necessary.
* const typedArray = new Float32Array(0);
*
* // typed arrays are transferable
* transferableObjects.push(typedArray)
*
* return {
* typedArray : typedArray
* };
* }
*/
/**
* A Web Worker message event handler function that handles the interaction with TaskProcessor,
* specifically, task ID management and posting a response message containing the result.
* @callback createTaskProcessorWorker.TaskProcessorWorkerFunction
*
* @param {object} event The onmessage event object.
*/
export default createTaskProcessorWorker;
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