cod-dicomweb-server
Version:
A wadors server proxy that get data from a Cloud Optimized Dicom format.
84 lines (83 loc) • 3.51 kB
JavaScript
import { CustomError } from '../../classes/customClasses';
import { createStreamingFileName, readFile, writeFile } from '../../fileAccessSystemUtils';
const fileStreaming = {
async stream(args, callBack) {
const { url, headers, useSharedArrayBuffer, directoryHandle } = args;
const controller = new AbortController();
let sharedArraybuffer = null;
let fileArraybuffer = null;
try {
const fileName = createStreamingFileName(url);
if (directoryHandle) {
const file = (await readFile(directoryHandle, fileName, { isJson: false }));
if (file) {
const totalLength = file.byteLength;
callBack({ url, position: totalLength, fileArraybuffer: new Uint8Array(file), totalLength });
return;
}
}
const response = await fetch(url, {
headers: { ...headers },
signal: controller.signal
});
if (!response.ok) {
throw new CustomError(`HTTP error! status: ${response.status}`);
}
const reader = response.body?.getReader();
if (!reader) {
throw new CustomError('Failed to get reader from response body');
}
let result;
let completed = false;
const totalLength = parseInt(response.headers.get('Content-Length') || '0', 10);
const firstChunk = await reader.read();
completed = firstChunk.done;
if (!firstChunk.value) {
throw new CustomError('The fetched chunks does not have value');
}
if (!completed) {
let position = firstChunk.value.length;
if (useSharedArrayBuffer) {
sharedArraybuffer = new SharedArrayBuffer(totalLength);
fileArraybuffer = new Uint8Array(sharedArraybuffer);
}
else {
fileArraybuffer = new Uint8Array(totalLength);
}
fileArraybuffer.set(firstChunk.value);
callBack({ url, position, fileArraybuffer, totalLength });
while (!completed) {
result = await reader.read();
if (result.done) {
completed = true;
continue;
}
const chunk = result.value;
fileArraybuffer.set(chunk, position);
position += chunk.length;
callBack({
isAppending: true,
url,
position: position,
chunk: !useSharedArrayBuffer ? chunk : undefined,
totalLength
});
}
if (directoryHandle) {
writeFile(directoryHandle, fileName, fileArraybuffer.slice().buffer);
}
}
}
catch (error) {
const streamingError = new CustomError('fileStreaming.ts: ' + error.message || 'An error occured when streaming');
console.error(streamingError.message, error);
throw streamingError;
}
finally {
sharedArraybuffer = null;
fileArraybuffer = null;
controller.abort();
}
}
};
export default fileStreaming;