Function uploadPart

apps/sim/lib/uploads/client/direct-upload.ts:436–482

({ partNumber, url }: PartUrl)

  try {
    const uploadPart = async ({ partNumber, url }: PartUrl): Promise<CompletedPart> => {
      const start = (partNumber - 1) * CHUNK_SIZE
      const end = Math.min(start + CHUNK_SIZE, file.size)
      const chunk = file.slice(start, end)

      for (let attempt = 0; attempt <= MULTIPART_MAX_RETRIES; attempt++) {
        try {
          const partResponse = await fetch(url, {
            method: 'PUT',
            body: chunk,
            signal,
            headers: { 'Content-Type': getFileContentType(file) },
          })

          if (!partResponse.ok) {
            throw new DirectUploadError(
              `Failed to upload part ${partNumber}: ${partResponse.statusText}`,
              'MULTIPART_ERROR',
              undefined,
              partResponse.status
            )
          }

          const etag = partResponse.headers.get('ETag') || undefined
          completedBytes[partNumber - 1] = end - start
          reportProgress()

          return { partNumber, etag: etag?.replace(/"/g, '') }
        } catch (partError) {
          const isClientError =
            partError instanceof DirectUploadError &&
            partError.status !== undefined &&
            partError.status >= 400 &&
            partError.status < 500
          if (isAbortError(partError) || isClientError || attempt >= MULTIPART_MAX_RETRIES) {
            throw partError
          }
          const delay = MULTIPART_RETRY_DELAY_MS * MULTIPART_RETRY_BACKOFF ** attempt
          logger.warn(
            `Part ${partNumber} failed (attempt ${attempt + 1}), retrying in ${Math.round(delay / 1000)}s`
          )
          await sleep(delay)
        }
      }

      throw new DirectUploadError(`Retries exhausted for part ${partNumber}`, 'MULTIPART_ERROR')
    }

    const partResults = await runWithConcurrency(
      presignedUrls,