Method handle304

lib/handler/cache-handler.js:197–272

(cachedValue)

    // https://www.rfc-editor.org/rfc/rfc9111.html#name-handling-304-not-modified
    if (statusCode === 304) {
      const handle304 = (cachedValue) => {
        if (!cachedValue) {
          // Do not create a new cache entry, as a 304 won't have a body - so cannot be cached.
          return downstreamOnHeaders()
        }

        // Re-use the cached value: statuscode, statusmessage, headers and body
        value.statusCode = cachedValue.statusCode
        value.statusMessage = cachedValue.statusMessage
        value.etag = cachedValue.etag
        value.headers = { ...cachedValue.headers, ...strippedHeaders }

        downstreamOnHeaders()

        this.#writeStream = this.#store.createWriteStream(this.#cacheKey, value)

        if (!this.#writeStream || !cachedValue?.body) {
          return
        }

        if (typeof cachedValue.body.values === 'function') {
          const bodyIterator = cachedValue.body.values()

          const streamCachedBody = () => {
            for (const chunk of bodyIterator) {
              const full = this.#writeStream.write(chunk) === false
              this.#handler.onResponseData?.(controller, chunk)
              // when stream is full stop writing until we get a 'drain' event
              if (full) {
                break
              }
            }
          }

          this.#writeStream
            .on('error', function () {
              handler.#writeStream = undefined
              handler.#store.delete(handler.#cacheKey)
            })
            .on('drain', () => {
              streamCachedBody()
            })
            .on('close', function () {
              if (handler.#writeStream === this) {
                handler.#writeStream = undefined
              }
            })

          streamCachedBody()
        } else if (typeof cachedValue.body.on === 'function') {
          // Readable stream body (e.g. from async/remote cache stores)
          cachedValue.body
            .on('data', (chunk) => {
              this.#writeStream.write(chunk)
              this.#handler.onResponseData?.(controller, chunk)
            })
            .on('end', () => {
              this.#writeStream.end()