And it's possible that for your use case, the solution is in one of them.

## Read the Tutorial first

You could still use most of the features in **FastAPI** with the knowledge from the main [Tutorial - User Guide](../tutorial/index.md){.internal-link target=_blank}.

And the next sections assume you already read it, and assume that you know those main ideas.

## External Courses

    /** The next byte to read. This is always less than or equal to [upstreamPos]. */
    private var sourcePos = 0L

    /**
     * Selects where to find the bytes for a read and read them. This is one of three sources.
     *
     * ## Upstream
     *
     * In this case the current thread is assigned as the upstream reader. We read bytes from

      }

      val read = super.read(sink, minOf(byteCount, bytesRemainingInChunk))
      if (read == -1L) {
        carrier.noNewExchanges() // The server didn't supply the promised chunk length.
        val e = ProtocolException("unexpected end of stream")
        responseBodyComplete()
        throw e
      }
      bytesRemainingInChunk -= read
      return read
    }

 - **CacheHit**
 - CallEnd
 
### Cache Miss

Under a cache miss the normal request events are seen but an additional event shows the presence of the cache.
Cache Miss will be typical if the item has not been read from the network, is uncacheable, or is past it's 
lifetime based on Response cache headers.

 - CallStart 
 - **CacheMiss**
 - ProxySelectStart
 - ... Standard Events ...
 - CallEnd
        

# Code of Conduct

      object : Source {
        var closed = false

        override fun close() {
          closed = true
        }

        override fun read(
          sink: Buffer,
          byteCount: Long,
        ): Long {
          check(!closed)
          return data.read(sink, byteCount)
        }

        override fun timeout(): Timeout {
          return Timeout.NONE
        }
      }

Please read the [Development - Contributing](https://fastapi.tiangolo.com/contributing/) guidelines in the documentation site....

* `write(data)`: Writes `data` (`str` or `bytes`) to the file.
* `read(size)`: Reads `size` (`int`) bytes/characters of the file.
* `seek(offset)`: Goes to the byte position `offset` (`int`) in the file.
    * E.g., `await myfile.seek(0)` would go to the start of the file.
    * This is especially useful if you run `await myfile.read()` once and then need to read the contents again.
* `close()`: Closes the file.

      object : Source {
        private var cacheRequestClosed = false

        @Throws(IOException::class)
        override fun read(
          sink: Buffer,
          byteCount: Long,
        ): Long {
          val bytesRead: Long
          try {
            bytesRead = source.read(sink, byteCount)
          } catch (e: IOException) {
            if (!cacheRequestClosed) {
              cacheRequestClosed = true

    taskFaker.runTasks()
    assertThat(client.closed).isFalse()
    server.processNextFrame() // Read client closing, send server close.
    server.listener.assertClosing(1000, "Hello!")
    server.webSocket!!.finishReader()
    server.webSocket!!.close(1000, "Goodbye!")
    client.processNextFrame() // Read server closing, close connection.
    taskFaker.runTasks()
    client.listener.assertClosing(1000, "Goodbye!")