chunked encoding + GZIP prevents keep-alive

[eddavisson]

GZIPInputStream.read() starts returning -1 once it finishes reading the gzip trailer. Depending on the underlying InputStream, this may occur before it has finished consuming the underlying InputStream.

In particular, if the underlying InputStream is a ChunkedInputStream, the ChunkedInputStream never reads the final chunk header (which indicates a chunk of length 0).

When ChunkedInputStream.close() is called, it is in a non-STATE_DONE state, and does not call HttpClient.finished(), which is required for the HttpClient object to get into the keep alive cache.

One possible fix is here:
https://github.com/google/google-http-java-client/blob/acdaeacc3c43402d795266d2ebcb584abe918961/google-http-client/src/main/java/com/google/api/client/http/HttpResponse.java#L363

Rather than returning a GZIPInputStream, return a proxy input stream that retains references to both the gzip stream and the underlying stream. The proxy's close() method first consumes the underlying stream by calling read() and then calls close() on the gzip stream.

[eddavisson]

It's possible this only applies for some HttpTransport types. For example, Apache's ChunkedInputStream.close() method indicates that it will consume the rest the stream automatically:
https://hc.apache.org/httpclient-3.x/apidocs/org/apache/commons/httpclient/ChunkedInputStream.html#close()

[wsh]

We've worked around this in our code for now, but it's definitely worth fixing in the underlying library. 😄