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Joe Tsai c27efce66b compress/flate: make Reader.Read return io.EOF eagerly
Rather than checking the block final bit on the next invocation
of nextBlock, we check it at the termination of the current block.
This ensures that we return (n, io.EOF) instead of (0, io.EOF)
more frequently for most streams.

However, there are certain situations where an eager io.EOF is not done:
1) We previously returned from Read because the write buffer of the internal
dictionary was full, and it just so happens that there is no more data
remaining in the stream.
2) There exists a [non-final, empty, raw block] after all blocks that
actually contain uncompressed data. We cannot return io.EOF eagerly here
since it would break flushing semantics.

Both situations happen infrequently, but it is still important to note that
this change does *not* guarantee that flate will *always* return (n, io.EOF).

Furthermore, this CL makes no changes to the pattern of ReadByte calls
to the underlying io.ByteReader.

Below is the motivation for this change, pulling the text from
@bradfitz's CL/21290:

net/http and other things work better when io.Reader implementations
return (n, io.EOF) at the end, instead of (n, nil) followed by (0,
io.EOF). Both are legal, but the standard library has been moving
towards n+io.EOF.

An investigation of net/http connection re-use in
https://github.com/google/go-github/pull/317 revealed that with gzip
compression + http/1.1 chunking, the net/http package was not
automatically reusing the underlying TCP connections when the final
EOF bytes were already read off the wire. The net/http package only
reuses the connection if the underlying Readers (many of them nested
in this case) all eagerly return io.EOF.

Previous related CLs:
    https://golang.org/cl/76400046 - tls.Reader
    https://golang.org/cl/58240043 - http chunked reader

In addition to net/http, this behavior also helps things like
ioutil.ReadAll (see comments about performance improvements in
https://codereview.appspot.com/49570044)

Updates #14867
Updates google/go-github#317

Change-Id: I637c45552efb561d34b13ed918b73c660f668378
Reviewed-on: https://go-review.googlesource.com/21302
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2016-03-31 22:19:12 +00:00
.github doc: update issue template 2016-03-09 00:52:16 +00:00
api api: update next.txt 2016-03-21 07:46:44 +00:00
doc doc: GCC 6 will have the Go 1.6 user libraries 2016-03-11 00:03:15 +00:00
lib/time misc: update timezone database to IANA 2016a 2016-02-03 03:14:59 +00:00
misc misc/cgo/testcarchive: more robust TestSignalForwardingExternal 2016-03-26 02:40:12 +00:00
src compress/flate: make Reader.Read return io.EOF eagerly 2016-03-31 22:19:12 +00:00
test cmd/compile: better job of naming compound types 2016-03-31 22:18:26 +00:00
.gitattributes .gitattributes: prevent all magic line ending changes 2014-12-12 23:14:54 +00:00
.gitignore .gitignore: ignore src/go/build/zcgo.go 2016-02-24 04:25:46 +00:00
AUTHORS A+C: manual updates 2016-01-08 06:02:39 +00:00
CONTRIBUTING.md doc: use new Gerrit URL and mention our instance in CONTRIBUTING.md 2016-03-09 00:52:42 +00:00
CONTRIBUTORS A+C: manual updates 2016-01-08 06:02:39 +00:00
favicon.ico godoc: update favicon 2012-10-11 17:02:36 +11:00
LICENSE doc: update licensing text one more time 2012-03-27 15:09:13 +11:00
PATENTS
README.md readme: emphasize issue tracker is for bugs/proposals 2015-10-02 18:44:14 +00:00
robots.txt

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