shashank created CAMEL-25656:
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Summary: camel-netty-http - available() of the request body stream
cache (NettyChannelBufferStreamCache) always returns 0 although the whole body
is in memory
Key: CAMEL-25656
URL: https://issues.apache.org/jira/browse/CAMEL-25656
Project: Camel
Issue Type: Improvement
Components: camel-netty-http
Reporter: shashank
Assignee: shashank
Follow-up requested in the review of the merged PR
[#27757|https://github.com/apache/camel/pull/27757] (CAMEL-25573).
{{NettyChannelBufferStreamCache}} holds the whole request body in a Netty
{{ByteBuf}} and is an {{InputStream}}, but it does not override
{{available()}}, so it falls back to the {{InputStream}} default and returns 0
(main 1de5ec5135f8: no {{available()}} in the class; {{length()}} at line 118
already returns {{buffer.readableBytes()}}). Returning 0 is allowed by the
contract, but readers that use {{available()}} get less than they could:
{{IOHelper.copy}} sizes its buffer from it, and
{{java.util.zip.GZIPInputStream}} has used it to decide whether another gzip
member follows (the reviewer's example; in the sources of JDK 21.0.11
{{GZIPInputStream}} does not call it, JDK 17 not checked).
h3. Proposed change
{{available()}} returns {{buffer.readableBytes()}}: the bytes left to read
without blocking, 0 at the end, the full length again after {{reset()}}.
h3. Test
New test {{availableIsTheNumberOfBytesLeft}} in
{{NettyChannelBufferStreamCacheTest}}: a 5-byte body in a buffer of capacity
16, {{available()}} after each read and after {{reset()}}. Without the change:
{{expected: <5> but was: <0>}}. camel-netty-http with the change: 313 tests, 0
failures, 8 skipped.
Camel's own copies of this stream are not affected: the two-argument
{{IOHelper.copy}} (used by {{writeTo}} and the type converters) goes through
{{transferTo}} and does not call {{available()}}; only the overloads that take
a buffer size read it, and their only core caller ({{CachedOutputStream}})
passes its own cache.
Affected: main, camel-4.23.x, camel-4.22.x and camel-4.18.x (no {{available()}}
in the class on any of them): read, not run. Not a user-visible failure; an
improvement of the stream contract.
_Filed with Claude Code on behalf of allthingssecurity._
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