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https://issues.apache.org/jira/browse/THRIFT-4914?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17269948#comment-17269948
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Yuxuan Wang commented on THRIFT-4914:
-------------------------------------
[~dcelasun] After wrote https://github.com/apache/thrift/pull/2314, thinking
about it more, I'm starting to think that maybe we should make a bigger
breaking change to make TClient.Call return both THeaderMap and error.
The current 2 step way (first use Call, then use the helper function to get the
response header map), makes it impossible for a client pool implementation to
abstract the pool part away. Ideally we would want a client pool implementation
to just implement the Call function by getting a client from the pool, call its
Call, then return the client back to the pool (this is how we currently
implement client pool in
https://github.com/reddit/baseplate.go/blob/fe86cb54978d69b04f3d7817ef2cbdb2d3901ff3/thriftbp/client_pool.go#L484-L499,
but we do not support response headers currently). Making Call return both
resolves that problem.
Also making change to TClient.Call might not be as big as a breaking change as
we thought it would be. For most users they don't really interact with
TClient.Call directly. They create a TStandardClient, then feed that into the
client from thrift compiled code, and call the service methods instead of using
the low-level Call. So with this change, we just make a compiler change, so
that the compiled clients will just store the header part, and provide a
LastResponseHeaders (name tbd) function to return the stored header.
To give a concrete example, say we have a thrift service of:
{code}
service Service {
i32 add(1: i32 a, 2: i32 b)
}
{code}
Then users would just write go code like:
{code:go}
client := pkg.NewServiceClient(thrift.NewTStandardClient(...))
result, err := client.Add(a, b)
headers := client.LastResponseHeaders()
{code}
What do you think?
> Go: Link between THeader and context object
> -------------------------------------------
>
> Key: THRIFT-4914
> URL: https://issues.apache.org/jira/browse/THRIFT-4914
> Project: Thrift
> Issue Type: New Feature
> Components: Go - Library
> Reporter: Yuxuan Wang
> Priority: Major
> Fix For: 0.14.0
>
> Time Spent: 1h
> Remaining Estimate: 0h
>
> We have "raw" THeader support for Go in THRIFT-4612 now, the next step would
> be to make them more easily accessible.
> The are 2 directions, 4 parts of this ticket:
> * client -> server (requests)
> ** Read headers on server
> ** Write headers on client
> * server -> client (responses)
> ** Write headers on server
> ** Read headers on client
> Take the reading on server as an example. Currently we can read the headers
> from either the transport or the protocol, but neither the transport nor the
> protocol objects are "easily accessible" when you are writing the business
> logic code (writing the request handler in the server code). It would be much
> better if we inject the headers into the context object passed into the
> request handlers.
> We already have code injecting the headers to the context object that lives
> outside of the thrift library working. I'll send out a PR in the coming days
> to add that to the thrift library, so the performance would be better (we no
> longer need to do the extra injecting work), and it would be a lot easier to
> use.
> We'll think about how to best do the client writing part (probably auto read
> the headers from the context object that passed into the client request code,
> and write to THeaderProtocol automatically), and send out a PR soon-ish.
> The other direction, server -> client, is used much less often with headers,
> so we'll probably punt on it for now, and come back revisit them in the
> future.
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