8350279: HttpClient: Add a new HttpResponse method to identify connections

[vy]

Adds HttpResponse::connectionLabel method that provides an identifier for the connection.

Implementation note: The feature is facilitated by HttpConnection::label, which should not be confused with HttpConnection::id. This distinction is explained in the JavaDoc of both properties.

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Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• Change requires CSR request JDK-8352751 to be approved

Issues

• JDK-8350279: HttpClient: Add a new HttpResponse method to identify connections (Enhancement - P4)
• JDK-8352751: HttpClient: Add a new HttpResponse method to identify connections (CSR)

Reviewing

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[bridgekeeper]

👋 Welcome back vyazici! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

❗ This change is not yet ready to be integrated.
See the Progress checklist in the description for automated requirements.

[openjdk]

@vy The following label will be automatically applied to this pull request:

• net

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[mlbridge]

Webrevs

• 02: Full - Incremental (a08c0cf1)
• 01: Full - Incremental (028999a7)
• 00: Full (2857dde0)

[dfuch]

/csr required

[openjdk]

@dfuch usage: /csr [needed|unneeded], requires that the issue the pull request refers to links to an approved CSR request.

[liach]

This new API returns an Optional.

1. Can users make any assumption about the connection identity when it is empty? Such as assuming such connections are all the same (as implied by your use of orElse(null) in tests) or all different?
2. If we cannot make any assumption about the empty return value, can users make any assumption that a HttpResponse obtained from the JDK built-in HttpClient always return non-empty for the label?

[vy]

/csr needed

[openjdk]

@vy has indicated that a compatibility and specification (CSR) request is needed for this pull request.

@vy please create a CSR request for issue JDK-8350279 with the correct fix version. This pull request cannot be integrated until the CSR request is approved.

[dfuch]

• Can users make any assumption about the connection identity when it is empty? Such as assuming such connections are all the same (as implied by your use of orElse(null) in tests) or all different?

No. If empty is returned you can make no assumptions. In practice this should never be null with our impl (except possibly in whitebox tests)

• If we cannot make any assumption about the empty return value, can users make any assumption that a HttpResponse obtained from the JDK built-in HttpClient always return non-empty for the label?

Yes.

[liach]

If we cannot make any assumption about the empty return value, can users make any assumption that a HttpResponse obtained from the JDK built-in HttpClient always return non-empty for the label?
Yes.

Should we specify this, like "The JDK built-in implementation of the {@code HttpClient} always assign a label to connections it create"?

[dfuch]

Should we specify this, like "The JDK built-in implementation of the {@code HttpClient} always assign a label to connections it create"?

Good question - that would be an @implNote - but I'm not sure this is required. The caller can determine whether a connection label is provided by testing whether the optional is empty.

[Michael-Mc-Mahon]

How about changing the wording to something like:

The format of the string is opaque, but the value will be fixed and unique for any connection, for the lifetime of its {@link HttpClient instance.

[dfuch]

How about:

The format of the string is opaque, but the value is fixed and unique for any connection in the scope of the associated {@link HttpClient} instance.