RFR: 8288330: Avoid redundant ConcurrentHashMap.get call in Http2ClientImpl.deleteConnection

[Andrey Turbanov]

On Thu, 9 Jun 2022 21:08:35 GMT, Andrey Turbanov <aturbanov at openjdk.org> wrote:

> https://github.com/openjdk/jdk/blob/900d967da52afca9b239d8a58aa81b48b9fe0a78/src/java.net.http/share/classes/jdk/internal/net/http/Http2ClientImpl.java#L191-L196
> 
> Method `Http2ClientImpl.deleteConnection` removes `Http2Connection` from `ConcurrentHashMap` if it's present in the map. It does it with 2 steps: first invoke `ConcurrentHashMap.get` and then check if result of `get` is equals to parameter.
> 
> We can do better: there is single method `ConcurrentHashMap.remove(Key, Value)` which does the same thing, but faster.
> 
> Testing: `test/jdk/java/net/httpclient` on Win x64 release.

src/java.net.http/share/classes/jdk/internal/net/http/Http2ClientImpl.java line 190:

> 188:         if (debug.on())
> 189:             debug.log("removing from the connection pool: %s", c);
> 190:         synchronized (this) {

BTW, this `synchronized` seems redundant now too.

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PR: https://git.openjdk.org/jdk/pull/9114