Use void promise when sending

[no2chem]

Overview

Description: When calling write or writeAndFlush, our RPC layer isn't interested in the completion of the write. By using voidPromise(), we inform Netty that we aren't interested and resources don't need to be help pending the completion of the write.

Why should this be merged: This very minor change should reduce memory pressure and slightly improve performance because Netty no longer needs to track completions.

Checklist (Definition of Done):

• There are no TODOs left in the code
• Coding conventions (e.g. for logging, unit tests) have been followed
• Change is covered by automated tests
• Public API has Javadoc

[coveralls]

Changes Unknown when pulling 96a56af on NettyVoidPromise into ** on master**.

[corfudb-performance]

Results automatically generated by CorfuDB Benchmark Framework to assess the performance of this pull request for commit 96a56af.

*** 0.0% transaction FAILURE rate for NonConflictingTx+Scan workload, 1 threads, Disk mode
*** 0.0% transaction FAILURE rate for NonConflictingTx+Scan workload, 5 threads, Disk mode
*** 0.0% transaction FAILURE rate for NonConflictingTx+Scan workload, 10 threads, Disk mode
*** 0.0% transaction FAILURE rate for NonConflictingTx workload, 1 threads, Disk mode
*** 0.0% transaction FAILURE rate for NonConflictingTx workload, 5 threads, Disk mode
*** 0.0% transaction FAILURE rate for NonConflictingTx workload, 10 threads, Disk mode

An interactive dashboard with Pull Request Performance Metrics for ALL cluster types and numbers of threads in run, is available at:
Pull Request #1062 Graphs

[Maithem]

Less generated garbage. Good.
Just rebase.

[corfu-repo]

SonarQube analysis reported 1 issue

Note: The following issues were found on lines that were not modified in the pull request. Because these issues can't be reported as line comments, they are summarized here:

1. NettyClientRouter.java#L447: Replace the call to "Thread.sleep(...)" with a call to "wait(...)".

[codecov]

Codecov Report

Merging #1062 into master will increase coverage by 0.17%.
The diff coverage is 40%.

@@            Coverage Diff             @@
##           master    #1062      +/-   ##
==========================================
+ Coverage   65.62%   65.79%   +0.17%     
==========================================
  Files         214      214              
  Lines        9970     9970              
  Branches      985      985              
==========================================
+ Hits         6543     6560      +17     
+ Misses       3043     3034       -9     
+ Partials      384      376       -8

Impacted Files	Coverage Δ
.../org/corfudb/infrastructure/NettyServerRouter.java	54.66% <100%> (ø)	⬆️
...org/corfudb/runtime/clients/NettyClientRouter.java	71.21% <25%> (ø)	⬆️
.../org/corfudb/protocols/wireprotocol/IMetadata.java	84.05% <0%> (-2.9%)	⬇️
...main/java/org/corfudb/runtime/view/LayoutView.java	85.6% <0%> (+0.75%)	⬆️
.../runtime/view/stream/AbstractQueuedStreamView.java	80.98% <0%> (+1.4%)	⬆️
...a/org/corfudb/infrastructure/ManagementServer.java	78.16% <0%> (+2.29%)	⬆️
...runtime/view/stream/AbstractContextStreamView.java	64.28% <0%> (+2.38%)	⬆️
...va/org/corfudb/runtime/view/SealServersHelper.java	82.6% <0%> (+2.89%)	⬆️
.../infrastructure/management/PeriodicPollPolicy.java	92.3% <0%> (+3.29%)	⬆️
...g/corfudb/runtime/object/StreamViewSMRAdapter.java	66.66% <0%> (+3.92%)	⬆️
... and 1 more

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