Clean up SocketFinder.findSocket(...) handling

[sehrope]

Cleans up SocketFinder.findSocket(...) a bit and simplifies the logic for the simple case of a single address being resolved.

This changes some of the prior functionality though I wouldn't consider it a breaking change as it's not documented functionality and the new approach seems (to me) to be more correct. Previously if a host resolved to both IPv4 and IPv6 addresses, each set would get half the time out and the IPv4 addresses would be attempted first. This PR changes the logic to handle all IP addresses concurrently using the full timeout.

It also centralizes the logic for handling the case where there's a single address. Regardless of JVM type it now attempts to directly connect to it. This changes the behavior for the IBM JDK as previously it would have attempted the NIO approach followed by a normal socket creation upon success. Again this seems like a better choice as the overall logic is simpler and end result is the same.

This PR was coded atop #662. See there for more details on the parent change.

[codecov-io]

Codecov Report

Merging #663 into dev will decrease coverage by 0.15%.
The diff coverage is 12.5%.

@@             Coverage Diff              @@
##                dev     #663      +/-   ##
============================================
- Coverage     48.32%   48.16%   -0.16%     
- Complexity     2623     2625       +2     
============================================
  Files           113      113              
  Lines         26626    26609      -17     
  Branches       4480     4472       -8     
============================================
- Hits          12867    12817      -50     
- Misses        11601    11662      +61     
+ Partials       2158     2130      -28

Flag	Coverage Δ	Complexity Δ
#JDBC42	47.56% <12.5%> (-0.23%)	2571 <0> (-2)
#JDBC43	48.05% <12.5%> (-0.14%)	2623 <0> (+3)

Impacted Files	Coverage Δ	Complexity Δ
...in/java/com/microsoft/sqlserver/jdbc/IOBuffer.java	53.16% <12.5%> (-1.69%)	0 <0> (ø)
...om/microsoft/sqlserver/jdbc/SimpleInputStream.java	51.11% <0%> (-1.49%)	11% <0%> (-1%)
...om/microsoft/sqlserver/jdbc/SQLServerBulkCopy.java	52.55% <0%> (+0.06%)	240% <0%> (ø)	⬇️
...m/microsoft/sqlserver/jdbc/SQLServerResultSet.java	33.43% <0%> (+0.15%)	248% <0%> (+1%)	⬆️
...n/java/com/microsoft/sqlserver/jdbc/Parameter.java	62.68% <0%> (+0.2%)	63% <0%> (ø)	⬇️
...ncurrentlinkedhashmap/ConcurrentLinkedHashMap.java	38.79% <0%> (+0.64%)	43% <0%> (+1%)	⬆️
...c/main/java/com/microsoft/sqlserver/jdbc/Util.java	61.57% <0%> (+0.65%)	89% <0%> (+1%)	⬆️

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[ulvii]

Hi @sehrope ,
Thanks for the contribution. We decided to merge #662 for now, will review and test your changes for one of the upcoming releases.

[ulvii]

Hi @sehrope ,

Would you mind resolving the conflicts?

[sehrope]

@ulvii Done.

[sehrope]

One more rebase as dev has been updated since the last one.

[cheenamalhotra]

I agree with the advantage of having a generic implementation for IBM JDK and OpenJDK - which was differently done before, also using full timeout for all IP addresses instead of splitting half between IPv4 and IPv6 makes it better.