RFR 8215155: Remove get_insert() from concurrent hashtable and gtests

[Gerard Ziemski]

Hi all,

Please review this enhancement followup to JDK-8214310 and JDK-8213791

Here we redo the relevant gtest tests to use get(),insert() and are now free to remove the get_insert() API from the concurrent hash table implementation. 

bug id:  https://bugs.openjdk.java.net/browse/JDK-8215155
webrev:  http://cr.openjdk.java.net/~gziemski/8215155_rev1
Testing: Passed Mach hs_tier1, another Mach hs_tier1,2,3,4,5,6 in progress…

P.S. I’d like to push this into JDK12 if there is no contention about this fix…


Cheers