Revert the deprecation of set in SyncVar

[scabug]

For some very strange reason the set method of SyncVar has been marked for deprecation. Please remove the deprecation and do not deprecate the set method.

The set method is what makes SyncVar a var in the first place. If the SyncVar only has put, then it will effectively become a size 1 bounded queue and is no longer a variable.

SyncVar needs to act like a variable. There must be a way to set the variable twise without reading or clearing it in between.

It must support the following flow:

• Thread 1 set variable to "a"
• Thread 1 set variable to "b" (discards value "a")
• Thread 2 read variable, get value "b"
• Thread 1 set variable to "c" (discards value "b")
• Thread 1 set variable to "d" (discards value "c")
• Thread 2 read variable, get value "d"

Alternatively stop calling it a SyncVar, and rename it to BoundedQueue1

[scabug]

Imported From: https://issues.scala-lang.org/browse/SI-7308?orig=1
Reporter: Heikki Vesalainen (hvesalai)
Affected Versions: 2.10.1

[SethTisue]

@hvesalai do you have a link to the PR that did the deprecation? curious about the history here

[NthPortal]

This issue needs to be resolved before scala/scala#6319 is merged, because this commit in that PR removes set and unset

[NthPortal]

It was deprecated in scala/scala#560, which fixed #5623

[hvesalai]

@SethTisue I must say I have no recollection about this. Furthermore I grepped SyncVar from our code and we are not using it any more, so I have no vested interest. I think everybody is using the java atomic stuff.

[lrytz]

Maybe @heathermiller has some memory of this (why were set and unset on SyncVar deprecated in scala/scala#560)?

[NthPortal]

Do we just close this as won't fix, at this point?

[SethTisue]

I'm just about to that point... let's do one last thing, let's rub @viktorklang's lamp and see if he appears