[bindings/go] Remove finalizers in favor of copying and destroying the native resources immediately

[ryanworl]

Fixes #1340

Except for futureKeyValueArray, all futures which allocate native heap resources (other than the futures themselves) now allocate Go resources and copy from native to Go, then destroy the native heap resources.

This adds an explicit Close() function to RangeIterator which users should call.

I also added an optimization for futureKeyValueArray which allocates one large []byte for the result of each batch and subdivides within that instead of allocating individual []byte for each key and value.

I haven't evaluated this much yet, so I'd like to do that before merging. I'll comment once I have.

Not ready yet.

[alexmiller-apple]

@fdb-build, ok to test

[ryanworl]

@alexmiller-apple is there a reason I can’t view the CI logs?

[alexmiller-apple]

@ryanworl, according to @AlvinMooreSr, we started getting throttled by bintray on uploading them, and the jury is out on when they'll unthrottle us. So it's a known our-side problem for now.

Documentation:

13:13:43 Warning, treated as error:
13:13:43 /foundationdb/documentation/sphinx/source/release-notes.rst:49: ERROR: Broken role invoked

CMake MacOS:

13:14:16 [ 64%] Built target fdb_flow_tester
13:14:16 # github.com/apple/foundationdb/bindings/go/src/fdb
13:14:16 src/github.com/apple/foundationdb/bindings/go/src/fdb/futures.go:370:13: could not determine kind of name for C.fdb_future_get_version
13:14:16 make[2]: *** [bindings/go/pkg/darwin_amd64/github.com/apple/foundationdb/bindings/go/src/fdb.a] Error 2
13:14:16 make[1]: *** [bindings/go/CMakeFiles/fdb_go.dir/all] Error 2

and MacOS is a known issue on all PRs right now.

[alexmiller-apple]

@fdb-build, test macos please

[ryanworl]

That one is a real error from my bringing my changes from 610 to 620.

[vishesh]

I would suggest using once instead of o (once.Do reads much better) and err instead of e in field names (I see err used at other parts of this file). I dunno what v is, which probably is good indicator that it should be renamed too.

[ryanworl]

In that case, it is the value the future will resolve with.

I agree with your assessment about the names, but I don’t know if this PR is the place to resolve it.

[vishesh]

Ah ok. I missed that it was that way already in other part of codebase.

[alexmiller-apple]

@ryanworl, we're going to be cutting the 7.0 release sometime over the next few weeks. If you're still interested in working on this, and would like it to get into the 7.0 release, then it'd be good to work towards getting it merged within a couple weeks.

[vishesh]

@fdb-build, test cmake please

[vishesh]

@fdb-build test ctest please

[vishesh]

@fdb-build, test cmake macos please

[vishesh]

@fdb-build, test ctest please