[Plasma] Move heap allocations to arrow memory pool

[asfimport]

At the moment we are allocating memory with std::vectors and even new in some places, this should be cleaned up.

Reporter: Philipp Moritz / @pcmoritz

_{Note: This issue was originally created as ARROW-1266. Please see the migration documentation for further details.}

[asfimport]

Wes McKinney / @wesm:
@pcmoritz is this still a problem?

[asfimport]

Philipp Moritz / @pcmoritz:
At a quick glance, the only structure that is still allocated with new is GetRequest here:

arrow/cpp/src/plasma/store.cc

Line 404 in 0c55b25

auto get_req = new GetRequest(client, object_ids);

The control flow is pretty clear and it is deleted here:

arrow/cpp/src/plasma/store.cc

Line 296 in 0c55b25

delete get_request;

However if somebody wants to make it a unique_ptr or shared_ptr ( @suquark?) I wouldn't mind.

[asfimport]

Wes McKinney / @wesm:
I think the question might be more APIs like

https://github.com/apache/arrow/blob/master/cpp/src/plasma/io.h#L55

Maybe the data allocated is not large enough to be meaningful. But it is worth knowing for sure.

Moving this to 0.14 as it is not actively causing a problem

[asfimport]

Antoine Pitrou / @pitrou:
According to previous comments, there's no significant heap allocation that goes through the system allocator.