Implements an ArrowRootAllocationProvider SPI

[drewfarris]

Other utilities that run within Emissary would benefit from a central source for getting access to an Arrow RootAllocator. This PR implements the ArrowRootAllocationProvider that creates a new RootAllocator and provides a static method for retrieving that instance. It also properly handles calling close() on the allocator at shutdown time. It can be initialized by including it in the META-INF/service/emissary.spi.InitializationProvider resource file.

In the current state, we leave it up to the consumer to decide whether to create a child allocator using the reference to the root allocator, or to use the root allocator directly. We could decide to force consumers to create child allocators instead of providing references to the root allocator, but I'm not convinced that it is worth doing that at this point.

See also:

• Arrow Java documentation on Memory Management
• Arrow RootAllocator javadoc

[drewfarris]

I'm not totally certain this is the best way to approach this, but it's a good point for discussion

[drewfarris]

This is marked outdated because I moved the exclusion to the dependencyManagement section, but it's still relevant to discuss.

[drewfarris]

This may need additional work. After doing some brief testing, if someone creates a child allocator from the root allocator, and that child allocator is not properly closed, calling shutdown on the provider seems to raise an IllegalStateException. Changing this to a draft PR in the meantime.

[drewfarris]

This may need additional work. After doing some brief testing, if someone creates a child allocator from the root allocator, and that child allocator is not properly closed, calling shutdown on the provider seems to raise an IllegalStateException. Changing this to a draft PR in the meantime.

The latest revision addresses this.