[WINDOWS] - MappedByteBuffer.force is extremely slow on Windows

[simerplaha]

val buffer: MappedByteBuffer = ...
buffer.force() //expensive

The force function is costly on Windows. This function is needed to guarantee memory-mapped writes are flushed to disk to recover from fatal machine crashes. But forcing this function for all use-cases is probably not needed so we can make this configurable. Currently force is invoked right before a memory-mapped file is closed (Pre-close) but this can be deferred to background threads that manage clearing and deleting memory-mapped files. I'm thinking the following configurations would cover all use-cases. Another option to log out time taken by force for benchmarking/debugging might be useful.

• Disabled - disables force
• Pre-close - invokes force before the mmap file is closed
• Pre-clear - invokes force before the mmap file's MappedByteBuffer is cleared from memory.
• Pre-delete - invoked force before deleting a mmap file.