Returns writeable copy of current chunk snapshot.
This buffer is valid until commit.
After commit this buffer becomes next immutable snapshot.
Returns null if chunk is not added and/or not loaded.
If write buffer was not yet created then it is created based on policy.
BUG: returned pointer points inside hash table.
If new write buffer is added hash table can reallocate.
Do not use more than one write buffer at a time.
Reallocation can prevent changes to buffers obtained earlier than reallocation to be invisible.
Returns writeable copy of current chunk snapshot. This buffer is valid until commit. After commit this buffer becomes next immutable snapshot. Returns null if chunk is not added and/or not loaded. If write buffer was not yet created then it is created based on policy. BUG: returned pointer points inside hash table. If new write buffer is added hash table can reallocate. Do not use more than one write buffer at a time. Reallocation can prevent changes to buffers obtained earlier than reallocation to be invisible.