Avoid cloning values during reduce #347
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`reduce_core` was previously forced to clone the output data before presenting it to the logic function for inspection. Simply annotating the type with a reference was not possible due to the buffer being held in the same struct as some of the data it contained, making it a self-referencial struct which the borrow checker doesn't allow. However, the only reason this buffer was held in the same struct was to reuse its allocation. This patch therefore creates a brand new vector every time we need to process data that contains references instead of cloned data. The expectation is that in the general case it's better to allocate a vector of references than clone a bunch of values. Signed-off-by: Petros Angelatos <[email protected]>
This patch brings back the benefits of re-using the output buffer allocation at the cost of some unsafe code reasoning. Since the buffer is always cleared after each use we can simply store its type erased pointer and temporarily bring it back to its Vec form whenever there is some processing to do. Signed-off-by: Petros Angelatos <[email protected]>
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This PR can be merged as-is or only its first commit depending on the type of trade-off we want to do:
computeis invoked. The expectation is that in most cases it makes sense to do one allocation for references than copy potentially complicated value types.