Graph function framework

[andyfengHKU]

No description provided.

[semihsalihoglu-uw]

I have a bunch of comments. We can discuss later today. Here is one other comment I have:

I saw the following in function.h:

    // Currently we only one variable-length function which is list creation. The expectation is
    // that all parameters must have the same type as parameterTypes[0].

• First there is a typo here. we only one -> we only have one
• Second, what is a variable-length function?
• Third, is the comment still accurate? That is do we still have 1 variable-length function.

[semihsalihoglu-uw]

I don't think we need a shared state because AlgorithmCall operator should not be sharing its state with any other operators, at least in the current design, right? This is a sink operator that should write data to FactorizedTable, or at least for now. See my other comments.

We can keep a separate "graph" and FactorizedTable" fields, which are currently wrapped in AlgorithmSharedState, as part of the Algorithm interface (assuming we want to provide those as part of the Algorithm interface). But we don't need to have a notion of a SharedState yet.

[semihsalihoglu-uw]

Factorized Table: Given that we will force users to indicate the schema of their output for binding purposes, we should also do the work of constructing the factorized table's schema on behalf of algorithm designer, so users can assume that by the time their Algorithm code is running, they have a factorized table that is consistent with the schema they defined. We could do this inside AlgorithmCall:initLocalStateInternal function, which could call super:initLocalStateInternal (or C++ equivalent of this) to let the implementing algorithm, e.g., PRAlgorithm to continue initializing local state internal.

In fact, we can wrap FactorizedTable around a new class, ImmutableSchemaFactorizedTable class, which has AlgorithmCall as a friend class, so that AlgorithmCall implementers, e.g., PRAlgorithm cannot further modify the schema of FactorizedTable.

[semihsalihoglu-uw]

Would be good if I took another quick look.