spec: support composite query #420
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spec/Candid.md
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| A function type describes the list of parameters and results and their respective types. It can optionally be annotated to be *query*, *composite_query* or *oneway*. | ||
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| * `query` indicates that the function does not modify any state and can potentially be executed more efficiently (e.g., on cached state). | ||
| * `composite_query` is a special `query` function that cannot be called in inter-canister calls. The composite query function can call other query and composite query functions on the same subnet. |
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cannot be called in inter-canister calls
I think it should be "cannot be called by update methods" because it is possible to make an inter-canister composite query call.
Could you please also add that the restriction about the "update method" and "same subnet" are due to the incompleteness of current implementation and may be lifted in the future?
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I am approving assuming this comment will be addressed.
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may be lifted in the future
Lifting all restrictions means we will have just the query method, and no composite query method, or it's the other way around?
Candid spec is quite high level, and tries to be platform agnostic. See the paragraph above about query method. It's only suggesting that query method can be more efficient. I prefer to describe composite query without mentioning subnet, but seems like it's not easy?
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Sorry for the delay. I thought I've replied already, but don't see my reply here.
Lifting all restrictions means we will have just the query method, and no composite query method, or it's the other way around?
Query and composite query will become the same thing:
- query will be able to call query and composite query
- composite query will be callable from an update
Candid spec is quite high level, and tries to be platform agnostic. See the paragraph above about query method. It's only suggesting that query method can be more efficient.
It seems inconsistent that we mention limitations of composite queries without mentioning the main limitation of query: it cannot call any other methods.
If we want to stay platform agnostic, then maybe we should write something more vague: "composite query is a kind of a query with additional platform-specific features and limitations"?
That's said, my personal preference would be to be more pragmatic and mention all information that might be useful for the users (maybe with some comment that it only applies to IC):
- composite queries can be called only from other composite queries.
- composite queries can call composite queries and queries.
- composite query calls cannot be made cross-subnets.
- queries cannot call any other methods.
All these limitations are temporary due to the implementation.
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I made another pass. PTAL.
composite queries can be called only from other composite queries.
It can also be called outside of IC.
queries cannot call any other methods.
There used to be a hack that a query function can call another terminating query function. Is this being removed?
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Thanks, the latest version lgtm!
There used to be a hack that a query function can call another terminating query function. Is this being removed?
Do you mean ICQC on system and verified application subnets? There non-replicated queries can call other queries on the same subnet. That is exactly what we are packaging as composite_query and releasing on all subnets.
Right now, queries on application subnets cannot call any other queries (terminating or not).
spec/Candid.md
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| A function type describes the list of parameters and results and their respective types. It can optionally be annotated to be *query*, *composite_query* or *oneway*. | ||
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| * `query` indicates that the function does not modify any state and can potentially be executed more efficiently (e.g., on cached state). | ||
| * `composite_query` is a special `query` function that cannot be called in inter-canister calls. The composite query function can call other query and composite query functions on the same subnet. |
There was a problem hiding this comment.
I am approving assuming this comment will be addressed.
This change adds a new query type: `composite_query` in idl.ts. It corresponds to the following changes in the upstream candid: - dfinity/candid#420 (spec change) - dfinity/candid#435 (rust change)
This change adds a new query type: `composite_query` in idl.ts. It corresponds to the following changes in the upstream candid: - dfinity/candid#420 (spec change) - dfinity/candid#435 (rust change)
Follow up with dfinity/interface-spec#144