Add dataloader pattern #159
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mike-marcacci
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ebrown32
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Aug 14, 2020
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| if (!a) { | ||
| throw new ForbiddenError( | ||
| "You must be authenticated to update an authority." | ||
| ); | ||
| } | ||
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| const strategies = executor.strategies; | ||
| const pool = executor.connection; | ||
| if (!(pool instanceof Pool)) { |
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No idea if this is a good idea, but it seems like this code fragment appears an awful lot. Could we have some kind of executor.pool getter?
ebrown32
reviewed
Aug 14, 2020
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| if (!a) { | ||
| throw new ForbiddenError("You must be authenticated to create a client."); | ||
| } | ||
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| const strategies = executor.strategies; | ||
| const pool = executor.connection; | ||
| if (!(pool instanceof Pool)) { |
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Since we do this a lot, we could change this to be some kind of executor.pool getter.
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This addresses #158 by using the dataloader pattern to batch and memoize entity calls within the same request.
The design followed here introduces the concept of an "execution context" or
Executor. AnExecutorinstance is unique to the request, and is to be used as a key toWeakMapcaches of entities.Special care must be taken to avoid reusing stale data after a mutation. Accordingly, the
Executorinstance is replaced in the broader context object by each mutation. Because GraphQL guarantees that mutations are run serially, we don't have to worry about race conditions here.