| hg-reviewers |
The docstring for iwireprotocolcommandcacher references
an onoutputfinished method. The actual name of the function
is onfinished.
| Automatic diff as part of commit; lint not applicable. |
| Automatic diff as part of commit; unit tests not applicable. |
| 6. The cacher's ``lookup()`` method is called to test for presence of | 6. The cacher's ``lookup()`` method is called to test for presence of | ||||
| the derived key in the cache. | the derived key in the cache. | ||||
| 7. If ``lookup()`` returns a hit, that cached result is used in place | 7. If ``lookup()`` returns a hit, that cached result is used in place | ||||
| of invoking the command function. ``__exit__`` is called and the instance | of invoking the command function. ``__exit__`` is called and the instance | ||||
| is discarded. | is discarded. | ||||
| 8. The command function is invoked. | 8. The command function is invoked. | ||||
| 9. ``onobject()`` is called for each object emitted by the command | 9. ``onobject()`` is called for each object emitted by the command | ||||
| function. | function. | ||||
| 10. After the final object is seen, ``onoutputfinished()`` is called. | 10. After the final object is seen, ``onfinished()`` is called. | ||||
| 11. ``__exit__`` is called to signal the end of use of the instance. | 11. ``__exit__`` is called to signal the end of use of the instance. | ||||
| Cache *key* derivation can be influenced by the instance. | Cache *key* derivation can be influenced by the instance. | ||||
| Cache keys are initially derived by a deterministic representation of | Cache keys are initially derived by a deterministic representation of | ||||
| the command request. This includes the command name, arguments, protocol | the command request. This includes the command name, arguments, protocol | ||||
| version, etc. This initial key derivation is performed by CBOR-encoding a | version, etc. This initial key derivation is performed by CBOR-encoding a | ||||
| data structure and feeding that output into a hasher. | data structure and feeding that output into a hasher. | ||||
| When receiving the objects emitted by the command function, instances | When receiving the objects emitted by the command function, instances | ||||
| can choose what to do with those objects. The simplest thing to do is | can choose what to do with those objects. The simplest thing to do is | ||||
| re-emit the original objects. They will be forwarded to the output | re-emit the original objects. They will be forwarded to the output | ||||
| layer and will be processed as if the cacher did not exist. | layer and will be processed as if the cacher did not exist. | ||||
| Implementations could also choose to not emit objects - instead locally | Implementations could also choose to not emit objects - instead locally | ||||
| buffering objects or their encoded representation. They could then emit | buffering objects or their encoded representation. They could then emit | ||||
| a single "coalesced" object when ``onoutputfinished()`` is called. In | a single "coalesced" object when ``onfinished()`` is called. In | ||||
| this way, the implementation would function as a filtering layer of | this way, the implementation would function as a filtering layer of | ||||
| sorts. | sorts. | ||||
| When caching objects, typically the encoded form of the object will | When caching objects, typically the encoded form of the object will | ||||
| be stored. Keep in mind that if the original object is forwarded to | be stored. Keep in mind that if the original object is forwarded to | ||||
| the output layer, it will need to be encoded there as well. For large | the output layer, it will need to be encoded there as well. For large | ||||
| output, this redundant encoding could add overhead. Implementations | output, this redundant encoding could add overhead. Implementations | ||||
| could wrap the encoded object data in ``wireprototypes.encodedresponse`` | could wrap the encoded object data in ``wireprototypes.encodedresponse`` | ||||