Improvements to the Transaction API #57
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…rrors; Returning the new value when the txn commits.
rockwotj
previously approved these changes
Aug 12, 2017
firebase_admin/db.py
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| Args: | ||
| transaction_update: function that takes in current database data as a parameter. | ||
| transaction_update: A function which will be passed tbe current data stored at this |
bjornick
requested changes
Aug 14, 2017
| value of this reference into a new value. If another client writes to this location before | ||
| the new value is successfully saved, the update function is called again with the new | ||
| current value, and the write will be retried. In case of repeated failures, this method | ||
| will retry the transaction up to 25 times before giving up and raising a TransactionError. |
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Do we want to make this number configurable?
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I think that's reasonable. I've created #58 to implement it. Since this requires an API review, I'll defer it to a future development cycle.
| while tries < _TRANSACTION_MAX_RETRIES: | ||
| success, etag, snapshot = self._update_with_etag(val, etag) | ||
| new_data = transaction_update(data) | ||
| success, etag, data = self._update_with_etag(new_data, etag) |
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Yes, in the next iteration of the loop etag gets passed to the _update_with_etag() call.
| return False | ||
| return new_data | ||
| tries += 1 | ||
| raise TransactionError('Transaction aborted after failed retries.') |
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Should we add the number of retries attempted to this error?
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Lets report that at #58 to be fixed in the future. We are trying to get a release build out at the moment.
bjornick
approved these changes
Aug 14, 2017
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Follow up to #54. Implements #56.
transaction()method.