Implement the GetKeyserverKeys endpoint. Used by clients to establish
X3DH connections with a keyserver.
https://linear.app/comm/issue/ENG-4445
Depends on D8721
Details
Details
- Setup localstack and run terraform
# Run identity service cd services/identity RUST_LOG=debug cargo run -- server # Separate terminal cd services/commtest cargo test --test identity_keyserver_tests
Diff Detail
Diff Detail
- Repository
- rCOMM Comm
- Lint
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No Test Coverage
Event Timeline
| services/identity/src/database.rs | ||
|---|---|---|
| 292–296 | ||
| 374 | This way you're doing unnecessary reads - you're reading all device's onetime keys just to try deleting one. That's inefficient. My idea is to do the following (pseudocode written by hand) loop { let otk = self.client.query() .key(partition_key_for_device_id_and_account_type) .limit(1) // try getting one key .send().await? .items[0]; // get first item, this is a pseudocode let Some(otk) = otk else { /* No one-time keys left */ }; let result = self.client.delete_item() .key(otk_composite_primary_key) .condition_expression('attribute_exists(sort_key)') // check again for races .send().await; let Err(failure) = result else { return Ok(otk); // Yay! we popped a key }; // here you can optionally match error type // e.g. DynamoDBError::ConditionalCheckFailedException means that race happened } // if we went here, either // - no keys left // - each time we had a failure, so might be good to distinguish and log error types ;) return Ok(None); This way, in optimistic case you do only 1 read and 1 delete instead of N reads + 1 delete What do you think? | |
| 375–381 | This way you won't have to unwrap below | |
| services/identity/src/database.rs | ||
|---|---|---|
| 265 | ||
| 292–296 | TIL you could have an else block when doing assignment. | |
| 317–340 | Should be moved into a TryFrom implementation for a struct. Can be done later though. | |
| 374 | Makes sense. Used to conventional RDMS like Prostgresql where searching by partition key is cheap, and returning 1-10 items isn't a significant difference. | |
| 375–381 | really liking the else clause... which i knew about it earlier. Looks like it was added after I read the rust book: https://rust-lang.github.io/rfcs/3137-let-else.html | |
| services/identity/src/database.rs | ||
|---|---|---|
| 377–388 ↗ | (On Diff #29797) | Up to you ;) P.S. Not sure if the unwrap_or(None) is still needed in my suggestion |
| 418 ↗ | (On Diff #29797) | Just curious - is anything after this place considered dead code by the compiler? It's likely smarter than me but let's consider the following case:
Isn't it an infinite loop? It's a very unlikely scenario though. One possible solution is to introduce a counter variable for last fetched key. If the same key is fetched three or more times (two is still very okay due to data races, the condition expression saves us here) we can break the loop with failure. |
| services/identity/src/database.rs | ||
|---|---|---|
| 377–388 ↗ | (On Diff #29797) | going to avoid let-else until we update cargo in nix environment |
| 418 ↗ | (On Diff #29797) | I'm going to remove this loop, and put back the "read all, then try to delete one key" logic I had before. In a later diff I need the item count to see if a device's keys are depleted, and I can only do that if I have the count. Since doing select(COUNT) is usually as expensive, I think it makes sense to just return all items anyway. Also avoid cases where we retrieve and attempt to delete the same key indefinitely. |
| 292–296 | until our git commit lint stage allows for this to occur with out error, I'm going to use the match unfortunately | |
| services/identity/src/database.rs | ||
|---|---|---|
| 418 ↗ | (On Diff #29797) | If the only reason behind reading all the items is to get their count, then why don't we maintain it as a separate value and update using transactions https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/transaction-apis.html? |
| services/identity/src/database.rs | ||
|---|---|---|
| 418 ↗ | (On Diff #29797) | Do you mind if I create a follow up task for this? A naive but easy to reason about solution seems fine for now. We can re-address this in the future if it does become an issue. |
| services/identity/src/database.rs | ||
|---|---|---|
| 435–443 ↗ | (On Diff #29802) | If we decide to go this way and defer this, can we at least add these lines for easier monitoring? |
| services/identity/src/database.rs | ||
|---|---|---|
| 418 ↗ | (On Diff #29797) | Ok, we can handle this as a follow-up, but I think this should be done before releasing the service to prod. |