fix(mapping): fix insert race conditions #255
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DEV-1618 Race condition of inserts with tunnelId
It seems that the cache should maybe be set before the insert. Sometimes mulitple tunnels with the same value try to get inserted at the same time |
samuelmasse
commented
Nov 23, 2021
laurentlp
reviewed
Nov 24, 2021
samuelmasse
commented
Nov 25, 2021
Comment on lines
+107
to
+119
| async map(tunnelId: uuid, threadId: uuid, userId: uuid): Promise<Convmap> { | ||
| const convmap = await this.getByThreadId(tunnelId, threadId) | ||
| if (convmap) { | ||
| return convmap | ||
| } | ||
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| return this.barrier.once(tunnelId, threadId, async () => { | ||
| const tunnel = await this.tunnels.get(tunnelId) | ||
| const conversation = await this.conversations.create(tunnel!.clientId, userId) | ||
| return this.create(tunnelId, conversation.id, threadId) | ||
| }) | ||
| } | ||
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@laurentlp here's a barrier in use. The code in the callback will be excuted only once, and return the same value for all Promises waiting on it. The way a single "task" is identified is with arguments before the callback. This particular barrier is a 2d barrier (similarly to our 2d caches), so the key is composed of two keys.
This was referenced Dec 2, 2021
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It's sometime possible that sometimes the server checks if a mapping exists, and then creates it if it doesn't. If this is done fast enough, it's possible that the check to see if the mapping exists returns false more than once, and the process of creating the mapping starts multiple times. The constraints in the db will prevent more than once request from succeeding, meaning that exceptions will be thrown.
This PR fixes this problem
Closes DEV-1618
Closes DEV-2104