PHPLIB-789: Snapshot query examples #900
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| // Start Snapshot Query Example 1 | ||
| $catsCollection = $client->selectCollection('pets', 'cats'); | ||
| $dogsCollection = $client->selectCollection('pets', 'dogs'); |
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These are purposely redefined in order to demonstrate selecting a collection from the client object within the example. For context, the docs team parses this file for code between various start/end comments and uses that to render language-specific examples in the MongoDB manual.
| public function testSnapshotQueries(): void | ||
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| if (version_compare($this->getServerVersion(), '5.0.0', '<')) { | ||
| $this->markTestSkipped('Snapshot queries outside of transactions are not supported'); |
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| ['session' => $session] | ||
| )->toArray()[0]->adoptableDogsCount; | ||
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| var_dump($adoptablePetsCount); |
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Various examples require printing output. Since we don't want that output to interfere with the test suite, we typically use output buffering to capture and discard it.
| $this->assertSame(3, $adoptablePetsCount); | ||
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| $catsCollection->drop(); | ||
| $dogsCollection->drop(); |
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Since these examples use specific database and collection names, the cleanup logic in tearDown() does not apply and we manually clean up after each test.
| @@ -1575,6 +1575,103 @@ public function testCausalConsistency(): void | |||
| ob_end_clean(); | |||
| } | |||
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| public function testSnapshotQueries(): void | |||
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I observed SnapshotUnavailable(246) errors in CI builds. This PR will require work-arounds for replica sets and sharded clusters, which we can adapt from RUBY-2909.
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Added private waitForSnapshot() and preventStaleDbVersionError() methods for replica sets and sharded clusters, respectively.
jmikola
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Includes work-arounds for SnapshotUnavailable(246) errors on replica sets and sharded clusters.
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@aleksandr-rudo did you have any feedback/questions before I merge this? |
| @@ -1751,4 +1867,39 @@ private function assertInventoryCount($count): void | |||
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| $this->assertCollectionCount($this->getDatabaseName() . '.' . $this->getCollectionName(), $count); | |||
| } | |||
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| private function waitForSnapshot(string $databaseName, string $collectionName): void | |||
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At a glance it seems to me, that the idea of custom function like waitForSnapshot can be useful for interacting with snapshots and in such case it can be organized in a library functionality?
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Note: this function was lifted from mongodb/mongo-ruby-driver@7c4117b#diff-7b02c2b4b34a58c688750366d0230014bb453e0381af394d736aa9d0a25538a5R374 in the Ruby driver.
The function itself is not generally useful, since we're targeting a specific collection. The server-side error message is:
Unable to read from a snapshot due to pending collection catalog changes; please retry the operation.
If a user were to encounter this, they would probably want to retry their original query. For our purposes here, ensuring any snapshot query (even one with a different query filter) succeeds seems to do the trick to avoid an error in the documentation example that calls this method.
tests/DocumentationExamplesTest.php
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| throw $e; | ||
| } | ||
| } while (microtime(true) < $startTime + 10); |
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May be it would be more flexible to make function input argument with definition of timeout for snapshot waiting?
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This is only called once, so I'm not inclined to parameterize the method; however, I do think this can be improved by removing the literal 10 here and changing the function to instead calculate the deadline up front (with a comment explaining the 10-second timeout).
https://jira.mongodb.org/browse/PHPLIB-789