Allow opening an existing DB in snapshot-only mode #13937
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Adds a new API call to `ZeebeDbFactory` which allows opening existing databases in a snapshot-only mode. This returns a `ZeebeDb` which can ONLY take snapshots, and will throw a `new UnsupportedOperationException` for any other operations. While it would be nice to have a proper read-only DB implementation, there are no transactions in a such a DB, and our whole access to the DB is coupled with the transaction API. As we were thinking of switching away from transactions, it will likely be easier after that to implement a read-only DB.
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Zelldon
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Aug 18, 2023
| @@ -56,31 +57,50 @@ public ZeebeRocksDbFactory( | |||
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| @Override | |||
| public ZeebeTransactionDb<ColumnFamilyType> createDb(final File pathName) { | |||
| final ZeebeTransactionDb<ColumnFamilyType> db; | |||
| final List<AutoCloseable> closeables = Collections.synchronizedList(new ArrayList<>()); | |||
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❓ Do you remember why this is actually a synchronized list 🤔
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No idea, I just copied it and assumed we have a good reason for it 😄 Possibly it's related to creating transaction/transaction contexts from possibly many threads? 🤷
zb-db/src/test/java/io/camunda/zeebe/db/impl/rocksdb/ZeebeRocksDbFactoryTest.java
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This pull request requires a change in zeebe-process-test: @npepinpe Please have a look |
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Description
This PR adds a new API call to
ZeebeDbFactorywhich allows opening existing databases in a snapshot-only mode. This returns aZeebeDbwhich can ONLY take snapshots, and will throw anew UnsupportedOperationExceptionfor any other operations.While it would be nice to have a proper read-only DB implementation, there are no transactions in a such a DB, and our whole access to the DB is coupled with the transaction API. As we were thinking of switching away from transactions, it will likely be easier after that to implement a read-only DB.
This will be used as part of the fix for #13775 to create the runtime directory faster via hard-links instead of a full copy.
Related issues
related to #13775
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