Fix per-thread txn leaks when SafeNdbTxn init fails

This addresses one failure path where if the value getter for a new transaction returns `nil`, it would leak a read transaction, causing it to remain open indefinitely, and leading to runaway storage usage. Changelog-Fixed: Fixed database transaction leak that could lead to higher storage usage Signed-off-by: Daniel D’Aquino <daniel@daquino.me>
2026-05-07 17:09:34 -07:00
parent 52b5afaaf3
commit 034f667869
2 changed files with 86 additions and 1 deletions
@@ -210,7 +210,22 @@ class SafeNdbTxn<T: ~Copyable> {
        print("txn: open  gen\(generation) '\(name)' \(txn_count)")
        #endif
        let placeholderTxn = PlaceholderNdbTxn(txn: txn)
-        guard let val = valueGetter(placeholderTxn) else { return nil }
+        guard let val = valueGetter(placeholderTxn) else {
+            if inherited {
+                if let refCount = Thread.current.threadDictionary["ndb_txn_ref_count"] as? Int {
+                    Thread.current.threadDictionary["ndb_txn_ref_count"] = max(0, refCount - 1)
+                }
+                return nil
+            }
+
+            _ = try? ndb.withNdb({
+                ndb_end_query(&placeholderTxn.txn)
+            }, maxWaitTimeout: .milliseconds(200))
+            Thread.current.threadDictionary.removeObject(forKey: "ndb_txn")
+            Thread.current.threadDictionary.removeObject(forKey: "ndb_txn_ref_count")
+            Thread.current.threadDictionary.removeObject(forKey: "txn_generation")
+            return nil
+        }
        return SafeNdbTxn<T>(ndb: ndb, txn: txn, val: val, generation: generation, inherited: inherited, name: name)
    }