fix(cairo): fix scoreboard race for new table readers #1811
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Fresh table reader instances were using 0 transaction number in scoreboard acquire/release calls which led to races in scoreboard's min value initialization. The init() method in scoreboard was swapping 0 min value with L_MIN and a later table reader was swapping this L_MIN value with its current transaction number. This could have led to min being set to a value greater than 0 while there are some fresh reader instances that haven't released their txn 0 yet. As the result of this race, the assertion in releaseTxn() was failing. To fix this race, TxnScoreboard now adds 1 to all received txn values.
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bluestreak01
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[PR Coverage check]😍 pass : 18 / 18 (100.00%) file detail
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Refs: #1559
Fresh table reader instances were using 0 transaction numbers in scoreboard acquire/release calls which led to races in the scoreboard's min value initialization. The init() method in scoreboard was swapping 0 min value with L_MIN and a later table reader was swapping this L_MIN value with its current transaction number. This could have led to min being set to a value greater than 0 while there are some fresh reader instances that haven't released their txn 0 yet. As the result of this race, the assertion in releaseTxn() was failing.
To fix this race, the TxnScoreboard Java class now adds 1 to all received txn values before calling the C++ implementation.