Package org.camunda.bpm.engine.impl

Class HistoryLevelSetupCommand

java.lang.Object

org.camunda.bpm.engine.impl.HistoryLevelSetupCommand

All Implemented Interfaces:

Command<Void>

public final class HistoryLevelSetupCommand
extends Object
implements Command<Void>

Constructor Summary

Constructors

Constructor	Description
HistoryLevelSetupCommand()

Method Summary

Modifier and Type	Method	Description
protected void	acquireExclusiveLock(CommandContext commandContext)
protected void	checkStartupLockExists(CommandContext commandContext)
static Integer	databaseHistoryLevel(CommandContext commandContext)
static void	dbCreateHistoryLevel(CommandContext commandContext)
protected void	determineAutoHistoryLevel(ProcessEngineConfigurationImpl engineConfiguration, HistoryLevel databaseHistoryLevel)
Void	execute(CommandContext commandContext)
boolean	isRetryable()	When CockroachDB is used, this command may be retried multiple times until it is successful, or the retries are exhausted.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

HistoryLevelSetupCommand

public HistoryLevelSetupCommand()

Method Detail

execute

public Void execute(CommandContext commandContext)

Specified by:

execute in interface Command<Void>

dbCreateHistoryLevel

public static void dbCreateHistoryLevel(CommandContext commandContext)

databaseHistoryLevel

public static Integer databaseHistoryLevel(CommandContext commandContext)

Returns:

Integer value representing the history level or null if none found

determineAutoHistoryLevel

protected void determineAutoHistoryLevel(ProcessEngineConfigurationImpl engineConfiguration,
                                         HistoryLevel databaseHistoryLevel)

checkStartupLockExists

protected void checkStartupLockExists(CommandContext commandContext)

acquireExclusiveLock

protected void acquireExclusiveLock(CommandContext commandContext)

isRetryable

public boolean isRetryable()

When CockroachDB is used, this command may be retried multiple times until it is successful, or the retries are exhausted. CockroachDB uses a stricter, SERIALIZABLE transaction isolation which ensures a serialized manner of transaction execution. A concurrent transaction that attempts to modify the same data as another transaction is required to abort, rollback and retry. This also makes our use-case of pessimistic locks redundant since we only use them as synchronization barriers, and not to lock actual data which would protect it from concurrent modifications. The HistoryLevelSetup command only executes internal code, so we are certain that a retry of a failed command will not impact user data, and may be performed multiple times.

Specified by:

isRetryable in interface Command<Void>

Returns:

true if the CrdbTransactionRetryInterceptor can make a transparent retry of this command upon failure with a CrdbTransactionRetryException (only used when running on CockroachDB).