DbLockHandler (Cyclos 4.16.19 Scripting API Documentation)

```
public interface DbLockHandler
```
Manages the database lock, via the db_lock table. The database lock avoids 2 independent Cyclos instances from using the same database at the same time, which could lead to data corruption.

Field Summary

Fields
Modifier and Type Field Description

static int KEEPALIVE_SECONDS
Interval in seconds which nodes should update the db_lock row

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`void`	`keepalive(String hostId)`	Send a keep-alive to the database
`void`	`lock(String host, DbLock dbLock)`	Locks the database, by either inserting or updating the existing row in db_lock table, and schedules a timer to update the table every few seconds
`void`	`prepare()`	Makes sure the table exists
`DbLock`	`read()`	Return the current row, if any
`void`	`sleepUntilTryingAgain(DbLock dbLock)`	Sleeps for a few seconds before attempting to check again if the db is locked
`void`	`throwAlreadyLocked(DbLock dbLock)`	Throws an appropriate error indicating the current db is already locked
`void`	`unlock()`	Delete the row

- Field Detail
  - KEEPALIVE_SECONDS
```
static final int KEEPALIVE_SECONDS
```
    Interval in seconds which nodes should update the db_lock row
    
    See Also:
    
    Constant Field Values
- Method Detail
  - keepalive
```
void keepalive(String hostId)
```
    Send a keep-alive to the database
  - lock
```
void lock(String host,
          @Nullable
          DbLock dbLock)
```
    Locks the database, by either inserting or updating the existing row in db_lock table, and schedules a timer to update the table every few seconds
  - prepare
```
void prepare()
```
    Makes sure the table exists
  - read
```
@Nullable
DbLock read()
```
    Return the current row, if any
  - sleepUntilTryingAgain
```
void sleepUntilTryingAgain(@Nonnull
                           DbLock dbLock)
```
    Sleeps for a few seconds before attempting to check again if the db is locked
  - throwAlreadyLocked
```
void throwAlreadyLocked(@Nullable
                        DbLock dbLock)
```
    Throws an appropriate error indicating the current db is already locked
  - unlock
```
void unlock()
```
    Delete the row