Package org.apache.cassandra.schema
Interface SchemaUpdateHandler
-
- All Known Implementing Classes:
DefaultSchemaUpdateHandler
,OfflineSchemaUpdateHandler
public interface SchemaUpdateHandler
Schema update handler is responsible for maintaining the shared schema and synchronizing it with other nodes in the cluster, which means pushing and pulling changes, as well as tracking the current version in the cluster. The interface has been extracted to abstract out that functionality. It allows for various implementations like Gossip based (the default), ETCD, offline, etc., and make it easier for mocking in unit tests.
-
-
Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description SchemaTransformation.SchemaTransformationResult
apply(SchemaTransformation transformation, boolean local)
Applies schema transformation in the underlying storage and synchronizes with other nodes.Awaitable
clear()
Marks the local schema to be cleared and refreshed.void
reset(boolean local)
Resets the schema either by reloading data from the local storage or from the other nodes.void
start()
Starts actively synchronizing schema with the rest of the cluster.boolean
waitUntilReady(java.time.Duration timeout)
Waits until the schema update handler is ready and returns the result.
-
-
-
Method Detail
-
start
void start()
Starts actively synchronizing schema with the rest of the cluster. It is called in the very beginning of the node startup. It is not expected to block - to await for the startup completion we have another methodwaitUntilReady(Duration)
.
-
waitUntilReady
boolean waitUntilReady(java.time.Duration timeout)
Waits until the schema update handler is ready and returns the result. If the method returnsfalse
it means that readiness could not be achieved within the specified period of time. The method can be used just to check if schema is ready by passingDuration.ZERO
as the timeout - in such case it returns immediately.- Parameters:
timeout
- the maximum time to wait for schema readiness- Returns:
- whether readiness is achieved
-
apply
SchemaTransformation.SchemaTransformationResult apply(SchemaTransformation transformation, boolean local)
Applies schema transformation in the underlying storage and synchronizes with other nodes.- Parameters:
transformation
- schema transformation to be performedlocal
- if true, the caller does not require synchronizing schema with other nodes - in practise local is used only in some tests- Returns:
- transformation result
-
reset
void reset(boolean local)
Resets the schema either by reloading data from the local storage or from the other nodes. Once the schema is refreshed, the callbacks provided in the factory method are executed, and the updated schema version is announced.- Parameters:
local
- whether we should reset with locally stored schema or fetch the schema from other nodes
-
clear
Awaitable clear()
Marks the local schema to be cleared and refreshed. Since calling this method, the update handler tries to obtain a fresh schema definition from a remote source. Once the schema definition is received, the local schema is replaced (instead of being merged which usually happens when the update is received). The returned awaitable is fulfilled when the schema is received and applied.
-
-