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java.lang.Objectorg.apache.s4.core.ft.SafeKeeper
public final class SafeKeeper
This class is responsible for coordinating interactions between the S4 event processor and the checkpoint storage backend. In particular, it schedules asynchronous save tasks to be executed on the backend.
Nested Class Summary |
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Nested classes/interfaces inherited from interface org.apache.s4.core.ft.CheckpointingFramework |
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CheckpointingFramework.StorageResultCode |
Constructor Summary | |
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SafeKeeper()
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Method Summary | |
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byte[] |
fetchSerializedState(CheckpointId key)
Fetches checkpoint data from storage for a given PE |
boolean |
isCheckpointable(ProcessingElement pe)
Evaluates whether specified PE should be checkpointed, based on: whether checkpointing enabled whether the pe is "dirty" the checkpointing frequency settings This is used for count-based checkpointing intervals. |
StorageCallback |
saveState(ProcessingElement pe)
Serializes and stores state to the storage backend. |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public SafeKeeper()
Method Detail |
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public StorageCallback saveState(ProcessingElement pe)
CheckpointingFramework
saveState
in interface CheckpointingFramework
public byte[] fetchSerializedState(CheckpointId key)
CheckpointingFramework
fetchSerializedState
in interface CheckpointingFramework
key
- safeKeeperId
public boolean isCheckpointable(ProcessingElement pe)
CheckpointingFramework
isCheckpointable
in interface CheckpointingFramework
pe
- processing element to evaluate
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