Package org.elasticsearch.gateway
Class MetadataStateFormat<T>
java.lang.Object
org.elasticsearch.gateway.MetadataStateFormat<T>
- Type Parameters:
T
- the type of the XContent base data-structure
MetadataStateFormat is a base class to write checksummed
XContent based files to one or more directories in a standardized directory structure.
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Field Summary
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Constructor Summary
ModifierConstructorDescriptionprotected
MetadataStateFormat(String prefix)
Creates a newMetadataStateFormat
instance -
Method Summary
Modifier and TypeMethodDescriptionvoid
cleanupOldFiles(long currentGeneration, Path[] locations)
Clean ups all state files not matching passed generation.static void
deleteMetaState(Path... dataLocations)
Deletes all meta state directories recursively for the given data locationsabstract T
fromXContent(org.elasticsearch.common.xcontent.XContentParser parser)
Reads a new instance of the state from the given XContentParser Subclasses need to implement this class for theirs specific state.getStateFileName(long generation)
loadGeneration(org.apache.logging.log4j.Logger logger, org.elasticsearch.common.xcontent.NamedXContentRegistry namedXContentRegistry, long generation, Path... dataLocations)
Tries to load the state of particular generation from the given data-locations.loadLatestState(org.apache.logging.log4j.Logger logger, org.elasticsearch.common.xcontent.NamedXContentRegistry namedXContentRegistry, Path... dataLocations)
Tries to load the latest state from the given data-locations.loadLatestStateWithGeneration(org.apache.logging.log4j.Logger logger, org.elasticsearch.common.xcontent.NamedXContentRegistry namedXContentRegistry, Path... dataLocations)
Tries to load the latest state from the given data-locations.protected org.apache.lucene.store.Directory
newDirectory(Path dir)
protected org.elasticsearch.common.xcontent.XContentBuilder
newXContentBuilder(org.elasticsearch.common.xcontent.XContentType type, OutputStream stream)
Reads the state from a given file and compares the expected version against the actual version of the state.abstract void
toXContent(org.elasticsearch.common.xcontent.XContentBuilder builder, T state)
Writes the given state to the given XContentBuilder Subclasses need to implement this class for theirs specific state.long
Writes the given state to the given directories.long
writeAndCleanup(T state, Path... locations)
Writes the given state to the given directories and performs cleanup of old state files if the write succeeds or newly created state file if write fails.
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Field Details
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FORMAT
public static final org.elasticsearch.common.xcontent.XContentType FORMAT -
STATE_DIR_NAME
- See Also:
- Constant Field Values
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STATE_FILE_EXTENSION
- See Also:
- Constant Field Values
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Constructor Details
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MetadataStateFormat
Creates a newMetadataStateFormat
instance
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Method Details
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writeAndCleanup
Writes the given state to the given directories and performs cleanup of old state files if the write succeeds or newly created state file if write fails. See alsowrite(Object, Path...)
andcleanupOldFiles(long, Path[])
.- Throws:
WriteStateException
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write
Writes the given state to the given directories. The state is written to a state directory ("_state") underneath each of the given file locations and is created if it doesn't exist. The state is serialized to a temporary file in that directory and is then atomically moved to it's target filename of the pattern{prefix}{version}.st
. If this method returns without exception there is a guarantee that state is persisted to the disk and loadLatestState will return it.
This method always performs cleanup of temporary files regardless whether it succeeds or fails. Cleanup logic for state files is more involved. If this method fails with an exception, it performs cleanup of newly created state file. But if this method succeeds, it does not perform cleanup of old state files. If this write succeeds, but some further write fails, you may want to rollback the transaction and keep old file around. After transaction is finished usecleanupOldFiles(long, Path[])
for the clean-up. If this write is not a part of bigger transaction, consider usingwriteAndCleanup(Object, Path...)
method instead.- Parameters:
state
- the state object to writelocations
- the locations where the state should be written to.- Returns:
- generation of newly written state.
- Throws:
WriteStateException
- if some exception during writing state occurs. See alsoWriteStateException.isDirty()
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newXContentBuilder
protected org.elasticsearch.common.xcontent.XContentBuilder newXContentBuilder(org.elasticsearch.common.xcontent.XContentType type, OutputStream stream) throws IOException- Throws:
IOException
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toXContent
public abstract void toXContent(org.elasticsearch.common.xcontent.XContentBuilder builder, T state) throws IOExceptionWrites the given state to the given XContentBuilder Subclasses need to implement this class for theirs specific state.- Throws:
IOException
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fromXContent
public abstract T fromXContent(org.elasticsearch.common.xcontent.XContentParser parser) throws IOExceptionReads a new instance of the state from the given XContentParser Subclasses need to implement this class for theirs specific state.- Throws:
IOException
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read
public final T read(org.elasticsearch.common.xcontent.NamedXContentRegistry namedXContentRegistry, Path file) throws IOExceptionReads the state from a given file and compares the expected version against the actual version of the state.- Throws:
IOException
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newDirectory
- Throws:
IOException
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cleanupOldFiles
Clean ups all state files not matching passed generation.- Parameters:
currentGeneration
- state generation to keep.locations
- state paths.
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getStateFileName
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loadGeneration
public T loadGeneration(org.apache.logging.log4j.Logger logger, org.elasticsearch.common.xcontent.NamedXContentRegistry namedXContentRegistry, long generation, Path... dataLocations)Tries to load the state of particular generation from the given data-locations. If any of data locations contain state files with given generation, state will be loaded from these state files.- Parameters:
logger
- a logger instance.generation
- the generation to be loaded.dataLocations
- the data-locations to try.- Returns:
- the state of asked generation or
null
if no state was found.
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loadLatestStateWithGeneration
public org.elasticsearch.core.Tuple<T,Long> loadLatestStateWithGeneration(org.apache.logging.log4j.Logger logger, org.elasticsearch.common.xcontent.NamedXContentRegistry namedXContentRegistry, Path... dataLocations) throws IOExceptionTries to load the latest state from the given data-locations.- Parameters:
logger
- a logger instance.dataLocations
- the data-locations to try.- Returns:
- tuple of the latest state and generation. (null, -1) if no state is found.
- Throws:
IOException
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loadLatestState
public T loadLatestState(org.apache.logging.log4j.Logger logger, org.elasticsearch.common.xcontent.NamedXContentRegistry namedXContentRegistry, Path... dataLocations) throws IOExceptionTries to load the latest state from the given data-locations.- Parameters:
logger
- a logger instance.dataLocations
- the data-locations to try.- Returns:
- the latest state or
null
if no state was found. - Throws:
IOException
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deleteMetaState
Deletes all meta state directories recursively for the given data locations- Parameters:
dataLocations
- the data location to delete- Throws:
IOException
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getPrefix
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