Package org.axonframework.eventhandling.tokenstore.jpa

Class JpaTokenStore

java.lang.Object
org.axonframework.eventhandling.tokenstore.jpa.JpaTokenStore
All Implemented Interfaces:
TokenStore
public class JpaTokenStore extends Object implements TokenStore
Implementation of a token store that uses JPA to save and load tokens. This implementation uses TokenEntry entities.
Since:
3.0
Author:
Rene de Waele

  • Constructor Details

  • Method Details

    • builder

      public static JpaTokenStore.Builder builder()
      Instantiate a Builder to be able to create a JpaTokenStore.

      The claimTimeout to a 10 seconds duration, and nodeId is defaulted to the name of the managed bean for the runtime system of the Java virtual machine. The EntityManagerProvider and Serializer are a hard requirements and as such should be provided.

      Returns:
      a Builder to be able to create a JpaTokenStore

    • initializeTokenSegments

      public void initializeTokenSegments(@Nonnull String processorName, int segmentCount) throws UnableToClaimTokenException
      Description copied from interface: TokenStore
      Initializes the given segmentCount number of segments for the given processorName to track its tokens. This method should only be invoked when no tokens have been stored for the given processor, yet.

      This method will initialize the tokens, but not claim them. It will create the segments ranging from 0 until segmentCount - 1.

      The exact behavior when this method is called while tokens were already present, is undefined in case the token already present is not owned by the initializing process.

      Specified by:
      initializeTokenSegments in interface TokenStore
      Parameters:
      processorName - The name of the processor to initialize segments for
      segmentCount - The number of segments to initialize
      Throws:
      UnableToClaimTokenException - when a segment has already been created

    • initializeTokenSegments

      public void initializeTokenSegments(@Nonnull String processorName, int segmentCount, @Nullable TrackingToken initialToken) throws UnableToClaimTokenException
      Description copied from interface: TokenStore
      Initializes the given segmentCount number of segments for the given processorName to track its tokens. This method should only be invoked when no tokens have been stored for the given processor, yet.

      This method will store initialToken for all segments as starting point for processor, but not claim them. It will create the segments ranging from 0 until segmentCount - 1.

      The exact behavior when this method is called while tokens were already present, is undefined in case the token already present is not owned by the initializing process.

      Specified by:
      initializeTokenSegments in interface TokenStore
      Parameters:
      processorName - The name of the processor to initialize segments for
      segmentCount - The number of segments to initialize
      initialToken - The initial token which is used as a starting point for processor
      Throws:
      UnableToClaimTokenException - when a segment has already been created

    • storeToken

      public void storeToken(@Nullable TrackingToken token, @Nonnull String processorName, int segment)
      Description copied from interface: TokenStore
      Stores the given token in the store. The token marks the current position of the process with given processorName and segment. The given token may be null.

      Any claims made by the current process have their timestamp updated.

      This method should throw an UnableToClaimTokenException when the given segment has not been initialized with a Token (albeit null) yet. In that case, a segment must have been explicitly initialized. A TokenStore implementation's ability to do so is exposed by the TokenStore.requiresExplicitSegmentInitialization() method. If that method returns false, this method may implicitly initialize a token and return that token upon invocation.

      Specified by:
      storeToken in interface TokenStore
      Parameters:
      token - The token to store for a given process and segment. May be null.
      processorName - The name of the process for which to store the token
      segment - The index of the segment for which to store the token

    • releaseClaim

      public void releaseClaim(@Nonnull String processorName, int segment)
      Description copied from interface: TokenStore
      Release a claim of the token for given processorName and segment. If no such claim existed, nothing happens.

      The caller must ensure not to use any streams opened based on the token for which the claim is released.

      Specified by:
      releaseClaim in interface TokenStore
      Parameters:
      processorName - The name of the process owning the token (e.g. a TrackingEventProcessor name)
      segment - the segment for which a token was obtained

    • initializeSegment

      public void initializeSegment(@Nullable TrackingToken token, @Nonnull String processorName, int segment) throws UnableToInitializeTokenException
      Description copied from interface: TokenStore
      Initializes a segment with given segment for the processor with given processorName to contain the given token.

      This method fails if a Token already exists for the given processor and segment, even if that token has been claimed by the active instance.

      This method will not claim the initialized segment. Use TokenStore.fetchToken(String, int) to retrieve and claim the token.

      Specified by:
      initializeSegment in interface TokenStore
      Parameters:
      token - The token to initialize the segment with
      processorName - The name of the processor to create the segment for
      segment - The identifier of the segment to initialize
      Throws:
      UnableToInitializeTokenException - if a Token already exists

    • requiresExplicitSegmentInitialization

      public boolean requiresExplicitSegmentInitialization()
      Description copied from interface: TokenStore
      Indicates whether this TokenStore instance requires segments to be explicitly initialized, before any tokens can be claimed for that segment.
      Specified by:
      requiresExplicitSegmentInitialization in interface TokenStore
      Returns:
      true if this instance requires tokens to be explicitly initialized, otherwise false.
      See Also:

    • deleteToken

      public void deleteToken(@Nonnull String processorName, int segment) throws UnableToClaimTokenException
      Description copied from interface: TokenStore
      Deletes the token for the processor with given processorName and segment. The token must be owned by the current node, to be able to delete it.

      Implementations should implement this method only when TokenStore.requiresExplicitSegmentInitialization() is overridden to return true. Deleting tokens using implementations that do not require explicit token initialization is unsafe, as a claim will automatically recreate the deleted token instance, which may result in concurrency issues.

      Specified by:
      deleteToken in interface TokenStore
      Parameters:
      processorName - The name of the processor to remove the token for
      segment - The segment to delete
      Throws:
      UnableToClaimTokenException - if the token is not currently claimed by this node

    • fetchToken

      public TrackingToken fetchToken(@Nonnull String processorName, int segment)
      Description copied from interface: TokenStore
      Returns the last stored token for the given processorName and segment. Returns null if the stored token for the given process and segment is null.

      This method should throw an UnableToClaimTokenException when the given segment has not been initialized with a Token (albeit null) yet. In that case, a segment must have been explicitly initialized. A TokenStore implementation's ability to do so is exposed by the TokenStore.requiresExplicitSegmentInitialization() method. If that method returns false, this method may implicitly initialize a token and return that token upon invocation.

      The token will be claimed by the current process (JVM instance), preventing access by other instances. To release the claim, use TokenStore.releaseClaim(String, int)

      Specified by:
      fetchToken in interface TokenStore
      Parameters:
      processorName - The process name for which to fetch the token
      segment - The segment index for which to fetch the token
      Returns:
      The last stored TrackingToken or null if the store holds no token for given process and segment

    • fetchToken

      public TrackingToken fetchToken(@Nonnull String processorName, @Nonnull Segment segment) throws UnableToClaimTokenException
      Description copied from interface: TokenStore
      Returns the last stored token for the given processorName and segment. Returns null if the stored token for the given process and segment is null.

      This method should throw an UnableToClaimTokenException when the given segment has not been initialized with a Token (albeit null) yet. In that case, a segment must have been explicitly initialized. A TokenStore implementation's ability to do so is exposed by the TokenStore.requiresExplicitSegmentInitialization() method. If that method returns false, this method may implicitly initialize a token and return that token upon invocation.

      The token will be claimed by the current process (JVM instance), preventing access by other instances. To release the claim, use TokenStore.releaseClaim(String, int)

      Specified by:
      fetchToken in interface TokenStore
      Parameters:
      processorName - The process name for which to fetch the token
      segment - The segment for which to fetch the token
      Returns:
      The last stored TrackingToken or null if the store holds no token for given process and segment
      Throws:
      UnableToClaimTokenException - if there is a token for given processorName and segment, but they are claimed by another process, or if the segment has been split or merged concurrently

    • extendClaim

      public void extendClaim(@Nonnull String processorName, int segment) throws UnableToClaimTokenException
      Description copied from interface: TokenStore
      Extends the claim on the current token held by the this node for the given processorName and segment.
      Specified by:
      extendClaim in interface TokenStore
      Parameters:
      processorName - The process name for which to fetch the token
      segment - The segment index for which to fetch the token
      Throws:
      UnableToClaimTokenException - if there is no token for given processorName and segment, or if it has been claimed by another process.

    • fetchSegments

      public int[] fetchSegments(@Nonnull String processorName)
      Description copied from interface: TokenStore
      Returns an array of known segments for a given processorName.

      The segments returned are segments for which a token has been stored previously. When the TokenStore is empty, an empty array is returned.

      Specified by:
      fetchSegments in interface TokenStore
      Parameters:
      processorName - The process name for which to fetch the segments
      Returns:
      an array of segment identifiers.

    • fetchAvailableSegments

      public List<Segment> fetchAvailableSegments(@Nonnull String processorName)
      Description copied from interface: TokenStore
      Returns a List of known available segments for a given processorName. A segment is considered available if it is not claimed by any other event processor.

      The segments returned are segments for which a token has been stored previously and have not been claimed by another processor. When the TokenStore is empty, an empty list is returned. By default, if this method is not implemented, we will return all segments instead, whether they are available or not.

      Specified by:
      fetchAvailableSegments in interface TokenStore
      Parameters:
      processorName - the processor's name for which to fetch the segments
      Returns:
      a List of available segment identifiers for the specified processorName

    • loadToken

      protected TokenEntry loadToken(String processorName, int segment, jakarta.persistence.EntityManager entityManager)
      Loads an existing TokenEntry or creates a new one using the given entityManager for given processorName and segment.
      Parameters:
      processorName - the name of the event processor
      segment - the segment of the event processor
      entityManager - the entity manager instance to use for the query
      Returns:
      the token entry for the given processor name and segment
      Throws:
      UnableToClaimTokenException - if there is a token for given processorName and segment, but it is claimed by another process.

    • loadToken

      protected TokenEntry loadToken(String processorName, Segment segment, jakarta.persistence.EntityManager entityManager)
      Tries loading an existing token owned by a processor with given processorName and segment. If such a token entry exists an attempt will be made to claim the token. If that succeeds the token will be returned. If the token is already owned by another node an UnableToClaimTokenException will be thrown.

      If no such token exists yet, a new token entry will be inserted with a null token, owned by this node, and this method returns null.

      If a token has been claimed, the segment will be validated by checking the database for the split and merge candidate segments. If a concurrent split or merge operation has been detected, the calim will be released and an UnableToClaimTokenException will be thrown.}

      Parameters:
      processorName - the name of the processor to load or insert a token entry for
      segment - the segment of the processor to load or insert a token entry for
      entityManager - the entity manager instance to use for the query
      Returns:
      the tracking token of the fetched entry or null if a new entry was inserted
      Throws:
      UnableToClaimTokenException - if the token cannot be claimed because another node currently owns the token or if the segment has been split or merged concurrently

    • retrieveStorageIdentifier

      public Optional<String> retrieveStorageIdentifier()
      Description copied from interface: TokenStore
      Returns a unique identifier that uniquely identifies the storage location of the tokens in this store. Two token store implementations that share state, must return the same identifier. Two token store implementations that do not share a location, must return a different identifier (or an empty optional if identifiers are not supported).

      Note that this method may require the implementation to consult its underlying storage. Therefore, a Transaction should be active when this method is called, similarly to invocations like TokenStore.fetchToken(String, int), TokenStore.fetchSegments(String), etc. When no Transaction is active, the behavior is undefined.

      Specified by:
      retrieveStorageIdentifier in interface TokenStore
      Returns:
      an identifier to uniquely identify the storage location of tokens in this TokenStore.

    • serializer

      public Serializer serializer()
      Returns the serializer used by the Token Store to serialize tokens.
      Returns:
      the serializer used by the Token Store to serialize tokens