Package org.apache.cassandra.service.paxos.uncommitted

Class PaxosUncommittedIndex

  • All Implemented Interfaces:
    Index, PaxosUncommittedTracker.UpdateSupplier
    public class PaxosUncommittedIndex
extends java.lang.Object
implements Index, PaxosUncommittedTracker.UpdateSupplier
    A 2i implementation made specifically for system.paxos that listens for changes to paxos state by interpreting mutations against system.paxos and updates the uncommitted tracker accordingly. No read expressions are supported by the index. This is implemented as a 2i so it can piggy back off the commit log and paxos table flushes, and avoid worrying about implementing a parallel log/flush system for the tracker and potential bugs there. It also means we don't have to worry about cases where the tracker can become out of sync with the paxos table due to failure/edge cases outside of the PaxosTableState class itself.

    • Method Detail

      • indexes

        public static Indexes indexes()

      • getInitializationTask

        public java.util.concurrent.Callable<?> getInitializationTask()
        Description copied from interface: Index
        Return a task to perform any initialization work when a new index instance is created. This may involve costly operations such as (re)building the index, and is performed asynchronously by SecondaryIndexManager
        Specified by:
        getInitializationTask in interface Index
        Returns:
        a task to perform any necessary initialization work

      • getIndexMetadata

        public IndexMetadata getIndexMetadata()
        Description copied from interface: Index
        Returns the IndexMetadata which configures and defines the index instance. This should be the same object passed as the argument to setIndexMetadata.
        Specified by:
        getIndexMetadata in interface Index
        Returns:
        the index's metadata

      • getMetadataReloadTask

        public java.util.concurrent.Callable<?> getMetadataReloadTask​(IndexMetadata indexMetadata)
        Description copied from interface: Index
        Return a task to reload the internal metadata of an index. Called when the base table metadata is modified or when the configuration of the Index is updated Implementations should return a task which performs any necessary work to be done due to updating the configuration(s) such as (re)building etc. This task is performed asynchronously by SecondaryIndexManager
        Specified by:
        getMetadataReloadTask in interface Index
        Returns:
        task to be executed by the index manager during a reload

      • register

        public void register​(IndexRegistry registry)
        Description copied from interface: Index
        An index must be registered in order to be able to either subscribe to update events on the base table and/or to provide Searcher functionality for reads. The double dispatch involved here, where the Index actually performs its own registration by calling back to the supplied IndexRegistry's own registerIndex method, is to make the decision as to whether or not to register an index belong to the implementation, not the manager.
        Specified by:
        register in interface Index
        Parameters:
        registry - the index registry to register the instance with

      • getBackingTable

        public java.util.Optional<ColumnFamilyStore> getBackingTable()
        Description copied from interface: Index
        If the index implementation uses a local table to store its index data this method should return a handle to it. If not, an empty Optional should be returned. Typically, this is useful for the built-in Index implementations.
        Specified by:
        getBackingTable in interface Index
        Returns:
        an Optional referencing the Index's backing storage table if it has one, or Optional.empty() if not.

      • getBlockingFlushTask

        public java.util.concurrent.Callable<?> getBlockingFlushTask()
        Description copied from interface: Index
        Return a task which performs a blocking flush of any in-memory index data to persistent storage, independent of any flush of the base table. Note that this method is only invoked outside of normal flushes: if there is no in-memory storage for this index, and it only extracts data on flush from the base table's Memtable, then it is safe to perform no work.
        Specified by:
        getBlockingFlushTask in interface Index
        Returns:
        task to be executed by the index manager to perform the flush.

      • getBlockingFlushTask

        public java.util.concurrent.Callable<?> getBlockingFlushTask​(Memtable paxos)
        Description copied from interface: Index
        Return a task which performs a blocking flush of the index's data corresponding to the provided base table's Memtable. This may extract any necessary data from the base table's Memtable as part of the flush. This version of the method is invoked whenever we flush the base table. If the index stores no in-memory data of its own, it is safe to only implement this method.
        Specified by:
        getBlockingFlushTask in interface Index
        Returns:
        task to be executed by the index manager to perform the flush.

      • getInvalidateTask

        public java.util.concurrent.Callable<?> getInvalidateTask()
        Description copied from interface: Index
        Return a task which invalidates the index, indicating it should no longer be considered usable. This should include an clean up and releasing of resources required when dropping an index.
        Specified by:
        getInvalidateTask in interface Index
        Returns:
        task to be executed by the index manager to invalidate the index.

      • getTruncateTask

        public java.util.concurrent.Callable<?> getTruncateTask​(long truncatedAt)
        Description copied from interface: Index
        Return a task to truncate the index with the specified truncation timestamp. Called when the base table is truncated.
        Specified by:
        getTruncateTask in interface Index
        Parameters:
        truncatedAt - timestamp of the truncation operation. This will be the same timestamp used in the truncation of the base table.
        Returns:
        task to be executed by the index manager when the base table is truncated.

      • shouldBuildBlocking

        public boolean shouldBuildBlocking()
        Description copied from interface: Index
        Return true if this index can be built or rebuilt when the index manager determines it is necessary. Returning false enables the index implementation (or some other component) to control if and when SSTable data is incorporated into the index. This is called by SecondaryIndexManager in buildIndexBlocking, buildAllIndexesBlocking and rebuildIndexesBlocking where a return value of false causes the index to be exluded from the set of those which will process the SSTable data.
        Specified by:
        shouldBuildBlocking in interface Index
        Returns:
        if the index should be included in the set which processes SSTable data, false otherwise.

      • dependsOn

        public boolean dependsOn​(ColumnMetadata column)
        Description copied from interface: Index
        Called to determine whether this index targets a specific column. Used during schema operations such as when dropping or renaming a column, to check if the index will be affected by the change. Typically, if an index answers that it does depend upon a column, then schema operations on that column are not permitted until the index is dropped or altered.
        Specified by:
        dependsOn in interface Index
        Parameters:
        column - the column definition to check
        Returns:
        true if the index depends on the supplied column being present; false if the column may be safely dropped or modified without adversely affecting the index

      • supportsExpression

        public boolean supportsExpression​(ColumnMetadata column,
                                  Operator operator)
        Description copied from interface: Index
        Called to determine whether this index can provide a searcher to execute a query on the supplied column using the specified operator. This forms part of the query validation done before a CQL select statement is executed.
        Specified by:
        supportsExpression in interface Index
        Parameters:
        column - the target column of a search query predicate
        operator - the operator of a search query predicate
        Returns:
        true if this index is capable of supporting such expressions, false otherwise

      • customExpressionValueType

        public AbstractType<?> customExpressionValueType()
        Description copied from interface: Index
        If the index supports custom search expressions using the SELECT * FROM table WHERE expr(index_name, expression) syntax, this method should return the expected type of the expression argument. For example, if the index supports custom expressions as Strings, calls to this method should return UTF8Type.instance. If the index implementation does not support custom expressions, then it should return null.
        Specified by:
        customExpressionValueType in interface Index
        Returns:
        an the type of custom index expressions supported by this index, or an null if custom expressions are not supported.

      • getPostIndexQueryFilter

        public RowFilter getPostIndexQueryFilter​(RowFilter filter)
        Description copied from interface: Index
        Transform an initial RowFilter into the filter that will still need to applied to a set of Rows after the index has performed it's initial scan. Used in ReadCommand#executeLocal to reduce the amount of filtering performed on the results of the index query.
        Specified by:
        getPostIndexQueryFilter in interface Index
        Parameters:
        filter - the intial filter belonging to a ReadCommand
        Returns:
        the (hopefully) reduced filter that would still need to be applied after the index was used to narrow the initial result set

      • getEstimatedResultRows

        public long getEstimatedResultRows()
        Description copied from interface: Index
        Return an estimate of the number of results this index is expected to return for any given query that it can be used to answer. Used in conjunction with indexes() and supportsExpression() to determine the most selective index for a given ReadCommand. Additionally, this is also used by StorageProxy.estimateResultsPerRange to calculate the initial concurrency factor for range requests
        Specified by:
        getEstimatedResultRows in interface Index
        Returns:
        the estimated average number of results a Searcher may return for any given query

      • validate

        public void validate​(PartitionUpdate update)
              throws InvalidRequestException
        Description copied from interface: Index
        Called at write time to ensure that values present in the update are valid according to the rules of all registered indexes which will process it. The partition key as well as the clustering and cell values for each row in the update may be checked by index implementations
        Specified by:
        validate in interface Index
        Parameters:
        update - PartitionUpdate containing the values to be validated by registered Index implementations
        Throws:
        InvalidRequestException

      • indexerFor

        public Index.Indexer indexerFor​(DecoratedKey key,
                                RegularAndStaticColumns columns,
                                int nowInSec,
                                WriteContext ctx,
                                IndexTransaction.Type transactionType)
        Description copied from interface: Index
        Creates an new Indexer object for updates to a given partition.
        Specified by:
        indexerFor in interface Index
        Parameters:
        key - key of the partition being modified
        columns - the regular and static columns the created indexer will have to deal with. This can be empty as an update might only contain partition, range and row deletions, but the indexer is guaranteed to not get any cells for a column that is not part of columns.
        nowInSec - current time of the update operation
        ctx - WriteContext spanning the update operation
        transactionType - indicates what kind of update is being performed on the base data i.e. a write time insert/update/delete or the result of compaction
        Returns:
        the newly created indexer or null if the index is not interested by the update (this could be because the index doesn't care about that particular partition, doesn't care about that type of transaction, ...).

      • postProcessorFor

        public java.util.function.BiFunction<PartitionIterator,​ReadCommand,​PartitionIterator> postProcessorFor​(ReadCommand command)
        Description copied from interface: Index
        Return a function which performs post processing on the results of a partition range read command. In future, this may be used as a generalized mechanism for transforming results on the coordinator prior to returning them to the caller. This is used on the coordinator during execution of a range command to perform post processing of merged results obtained from the necessary replicas. This is the only way in which results are transformed in this way but this may change over time as usage is generalized. See CASSANDRA-8717 for further discussion. The function takes a PartitionIterator of the results from the replicas which has already been collated and reconciled, along with the command being executed. It returns another PartitionIterator containing the results of the transformation (which may be the same as the input if the transformation is a no-op).
        Specified by:
        postProcessorFor in interface Index

      • searcherFor

        public Index.Searcher searcherFor​(ReadCommand command)
        Description copied from interface: Index
        Factory method for query time search helper.
        Specified by:
        searcherFor in interface Index
        Parameters:
        command - the read command being executed
        Returns:
        an Searcher with which to perform the supplied command