Package org.h2.mvstore

Class StreamStore

  • public final class StreamStore
extends java.lang.Object
    A facility to store streams in a map. Streams are split into blocks, which are stored in a map. Very small streams are inlined in the stream id.

    The key of the map is a long (incremented for each stored block). The default initial value is 0. Before storing blocks into the map, the stream store checks if there is already a block with the next key, and if necessary searches the next free entry using a binary search (0 to Long.MAX_VALUE).

    Before storing

    The format of the binary id is: An empty id represents 0 bytes of data. In-place data is encoded as 0, the size (a variable size int), then the data. A stored block is encoded as 1, the length of the block (a variable size int), then the key (a variable size long). Multiple ids can be concatenated to concatenate the data. If the id is large, it is stored itself, which is encoded as 2, the total length (a variable size long), and the key of the block that contains the id (a variable size long).

    • Constructor Summary

      Constructors 
      Constructor Description
      StreamStore​(java.util.Map<java.lang.Long,​byte[]> map)
      Create a stream store instance.
      StreamStore​(java.util.Map<java.lang.Long,​byte[]> map, int minBlockSize, int maxBlockSize)  
      StreamStore​(java.util.Map<java.lang.Long,​byte[]> map, int minBlockSize, int maxBlockSize, java.util.function.IntConsumer onStoreCallback)  
      StreamStore​(java.util.Map<java.lang.Long,​byte[]> map, java.util.function.IntConsumer onStoreCallback)  

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      java.io.InputStream get​(byte[] id)
      Open an input stream to read data.
      java.util.Map<java.lang.Long,​byte[]> getMap()  
      long getMaxBlockKey​(byte[] id)
      Get the key of the biggest block, of -1 for inline data.
      long getMaxBlockSize()  
      int getMinBlockSize()  
      long getNextKey()  
      boolean isInPlace​(byte[] id)
      Check whether the id itself contains all the data.
      long length​(byte[] id)
      Calculate the number of data bytes for the given id.
      byte[] put​(java.io.InputStream in)
      Store the stream, and return the id.
      void remove​(byte[] id)
      Remove all stored blocks for the given id.
      void setNextKey​(long nextKey)  
      static java.lang.String toString​(byte[] id)
      Convert the id to a human-readable string.

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Constructor Detail

      • StreamStore

        public StreamStore​(java.util.Map<java.lang.Long,​byte[]> map)
        Create a stream store instance.
        Parameters:
        map - the map to store blocks of data

      • StreamStore

        public StreamStore​(java.util.Map<java.lang.Long,​byte[]> map,
                   int minBlockSize,
                   int maxBlockSize)

      • StreamStore

        public StreamStore​(java.util.Map<java.lang.Long,​byte[]> map,
                   java.util.function.IntConsumer onStoreCallback)

      • StreamStore

        public StreamStore​(java.util.Map<java.lang.Long,​byte[]> map,
                   int minBlockSize,
                   int maxBlockSize,
                   java.util.function.IntConsumer onStoreCallback)

    • Method Detail

      • getMap

        public java.util.Map<java.lang.Long,​byte[]> getMap()

      • setNextKey

        public void setNextKey​(long nextKey)

      • getNextKey

        public long getNextKey()

      • getMinBlockSize

        public int getMinBlockSize()

      • getMaxBlockSize

        public long getMaxBlockSize()

      • put

        public byte[] put​(java.io.InputStream in)
           throws java.io.IOException
        Store the stream, and return the id. The stream is not closed.
        Parameters:
        in - the stream
        Returns:
        the id (potentially an empty array)
        Throws:
        java.io.IOException - If an I/O error occurs

      • getMaxBlockKey

        public long getMaxBlockKey​(byte[] id)
        Get the key of the biggest block, of -1 for inline data. This method is used to garbage collect orphaned blocks.
        Parameters:
        id - the id
        Returns:
        the key, or -1

      • remove

        public void remove​(byte[] id)
        Remove all stored blocks for the given id.
        Parameters:
        id - the id

      • toString

        public static java.lang.String toString​(byte[] id)
        Convert the id to a human-readable string.
        Parameters:
        id - the stream id
        Returns:
        the string

      • length

        public long length​(byte[] id)
        Calculate the number of data bytes for the given id. As the length is encoded in the id, this operation does not cause any reads in the map.
        Parameters:
        id - the id
        Returns:
        the length

      • isInPlace

        public boolean isInPlace​(byte[] id)
        Check whether the id itself contains all the data. This operation does not cause any reads in the map.
        Parameters:
        id - the id
        Returns:
        if the id contains the data

      • get

        public java.io.InputStream get​(byte[] id)
        Open an input stream to read data.
        Parameters:
        id - the id
        Returns:
        the stream