Package org.h2.mvstore

Class StreamStore

java.lang.Object
org.h2.mvstore.StreamStore
public final class StreamStore extends 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 Details

    • StreamStore

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

    • StreamStore

      public StreamStore(Map<Long,byte[]> map, int minBlockSize, int maxBlockSize)

    • StreamStore

      public StreamStore(Map<Long,byte[]> map, IntConsumer onStoreCallback)

    • StreamStore

      public StreamStore(Map<Long,byte[]> map, int minBlockSize, int maxBlockSize, IntConsumer onStoreCallback)

  • Method Details

    • getMap

      public Map<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(InputStream in) throws 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:
      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 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 InputStream get(byte[] id)
      Open an input stream to read data.
      Parameters:
      id - the id
      Returns:
      the stream