Examples with Memory org.apache.cassandra.io.util.Memory used on opensource projects

Example 1 with Memory

use of org.apache.cassandra.io.util.Memory in project cassandra by apache.

the class IndexSummaryBuilder method downsample.

/**
     * Downsamples an existing index summary to a new sampling level.
     * @param existing an existing IndexSummary
     * @param newSamplingLevel the target level for the new IndexSummary.  This must be less than the current sampling
     *                         level for `existing`.
     * @param partitioner the partitioner used for the index summary
     * @return a new IndexSummary
     */
@SuppressWarnings("resource")
public static IndexSummary downsample(IndexSummary existing, int newSamplingLevel, int minIndexInterval, IPartitioner partitioner) {
    // To downsample the old index summary, we'll go through (potentially) several rounds of downsampling.
    // Conceptually, each round starts at position X and then removes every Nth item.  The value of X follows
    // a particular pattern to evenly space out the items that we remove.  The value of N decreases by one each
    // round.
    int currentSamplingLevel = existing.getSamplingLevel();
    assert currentSamplingLevel > newSamplingLevel;
    assert minIndexInterval == existing.getMinIndexInterval();
    // calculate starting indexes for downsampling rounds
    int[] startPoints = Downsampling.getStartPoints(currentSamplingLevel, newSamplingLevel);
    // calculate new off-heap size
    int newKeyCount = existing.size();
    long newEntriesLength = existing.getEntriesLength();
    for (int start : startPoints) {
        for (int j = start; j < existing.size(); j += currentSamplingLevel) {
            newKeyCount--;
            long length = existing.getEndInSummary(j) - existing.getPositionInSummary(j);
            newEntriesLength -= length;
        }
    }
    Memory oldEntries = existing.getEntries();
    Memory newOffsets = Memory.allocate(newKeyCount * 4);
    Memory newEntries = Memory.allocate(newEntriesLength);
    // Copy old entries to our new Memory.
    int i = 0;
    int newEntriesOffset = 0;
    outer: for (int oldSummaryIndex = 0; oldSummaryIndex < existing.size(); oldSummaryIndex++) {
        // and see if the entry's index is covered by that round
        for (int start : startPoints) {
            if ((oldSummaryIndex - start) % currentSamplingLevel == 0)
                continue outer;
        }
        // write the position of the actual entry in the index summary (4 bytes)
        newOffsets.setInt(i * 4, newEntriesOffset);
        i++;
        long start = existing.getPositionInSummary(oldSummaryIndex);
        long length = existing.getEndInSummary(oldSummaryIndex) - start;
        newEntries.put(newEntriesOffset, oldEntries, start, length);
        newEntriesOffset += length;
    }
    assert newEntriesOffset == newEntriesLength;
    return new IndexSummary(partitioner, newOffsets, newKeyCount, newEntries, newEntriesLength, existing.getMaxNumberOfEntries(), minIndexInterval, newSamplingLevel);
}

Example 2 with Memory

use of org.apache.cassandra.io.util.Memory in project cassandra by apache.

the class CompressionMetadata method readChunkOffsets.

/**
     * Read offsets of the individual chunks from the given input.
     *
     * @param input Source of the data.
     *
     * @return collection of the chunk offsets.
     */
private Memory readChunkOffsets(DataInput input) {
    final int chunkCount;
    try {
        chunkCount = input.readInt();
        if (chunkCount <= 0)
            throw new IOException("Compressed file with 0 chunks encountered: " + input);
    } catch (IOException e) {
        throw new FSReadError(e, indexFilePath);
    }
    @SuppressWarnings("resource") Memory offsets = Memory.allocate(chunkCount * 8L);
    int i = 0;
    try {
        for (i = 0; i < chunkCount; i++) {
            offsets.setLong(i * 8L, input.readLong());
        }
        return offsets;
    } catch (IOException e) {
        if (offsets != null)
            offsets.close();
        if (e instanceof EOFException) {
            String msg = String.format("Corrupted Index File %s: read %d but expected %d chunks.", indexFilePath, i, chunkCount);
            throw new CorruptSSTableException(new IOException(msg, e), indexFilePath);
        }
        throw new FSReadError(e, indexFilePath);
    }
}

Example 3 with Memory

use of org.apache.cassandra.io.util.Memory in project cassandra by apache.

the class OffHeapBitSet method deserialize.

@SuppressWarnings("resource")
public static OffHeapBitSet deserialize(DataInput in) throws IOException {
    long byteCount = in.readInt() * 8L;
    Memory memory = Memory.allocate(byteCount);
    for (long i = 0; i < byteCount; ) {
        long v = in.readLong();
        memory.setByte(i++, (byte) (v >>> 0));
        memory.setByte(i++, (byte) (v >>> 8));
        memory.setByte(i++, (byte) (v >>> 16));
        memory.setByte(i++, (byte) (v >>> 24));
        memory.setByte(i++, (byte) (v >>> 32));
        memory.setByte(i++, (byte) (v >>> 40));
        memory.setByte(i++, (byte) (v >>> 48));
        memory.setByte(i++, (byte) (v >>> 56));
    }
    return new OffHeapBitSet(memory);
}