Package org.neo4j.gds.core.utils.paged

Class HugeDoubleArray

  • All Implemented Interfaces:
    HugeCursorSupport<double[]>
    public abstract class HugeDoubleArray
extends HugeArray<double[],​java.lang.Double,​HugeDoubleArray>
    A long-indexable version of a primitive double array (double[]) that can contain more than 2 bn. elements.

    It is implemented by paging of smaller double-arrays (double[][]) to support approx. 32k bn. elements. If the provided size is small enough, an optimized view of a single double[] might be used.

    • The array is of a fixed size and cannot grow or shrink dynamically.
    • The array is not optimized for sparseness and has a large memory overhead if the values written to it are very sparse.
    • The array does not support default values and returns the same default for unset values that a regular double[] does (0).

    Basic Usage

     
 AllocationTracker allocationTracker = ...;
 long arraySize = 42L;
 HugeDoubleArray array = HugeDoubleArray.newArray(arraySize, allocationTracker);
 array.set(13L, 37D);
 double value = array.get(13L);
 // value = 37D

    • Constructor Detail

      • HugeDoubleArray

        public HugeDoubleArray()

    • Method Detail

      • get

        public abstract double get​(long index)
        Returns:
        the double value at the given index
        Throws:
        java.lang.ArrayIndexOutOfBoundsException - if the index is not within size()

      • set

        public abstract void set​(long index,
                         double value)
        Sets the double value at the given index to the given value.
        Throws:
        java.lang.ArrayIndexOutOfBoundsException - if the index is not within size()

      • addTo

        public abstract void addTo​(long index,
                           double value)
        Adds (+) the existing value and the provided value at the given index and stored the result into the given index. If there was no previous value, the final result is set to the provided value (x + 0 == x).
        Throws:
        java.lang.ArrayIndexOutOfBoundsException - if the index is not within size()

      • setAll

        public abstract void setAll​(java.util.function.LongToDoubleFunction gen)
        Set all elements using the provided generator function to compute each element.

        The behavior is identical to Arrays.setAll(double[], java.util.function.IntToDoubleFunction).

      • fill

        public abstract void fill​(double value)
        Assigns the specified double value to each element.

        The behavior is identical to Arrays.fill(double[], double).

      • size

        public abstract long size()
        Returns the length of this array.

        If the size is greater than zero, the highest supported index is size() - 1

        The behavior is identical to calling array.length on primitive arrays.

        Specified by:
        size in interface HugeCursorSupport<double[]>
        Specified by:
        size in class HugeArray<double[],​java.lang.Double,​HugeDoubleArray>

      • sizeOf

        public abstract long sizeOf()
        Specified by:
        sizeOf in class HugeArray<double[],​java.lang.Double,​HugeDoubleArray>
        Returns:
        the amount of memory used by the instance of this array, in bytes. This should be the same as returned from HugeArray.release() without actually releasing the array.

      • release

        public abstract long release()
        Destroys the data, allowing the underlying storage arrays to be collected as garbage. The array is unusable after calling this method and will throw NullPointerExceptions on virtually every method invocation.

        Note that the data might not immediately collectible if there are still cursors alive that reference this array. You have to HugeCursor.close() every cursor instance as well.

        The amount is not removed from the AllocationTracker that had been provided in the constructor.

        Specified by:
        release in class HugeArray<double[],​java.lang.Double,​HugeDoubleArray>
        Returns:
        the amount of memory freed, in bytes.

      • stream

        public abstract java.util.stream.DoubleStream stream()

      • copyTo

        public abstract void copyTo​(HugeDoubleArray dest,
                            long length)
        Copies the content of this array into the target array.

        The behavior is identical to System.arraycopy(Object, int, Object, int, int).

        Specified by:
        copyTo in class HugeArray<double[],​java.lang.Double,​HugeDoubleArray>

      • toArray

        public double[] toArray()
        Specified by:
        toArray in class HugeArray<double[],​java.lang.Double,​HugeDoubleArray>
        Returns:
        the contents of this array as a flat java primitive array. The returned array might be shared and changes would then be reflected and visible in this array.

      • newArray

        public static HugeDoubleArray newArray​(long size,
                                       AllocationTracker allocationTracker)
        Creates a new array of the given size, tracking the memory requirements into the given AllocationTracker. The tracker is no longer referenced, as the arrays do not dynamically change their size.

      • memoryEstimation

        public static long memoryEstimation​(long size)