ai.vespa.utils.BytesQuantity Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of vespajlib Show documentation
Library for use in Java components of Vespa. Shared code which do not fit anywhere else.
There is a newer version: 8.441.21
package ai.vespa.utils;

import java.util.Locale;
import java.util.Objects;
import java.util.regex.Pattern;

/**
 * Reprents a quantity of bytes with a human-readable string representation.
 * Currently only supports binary units (e.g. 1 kB = 1024 bytes).
 *
 * @author bjorncs
 */
public class BytesQuantity {
    public enum Unit {
        BYTES, KB, MB, GB, TB;

        public long binarySize() {
            return switch (this) {
                case BYTES -> 1;
                case KB -> 1 << 10;
                case MB -> 1 << 20;
                case GB -> 1 << 30;
                case TB -> 1L << 40;
            };
        }

        public String toUnitString() {
            return switch (this) {
                case BYTES -> "bytes";
                case KB -> "kB";
                case MB -> "MB";
                case GB -> "GB";
                case TB -> "TB";
            };
        }

        static Unit fromString(String s) {
            return switch (s) {
                case "", "B", "bytes", "byte" -> BYTES;
                case "kB", "k", "K", "KB" -> KB;
                case "MB", "m", "M" -> MB;
                case "GB", "g", "G" -> GB;
                case "TB", "t", "T" -> TB;
                default -> throw new IllegalArgumentException("Invalid unit: " + s);
            };
        }
    }

    private final long bytes;
    private BytesQuantity(long bytes) { this.bytes = bytes; }

    public long toBytes() { return bytes; }

    public static BytesQuantity ofBytes(long bytes) { return new BytesQuantity(bytes); }
    public static BytesQuantity ofKB(long kb) { return BytesQuantity.of(kb, Unit.KB); }
    public static BytesQuantity ofMB(long mb) { return BytesQuantity.of(mb, Unit.MB); }
    public static BytesQuantity ofGB(long gb) { return BytesQuantity.of(gb, Unit.GB); }
    public static BytesQuantity ofTB(long tb) { return BytesQuantity.of(tb, Unit.TB); }
    public static BytesQuantity of(long value, Unit unit) { return new BytesQuantity(value * unit.binarySize()); }

    private static final Pattern PATTERN = Pattern.compile("^(?\\d+)\\s*(?[a-zA-Z]*)$");
    public static BytesQuantity fromString(String value) {
        var matcher = PATTERN.matcher(value);
        if (!matcher.matches())
            throw new IllegalArgumentException(
                    "Bytes quantity '%s' does not match pattern '%s'".formatted(value, PATTERN.pattern()));
        var digits = Long.parseLong(matcher.group("digits"));
        var unit = Unit.fromString(matcher.group("unit"));
        return BytesQuantity.of(digits, unit);
    }

    public String asPrettyString() {
        if (bytes == 0) return "0 bytes";
        if (bytes == 1) return "1 byte";
        long remaining = bytes;
        int unit = 0;
        for (; remaining % 1024 == 0 && unit < Unit.values().length - 1; unit++) remaining /= 1024;
        return String.format(Locale.ENGLISH, "%d %s", remaining, Unit.values()[unit].toUnitString());
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        BytesQuantity that = (BytesQuantity) o;
        return bytes == that.bytes;
    }

    @Override public int hashCode() { return Objects.hashCode(bytes); }
    @Override public String toString() { return asPrettyString(); }
}