Class LongAdder

output/java_guava/1.4.17/LongAdder.java:50–236

One or more variables that together maintain an initially zero long sum. When updates (method #add) are contended across threads, the set of variables may grow dynamically to reduce contention. Method #sum (or, equivalently, #longValue) returns the current total comb

@GwtCompatible(emulated = true)
final class LongAdder extends Striped64 implements Serializable, LongAddable {
  private static final long serialVersionUID = 7249069246863182397L;

    /**
     * Version of plus for use in retryUpdate
     */
  final long fn(long v, long x) {
    return v + x;
  }

    /**
     * Creates a new adder with initial sum of zero.
     */


  public LongAdder() {}

    /**
     * Adds the given value.
     *
     * @param x the value to add
     */


  public void add(long x) {
    Cell[] as;
    long b, v;
    int[] hc;
    Cell a;
    int n;
    if ((as = cells) != null || !casBase(b = base, b + x)) {
      boolean uncontended = true;
      if ((hc = threadHashCode.get()) == null || as == null || (n = as.length) < 1

          || (a = as[(n - 1) & hc[0]]) == null || !(uncontended = a.cas(v = a.value, v + x))) retryUpdate(x, hc, uncontended);
    }
  }

    /**
     * Equivalent to {@code add(1)}.
     */


  public void increment() {
    add(1L);
  }

    /**
     * Equivalent to {@code add(-1)}.
     */


  public void decrement() {
    add(-1L);
  }

    /**