src/main/java/io/reactivex/internal/util/BackpressureHelper.java
public static long multiplyCap(long a, long b) {
        long u = a * b;
        if (((a | b) >>> 31) != 0) {
            if (u / a != b) {
                return Long.MAX_VALUE;
            }
        }
        return u;
    }
public static long multiplyCap(long a, long b) {
        long u = a * b;
        if (((a | b) >>> 31) != 0) {
            if (u / a != b) {
                return Long.MAX_VALUE;
            }
        }
        return u;
    }
Multiplies two long values and caps the product at Long.MAX_VALUE.
@param a the first value
@param b the second value
@return the product capped at Long.MAX_VALUE