primesieve-java

primesieve-java provides a native wrapper to kimwalisch/primesieve.

Prerequisites

primesieve-java is currently built and tested on MacOSX, ubuntu x86_64, and requires kimwalisch/primesieve to be installed or built locally first. See Build.

Build

primesieve-java must be built locally and requires primesieve to be built or installed.

Ubuntu

Ubuntu is built automatically as part of the github workflow, see gradle.yml. On unbuntu run:

• src/scripts/ubuntu-install-primesieve.sh
• ./gradlew build

Check that the libraries and headers are installed (copy if needed):

• ls /usr/local/include/primesieve*
  • Should include primesieve.hpp, primes/StorePrimes.hpp, primes/iterator.hpp
• ls /usr/local/lib/libprimesieve.*
  • ex: libprimesieve.a, libprimesieve.dylib

OSX

Run brew install primesieve Check that the libraries and headers are installed:

• ls /usr/local/include/primesieve*
  • Should include primesieve.hpp, primes/StorePrimes.hpp, primes/iterator.hpp
• ls /usr/local/lib/libprimesieve.*
  • ex: libprimesieve.a, libprimesieve.dylib

Build primesieve-java:

• git clone https://github.com/buildingnicesoftware/primesieve-java.git
• cd primesieve-java
• ./gradlew build

Sample application

A sample app is provided which simply retrieves and counts primes, see PrimeSieveMain.java:

./gradlew run
> Task :primesieve-main:run
0    [main] INFO  org.math.primesieve.PrimeSieveMain  - Calling native primesieve...
1    [main] INFO  org.math.primesieve.PrimeSieveMain  - Version: 12.6
907  [main] INFO  org.math.primesieve.PrimeSieveMain  - Generated primes from 1 to 1000000000: found 50847534 primes

Performance

Using all 8 CPU cores and 16 threads primesieve-java generates all primes up to 1 billion into a java long[] array in ~500ms. For comparison, a naive, serial Sieve of Eratosthenes was implemented in Java and took over 8s. The test is implemented in StorePrimesTest.java.

Usage

The subproject primesieve-main shows an example of using primesieve-java as a dependency, ex:

dependencies {
    // This dependency is used by the application.
    implementation(project(":primesieve"))
    //...

The following headers are supported:

• primesieve.hpp -> PrimeSieve.java
• iterator.hpp -> PrimeIterator.java
  • Use newPrimeIterator methods in PrimeSieve.java
• StorePrimes.hpp
  • Use storePrimes methods in PrimeSieve.java

The unit tests show example usage of primesieve-java. For example:

    @Test
    public void testStorePrimes() {
        long[] primes = LongStream.of(PrimeSieve.storePrimes(1, 100)).filter(p->p!=0).toArray();
        Assert.assertEquals(25, primes.length);
        Assert.assertArrayEquals(new long[] {2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37,
                41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97}, primes);
    }

Where appropriate UnsignedLong is used from the guava dependency. In general this is provided for convenience and it is not recommended to use boxed primitives for performance reasons. As an example where unsigned long might be useful:

    @Test
    public void testPrimeIterationUL() throws Exception {
        BigInteger outOfRangeStart = BigInteger.TWO.pow(63).add(BigInteger.ONE);
        Assert.assertTrue(outOfRangeStart.compareTo(BigInteger.valueOf(Long.MAX_VALUE)) > 0);
        try (PrimeIterator primeItr = PrimeSieve.newPrimeIterator(UnsignedLong.valueOf(outOfRangeStart.toString()))) {
            Assert.assertEquals(UnsignedLong.valueOf("9223372036854775837"), primeItr.nextULPrime());
            Assert.assertEquals(UnsignedLong.valueOf("9223372036854775783"), primeItr.prevULPrime());
        }
    }

In general all primesieve methods to count and get nth prime etc are implemented as well as primesieve::iterator and StorePrimes generating primes efficiently until a max n. For more details see Development.

Note that generating primes will allocate java long[] arrays larger than required. For performance reasons primesieve-java natively sizes the array one time and uses memcpy for efficient copies from primesieve::iterator Implementations need to check for trailing zeros which mark the end of the arrays. See the classes and javadoc for more information.

Development

primesieve-java uses nokee to compile natively. The compiler and linker arguments are set in build.gradle.kts under the library section. If building on other platforms, this section will need updating to be platform specific and include the required options.

Note the following:

• Not all of the print options are wrapped because they don't make sense for library usage
• PrimeStore generating n primes is not implemented
• primesieve error conditions and handling mapped to exceptions not implemented yet
• A repo distribution is not assembled or published currently but I can develop one of you have need for it
• Currently tested on ubuntu using the github workflow, and MacOSX with the following:
  • x86_64-apple-darwin24.2.0 (Sequoia 15.2)
  • primesieve 12.6
  • Xcode 16.2 (Build version 16C5032a)
  • JDK: GraalVM 23.0.1+11.1 (build 23.0.1+11-jvmci-b01)

Contributing

Contributions are welcome, please contact Rich Giuli rich@giuli.com.