chrisvest

import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodType;
import java.util.concurrent.ThreadLocalRandom;

import org.openjdk.jmh.annotations.Benchmark;

public class MethodHandleBenchmark
{
    private static final MethodHandle workHandle = createWorkHandle();

chrisvest

package org.openjdk.jol.samples;

import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodType;
import java.lang.reflect.Field;

import org.openjdk.jol.util.VMSupport;

import static java.lang.System.out;

chrisvest

This is a very simple approach to doing role-based access control with Neo4j. It is optimistic, in the sense that all items are assumed to be world-accessible unless they have specific constraints. Item visibility can be constrained to either individual users or all users who belong to a role. Roles are also hierarchical, so can inherit privileges from other roles.

First, lets create our basic example data:

chrisvest

<dependency>
  <groupId>com.github.chrisvest</groupId>
  <artifactId>stormpot</artifactId>
  <version>2.3</version>
</dependency>

chrisvest

import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.Fork;
import org.openjdk.jmh.annotations.Measurement;
import org.openjdk.jmh.annotations.OutputTimeUnit;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.Setup;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.annotations.Threads;
import org.openjdk.jmh.annotations.Warmup;
import sun.misc.Unsafe;

chrisvest

public class MemoryHolder {
    private long pointer;

    public MemoryHolder() {
        pointer = unsafe.allocateMemory(MEMORY);
    }

    @Override
    protected void finalize() {
        unsafe.freeMemory(pointer);

chrisvest

    public static void main(String[] args) {
        MemoryHolder holder = new MemoryHolder();
        long p = holder.pointer; // last use of 'holder'
        int n = unsafe.getInt(null, p);
        System.out.println("holder.getInt() = " + n);
    }

chrisvest

    public static void main(String[] args) {
        MemoryHolder holder = new MemoryHolder();
        System.out.println("holder.getInt() = " + holder.getInt());
        reachabilityFence(holder);
    }

chrisvest

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chrisvest

nitsan:object-pool-benchmarks% java -jar target/benchmarks.jar 'Simulation.(newObject|claimReleaseWithout)' -bm sample -i 10 -wi 10 -tu ns -t 1 -f 1 -r 10 -jvmArgsPrepend '-XX:+UseConcMarkSweepGC'
# JMH 1.5.1 (released 10 days ago)
# VM invoker: /usr/lib/jvm/java-8-jdk/jre/bin/java
# VM options: -XX:+UseConcMarkSweepGC
# Warmup: 10 iterations, 1 s each
# Measurement: 10 iterations, 10 s each
# Timeout: 10 min per iteration
# Threads: 1 thread, will synchronize iterations
# Benchmark mode: Sampling time
# Benchmark: objectpoolbenchmark.specific.stormpot.Simulation.claimReleaseWithoutReturn