[GROOVY-4518] add support for @WithReadLock and @WithWriteLock declarative synchronization

• Type: New Feature
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.8-beta-3
• Flags: Patch
• Assignee: Hamlet D'Arcy
• Reporter: Hamlet D'Arcy
• Created: 19/Nov/10 14:57
• Updated: 05/Apr/15 14:44
• Resolved: 22/Nov/10 14:18

Description

add support for @WithReadLock and @WithWriteLock declarative synchronization

As per the discussion here: http://groovy.329449.n5.nabble.com/new-transform-declarative-synchronization-td3271562.html

I'll commit this myself, but am looking for feedback.

This code:

import groovy.transform.*;

public class ResourceProvider {

    private final Map<String, String> data = new HashMap<String, String>();

    @WithReadLock
    public String getResource(String key) throws Exception {
            return data.get(key);
    }

    @WithWriteLock
    public void refresh() throws Exception {
            //reload the resources into memory
    }
}

Becomes this Code:

import java.util.concurrent.locks.ReentrantReadWriteLock;
import java.util.concurrent.locks.ReadWriteLock;

public class ResourceProvider {

    private final ReadWriteLock $reentrantlock = new ReentrantReadWriteLock();
    private final Map<String, String> data = new HashMap<String, String>();

    public String getResource(String key) throws Exception {
        $reentrantlock.readLock().lock();
        try {
            return data.get(key);
        } finally {
            $reentrantlock.readLock().unlock();
        }
    }

    public void refresh() throws Exception {
        $reentrantlock.writeLock().lock();
        try {
            //reload the resources into memory
        } finally {
            $reentrantlock.writeLock().unlock();
        }
    }
}

You can also specify your own lock, like so:

import groovy.transforms.*;

public class ResourceProvider {

    private final ReadWriteLock myLock = new ReentrantReadWriteLock();
    private final Map<String, String> data = new HashMap<String, String>();

    @WithReadLock('myLock')
    public String getResource(String key) throws Exception {
            return data.get(key);
    }

    @WithWriteLock('myLock')
    public void refresh() throws Exception {
            //reload the resources into memory
    }
}

In which case the code becomes:

public class ResourceProvider {

    private final ReadWriteLock myLock = new ReentrantReadWriteLock();
    private final Map<String, String> data = new HashMap<String, String>();

    public String getResource(String key) throws Exception {
        myLock.readLock().lock();
        try {
            return data.get(key);
        } finally {
            myLock.readLock().unlock();
        }
    }

    public void refresh() throws Exception {
        myLock.writeLock().lock();
        try {
            //reload the resources into memory
        } finally {
            myLock.writeLock().unlock();
        }
    }
}