Unnecessary synchronisation?

[sebbASF]

The synch. here appears to be unnecessary:

jna/src/com/sun/jna/NativeLibrary.java

Lines 186 to 188 in 3656295

	synchronized (customPaths) {
	searchPath.addAll(customPaths);
	}

searchPaths is a ConcurrentHashMap, so does it need synch?
It also does not make sense to me to synch. on the value being added, rather than the target being updated.

[matthiasblaesing]

That guard looks unnecessary, but this might be problematic:

jna/src/com/sun/jna/NativeLibrary.java

Lines 521 to 529 in 3656295

	public static final void addSearchPath(String libraryName, String path) {
	List<String> customPaths = searchPaths.get(libraryName);
	if (customPaths == null) {
	customPaths = Collections.synchronizedList(new ArrayList<String>());
	searchPaths.put(libraryName, customPaths);
	}
	customPaths.add(path);
	}

Here is a real race and that could now (JDK8 as baseline) be fixed using ConcurrentHashMap#computeIfAbsent.