static ThreadLocal<Uint8List> threadBuffer = new ThreadLocal<Uint8List>() {
@Override
public byte[] initialValue() {
return new byte[512];
}
};
In Java, ThreadLocal is a class that provides thread-local variables. These are variables that are specific to a particular thread and are not shared among other threads.
So what is equivalent of this code snippets in dart.
On
Dart does not have a direct equivalent of a Thread-local value. All static and top-level fields in Dart are independent to the isolate running the code. In other words, every value in Dart is thread-local.
So the equivalent of that code snippet in Dart would just be:
static Uint8List threadBuffer = Uint8List(512);
Dart does not have thread-shared memory. Every isolate is single-threaded. Instead of concurrency, asynchronous code is event based.
You may still want to have "semi-global" state which is preserved across awaits, but is not shared by other events happening in-between.
You can use zones for that.
Future<void> doSomething
for (var id in [1, 2, 3]) {
runZoned(zoneValues: {#id: 42}, () async {
await firstPart();
var id = Zone.current[#id] as int; // Read id from zone
print(id);
await secondPart();
});
}
This code runs the same code three times, but in different zones with different values bound to the #id symbol.
That's the closest thing to thread-local values in Dart.
The dart equivalent is simply:
In dart you have isolates instead of threads. Isolates do not share memory (state of variables), so the behavior is similar to
ThreadLocal.Consider this example:
Which prints out:
Notice that
threadBufferon the main isolate was unaffected by changes tothreadBufferin each of the spawned isolates. This is because the spawned isolates are working on their own independent copy ofthreadBufferrather than sharing a single instance ofthreadBuffer.