This package provides various synchronization implementations:
-
Lock for exclusive access This lock can be used to execute critical sections of code. The provided implementation supports reentrancy.
-
ReaderWriterLock for single writer/multiple reader synchronization The provided implementation does not supports reentrancy, but locks can be upgraded and/or downgraded.
-
Semaphore for controlling access to resources.
Implementations are based on package using and support
cancelation tokens as well as automatic
releasing via use() / useAsync() / execute() / executeAsync().
void main() {
final cache = <String, Data>{};
Future<Data?> fromCache(String key) =>
ReaderWriterLock.read(cache).useAsync((reader) async {
// multiple readers may retrieve some data from the cache
if (cache.containsKey(key)) {
return cache[key]!;
}
// when the data is not in cache, the lock is upgraded
return reader.upgrade().useAsync((writer) async {
// we now have exclusive access to load or compute data and update
// the cache
// ... load data, update cache ...
return data;
})
});
}