Remove upper case constants (#13)

Remove usage of upper-case constants.

Updates SDK version to 2.0.0-dev.17.0
4 files changed
tree: 8508c5c798d9a01151d49f494a89dcccf366cd54
  1. lib/
  2. test/
  3. .gitignore
  4. .test_config
  5. .travis.yml
  6. analysis_options.yaml
  7. CHANGELOG.md
  8. codereview.settings
  9. LICENSE
  10. pubspec.yaml
  11. README.md
README.md

The pool package exposes a Pool class which makes it easy to manage a limited pool of resources.

The easiest way to use a pool is by calling withResource. This runs a callback and returns its result, but only once there aren't too many other callbacks currently running.

// Create a Pool that will only allocate 10 resources at once. After 30 seconds
// of inactivity with all resources checked out, the pool will throw an error.
final pool = new Pool(10, timeout: new Duration(seconds: 30));

Future<String> readFile(String path) {
  // Since the call to [File.readAsString] is within [withResource], no more
  // than ten files will be open at once.
  return pool.withResource(() => new File(path).readAsString());
}

For more fine-grained control, the user can also explicitly request generic PoolResource objects that can later be released back into the pool. This is what withResource does under the covers: requests a resource, then releases it once the callback completes.

Pool ensures that only a limited number of resources are allocated at once. It‘s the caller’s responsibility to ensure that the corresponding physical resource is only consumed when a PoolResource is allocated.

class PooledFile implements RandomAccessFile {
  final RandomAccessFile _file;
  final PoolResource _resource;

  static Future<PooledFile> open(String path) {
    return pool.request().then((resource) {
      return new File(path).open().then((file) {
        return new PooledFile._(file, resource);
      });
    });
  }

  PooledFile(this._file, this._resource);

  // ...

  Future<RandomAccessFile> close() {
    return _file.close.then((_) {
      _resource.release();
      return this;
    });
  }
}