Move pub/barback's Pool class into its own package.
R=rnystrom@google.com
Review URL: https://codereview.chromium.org//399963004
git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@38525 260f80e4-7a28-3924-810f-c04153c831b5
diff --git a/CHANGELOG.md b/CHANGELOG.md
index deed1bc..6edf327 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 0.14.1+3
+
+* Add a dependency on the `pool` package.
+
## 0.14.1+2
* Automatically log how long it takes long-running transforms to run.
diff --git a/lib/src/utils/file_pool.dart b/lib/src/utils/file_pool.dart
index 6bea4a4..6a23337 100644
--- a/lib/src/utils/file_pool.dart
+++ b/lib/src/utils/file_pool.dart
@@ -8,10 +8,10 @@
import 'dart:convert';
import 'dart:io';
+import 'package:pool/pool.dart';
import 'package:stack_trace/stack_trace.dart';
import '../utils.dart';
-import 'pool.dart';
/// Manages a pool of files that are opened for reading to cope with maximum
/// file descriptor limits.
diff --git a/lib/src/utils/pool.dart b/lib/src/utils/pool.dart
deleted file mode 100644
index c1c76bc..0000000
--- a/lib/src/utils/pool.dart
+++ /dev/null
@@ -1,141 +0,0 @@
-// Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-library barback.utils.pool;
-
-import 'dart:async';
-import 'dart:collection';
-
-import 'package:stack_trace/stack_trace.dart';
-
-import '../utils.dart';
-
-// TODO(nweiz): put this somewhere that it can be shared between packages.
-/// Manages an abstract pool of resources with a limit on how many may be in use
-/// at once.
-///
-/// When a resource is needed, the user should call [request]. When the returned
-/// future completes with a [PoolResource], the resource may be allocated. Once
-/// the resource has been released, the user should call [PoolResource.release].
-/// The pool will ensure that only a certain number of [PoolResource]s may be
-/// allocated at once.
-class Pool {
- /// Completers for requests beyond the first [_maxAllocatedResources].
- ///
- /// When an item is released, the next element of [_requestedResources] will
- /// be completed.
- final _requestedResources = new Queue<Completer<PoolResource>>();
-
- /// The maximum number of resources that may be allocated at once.
- final int _maxAllocatedResources;
-
- /// The number of resources that are currently allocated.
- int _allocatedResources = 0;
-
- /// The timeout timer.
- ///
- /// If [_timeout] isn't null, this timer is set as soon as the resource limit
- /// is reached and is reset every time an resource is released or a new
- /// resource is requested. If it fires, that indicates that the caller became
- /// deadlocked, likely due to files waiting for additional files to be read
- /// before they could be closed.
- Timer _timer;
-
- /// The amount of time to wait before timing out the pending resources.
- Duration _timeout;
-
- /// Creates a new pool with the given limit on how many resources may be
- /// allocated at once.
- ///
- /// If [timeout] is passed, then if that much time passes without any activity
- /// all pending [request] futures will throw an exception. This is indented
- /// to avoid deadlocks.
- Pool(this._maxAllocatedResources, {Duration timeout})
- : _timeout = timeout;
-
- /// Request a [PoolResource].
- ///
- /// If the maximum number of resources is already allocated, this will delay
- /// until one of them is released.
- Future<PoolResource> request() {
- if (_allocatedResources < _maxAllocatedResources) {
- _allocatedResources++;
- return new Future.value(new PoolResource._(this));
- } else {
- var completer = new Completer<PoolResource>();
- _requestedResources.add(completer);
- _resetTimer();
- return completer.future;
- }
- }
-
- /// Requests a resource for the duration of [callback], which may return a
- /// Future.
- ///
- /// The return value of [callback] is piped to the returned Future.
- Future withResource(callback()) {
- return request().then((resource) =>
- syncFuture(callback).whenComplete(resource.release));
- }
-
- /// If there are any pending requests, this will fire the oldest one.
- void _onResourceReleased() {
- if (_requestedResources.isEmpty) {
- _allocatedResources--;
- if (_timer != null) {
- _timer.cancel();
- _timer = null;
- }
- return;
- }
-
- _resetTimer();
- var pending = _requestedResources.removeFirst();
- pending.complete(new PoolResource._(this));
- }
-
- /// A resource has been requested, allocated, or released.
- void _resetTimer() {
- if (_timer != null) _timer.cancel();
- if (_timeout == null) {
- _timer = null;
- } else {
- _timer = new Timer(_timeout, _onTimeout);
- }
- }
-
- /// Handles [_timer] timing out by causing all pending resource completers to
- /// emit exceptions.
- void _onTimeout() {
- for (var completer in _requestedResources) {
- completer.completeError("Pool deadlock: all resources have been "
- "allocated for too long.", new Chain.current());
- }
- _requestedResources.clear();
- _timer = null;
- }
-}
-
-/// A member of a [Pool].
-///
-/// A [PoolResource] is a token that indicates that a resource is allocated.
-/// When the associated resource is released, the user should call [release].
-class PoolResource {
- final Pool _pool;
-
- /// Whether [this] has been released yet.
- bool _released = false;
-
- PoolResource._(this._pool);
-
- /// Tells the parent [Pool] that the resource associated with this resource is
- /// no longer allocated, and that a new [PoolResource] may be allocated.
- void release() {
- if (_released) {
- throw new StateError("A PoolResource may only be released once.");
- }
- _released = true;
- _pool._onResourceReleased();
- }
-}
diff --git a/pubspec.yaml b/pubspec.yaml
index cc7f5df..9d6fec3 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -7,7 +7,7 @@
#
# When the minor or patch version of this is upgraded, you *must* update that
# version constraint in pub to stay in sync with this.
-version: 0.14.1+3
+version: 0.14.1+4
author: "Dart Team <misc@dartlang.org>"
homepage: http://www.dartlang.org
@@ -23,6 +23,7 @@
responsiveness.
dependencies:
path: ">=0.9.0 <2.0.0"
+ pool: ">=1.0.0 <2.0.0"
source_maps: ">=0.9.0 <0.10.0"
stack_trace: ">=0.9.1 <2.0.0"
collection: ">=0.9.1 <0.10.0"
