rework refresh queue

MediaBrowser.Providers/Manager/SimplePriorityQueue.cs

@@ -0,0 +1,243 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Priority_Queue
+{
+    /// <summary>
+    /// Credit: https://github.com/BlueRaja/High-Speed-Priority-Queue-for-C-Sharp
+    /// A simplified priority queue implementation.  Is stable, auto-resizes, and thread-safe, at the cost of being slightly slower than
+    /// FastPriorityQueue
+    /// </summary>
+    /// <typeparam name="TItem">The type to enqueue</typeparam>
+    /// <typeparam name="TPriority">The priority-type to use for nodes.  Must extend IComparable&lt;TPriority&gt;</typeparam>
+    public class SimplePriorityQueue<TItem, TPriority> : IPriorityQueue<TItem, TPriority>
+        where TPriority : IComparable<TPriority>
+    {
+        private class SimpleNode : GenericPriorityQueueNode<TPriority>
+        {
+            public TItem Data { get; private set; }
+
+            public SimpleNode(TItem data)
+            {
+                Data = data;
+            }
+        }
+
+        private const int INITIAL_QUEUE_SIZE = 10;
+        private readonly GenericPriorityQueue<SimpleNode, TPriority> _queue;
+
+        public SimplePriorityQueue()
+        {
+            _queue = new GenericPriorityQueue<SimpleNode, TPriority>(INITIAL_QUEUE_SIZE);
+        }
+
+        /// <summary>
+        /// Given an item of type T, returns the exist SimpleNode in the queue
+        /// </summary>
+        private SimpleNode GetExistingNode(TItem item)
+        {
+            var comparer = EqualityComparer<TItem>.Default;
+            foreach (var node in _queue)
+            {
+                if (comparer.Equals(node.Data, item))
+                {
+                    return node;
+                }
+            }
+            throw new InvalidOperationException("Item cannot be found in queue: " + item);
+        }
+
+        /// <summary>
+        /// Returns the number of nodes in the queue.
+        /// O(1)
+        /// </summary>
+        public int Count
+        {
+            get
+            {
+                lock (_queue)
+                {
+                    return _queue.Count;
+                }
+            }
+        }
+
+
+        /// <summary>
+        /// Returns the head of the queue, without removing it (use Dequeue() for that).
+        /// Throws an exception when the queue is empty.
+        /// O(1)
+        /// </summary>
+        public TItem First
+        {
+            get
+            {
+                lock (_queue)
+                {
+                    if (_queue.Count <= 0)
+                    {
+                        throw new InvalidOperationException("Cannot call .First on an empty queue");
+                    }
+
+                    SimpleNode first = _queue.First;
+                    return (first != null ? first.Data : default(TItem));
+                }
+            }
+        }
+
+        /// <summary>
+        /// Removes every node from the queue.
+        /// O(n)
+        /// </summary>
+        public void Clear()
+        {
+            lock (_queue)
+            {
+                _queue.Clear();
+            }
+        }
+
+        /// <summary>
+        /// Returns whether the given item is in the queue.
+        /// O(n)
+        /// </summary>
+        public bool Contains(TItem item)
+        {
+            lock (_queue)
+            {
+                var comparer = EqualityComparer<TItem>.Default;
+                foreach (var node in _queue)
+                {
+                    if (comparer.Equals(node.Data, item))
+                    {
+                        return true;
+                    }
+                }
+                return false;
+            }
+        }
+
+        /// <summary>
+        /// Removes the head of the queue (node with minimum priority; ties are broken by order of insertion), and returns it.
+        /// If queue is empty, throws an exception
+        /// O(log n)
+        /// </summary>
+        public TItem Dequeue()
+        {
+            lock (_queue)
+            {
+                if (_queue.Count <= 0)
+                {
+                    throw new InvalidOperationException("Cannot call Dequeue() on an empty queue");
+                }
+
+                SimpleNode node = _queue.Dequeue();
+                return node.Data;
+            }
+        }
+
+        /// <summary>
+        /// Enqueue a node to the priority queue.  Lower values are placed in front. Ties are broken by first-in-first-out.
+        /// This queue automatically resizes itself, so there's no concern of the queue becoming 'full'.
+        /// Duplicates are allowed.
+        /// O(log n)
+        /// </summary>
+        public void Enqueue(TItem item, TPriority priority)
+        {
+            lock (_queue)
+            {
+                SimpleNode node = new SimpleNode(item);
+                if (_queue.Count == _queue.MaxSize)
+                {
+                    _queue.Resize(_queue.MaxSize * 2 + 1);
+                }
+                _queue.Enqueue(node, priority);
+            }
+        }
+
+        /// <summary>
+        /// Removes an item from the queue.  The item does not need to be the head of the queue.  
+        /// If the item is not in the queue, an exception is thrown.  If unsure, check Contains() first.
+        /// If multiple copies of the item are enqueued, only the first one is removed. 
+        /// O(n)
+        /// </summary>
+        public void Remove(TItem item)
+        {
+            lock (_queue)
+            {
+                try
+                {
+                    _queue.Remove(GetExistingNode(item));
+                }
+                catch (InvalidOperationException ex)
+                {
+                    throw new InvalidOperationException("Cannot call Remove() on a node which is not enqueued: " + item, ex);
+                }
+            }
+        }
+
+        /// <summary>
+        /// Call this method to change the priority of an item.
+        /// Calling this method on a item not in the queue will throw an exception.
+        /// If the item is enqueued multiple times, only the first one will be updated.
+        /// (If your requirements are complex enough that you need to enqueue the same item multiple times <i>and</i> be able
+        /// to update all of them, please wrap your items in a wrapper class so they can be distinguished).
+        /// O(n)
+        /// </summary>
+        public void UpdatePriority(TItem item, TPriority priority)
+        {
+            lock (_queue)
+            {
+                try
+                {
+                    SimpleNode updateMe = GetExistingNode(item);
+                    _queue.UpdatePriority(updateMe, priority);
+                }
+                catch (InvalidOperationException ex)
+                {
+                    throw new InvalidOperationException("Cannot call UpdatePriority() on a node which is not enqueued: " + item, ex);
+                }
+            }
+        }
+
+        public IEnumerator<TItem> GetEnumerator()
+        {
+            List<TItem> queueData = new List<TItem>();
+            lock (_queue)
+            {
+                //Copy to a separate list because we don't want to 'yield return' inside a lock
+                foreach (var node in _queue)
+                {
+                    queueData.Add(node.Data);
+                }
+            }
+
+            return queueData.GetEnumerator();
+        }
+
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            return GetEnumerator();
+        }
+
+        public bool IsValidQueue()
+        {
+            lock (_queue)
+            {
+                return _queue.IsValidQueue();
+            }
+        }
+    }
+
+    /// <summary>
+    /// A simplified priority queue implementation.  Is stable, auto-resizes, and thread-safe, at the cost of being slightly slower than
+    /// FastPriorityQueue
+    /// This class is kept here for backwards compatibility.  It's recommended you use Simple
+    /// </summary>
+    /// <typeparam name="TItem">The type to enqueue</typeparam>
+    public class SimplePriorityQueue<TItem> : SimplePriorityQueue<TItem, float> { }
+}