https://referencesource.microsoft.com/#mscorlib/system/collections/queue.cs
aperçu
- Initialisation : 32 par défaut, double expansion à chaque fois. Par conséquent, lors de l'initialisation, la taille peut être prédéfinie pour éviter une expansion fréquente
public Queue()
: this(32, (float)2.0)
- Rejoindre l'équipe pour augmenter la capacité : l'intérieur est un tableau, si la taille s'avère insuffisante, augmentez la capacité. Lorsque l'index de la tête est avant l'index de la queue, copiez la taille de la taille dans le nouveau nouveau tableau ; lorsque l'index de la queue est avant la tête, copiez d'abord la tête dans le tableau taille-1, puis copiez le tableau 0 à la fin
private void SetCapacity(int capacity)
{
Object[] newarray = new Object[capacity];
if (_size > 0)
{
//如果头在前面
if (_head < _tail)
{
Array.Copy(_array, _head, newarray, 0, _size);
}
//尾在前，头在后，中间是null
else
{
//先复制头到数组size-1标
Array.Copy(_array, _head, newarray, 0, _array.Length - _head);
//再复制数组0标到尾
Array.Copy(_array, 0, newarray, _array.Length - _head, _tail);
}
}
_array = newarray;
_head = 0;
_tail = (_size == capacity) ? 0 : _size; //_size 是指原_array不为空元素的数量
_version++;
}
- Mettre en file d'attente : capacité suffisante, placez-la à la marque _tail du tableau, et en même temps _tail = (_tail + 1) % _array.Length, ce qui peut entraîner _head > _tail. Si vous avez besoin d'étendre la capacité ultérieurement, vous devez pour le diviser en deux étapes. Tout d'abord, copiez la tête sur la marque de taille de tableau -1, puis copiez la marque de tableau 0 à la fin ; la capacité n'est pas suffisante, augmentez d'abord la capacité
// Adds obj to the tail of the queue.
//
public virtual void Enqueue(Object obj)
{
if (_size == _array.Length)
{
int newcapacity = (int)((long)_array.Length * (long)_growFactor / 100);
if (newcapacity < _array.Length + _MinimumGrow)
{
newcapacity = _array.Length + _MinimumGrow;
}
SetCapacity(newcapacity);
}
_array[_tail] = obj;
_tail = (_tail + 1) % _array.Length;
_size++;
_version++;
}
- Dequeuing : l'en-tête _head est copié dans le nouvel objet, _array[_head] = null ; (effacer la mémoire), puis _head = (_head + 1) % _array.Length ;
public virtual Object Dequeue()
{
if (Count == 0)
throw new InvalidOperationException(("InvalidOperation_EmptyQueue"));
Contract.EndContractBlock();
Object removed = _array[_head];
_array[_head] = null;
_head = (_head + 1) % _array.Length;
_size--;
_version++;
return removed;
}
Tout le code source de la file d'attente C#
// ==++==
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
// ==--==
/*=============================================================================
**
** Class: Queue
**
** <OWNER>Microsoft</OWNER>
**
** Purpose: A circular-array implementation of a queue.
**
**
=============================================================================*/
namespace System.Collections {
using System;
using System.Security.Permissions;
using System.Diagnostics;
using System.Diagnostics.CodeAnalysis;
using System.Diagnostics.Contracts;
// A simple Queue of objects. Internally it is implemented as a circular
// buffer, so Enqueue can be O(n). Dequeue is O(1).
[DebuggerTypeProxy(typeof(System.Collections.Queue.QueueDebugView))]
[DebuggerDisplay("Count = {Count}")]
[System.Runtime.InteropServices.ComVisible(true)]
[Serializable]
public class Queue : ICollection, ICloneable {
private Object[] _array;
private int _head; // First valid element in the queue
private int _tail; // Last valid element in the queue
private int _size; // Number of elements.
private int _growFactor; // 100 == 1.0, 130 == 1.3, 200 == 2.0
private int _version;
[NonSerialized]
private Object _syncRoot;
private const int _MinimumGrow = 4;
private const int _ShrinkThreshold = 32;
// Creates a queue with room for capacity objects. The default initial
// capacity and grow factor are used.
public Queue()
: this(32, (float)2.0) {
}
// Creates a queue with room for capacity objects. The default grow factor
// is used.
//
public Queue(int capacity)
: this(capacity, (float)2.0) {
}
// Creates a queue with room for capacity objects. When full, the new
// capacity is set to the old capacity * growFactor.
//
public Queue(int capacity, float growFactor) {
if (capacity < 0)
throw new ArgumentOutOfRangeException("capacity", Environment.GetResourceString("ArgumentOutOfRange_NeedNonNegNum"));
if (!(growFactor >= 1.0 && growFactor <= 10.0))
throw new ArgumentOutOfRangeException("growFactor", Environment.GetResourceString("ArgumentOutOfRange_QueueGrowFactor", 1, 10));
Contract.EndContractBlock();
_array = new Object[capacity];
_head = 0;
_tail = 0;
_size = 0;
_growFactor = (int)(growFactor * 100);
}
// Fills a Queue with the elements of an ICollection. Uses the enumerator
// to get each of the elements.
//
public Queue(ICollection col) : this((col==null ? 32 : col.Count))
{
if (col==null)
throw new ArgumentNullException("col");
Contract.EndContractBlock();
IEnumerator en = col.GetEnumerator();
while(en.MoveNext())
Enqueue(en.Current);
}
public virtual int Count {
get { return _size; }
}
public virtual Object Clone() {
Queue q = new Queue(_size);
q._size = _size;
int numToCopy = _size;
int firstPart = (_array.Length - _head < numToCopy) ? _array.Length - _head : numToCopy;
Array.Copy(_array, _head, q._array, 0, firstPart);
numToCopy -= firstPart;
if (numToCopy > 0)
Array.Copy(_array, 0, q._array, _array.Length - _head, numToCopy);
q._version = _version;
return q;
}
public virtual bool IsSynchronized {
get { return false; }
}
public virtual Object SyncRoot {
get {
if( _syncRoot == null) {
System.Threading.Interlocked.CompareExchange(ref _syncRoot, new Object(), null);
}
return _syncRoot;
}
}
// Removes all Objects from the queue.
public virtual void Clear() {
if (_head < _tail)
Array.Clear(_array, _head, _size);
else {
Array.Clear(_array, _head, _array.Length - _head);
Array.Clear(_array, 0, _tail);
}
_head = 0;
_tail = 0;
_size = 0;
_version++;
}
// CopyTo copies a collection into an Array, starting at a particular
// index into the array.
//
public virtual void CopyTo(Array array, int index)
{
if (array==null)
throw new ArgumentNullException("array");
if (array.Rank != 1)
throw new ArgumentException(Environment.GetResourceString("Arg_RankMultiDimNotSupported"));
if (index < 0)
throw new ArgumentOutOfRangeException("index", Environment.GetResourceString("ArgumentOutOfRange_Index"));
Contract.EndContractBlock();
int arrayLen = array.Length;
if (arrayLen - index < _size)
throw new ArgumentException(Environment.GetResourceString("Argument_InvalidOffLen"));
int numToCopy = _size;
if (numToCopy == 0)
return;
int firstPart = (_array.Length - _head < numToCopy) ? _array.Length - _head : numToCopy;
Array.Copy(_array, _head, array, index, firstPart);
numToCopy -= firstPart;
if (numToCopy > 0)
Array.Copy(_array, 0, array, index+_array.Length - _head, numToCopy);
}
// Adds obj to the tail of the queue.
//
public virtual void Enqueue(Object obj) {
if (_size == _array.Length) {
int newcapacity = (int)((long)_array.Length * (long)_growFactor / 100);
if (newcapacity < _array.Length + _MinimumGrow) {
newcapacity = _array.Length + _MinimumGrow;
}
SetCapacity(newcapacity);
}
_array[_tail] = obj;
_tail = (_tail + 1) % _array.Length;
_size++;
_version++;
}
// GetEnumerator returns an IEnumerator over this Queue. This
// Enumerator will support removing.
//
public virtual IEnumerator GetEnumerator()
{
return new QueueEnumerator(this);
}
// Removes the object at the head of the queue and returns it. If the queue
// is empty, this method simply returns null.
public virtual Object Dequeue() {
if (Count == 0)
throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_EmptyQueue"));
Contract.EndContractBlock();
Object removed = _array[_head];
_array[_head] = null;
_head = (_head + 1) % _array.Length;
_size--;
_version++;
return removed;
}
// Returns the object at the head of the queue. The object remains in the
// queue. If the queue is empty, this method throws an
// InvalidOperationException.
public virtual Object Peek() {
if (Count == 0)
throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_EmptyQueue"));
Contract.EndContractBlock();
return _array[_head];
}
// Returns a synchronized Queue. Returns a synchronized wrapper
// class around the queue - the caller must not use references to the
// original queue.
//
[HostProtection(Synchronization=true)]
public static Queue Synchronized(Queue queue)
{
if (queue==null)
throw new ArgumentNullException("queue");
Contract.EndContractBlock();
return new SynchronizedQueue(queue);
}
// Returns true if the queue contains at least one object equal to obj.
// Equality is determined using obj.Equals().
//
// Exceptions: ArgumentNullException if obj == null.
public virtual bool Contains(Object obj) {
int index = _head;
int count = _size;
while (count-- > 0) {
if (obj == null) {
if (_array[index] == null)
return true;
} else if (_array[index] != null && _array[index].Equals(obj)) {
return true;
}
index = (index + 1) % _array.Length;
}
return false;
}
internal Object GetElement(int i)
{
return _array[(_head + i) % _array.Length];
}
// Iterates over the objects in the queue, returning an array of the
// objects in the Queue, or an empty array if the queue is empty.
// The order of elements in the array is first in to last in, the same
// order produced by successive calls to Dequeue.
public virtual Object[] ToArray()
{
Object[] arr = new Object[_size];
if (_size==0)
return arr;
if (_head < _tail) {
Array.Copy(_array, _head, arr, 0, _size);
} else {
Array.Copy(_array, _head, arr, 0, _array.Length - _head);
Array.Copy(_array, 0, arr, _array.Length - _head, _tail);
}
return arr;
}
// PRIVATE Grows or shrinks the buffer to hold capacity objects. Capacity
// must be >= _size.
private void SetCapacity(int capacity) {
Object[] newarray = new Object[capacity];
if (_size > 0) {
if (_head < _tail) {
Array.Copy(_array, _head, newarray, 0, _size);
} else {
Array.Copy(_array, _head, newarray, 0, _array.Length - _head);
Array.Copy(_array, 0, newarray, _array.Length - _head, _tail);
}
}
_array = newarray;
_head = 0;
_tail = (_size == capacity) ? 0 : _size;
_version++;
}
public virtual void TrimToSize()
{
SetCapacity(_size);
}
// Implements a synchronization wrapper around a queue.
[Serializable]
private class SynchronizedQueue : Queue
{
private Queue _q;
private Object root;
internal SynchronizedQueue(Queue q) {
this._q = q;
root = _q.SyncRoot;
}
public override bool IsSynchronized {
get { return true; }
}
public override Object SyncRoot {
get {
return root;
}
}
public override int Count {
get {
lock (root) {
return _q.Count;
}
}
}
public override void Clear() {
lock (root) {
_q.Clear();
}
}
public override Object Clone() {
lock (root) {
return new SynchronizedQueue((Queue)_q.Clone());
}
}
public override bool Contains(Object obj) {
lock (root) {
return _q.Contains(obj);
}
}
public override void CopyTo(Array array, int arrayIndex) {
lock (root) {
_q.CopyTo(array, arrayIndex);
}
}
public override void Enqueue(Object value) {
lock (root) {
_q.Enqueue(value);
}
}
[SuppressMessage("Microsoft.Contracts", "CC1055")] // Thread safety problems with precondition - can't express the precondition as of Dev10.
public override Object Dequeue() {
lock (root) {
return _q.Dequeue();
}
}
public override IEnumerator GetEnumerator() {
lock (root) {
return _q.GetEnumerator();
}
}
[SuppressMessage("Microsoft.Contracts", "CC1055")] // Thread safety problems with precondition - can't express the precondition as of Dev10.
public override Object Peek() {
lock (root) {
return _q.Peek();
}
}
public override Object[] ToArray() {
lock (root) {
return _q.ToArray();
}
}
public override void TrimToSize() {
lock (root) {
_q.TrimToSize();
}
}
}
// Implements an enumerator for a Queue. The enumerator uses the
// internal version number of the list to ensure that no modifications are
// made to the list while an enumeration is in progress.
[Serializable]
private class QueueEnumerator : IEnumerator, ICloneable
{
private Queue _q;
private int _index;
private int _version;
private Object currentElement;
internal QueueEnumerator(Queue q) {
_q = q;
_version = _q._version;
_index = 0;
currentElement = _q._array;
if (_q._size == 0)
_index = -1;
}
public Object Clone()
{
return MemberwiseClone();
}
public virtual bool MoveNext() {
if (_version != _q._version) throw new InvalidOperationException(Environment.GetResourceString(ResId.InvalidOperation_EnumFailedVersion));
if (_index < 0) {
currentElement = _q._array;
return false;
}
currentElement = _q.GetElement(_index);
_index++;
if (_index == _q._size)
_index = -1;
return true;
}
public virtual Object Current {
get {
if (currentElement == _q._array)
{
if (_index == 0)
throw new InvalidOperationException(Environment.GetResourceString(ResId.InvalidOperation_EnumNotStarted));
else
throw new InvalidOperationException(Environment.GetResourceString(ResId.InvalidOperation_EnumEnded));
}
return currentElement;
}
}
public virtual void Reset() {
if (_version != _q._version) throw new InvalidOperationException(Environment.GetResourceString(ResId.InvalidOperation_EnumFailedVersion));
if (_q._size == 0)
_index = -1;
else
_index = 0;
currentElement = _q._array;
}
}
internal class QueueDebugView {
private Queue queue;
public QueueDebugView( Queue queue) {
if( queue == null)
throw new ArgumentNullException("queue");
Contract.EndContractBlock();
this.queue = queue;
}
[DebuggerBrowsable(DebuggerBrowsableState.RootHidden)]
public Object[] Items {
get {
return queue.ToArray();
}
}
}
}
}
Test du code source
https://github.com/luoyikun/UnityForTest
MyQueue.cs