ConcurrentDictionary内部机制粗解

ConcurrentDictionary是线程安全类，是什么在保证？

内部类

private class Tables
        {
            internal readonly Node[] m_buckets; // A singly-linked list for each bucket.
            internal readonly object[] m_locks // A set of locks, each guarding a section of the table.
           ……
        }
构造函数

  internal ConcurrentDictionary(int concurrencyLevel, int capacity, bool growLockArray, IEqualityComparer<TKey> comparer)
        {
            if (concurrencyLevel < 1)
            {
                throw new ArgumentOutOfRangeException("concurrencyLevel", GetResource("ConcurrentDictionary_ConcurrencyLevelMustBePositive"));
            }
            if (capacity < 0)
            {
                throw new ArgumentOutOfRangeException("capacity", GetResource("ConcurrentDictionary_CapacityMustNotBeNegative"));
            }
            if (comparer == null) throw new ArgumentNullException("comparer");

            // The capacity should be at least as large as the concurrency level. Otherwise, we would have locks that don't guard
            // any buckets.
            if (capacity < concurrencyLevel)
            {
                capacity = concurrencyLevel;
            }

            object[] locks = new object[concurrencyLevel];
            for (int i = 0; i < locks.Length; i++)
            {
                locks[i] = new object();
            }

            int[] countPerLock = new int[locks.Length];
            Node[] buckets = new Node[capacity];
            m_tables = new Tables(buckets, locks, countPerLock, comparer);
……
        }

TryAdd内部实现
……

Monitor.Enter(tables.m_locks[lockNo], ref lockTaken);
……

Monitor.Exit(tables.m_locks[lockNo]);

……

实质是维护了一个tables，m_buckets  负责存储，m_locks负责保存锁。至于用哪个bucket，用哪个lock，是有一定的算法，和hash有关。