November 2020
Intermediate to advanced
226 pages
5h 34m
Chinese
Content preview from C#并发编程经典实例（第2版）
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.
集合
｜
113
9.5
线程安全的字典
问题
假设现在有一个键
–
值对集合需要保持同步，比如内存缓存，不过有多个线程正在对其执
行读写操作。
解决方案
.NET
框架中的
ConcurrentDictionary<TKey, TValue>
类型就是数据结构中的宝藏。它
是线程安全的，混用细粒度锁和无锁技术，确保能在大多数场景中快速访问。另外，它
的
API
需要花些功夫来熟悉。它必须处理来自多个线程的并发访问，这一点与标准的
Dictionary<TKey, TValue>
类型非常不同。但是，一旦学会了本节中的基础知识，就会发
现
ConcurrentDictionary<TKey, TValue>
是非常实用的集合类型。
首先来看如何对集合写入值。可以通过
AddOrUpdate
实现给键赋值：
var
dictionary =
new
ConcurrentDictionary<
int
,
string
>();
string
newValue = dictionary.AddOrUpdate(0,
key =>
"
Zero",
(key, oldValue) =>
"
Zero");
AddOrUpdate
有一些复杂，它要根据并发字典当前的内容处理若干件事情。第
1
个参数是
键，第
2
个参数是委托，通过委托将键（本例中为
0
）转换为待添加至字典的值（本例中
为
“Zero”
）。只有当字典中不存在该键时，才会调用该委托。第
3
个参数是另一个委托，
它把键（
0
）和旧值转换为已更新的、待存入字典的值（
“Zero”
）。同样，只有当字典中不 ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.