http://www.drdobbs.com/lock-free-data-structures-with-hazard-po/184401890 memory deallocation  lock-free session.h /* * WT_HAZARD -- * A hazard pointer. */ struct __wt_hazard { WT_PAGE *page; /* Page address */ #ifdef HAVE_DIAGNOSTIC const char *file…

关于Hazard Pointers的话题, 起源于这个文章: 实现无锁的栈与队列(4) http://www.cnblogs.com/catch/p/3176636.html 其实他的系列文章(3)之前我也看过, 里面写的内容是有小问题的, 不过关键不在这, 我比较看中的是他引入的无锁队列问题. 其实之前也有过人发表过更完整的无锁哈希表的实现, 不过(4)文作者比较多的融入自己的想法(虽然不一定对), 还是有一定启发的. (4)中讨论的Hazard Pointers我比较感兴趣.…

WiredTiger是一种高性能的开源存储引擎,现已在MongoDB中作为内模式应用.WiredTiger支持行存储.列存储两种存储模式,采用LSM Tree方式进行索引记录 WiredTiger支持事务的ACID特性(原子性.一致性.隔离性.持久性).对数据的存储方式可采用简易的key/value形式进行存储,也可以使用包含索引映射的数据模式层的方式进行存储. WiredTiger存储引擎可应用于现代多核CPU架构之上.采用多种实现方式,如风险指针(hazard pointers).无锁算法(…

lock free数据结构一般来说拥有比基于lock实现的数据结构更高的性能,但是其实现比基于lock的实现更为复杂,需要处理的难题包括预防ABA问题,内存如何重用和回收等.通常,最简单最有效的处理ABA问题的方法是在目标内存区域加入一个tag,每次目标内存区域被更新或者被重用时增加tag.线程最后一次读取目标内存区域后tag没有改变,CAS操作才能成功.比如对于无锁链表来说,目标内存区域就是链表节点. 但是,在目标内存区域中包含tag这种方法,当所有线程都不再需要使用某块内存区域时,没有机制可…

Lock-Free Data Structures with Hazard Pointers 锁无关的数据结构与Hazard指针----操纵有限的资源 By Andrei Alexandrescu and Maged Michael 刘未鹏(pp_liu@msn.com) 译 Andrei Alexandrescu是华盛顿大学计算机科学系的在读研究生,也是<Modern C++ Design>一书的作者.他的邮箱是 andrei@metalanguage.com. Maged Michael是…

导语:计算机硬件在飞速发展,数据规模在急速膨胀,但是数据库仍然使用是十年以前的架构体系,WiredTiger 尝试打破这一切,充分利用多核与大内存时代,开发一种真正满足未来大数据管理所需的数据库.本文由袁荣喜向「高可用架构」投稿,介绍对 WiredTiger 源代码学习过程中对数据库设计的感悟. 袁荣喜,学霸君工程师,2015年加入学霸君,负责学霸君的网络实时传输和分布式系统的架构设计和实现,专注于基础技术领域,在网络传输.数据库内核.分布式系统和并发编程方面有一定了解. WiredTiger…

题目链接:Populating Next Right Pointers in Each Node II | LeetCode OJ Follow up for problem "Populating Next Right Pointers in Each Node". What if the given tree could be any binary tree? Would your previous solution still work? Note: You may only u…

题目链接:Populating Next Right Pointers in Each Node | LeetCode OJ Given a binary tree struct TreeLinkNode { TreeLinkNode *left; TreeLinkNode *right; TreeLinkNode *next; } Populate each next pointer to point to its next right node. If there is no next ri…

存储引擎(Storage Engine)是MongoDB的核心组件,负责管理数据如何存储在硬盘(Disk)和内存(Memory)上.从MongoDB 3.2 版本开始,MongoDB 支持多数据存储引擎(Storage Engine),MongoDB支持的存储引擎有:WiredTiger,MMAPv1和In-Memory. 从MongoDB 3.2 版本开始,WiredTiger成为MongDB默认的Storage Engine,用于将数据持久化存储到硬盘文件中,WiredTiger提供文档级别…

Follow up for problem "Populating Next Right Pointers in Each Node". What if the given tree could be any binary tree? Would your previous solution still work? Note: You may only use constant extra space. For example,Given the following binary tr…

Given a binary tree struct TreeLinkNode { TreeLinkNode *left; TreeLinkNode *right; TreeLinkNode *next; } Populate each next pointer to point to its next right node. If there is no next right node, the next pointer should be set to NULL. Initially, al…

内存管理方面的知识 基础实例: #include <iostream> #include <stack> #include <memory> using namespace std; struct X { X() { cout << "X() ";} ~X() { cout << "~X() ";} }; struct Y { Y() { cout << "Y() ";} ~…

一.MongoDB3.0.x的版本特性(相对于MongoDB2.6及以下): 增加了wiredtiger引擎: 开源的存储引擎: 支持多核CPU.充分利用内存/芯片级别缓存(注:10月14日刚刚发布的3.0.7版本中,进一步改进了内存操作的性能): 基于B-TREE及LSM算法: 提供文档级锁(document-level concurrency control),类似于关系型数据库的的行级锁: 支持文件压缩(其中snappy压缩机制可以在5%的额外CPU消耗,减少70%的空间使用,也可以根据需…

Populating Next Right Pointers in Each Node Given a binary tree struct TreeLinkNode { TreeLinkNode *left; TreeLinkNode *right; TreeLinkNode *next; } Populate each next pointer to point to its next right node. If there is no next right node, the next…

Given a binary tree struct TreeLinkNode { TreeLinkNode *left; TreeLinkNode *right; TreeLinkNode *next; } Populate each next pointer to point to its next right node. If there is no next right node, the next pointer should be set to NULL. Initially, al…

METHOD 1: Consider the case where we do not know the number of elements in each row at compile time, i.e. both the number of rows and number of columns must be determined at run time. One way of doing this would be to create an array of pointers to t…

题目: Follow up for problem "Populating Next Right Pointers in Each Node". What if the given tree could be any binary tree? Would your previous solution still work? Note: You may only use constant extra space. For example, Given the following bina…

题目: Given a binary tree struct TreeLinkNode { TreeLinkNode *left; TreeLinkNode *right; TreeLinkNode *next; } Populate each next pointer to point to its next right node. If there is no next right node, the next pointer should be set to NULL. Initially…

C# unmanaged function pointers for iOS Just a reminder to myself when I need this thing next time for making Unity work with native code: delegate method should be static to please AOT compiler required for iOS method should have have [MonoPInvokeCal…

Populating Next Right Pointers in Each Node II Follow up for problem "Populating Next Right Pointers in Each Node". What if the given tree could be any binary tree? Would your previous solution still work? Note: You may only use constant extra s…

Populating Next Right Pointers in Each Node Given a binary tree struct TreeLinkNode { TreeLinkNode *left; TreeLinkNode *right; TreeLinkNode *next; } Populate each next pointer to point to its next right node. If there is no next right node, the next…

Given a binary tree struct TreeLinkNode { TreeLinkNode *left; TreeLinkNode *right; TreeLinkNode *next; } Populate each next pointer to point to its next right node. If there is no next right node, the next pointer should be set to NULL. Initially, al…

题目来源 https://leetcode.com/problems/populating-next-right-pointers-in-each-node/ Given a binary tree struct TreeLinkNode { TreeLinkNode *left; TreeLinkNode *right; TreeLinkNode *next; } Populate each next pointer to point to its next right node. If th…

Populating Next Right Pointers in Each Node OJ: https://oj.leetcode.com/problems/populating-next-right-pointers-in-each-node/ Given a binary tree struct TreeLinkNode { TreeLinkNode *left; TreeLinkNode *right; TreeLinkNode *next; } Populate each next…

Follow up for problem "Populating Next Right Pointers in Each Node". What if the given tree could be any binary tree? Would your previous solution still work? Note: You may only use constant extra space.   For example,Given the following binary…

该文介绍了如何使用指针中一些未使用的位来隐藏一些数据. When we write C code, pointers are everywhere. We can make a little extra use of pointers and sneak in some extra information in them. To pull this trick off, we exploit the natural alignment of data in memory. Data in mem…

Given a binary tree struct TreeLinkNode { TreeLinkNode *left; TreeLinkNode *right; TreeLinkNode *next; } Populate each next pointer to point to its next right node. If there is no next right node, the next pointer should be set to NULL. Initially, al…

两年多以前随手写了点与 lock free 相关的笔记:1,2,3,4,质量都不是很高其实(读者见谅),但两年来陆陆续续竟也有些阅读量了(可见剑走偏锋的技巧是多容易吸引眼球).笔记当中在解决内存释放和 ABA 问题时提到了 Hazard Pointer 这个东西,有两三个读者来信问这是什么,让详细讲一下,我想了想,反正以前在看这东西的时候也记了些东西,干脆整理一下发出来. 前面写的那几篇笔记都来源于 Maged Michael 的学术论文,Hazard pointer 也是他的创想,academ…

今天开始看MongoDB 3.2的文档,发现了这么两句话 Support for Multiple Storage Engines MongoDB supports multiple storage engines, such as: WiredTiger Storage Engine and MMAPv1 Storage Engine. 可能阅读的中文书籍太Low了,第一次看到这两个存储引擎,在中文社区看到对WiredTiger方面的介绍,转载到此处 Mongodb-3.2已经WiredTig…

LeetCode:Populating Next Right Pointers in Each Node Given a binary tree struct TreeLinkNode { TreeLinkNode *left; TreeLinkNode *right; TreeLinkNode *next; } Populate each next pointer to point to its next right node. If there is no next right node,…