-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy pathredis-study.html
763 lines (301 loc) · 22.4 KB
/
redis-study.html
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
<!DOCTYPE html>
<html class="theme-next muse use-motion" lang="zh-Hans">
<head>
<meta charset="UTF-8"/>
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1"/>
<meta name="theme-color" content="#222">
<meta http-equiv="Cache-Control" content="no-transform" />
<meta http-equiv="Cache-Control" content="no-siteapp" />
<link href="/lib/fancybox/source/jquery.fancybox.css?v=2.1.5" rel="stylesheet" type="text/css" />
<link href="/lib/font-awesome/css/font-awesome.min.css?v=4.6.2" rel="stylesheet" type="text/css" />
<link href="/css/main.css?v=5.1.4" rel="stylesheet" type="text/css" />
<link rel="apple-touch-icon" sizes="180x180" href="/images/apple-touch-icon-next.png?v=5.1.4">
<link rel="icon" type="image/png" sizes="32x32" href="/images/favicon-32x32-next.png?v=5.1.4">
<link rel="icon" type="image/png" sizes="16x16" href="/images/favicon-16x16-next.png?v=5.1.4">
<link rel="mask-icon" href="/images/logo.svg?v=5.1.4" color="#222">
<meta name="keywords" content="redis," />
<link rel="alternate" href="/atom.xml" title="个人博客" type="application/atom+xml" />
<meta name="description" content="redis 数据结构简单动态字符串redis中字符串是自己定义的结构，名为SDS。不是用的c语言的字符串。SDS的定义如下：12345678struct sdshdr { // 记录buf数组中已使用字节的数量 int len; // 记录buf数组中未使用字节的数量 int free; // 字节数组，用于存储字符串;其中最后一位保存'\0&#x">
<meta property="og:type" content="article">
<meta property="og:title" content="redis study">
<meta property="og:url" content="https://lightnine/github.io/redis-study.html">
<meta property="og:site_name" content="个人博客">
<meta property="og:description" content="redis 数据结构简单动态字符串redis中字符串是自己定义的结构，名为SDS。不是用的c语言的字符串。SDS的定义如下：12345678struct sdshdr { // 记录buf数组中已使用字节的数量 int len; // 记录buf数组中未使用字节的数量 int free; // 字节数组，用于存储字符串;其中最后一位保存'\0&#x">
<meta property="og:locale">
<meta property="article:published_time" content="2024-04-01T11:33:09.000Z">
<meta property="article:modified_time" content="2024-06-10T07:00:19.059Z">
<meta property="article:author" content="liang">
<meta property="article:tag" content="redis">
<meta name="twitter:card" content="summary">
<script type="text/javascript" id="hexo.configurations">
var NexT = window.NexT || {};
var CONFIG = {
root: '',
scheme: 'Muse',
version: '5.1.4',
sidebar: {"position":"left","display":"post","offset":12,"b2t":false,"scrollpercent":false,"onmobile":false},
fancybox: true,
tabs: true,
motion: {"enable":true,"async":false,"transition":{"post_block":"fadeIn","post_header":"slideDownIn","post_body":"slideDownIn","coll_header":"slideLeftIn","sidebar":"slideUpIn"}},
duoshuo: {
userId: '0',
author: '博主'
},
algolia: {
applicationID: '',
apiKey: '',
indexName: '',
hits: {"per_page":10},
labels: {"input_placeholder":"Search for Posts","hits_empty":"We didn't find any results for the search: ${query}","hits_stats":"${hits} results found in ${time} ms"}
}
};
</script>
<link rel="canonical" href="https://lightnine/github.io/redis-study.html"/>
<title>redis study | 个人博客</title>
<meta name="generator" content="Hexo 7.0.0"></head>
<body itemscope itemtype="http://schema.org/WebPage" lang="zh-Hans">
<div class="container sidebar-position-left page-post-detail">
<div class="headband"></div>
<header id="header" class="header" itemscope itemtype="http://schema.org/WPHeader">
<div class="header-inner"><div class="site-brand-wrapper">
<div class="site-meta ">
<div class="custom-logo-site-title">
<a href="/" class="brand" rel="start">
<span class="logo-line-before"><i></i></span>
<span class="site-title">个人博客</span>
<span class="logo-line-after"><i></i></span>
</a>
</div>
<p class="site-subtitle"></p>
</div>
<div class="site-nav-toggle">
<button>
<span class="btn-bar"></span>
<span class="btn-bar"></span>
<span class="btn-bar"></span>
</button>
</div>
</div>
<nav class="site-nav">
<ul id="menu" class="menu">
<li class="menu-item menu-item-home">
<a href="/" rel="section">
<i class="menu-item-icon fa fa-fw fa-home"></i> <br />
首页
</a>
</li>
<li class="menu-item menu-item-about">
<a href="/about/" rel="section">
<i class="menu-item-icon fa fa-fw fa-user"></i> <br />
关于
</a>
</li>
<li class="menu-item menu-item-tags">
<a href="/tags/" rel="section">
<i class="menu-item-icon fa fa-fw fa-tags"></i> <br />
标签
</a>
</li>
<li class="menu-item menu-item-categories">
<a href="/categories/" rel="section">
<i class="menu-item-icon fa fa-fw fa-th"></i> <br />
分类
</a>
</li>
<li class="menu-item menu-item-archives">
<a href="/archives/" rel="section">
<i class="menu-item-icon fa fa-fw fa-archive"></i> <br />
归档
</a>
</li>
</ul>
</nav>
</div>
</header>
<main id="main" class="main">
<div class="main-inner">
<div class="content-wrap">
<div id="content" class="content">
<div id="posts" class="posts-expand">
<article class="post post-type-normal" itemscope itemtype="http://schema.org/Article">
<div class="post-block">
<link itemprop="mainEntityOfPage" href="https://lightnine/github.io/redis-study.html">
<span hidden itemprop="author" itemscope itemtype="http://schema.org/Person">
<meta itemprop="name" content="">
<meta itemprop="description" content="">
<meta itemprop="image" content="/images/avatar.gif">
</span>
<span hidden itemprop="publisher" itemscope itemtype="http://schema.org/Organization">
<meta itemprop="name" content="个人博客">
</span>
<header class="post-header">
<h1 class="post-title" itemprop="name headline">redis study</h1>
<div class="post-meta">
<span class="post-time">
<span class="post-meta-item-icon">
<i class="fa fa-calendar-o"></i>
</span>
<span class="post-meta-item-text">发表于</span>
<time title="创建于" itemprop="dateCreated datePublished" datetime="2024-04-01T19:33:09+08:00">
2024-04-01
</time>
</span>
<span class="post-category" >
<span class="post-meta-divider">|</span>
<span class="post-meta-item-icon">
<i class="fa fa-folder-o"></i>
</span>
<span class="post-meta-item-text">分类于</span>
<span itemprop="about" itemscope itemtype="http://schema.org/Thing">
<a href="/categories/redis/" itemprop="url" rel="index">
<span itemprop="name">redis</span>
</a>
</span>
</span>
</div>
</header>
<div class="post-body" itemprop="articleBody">
<h2 id="redis-数据结构"><a href="#redis-数据结构" class="headerlink" title="redis 数据结构"></a>redis 数据结构</h2><h3 id="简单动态字符串"><a href="#简单动态字符串" class="headerlink" title="简单动态字符串"></a>简单动态字符串</h3><p>redis中字符串是自己定义的结构，名为SDS。不是用的c语言的字符串。<br>SDS的定义如下：<br><figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br></pre></td><td class="code"><pre><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">sdshdr</span> {</span></span><br><span class="line"> <span class="comment">// 记录buf数组中已使用字节的数量</span></span><br><span class="line"> <span class="type">int</span> len;</span><br><span class="line"> <span class="comment">// 记录buf数组中未使用字节的数量</span></span><br><span class="line"> <span class="type">int</span> <span class="built_in">free</span>;</span><br><span class="line"> <span class="comment">// 字节数组，用于存储字符串;其中最后一位保存'\0'字符</span></span><br><span class="line"> <span class="type">char</span> buf[];</span><br><span class="line">}</span><br></pre></td></tr></table></figure><br>为什么要自己实现，而不是复用c中对于字符串的定义？</p>
<ul>
<li>获取字符串长度，在O(1)复杂度获取</li>
<li>杜绝缓冲区溢出。SDS在进行修改时，会检查SDS空间是否满足要求。若不满足，则会进行扩容。</li>
<li>二进制安全，c中的字符串必须符合某种编码格式(比如ASCII)，并且除了字符串的末尾之外，字符串中不能包含空字符。而sds使用len记录字符串长度，所以是二进制安全的。</li>
</ul>
<p>SDS的扩容机制：</p>
<ul>
<li>空间预分配（若对sds进行修改，先将len设置为需要的空间大小）<ul>
<li>若sds中len小于1MB，则将free设置为跟len一样的大小</li>
<li>若sds中len大于1MB，则将free设置为1MB</li>
</ul>
</li>
<li>惰性空间释放<ul>
<li>若释放sds中内容，则free中进行增加。实际占用的空间不释放；当然也提供了相应的api，在需要时，真正释放sds未使用空间。</li>
</ul>
</li>
</ul>
<h3 id="链表"><a href="#链表" class="headerlink" title="链表"></a>链表</h3><p>redis中链表结构<br>链表中节点定义<br><figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">typedef</span> <span class="class"><span class="keyword">struct</span> <span class="title">listNode</span> {</span></span><br><span class="line"> <span class="comment">// 前置节点</span></span><br><span class="line"> <span class="class"><span class="keyword">struct</span> <span class="title">listNode</span> *<span class="title">prev</span>;</span></span><br><span class="line"> <span class="comment">// 后置节点</span></span><br><span class="line"> <span class="class"><span class="keyword">struct</span> <span class="title">listNode</span> *<span class="title">next</span>;</span></span><br><span class="line"> <span class="comment">// 节点值</span></span><br><span class="line"> <span class="type">void</span> *value;</span><br><span class="line">} listNode;</span><br></pre></td></tr></table></figure><br>链表定义<br><figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">typedef</span> <span class="class"><span class="keyword">struct</span> <span class="title">list</span> {</span></span><br><span class="line"> <span class="comment">// 表头节点</span></span><br><span class="line"> listNode *head;</span><br><span class="line"> <span class="comment">// 表尾节点</span></span><br><span class="line"> listNode *tail;</span><br><span class="line"> <span class="comment">// 链表包含的节点数量</span></span><br><span class="line"> <span class="type">unsigned</span> <span class="type">long</span> len;</span><br><span class="line"> <span class="comment">// 节点值复制函数</span></span><br><span class="line"> <span class="type">void</span> *(*dup) (<span class="type">void</span> *ptr);</span><br><span class="line"> <span class="comment">// 节点值释放函数</span></span><br><span class="line"> <span class="type">void</span> (*<span class="built_in">free</span>) (<span class="type">void</span> *ptr);</span><br><span class="line"> <span class="comment">// 节点值对比函数</span></span><br><span class="line"> <span class="type">int</span> (*match) (<span class="type">void</span> *ptr, <span class="type">void</span> *key);</span><br><span class="line">} <span class="built_in">list</span>;</span><br></pre></td></tr></table></figure><br>注：链表节点使用 void*指针保存节点值，并且通过list中的dup、free、match三个属性为节点值设置类型特定函数，所以链表可以保存各种不同类型的值。</p>
<h3 id="字典"><a href="#字典" class="headerlink" title="字典"></a>字典</h3><h3 id="跳跃表"><a href="#跳跃表" class="headerlink" title="跳跃表"></a>跳跃表</h3><h3 id="整数集合"><a href="#整数集合" class="headerlink" title="整数集合"></a>整数集合</h3><h3 id="压缩列表"><a href="#压缩列表" class="headerlink" title="压缩列表"></a>压缩列表</h3><h3 id="对象"><a href="#对象" class="headerlink" title="对象"></a>对象</h3>
</div>
<footer class="post-footer">
<div class="post-tags">
<a href="/tags/redis/" rel="tag"># redis</a>
</div>
<div class="post-nav">
<div class="post-nav-next post-nav-item">
<a href="/Top-5-things-every-apache-kafka-developer-should-know.html" rel="next" title="Top 5 things every apache kafka developer should know">
<i class="fa fa-chevron-left"></i> Top 5 things every apache kafka developer should know
</a>
</div>
<span class="post-nav-divider"></span>
<div class="post-nav-prev post-nav-item">
<a href="/%E8%BF%90%E8%A1%8Ckubectl-run%E4%BC%9A%E5%8F%91%E7%94%9F%E4%BB%80%E4%B9%88-what-happens-when-i-type-kubectl-run.html" rel="prev" title="运行kubectl run会发生什么(what happens when i type kubectl run)">
运行kubectl run会发生什么(what happens when i type kubectl run) <i class="fa fa-chevron-right"></i>
</a>
</div>
</div>
</footer>
</div>
</article>
<div class="post-spread">
</div>
</div>
</div>
</div>
<div class="sidebar-toggle">
<div class="sidebar-toggle-line-wrap">
<span class="sidebar-toggle-line sidebar-toggle-line-first"></span>
<span class="sidebar-toggle-line sidebar-toggle-line-middle"></span>
<span class="sidebar-toggle-line sidebar-toggle-line-last"></span>
</div>
</div>
<aside id="sidebar" class="sidebar">
<div class="sidebar-inner">
<ul class="sidebar-nav motion-element">
<li class="sidebar-nav-toc sidebar-nav-active" data-target="post-toc-wrap">
文章目录
</li>
<li class="sidebar-nav-overview" data-target="site-overview-wrap">
站点概览
</li>
</ul>
<section class="site-overview-wrap sidebar-panel">
<div class="site-overview">
<div class="site-author motion-element" itemprop="author" itemscope itemtype="http://schema.org/Person">
<p class="site-author-name" itemprop="name"></p>
<p class="site-description motion-element" itemprop="description"></p>
</div>
<nav class="site-state motion-element">
<div class="site-state-item site-state-posts">
<a href="/archives/%7C%7C%20archive">
<span class="site-state-item-count">37</span>
<span class="site-state-item-name">日志</span>
</a>
</div>
<div class="site-state-item site-state-categories">
<a href="/categories/index.html">
<span class="site-state-item-count">22</span>
<span class="site-state-item-name">分类</span>
</a>
</div>
<div class="site-state-item site-state-tags">
<a href="/tags/index.html">
<span class="site-state-item-count">45</span>
<span class="site-state-item-name">标签</span>
</a>
</div>
</nav>
<div class="feed-link motion-element">
<a href="/atom.xml" rel="alternate">
<i class="fa fa-rss"></i>
RSS
</a>
</div>
</div>
</section>
<!--noindex-->
<section class="post-toc-wrap motion-element sidebar-panel sidebar-panel-active">
<div class="post-toc">
<div class="post-toc-content"><ol class="nav"><li class="nav-item nav-level-2"><a class="nav-link" href="#redis-%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84"><span class="nav-number">1.</span> <span class="nav-text">redis 数据结构</span></a><ol class="nav-child"><li class="nav-item nav-level-3"><a class="nav-link" href="#%E7%AE%80%E5%8D%95%E5%8A%A8%E6%80%81%E5%AD%97%E7%AC%A6%E4%B8%B2"><span class="nav-number">1.1.</span> <span class="nav-text">简单动态字符串</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#%E9%93%BE%E8%A1%A8"><span class="nav-number">1.2.</span> <span class="nav-text">链表</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#%E5%AD%97%E5%85%B8"><span class="nav-number">1.3.</span> <span class="nav-text">字典</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#%E8%B7%B3%E8%B7%83%E8%A1%A8"><span class="nav-number">1.4.</span> <span class="nav-text">跳跃表</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#%E6%95%B4%E6%95%B0%E9%9B%86%E5%90%88"><span class="nav-number">1.5.</span> <span class="nav-text">整数集合</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#%E5%8E%8B%E7%BC%A9%E5%88%97%E8%A1%A8"><span class="nav-number">1.6.</span> <span class="nav-text">压缩列表</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#%E5%AF%B9%E8%B1%A1"><span class="nav-number">1.7.</span> <span class="nav-text">对象</span></a></li></ol></li></ol></div>
</div>
</section>
<!--/noindex-->
</div>
</aside>
</div>
</main>
<footer id="footer" class="footer">
<div class="footer-inner">
<div class="copyright">© <span itemprop="copyrightYear">2024</span>
<span class="with-love">
<i class="fa fa-user"></i>
</span>
<span class="author" itemprop="copyrightHolder">liang</span>
</div>
<div class="powered-by">由 <a class="theme-link" target="_blank" href="https://hexo.io">Hexo</a> 强力驱动</div>
<span class="post-meta-divider">|</span>
<div class="theme-info">主题 — <a class="theme-link" target="_blank" href="https://github.com/iissnan/hexo-theme-next">NexT.Muse</a> v5.1.4</div>
</div>
</footer>
<div class="back-to-top">
<i class="fa fa-arrow-up"></i>
</div>
</div>
<script type="text/javascript">
if (Object.prototype.toString.call(window.Promise) !== '[object Function]') {
window.Promise = null;
}
</script>
<script type="text/javascript" src="/lib/jquery/index.js?v=2.1.3"></script>
<script type="text/javascript" src="/lib/fastclick/lib/fastclick.min.js?v=1.0.6"></script>
<script type="text/javascript" src="/lib/jquery_lazyload/jquery.lazyload.js?v=1.9.7"></script>
<script type="text/javascript" src="/lib/velocity/velocity.min.js?v=1.2.1"></script>
<script type="text/javascript" src="/lib/velocity/velocity.ui.min.js?v=1.2.1"></script>
<script type="text/javascript" src="/lib/fancybox/source/jquery.fancybox.pack.js?v=2.1.5"></script>
<script type="text/javascript" src="/js/src/utils.js?v=5.1.4"></script>
<script type="text/javascript" src="/js/src/motion.js?v=5.1.4"></script>
<script type="text/javascript" src="/js/src/scrollspy.js?v=5.1.4"></script>
<script type="text/javascript" src="/js/src/post-details.js?v=5.1.4"></script>
<script type="text/javascript" src="/js/src/bootstrap.js?v=5.1.4"></script>
</body>
</html>