nginx data structure collection (updated at any time)

When I’m learning nginx, because it has a lot of data structures, I usually forget it after reading it. So record it here while you study, so you can check it later.
ngx_buf_t: Buffer node

<code><span>1</span>： <span>typedef</span><span>struct</span> ngx_buf_s    ngx_buf_t;
   <span>2</span>: <span>typedef</span><span>void</span>  *ngx_buf_tag_t;
   <span>3</span>: <span>struct</span> ngx_buf_s {
   <span>4</span>:     <span>/*
   5:      * pos通常是用来告诉使用者本次应该从pos这个位置开始处理内存中的数据，这样设置是因为同一个
   6:      * ngx_buf_t可能被多次反复处理。当然，pos的含义是由使用它的模板定义的
   7:      */</span><span>8</span>:     u_char  *pos;
   <span>9</span>:                                
  <span>10</span>:     <span>/* last通常表示有效的内容到此为止，注意，pos与last之间的内存是希望nginx处理的内容 */</span><span>11</span>:     u_char  *last;
  <span>12</span>:                                
  <span>13</span>:     <span>/*
  14:      * 处理文件时，file_pos与file_last的含义与处理内存时的pos与last相同，
  15:      * file_pos表示将要处理的文件位置，file_last表示截至的文件位置。
  16:      */</span><span>17</span>:     off_t   file_pos;
  <span>18</span>:     off_t   file_last;
  <span>19</span>:                                
  <span>20</span>:     <span>/* 如果ngx_buf_t缓冲区用于内存，那么start指向这段内存的起始地址 */</span><span>21</span>:     u_char  *start;
  <span>22</span>:                                
  <span>23</span>:     <span>/* 与start成员对应，指向缓冲区内存的末尾 */</span><span>24</span>:     u_char  *end;
  <span>25</span>:                                
  <span>26</span>:     <span>/* 表示当前缓冲区的类型，例如由哪个模块使用就指向这个模块ngx_module_t变量的地址 */</span><span>27</span>:     ngx_buf_tag_t  tag;
  <span>28</span>:                                
  <span>29</span>:     <span>/* 引用的文件 */</span><span>30</span>:     ngx_file_t  *file;
  <span>31</span>:                                
  <span>32</span>:     <span>/*
  33:      * 当前缓冲区的影子缓冲区，该成员很少用到。当缓冲区转发上游服务器的响应时才使用了shadow成员，
  34:      * 这是因为nginx太节约内存了，分配一块内存并使用ngx_buf_t表示接收到的上游服务器响应后，
  35:      * 在向下游客户端转发时可能会把这块内存存储到文件中，也可能直接向下游发送，此时nginx绝对不会
  36:      * 重新复制一份内存用于新的目的，而是再次建立一个ngx_buf_t结构体指向原内存，这样多个ngx_buf_t
  37:      * 结构体指向了同一份内存，它们之间的关系就通过shadow成员来引用，一般不建议使用。
  38:      */</span><span>39</span>:     ngx_buf_t   *shadow;
  <span>40</span>:                                
  <span>41</span>:     <span>/* 临时内存标志位，为1时表示数据在内存中且这段内存可以修改 */</span><span>42</span>:     <span>unsigned</span>    temporay:<span>1</span>;
  <span>43</span>:                                
  <span>44</span>:     <span>/* 标志位，为1时表示数据在内存中且这段内存不可以修改 */</span><span>45</span>:     <span>unsigned</span>    memory:<span>1</span>;
  <span>46</span>:                                
  <span>47</span>:     <span>/* 标志位，为1时表示这段内存是用nmap系统调用映射过来的，不可以修改 */</span><span>48</span>:     <span>unsigned</span>    mmap:<span>1</span>;
  <span>49</span>:                                
  <span>50</span>:     <span>/* 标志位，为1时表示可回收 */</span><span>51</span>:     <span>unsigned</span>    recycled:<span>1</span>;
  <span>52</span>:                                
  <span>53</span>:     <span>/* 标志位，为1时表示这段缓冲区处理的是文件而不是内存 */</span><span>54</span>:     <span>unsigned</span>    in_file:<span>1</span>;
  <span>55</span>:                                
  <span>56</span>:     <span>/* 标志位，为1时表示需要执行flush操作 */</span><span>57</span>:     <span>unsigned</span>    flush:<span>1</span>;
  <span>58</span>:                                
  <span>59</span>:     <span>/*
  60:      * 标志位，对于操作这块缓冲区时是否使用同步方式，需谨慎考虑，这可能会阻塞nginx进程，nginx中所有
  61:      * 操作几乎都是异步的，这是它支持高并发的关键。有些框架代码在sync为1时可能会有阻塞的方式进行I/O
  62:      * 操作，它的意义视使用它的nginx模块而定。
  63:      */</span><span>64</span>:     <span>unsigned</span>    sync:<span>1</span>;
  <span>65</span>:                                
  <span>66</span>:     <span>/*
  67:      * 标志位，表示是否是最后一块缓冲区，因为ngx_buf_t可以由ngx_chain_t链表串联起来，因此为1时，
  68:      * 表示当前是最后一块待处理的缓冲区。   
  69:      */</span><span>70</span>:     <span>unsigned</span>    last_buf:<span>1</span>;
  <span>71</span>:                                
  <span>72</span>:     <span>/* 标志位，表示是否是ngx_chain_t中的最后一块缓冲区 */</span><span>73</span>:     <span>unsigned</span>    last_in_chain:<span>1</span>;
  <span>74</span>:                                
  <span>75</span>:     <span>/* 标志位，表示是否是最后一个影子缓冲区，与shadow域配合使用。通常不建议使用它 */</span><span>76</span>:     <span>unsigned</span>    last_shadow:<span>1</span>;
  <span>77</span>:                                
  <span>78</span>:     <span>/* 标志位，表示当前缓冲区是否属于临时文件 */</span><span>79</span>:     <span>unsigned</span>    temp_file:<span>1</span>;
  <span>80</span>: }</code>

ngx_chain_t: Buffer chain list

<code><span>typedef</span><span>struct</span> ngx_chain_s       ngx_chain_t;
   <span>struct</span> ngx_chain_s
    {
       ngx_buf_t    *buf; <span>//buf指向当前的ngx_buf_t缓冲区</span>
      ngx_chain_t  *next; <span>//next则用来指向下一个ngx_chain_t，如果这是最后一个ngx_chain_t，则需要把next置为NULL。</span>
   };</code>

ngx_http_upstream_t: Set the restrictive parameters of upstream

<code>typedef struct{
<span>...</span>
//连接上游服务器的超时时间，单位为毫秒
ngx_msec_t connect_timeout;
//发送TCP包到上游服务器的超时时间，单位为毫秒
ngx_msec_t connect_timeout;
//接收TCP包到上游服务器的超时时间，单位为毫秒
ngx_msec_t connect_timeout;
<span>...</span>
}ngx_http_upstream_conf_t;</code>

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The above introduces the data structure collection of nginx (updated at any time), including relevant content. I hope it will be helpful to friends who are interested in PHP tutorials.