struct evbuffer定义在evbuffer-internal.h文件中。

evbuffer结构内部保存一个以evbuffer-chain结构为节点的链表,evbuffer内部有两个分别指向首尾节点的指针。

 struct evbuffer {
/** The first chain in this buffer's linked list of chains. */
struct evbuffer_chain *first;
/** The last chain in this buffer's linked list of chains. */
struct evbuffer_chain *last; /** Pointer to the next pointer pointing at the 'last_with_data' chain.
*
* To unpack:
*
* The last_with_data chain is the last chain that has any data in it.
* If all chains in the buffer are empty, it is the first chain.
* If the buffer has no chains, it is NULL.
*
* The last_with_datap pointer points at _whatever 'next' pointer_
* points at the last_with_datap chain. If the last_with_data chain
* is the first chain, or it is NULL, then the last_with_datap pointer
* is &buf->first.
*/
struct evbuffer_chain **last_with_datap; /** Total amount of bytes stored in all chains.*/
size_t total_len; /** Number of bytes we have added to the buffer since we last tried to
* invoke callbacks. */
size_t n_add_for_cb;
/** Number of bytes we have removed from the buffer since we last
* tried to invoke callbacks. */
size_t n_del_for_cb; #ifndef EVENT__DISABLE_THREAD_SUPPORT
/** A lock used to mediate access to this buffer. */
void *lock;
#endif
/** True iff we should free the lock field when we free this
* evbuffer. */
unsigned own_lock : ;
/** True iff we should not allow changes to the front of the buffer
* (drains or prepends). */
unsigned freeze_start : ;
/** True iff we should not allow changes to the end of the buffer
* (appends) */
unsigned freeze_end : ;
/** True iff this evbuffer's callbacks are not invoked immediately
* upon a change in the buffer, but instead are deferred to be invoked
* from the event_base's loop. Useful for preventing enormous stack
* overflows when we have mutually recursive callbacks, and for
* serializing callbacks in a single thread. */
unsigned deferred_cbs : ;
#ifdef _WIN32
/** True iff this buffer is set up for overlapped IO. */
unsigned is_overlapped : ;
#endif
/** Zero or more EVBUFFER_FLAG_* bits */
ev_uint32_t flags; /** Used to implement deferred callbacks. */
struct event_base *cb_queue; /** A reference count on this evbuffer. When the reference count
* reaches 0, the buffer is destroyed. Manipulated with
* evbuffer_incref and evbuffer_decref_and_unlock and
* evbuffer_free. */
int refcnt; /** A struct event_callback handle to make all of this buffer's callbacks
* invoked from the event loop. */
struct event_callback deferred; /** A doubly-linked-list of callback functions */
LIST_HEAD(evbuffer_cb_queue, evbuffer_cb_entry) callbacks; /** The parent bufferevent object this evbuffer belongs to.
* NULL if the evbuffer stands alone. */
struct bufferevent *parent;
};

struct evbuffer_chain:

evbuffer-chain结构内部保存一个表示buffer内容长度的变量以及一个char*的指针指向buffer内容所在的位置。

 /** A single item in an evbuffer. */
struct evbuffer_chain {
/** points to next buffer in the chain */
struct evbuffer_chain *next; /** total allocation available in the buffer field. */
size_t buffer_len; /** unused space at the beginning of buffer or an offset into a
* file for sendfile buffers. */
ev_misalign_t misalign; /** Offset into buffer + misalign at which to start writing.
* In other words, the total number of bytes actually stored
* in buffer. */
size_t off; /** Set if special handling is required for this chain */
unsigned flags;
#define EVBUFFER_FILESEGMENT 0x0001 /**< A chain used for a file segment */
#define EVBUFFER_SENDFILE 0x0002 /**< a chain used with sendfile */
#define EVBUFFER_REFERENCE 0x0004 /**< a chain with a mem reference */
#define EVBUFFER_IMMUTABLE 0x0008 /**< read-only chain */
/** a chain that mustn't be reallocated or freed, or have its contents
* memmoved, until the chain is un-pinned. */
#define EVBUFFER_MEM_PINNED_R 0x0010
#define EVBUFFER_MEM_PINNED_W 0x0020
#define EVBUFFER_MEM_PINNED_ANY (EVBUFFER_MEM_PINNED_R|EVBUFFER_MEM_PINNED_W)
/** a chain that should be freed, but can't be freed until it is
* un-pinned. */
#define EVBUFFER_DANGLING 0x0040
/** a chain that is a referenced copy of another chain */
#define EVBUFFER_MULTICAST 0x0080 /** number of references to this chain */
int refcnt; /** Usually points to the read-write memory belonging to this
* buffer allocated as part of the evbuffer_chain allocation.
* For mmap, this can be a read-only buffer and
* EVBUFFER_IMMUTABLE will be set in flags. For sendfile, it
* may point to NULL.
*/
unsigned char *buffer;
}; /** callback for a reference chain; lets us know what to do with it when
* we're done with it. Lives at the end of an evbuffer_chain with the
* EVBUFFER_REFERENCE flag set */
struct evbuffer_chain_reference {
evbuffer_ref_cleanup_cb cleanupfn;
void *extra;
};

lievent源码分析:evbuffer的更多相关文章

  1. 【转】libevent源码分析

    libevent源码分析 转自:http://www.cnblogs.com/hustcat/archive/2010/08/31/1814022.html 这两天没事,看了一下Memcached和l ...

  2. Envoy 源码分析--buffer

    目录 Envoy 源码分析--buffer BufferFragment RawSlice Slice OwnedSlice SliceDeque UnownedSlice OwnedImpl Wat ...

  3. Envoy 源码分析--event

    目录 Envoy 源码分析--event libevent Timer SignalEvent FileEvent RealTimeSystem 任务队列 延迟析构 dispacth_thread E ...

  4. ABP源码分析一:整体项目结构及目录

    ABP是一套非常优秀的web应用程序架构,适合用来搭建集中式架构的web应用程序. 整个Abp的Infrastructure是以Abp这个package为核心模块(core)+15个模块(module ...

  5. HashMap与TreeMap源码分析

    1. 引言     在红黑树--算法导论(15)中学习了红黑树的原理.本来打算自己来试着实现一下,然而在看了JDK(1.8.0)TreeMap的源码后恍然发现原来它就是利用红黑树实现的(很惭愧学了Ja ...

  6. nginx源码分析之网络初始化

    nginx作为一个高性能的HTTP服务器,网络的处理是其核心,了解网络的初始化有助于加深对nginx网络处理的了解,本文主要通过nginx的源代码来分析其网络初始化. 从配置文件中读取初始化信息 与网 ...

  7. zookeeper源码分析之五服务端(集群leader)处理请求流程

    leader的实现类为LeaderZooKeeperServer,它间接继承自标准ZookeeperServer.它规定了请求到达leader时需要经历的路径: PrepRequestProcesso ...

  8. zookeeper源码分析之四服务端(单机)处理请求流程

    上文: zookeeper源码分析之一服务端启动过程 中,我们介绍了zookeeper服务器的启动过程,其中单机是ZookeeperServer启动,集群使用QuorumPeer启动,那么这次我们分析 ...

  9. zookeeper源码分析之三客户端发送请求流程

    znode 可以被监控,包括这个目录节点中存储的数据的修改,子节点目录的变化等,一旦变化可以通知设置监控的客户端,这个功能是zookeeper对于应用最重要的特性,通过这个特性可以实现的功能包括配置的 ...

随机推荐

  1. jquery的validate.js 和 form.js 的使用方法

    在使用 Jquery 的方法的验证并且修改 原Form 表单的提交方式的时候,需要引用的文件有 <script type="text/javascript" src=&quo ...

  2. 字典树(Trie Tree)

    在图示中,键标注在节点中,值标注在节点之下.每一个完整的英文单词对应一个特定的整数.Trie 可以看作是一个确定有限状态自动机,尽管边上的符号一般是隐含在分支的顺序中的.键不需要被显式地保存在节点中. ...

  3. c# 基础部分 (基本数据类型-- 表达式)

    一 基础部分 1.常用的基本数据类型 int  longing(长整) shortint(短整) string(文本型) char(字符型) bool (布尔型) false true 2.常量于变量 ...

  4. 在 Django 模板中遍历复杂数据结构的关键是句点字符

    在 Django 模板中遍历复杂数据结构的关键是句点字符 ( . ). 实例二 mysit/templates/myhtml2.html修改如下 <!DOCTYPE html> <h ...

  5. A trip through the Graphics Pipeline 2011_10_Geometry Shaders

    Welcome back.     Last time, we dove into bottom end of the pixel pipeline. This time, we’ll switch ...

  6. iostat监控磁盘io

    1.安装#yum install sysstat 2.启动#/etc/init.d/sysstat start 3.自启动#checkfig sysstat 4.基本使用#iostat -k 2每两秒 ...

  7. 【java基础学习】字符串

    字符串 1. java内存区域(堆区.栈区.常量池) 2. String方法 获取长度 length(); 获取位置 indexOf(index); lastIndexOf(index) 获取子串 c ...

  8. 并发队列ConcurrentLinkedQueue和阻塞队列LinkedBlockingQueue用法

    在Java多线程应用中,队列的使用率很高,多数生产消费模型的首选数据结构就是队列(先进先出).Java提供的线程安全的Queue可以分为阻塞队列和非阻塞队列,其中阻塞队列的典型例子是BlockingQ ...

  9. [LeetCode]题解(python):120 Triangle

    题目来源 https://leetcode.com/problems/triangle/ Given a triangle, find the minimum path sum from top to ...

  10. spring 以Ant Build方式运行build.xml文件,报warning: 'includeantruntime' was not set, defaulting to build.sysclasspath=last; set to false for repeatable builds 的解决办法

    Buildfile: F:\experience\spring_pdf\sourcecode\example1\build.xml compile: [javac] F:\experience\spr ...