Redis源代码分析(二十二)--- networking网络协议传输
上次我仅仅分析了Redis网络部分的代码一部分,今天我把networking的代码实现部分也学习了一遍,netWorking的代码很多其它偏重的是Clientclient的操作。里面addReply()系列的方法操作是基本的部分。
光光这个系列的方法,应该占领了一半的API的数量。我把API分成了3个部分:
/* ------------ API ---------------------- */ void *dupClientReplyValue(void *o) /* 复制value一份 */ int listMatchObjects(void *a, void *b) /* 比价2个obj是否相等 */ robj *dupLastObjectIfNeeded(list *reply) /* 返回回复列表中最后一个元素对象 */ void copyClientOutputBuffer(redisClient *dst, redisClient *src) /* 将源Client的输出buffer复制给目标Client */ static void acceptCommonHandler(int fd, int flags) /* 网络连接后的调用方法 */ void acceptTcpHandler(aeEventLoop *el, int fd, void *privdata, int mask) void acceptUnixHandler(aeEventLoop *el, int fd, void *privdata, int mask) void disconnectSlaves(void) /* 使server的slave失去连接 */ void replicationHandleMasterDisconnection(void) void flushSlavesOutputBuffers(void) /* 从方法将会在freeMemoryIfNeeded()。释放内存空间函数,将存在内存中数据操作结果刷新到磁盘中 */ int processEventsWhileBlocked(void) /* ------------- addReply API ----------------- */ int _addReplyToBuffer(redisClient *c, char *s, size_t len) /* 往client缓冲区中加入内容 */ void _addReplyObjectToList(redisClient *c, robj *o) /* robj加入到reply的列表中 */ void _addReplySdsToList(redisClient *c, sds s) /* 在回复列表中加入Sds字符串对象 */ void _addReplyStringToList(redisClient *c, char *s, size_t len) /* 在回复列表中加入字符串对象,參数中已经给定字符的长度 */ void addReply(redisClient *c, robj *obj) /* 在redisClient的buffer中写入数据,数据存在obj->ptr的指针中 */ void addReplySds(redisClient *c, sds s) /* 在回复中加入Sds字符串,以下的额addReply()系列方法原理基本相似 */ void addReplyString(redisClient *c, char *s, size_t len) void addReplyErrorLength(redisClient *c, char *s, size_t len) void addReplyError(redisClient *c, char *err) /* 往Reply中加入error类的信息 */ void addReplyErrorFormat(redisClient *c, const char *fmt, ...) void addReplyStatusLength(redisClient *c, char *s, size_t len) void addReplyStatus(redisClient *c, char *status) void addReplyStatusFormat(redisClient *c, const char *fmt, ...) void *addDeferredMultiBulkLength(redisClient *c) /* 在reply list 中加入一个空的obj对象 */ void setDeferredMultiBulkLength(redisClient *c, void *node, long length) void addReplyDouble(redisClient *c, double d) /* 在bulk reply中加入一个double类型值。bulk的意思为大块的。bulk reply的意思为大数据量的回复 */ void addReplyLongLongWithPrefix(redisClient *c, long long ll, char prefix) void addReplyLongLong(redisClient *c, long long ll) void addReplyMultiBulkLen(redisClient *c, long length) void addReplyBulkLen(redisClient *c, robj *obj) /* 加入bulk 大块的数据的长度 */ void addReplyBulk(redisClient *c, robj *obj) /* 将一个obj的数据。拆分成大块数据的加入 */ void addReplyBulkCBuffer(redisClient *c, void *p, size_t len) void addReplyBulkCString(redisClient *c, char *s) void addReplyBulkLongLong(redisClient *c, long long ll) /* ------------- Client API ----------------- */ redisClient *createClient(int fd) /* 创建redisClientclient,1.建立连接,2.设置数据库。3.属性设置 */ int prepareClientToWrite(redisClient *c) /* 此方法将会被调用于Client准备接受新数据之前调用。在fileEvent为client设定writer的handler处理事件 */ static void freeClientArgv(redisClient *c) void freeClient(redisClient *c) /* 释放freeClient,要分为Master和Slave2种情况作不同的处理 */ void freeClientAsync(redisClient *c) void freeClientsInAsyncFreeQueue(void) /* 异步的freeclient */ void sendReplyToClient(aeEventLoop *el, int fd, void *privdata, int mask) /* 将Client中的reply数据存入文件里 */ void resetClient(redisClient *c) int processInlineBuffer(redisClient *c) /* 处理redis Client的内链的buffer。就是c->querybuf */ static void setProtocolError(redisClient *c, int pos) int processMultibulkBuffer(redisClient *c) /* 处理大块的buffer */ void processInputBuffer(redisClient *c) /* 处理redisClient的查询buffer */ void readQueryFromClient(aeEventLoop *el, int fd, void *privdata, int mask) /* 从Client获取查询query语句 */ void getClientsMaxBuffers(unsigned long *longest_output_list, unsigned long *biggest_input_buffer) /* 获取Client中输入buffer和输出buffer的最大长度值 */ void formatPeerId(char *peerid, size_t peerid_len, char *ip, int port) /* 格式化ip,port端口号的输出,ip:port */ int genClientPeerId(redisClient *client, char *peerid, size_t peerid_len) /* 获取Clientclient的ip,port地址信息 */ char *getClientPeerId(redisClient *c) /* 获取c->peeridclient的地址信息 */ sds catClientInfoString(sds s, redisClient *client) /* 格式化的输出client的属性信息。直接返回一个拼接好的字符串 */ sds getAllClientsInfoString(void) /* 获取全部Clientclient的属性信息。并连接成一个总的字符串并输出 */ void clientCommand(redisClient *c) /* 运行client的命令的作法 */ void rewriteClientCommandVector(redisClient *c, int argc, ...) /* 重写client的命令集合,旧的命令集合的应用计数减1,新的Command Vector的命令集合增1 */ void rewriteClientCommandArgument(redisClient *c, int i, robj *newval) /* 重写Client中的第i个參数 */ unsigned long getClientOutputBufferMemoryUsage(redisClient *c) /* 获取Client中已经用去的输出buffer的大小 */ int getClientType(redisClient *c) int getClientTypeByName(char *name) /* Client中的名字的3种类型,normal,slave。pubsub */ char *getClientTypeName(int class) int checkClientOutputBufferLimits(redisClient *c) /* 推断Clint的输出缓冲区的已经占用大小是否超过软限制或是硬限制 */ void asyncCloseClientOnOutputBufferLimitReached(redisClient *c) /* 异步的关闭Client。假设缓冲区中的软限制或是硬限制已经到达的时候,缓冲区超出限制的结果会导致释放不安全, */我们从最简单的_addReplyToBuffer在缓冲区中加入回复数据開始说起,由于后面的各种addReply的方法都或多或少的调用了和这个歌方法。
/* ----------------------------------------------------------------------------- * Low level functions to add more data to output buffers. * -------------------------------------------------------------------------- */ /* 往client缓冲区中加入内容 */ int _addReplyToBuffer(redisClient *c, char *s, size_t len) { size_t available = sizeof(c->buf)-c->bufpos; if (c->flags & REDIS_CLOSE_AFTER_REPLY) return REDIS_OK; /* If there already are entries in the reply list, we cannot * add anything more to the static buffer. */ //假设当前的reply已经存在内容,则操作出错 if (listLength(c->reply) > 0) return REDIS_ERR; /* Check that the buffer has enough space available for this string. */ if (len > available) return REDIS_ERR; memcpy(c->buf+c->bufpos,s,len); c->bufpos+=len; return REDIS_OK; }最直接影响的一句话,就是memcpy(c->buf+c->bufpos,s,len);所以内容是加到c->buf中的,这也就是client的输出buffer。加入操作还有第二种形式是加入对象类型:
/* robj加入到reply的列表中 */ void _addReplyObjectToList(redisClient *c, robj *o) { robj *tail; if (c->flags & REDIS_CLOSE_AFTER_REPLY) return; if (listLength(c->reply) == 0) { incrRefCount(o); //在回复列表汇总加入robj内容 listAddNodeTail(c->reply,o); c->reply_bytes += zmalloc_size_sds(o->ptr); } else { tail = listNodeValue(listLast(c->reply)); /* Append to this object when possible. */ if (tail->ptr != NULL && sdslen(tail->ptr)+sdslen(o->ptr) <= REDIS_REPLY_CHUNK_BYTES) { c->reply_bytes -= zmalloc_size_sds(tail->ptr); tail = dupLastObjectIfNeeded(c->reply); tail->ptr = sdscatlen(tail->ptr,o->ptr,sdslen(o->ptr)); c->reply_bytes += zmalloc_size_sds(tail->ptr); } else { incrRefCount(o); listAddNodeTail(c->reply,o); c->reply_bytes += zmalloc_size_sds(o->ptr); } } asyncCloseClientOnOutputBufferLimitReached(c); }把robj对象载入reply列表中,而且改变reply的byte大小,最后还调用了一个asyncCloseClientOnOutputBufferLimitReached(c);方法,这种方法我是在这个文件的最底部找到的,一開始还真不知道什么意思,作用就是当加入完数据后,当client的输出缓冲的大小超出限制时,会被异步关闭:
/* Asynchronously close a client if soft or hard limit is reached on the * output buffer size. The caller can check if the client will be closed * checking if the client REDIS_CLOSE_ASAP flag is set. * * Note: we need to close the client asynchronously because this function is * called from contexts where the client can't be freed safely, i.e. from the * lower level functions pushing data inside the client output buffers. */ /* 异步的关闭Client。假设缓冲区中的软限制或是硬限制已经到达的时候。缓冲区超出限制的结果会导致释放不安全, */ void asyncCloseClientOnOutputBufferLimitReached(redisClient *c) { redisAssert(c->reply_bytes < ULONG_MAX-(1024*64)); if (c->reply_bytes == 0 || c->flags & REDIS_CLOSE_ASAP) return; if (checkClientOutputBufferLimits(c)) { sds client = catClientInfoString(sdsempty(),c); freeClientAsync(c); redisLog(REDIS_WARNING,"Client %s scheduled to be closed ASAP for overcoming of output buffer limits.", client); sdsfree(client); } }在addReply方法调用的时候,有时是须要一个前提的,我说的是在写数据事件发生的时候,你得先对写的文件创建一个监听事件:
/* 在回复中加入Sds字符串 */ void addReplySds(redisClient *c, sds s) { //在调用加入操作之前,都要先运行prepareClientToWrite(c),设置文件事件的写事件 if (prepareClientToWrite(c) != REDIS_OK) { /* The caller expects the sds to be free'd. */ sdsfree(s); return; } if (_addReplyToBuffer(c,s,sdslen(s)) == REDIS_OK) { sdsfree(s); } else { /* This method free's the sds when it is no longer needed. */ _addReplySdsToList(c,s); } }在这个prepareClientToWrite()里面是干嘛的呢?
/* This function is called every time we are going to transmit new data * to the client. The behavior is the following: * * If the client should receive new data (normal clients will) the function * returns REDIS_OK, and make sure to install the write handler in our event * loop so that when the socket is writable new data gets written. * * If the client should not receive new data, because it is a fake client, * a master, a slave not yet online, or because the setup of the write handler * failed, the function returns REDIS_ERR. * * Typically gets called every time a reply is built, before adding more * data to the clients output buffers. If the function returns REDIS_ERR no * data should be appended to the output buffers. */ /* 此方法将会被调用于Client准备接受新数据之前调用,在fileEvent为客户端设定writer的handler处理事件 */ int prepareClientToWrite(redisClient *c) { if (c->flags & REDIS_LUA_CLIENT) return REDIS_OK; if ((c->flags & REDIS_MASTER) && !(c->flags & REDIS_MASTER_FORCE_REPLY)) return REDIS_ERR; if (c->fd <= 0) return REDIS_ERR; /* Fake client */ if (c->bufpos == 0 && listLength(c->reply) == 0 && (c->replstate == REDIS_REPL_NONE || c->replstate == REDIS_REPL_ONLINE) && //在这里创建写的文件事件 aeCreateFileEvent(server.el, c->fd, AE_WRITABLE, sendReplyToClient, c) == AE_ERR) return REDIS_ERR; return REDIS_OK; }在addReply的方法里提到了一个addReplyBulk类型方法,Bulk的中文意思为大块的,说明addReplyBulk加入的都是一些比較大块的数据,找一个方法看看:
/* Add a Redis Object as a bulk reply */ /* 将一个obj的数据。拆分成大块数据的加入 */ void addReplyBulk(redisClient *c, robj *obj) { //reply加入长度 addReplyBulkLen(c,obj); //reply加入对象 addReply(c,obj); addReply(c,shared.crlf); }将原本一个robj的数据拆分成可3个普通的addReply的方法调用。
就变成了数据量变大了的数据。大数据的回复一个比較不好的地方是到时解析的时候或者是Data的复制的时候会比較耗时。在networking的方法里还提供了freeClient()的操作:
/* 释放freeClient,要分为Master和Slave2种情况作不同的处理 */ void freeClient(redisClient *c) { listNode *ln; /* If this is marked as current client unset it */ if (server.current_client == c) server.current_client = NULL; /* If it is our master that's beging disconnected we should make sure * to cache the state to try a partial resynchronization later. * * Note that before doing this we make sure that the client is not in * some unexpected state, by checking its flags. */ if (server.master && c->flags & REDIS_MASTER) { redisLog(REDIS_WARNING,"Connection with master lost."); if (!(c->flags & (REDIS_CLOSE_AFTER_REPLY| REDIS_CLOSE_ASAP| REDIS_BLOCKED| REDIS_UNBLOCKED))) { //假设是Master客户端,须要做缓存Client的处理,能够迅速又一次启用 replicationCacheMaster(c); return; } }...后面代码略去了
当Client中的输出buffer数据渐渐变多了的时候就要准备持久化到磁盘文件了。要调用以下这种方法了,
/* Helper function used by freeMemoryIfNeeded() in order to flush slave * output buffers without returning control to the event loop. */ /* 从方法将会在freeMemoryIfNeeded(),释放内存空间函数,将存在内存中数据操作结果刷新到磁盘中 */ void flushSlavesOutputBuffers(void) { listIter li; listNode *ln; listRewind(server.slaves,&li); while((ln = listNext(&li))) { redisClient *slave = listNodeValue(ln); int events; events = aeGetFileEvents(server.el,slave->fd); if (events & AE_WRITABLE && slave->replstate == REDIS_REPL_ONLINE && listLength(slave->reply)) { //在这里调用了write的方法 sendReplyToClient(server.el,slave->fd,slave,0); } } }这种方法的核心调用又在sendReplyToClient()方法,就是把Client的reply内容和buf内容存入文件。以上就是我的理解了,代码量有点大,的确看的我头有点大。
posted on 2017-05-25 16:28 gavanwanggw 阅读(184) 评论(0) 编辑 收藏 举报