redis6.0.5之t_list.c阅读笔记--列表
2021/7/15 19:06:17
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********************************************************************************************************************* /*----------------------------------------------------------------------------- * List API 列表API *----------------------------------------------------------------------------*/ /* The function pushes an element to the specified list object 'subject', * at head or tail position as specified by 'where'. * * There is no need for the caller to increment the refcount of 'value' as * the function takes care of it if needed. */ 本函数把一个元素压入到特定的列表对象subject,根据where指定的方向压入到头部或者尾部 这里不需要调用者去增加值的引用,如果有需要函数自身会处理它 void listTypePush(robj *subject, robj *value, int where) { if (subject->encoding == OBJ_ENCODING_QUICKLIST) { 如果编码是快速列表 int pos = (where == LIST_HEAD) ? QUICKLIST_HEAD : QUICKLIST_TAIL; 根据where确定压入位置 value = getDecodedObject(value); 获取字符串对象 size_t len = sdslen(value->ptr); 字符串对象中字符串的长度 quicklistPush(subject->ptr, value->ptr, len, pos); 压入到快速列表 decrRefCount(value); 将获取的对象引用减少1,因为这个对象后面不会再用了,减少不必要的浪费 } else { serverPanic("Unknown list encoding"); } } ********************************************************************************************************************* 保存弹出的数据 void *listPopSaver(unsigned char *data, unsigned int sz) { return createStringObject((char*)data,sz); 根据传入的参数创建新的字符串对象 } ********************************************************************************************************************* 弹出快速列表的一个元素 robj *listTypePop(robj *subject, int where) { long long vlong; robj *value = NULL; int ql_where = where == LIST_HEAD ? QUICKLIST_HEAD : QUICKLIST_TAIL; if (subject->encoding == OBJ_ENCODING_QUICKLIST) { 快速列表 if (quicklistPopCustom(subject->ptr, ql_where, (unsigned char **)&value, NULL, &vlong, listPopSaver)) { if (!value) 非字符串类型,需要转化为字符串 value = createStringObjectFromLongLong(vlong); } } else { serverPanic("Unknown list encoding"); } return value; } ********************************************************************************************************************* 返回列表的元素个数 unsigned long listTypeLength(const robj *subject) { if (subject->encoding == OBJ_ENCODING_QUICKLIST) { return quicklistCount(subject->ptr); 这里返回列表的元素个数 } else { serverPanic("Unknown list encoding"); } } ********************************************************************************************************************* /* Initialize an iterator at the specified index. */ 根据特定的额索引初始化一个迭代器 /* Structure to hold list iteration abstraction. */ 保持列表迭代器的数据结构 typedef struct { robj *subject; unsigned char encoding; unsigned char direction; /* Iteration direction */ quicklistIter *iter; } listTypeIterator; listTypeIterator *listTypeInitIterator(robj *subject, long index, unsigned char direction) { listTypeIterator *li = zmalloc(sizeof(listTypeIterator)); li->subject = subject; li->encoding = subject->encoding; li->direction = direction; li->iter = NULL; /* LIST_HEAD means start at TAIL and move *towards* head. * LIST_TAIL means start at HEAD and move *towards tail. */ LIST_HEAD 意思为 从尾部开始,向头部移动 LIST_TAIL 意思为 从头部开始,向尾部移动 int iter_direction = direction == LIST_HEAD ? AL_START_TAIL : AL_START_HEAD; if (li->encoding == OBJ_ENCODING_QUICKLIST) { 根据索引所在的位置初始化迭代器 li->iter = quicklistGetIteratorAtIdx(li->subject->ptr, iter_direction, index); } else { serverPanic("Unknown list encoding"); } return li; } ********************************************************************************************************************* /* Clean up the iterator. */ 清除迭代器 void listTypeReleaseIterator(listTypeIterator *li) { zfree(li->iter); 释放迭代器 zfree(li); 释放保存迭代器的结构 } ********************************************************************************************************************* /* Stores pointer to current the entry in the provided entry structure * and advances the position of the iterator. Returns 1 when the current * entry is in fact an entry, 0 otherwise. */ 存储指针指向的当前实体提供了 迭代器的实体结构和位置。 返回1如果当前实体是有效的,否则返回0(返回实体无效的情况下) int listTypeNext(listTypeIterator *li, listTypeEntry *entry) { /* Protect from converting when iterating */ 转变编码格式时的保护确认 serverAssert(li->subject->encoding == li->encoding); entry->li = li; if (li->encoding == OBJ_ENCODING_QUICKLIST) { return quicklistNext(li->iter, &entry->entry); 返回找到的内容 } else { serverPanic("Unknown list encoding"); } return 0; } ********************************************************************************************************************* /* Return entry or NULL at the current position of the iterator. */ 返回迭代器当前位置的实体或者空 robj *listTypeGet(listTypeEntry *entry) { robj *value = NULL; if (entry->li->encoding == OBJ_ENCODING_QUICKLIST) { if (entry->entry.value) { 是字符串类型的值 value = createStringObject((char *)entry->entry.value, entry->entry.sz); 根据长度和字符串创建字符串对象 } else { value = createStringObjectFromLongLong(entry->entry.longval); 将整型转化为字符串 } } else { serverPanic("Unknown list encoding"); } return value; } ********************************************************************************************************************* 在列表插入一个实体元素 void listTypeInsert(listTypeEntry *entry, robj *value, int where) { if (entry->li->encoding == OBJ_ENCODING_QUICKLIST) { value = getDecodedObject(value); 获取字符串对象 sds str = value->ptr; sds字符串 size_t len = sdslen(str); if (where == LIST_TAIL) { quicklistInsertAfter((quicklist *)entry->entry.quicklist, &entry->entry, str, len); 在尾部插入 } else if (where == LIST_HEAD) { quicklistInsertBefore((quicklist *)entry->entry.quicklist, &entry->entry, str, len); 在头部插入 } decrRefCount(value); 减少引用计数 } else { serverPanic("Unknown list encoding"); } } ********************************************************************************************************************* /* Compare the given object with the entry at the current position. */ 比较给定对象和在当前位置的实体对象 int listTypeEqual(listTypeEntry *entry, robj *o) { if (entry->li->encoding == OBJ_ENCODING_QUICKLIST) { 当前位置实体的编码 serverAssertWithInfo(NULL,o,sdsEncodedObject(o)); return quicklistCompare(entry->entry.zi,o->ptr,sdslen(o->ptr)); 比较两个字符串 } else { serverPanic("Unknown list encoding"); } } ********************************************************************************************************************* /* Delete the element pointed to. */ 删除迭代器指向的元素(entry就是iter指向的元素) void listTypeDelete(listTypeIterator *iter, listTypeEntry *entry) { if (entry->li->encoding == OBJ_ENCODING_QUICKLIST) { quicklistDelEntry(iter->iter, &entry->entry); 删除迭代器指向的元素,同时更新迭代器 } else { serverPanic("Unknown list encoding"); } } ********************************************************************************************************************* /* Create a quicklist from a single ziplist */ createIntConfig("list-max-ziplist-size", NULL, MODIFIABLE_CONFIG, INT_MIN, INT_MAX, server.list_max_ziplist_size, -2, INTEGER_CONFIG, NULL, NULL), 默认配置为-2,但是实际取值会经过转化 size_t offset = (-fill) - 1; static const size_t optimization_level[] = {4096, 8192, 16384, 32768, 65536}; 所以-2对应的位置是8192个字节 createIntConfig("list-compress-depth", NULL, MODIFIABLE_CONFIG, 0, INT_MAX, server.list_compress_depth, 0, INTEGER_CONFIG, NULL, NULL), 默认设置为0 从一个压缩列表创建快速列表 void listTypeConvert(robj *subject, int enc) { serverAssertWithInfo(NULL,subject,subject->type==OBJ_LIST); 确认是列表对象 serverAssertWithInfo(NULL,subject,subject->encoding==OBJ_ENCODING_ZIPLIST); 确认是压缩列表编码 if (enc == OBJ_ENCODING_QUICKLIST) { 确认目标编码为快速列表 size_t zlen = server.list_max_ziplist_size; 设置为默认的初始化值-2 int depth = server.list_compress_depth; 设置默认值为0, 不压缩列表 subject->ptr = quicklistCreateFromZiplist(zlen, depth, subject->ptr); 从压缩列表转化为快速列表 subject->encoding = OBJ_ENCODING_QUICKLIST; } else { serverPanic("Unsupported list conversion"); } } ********************************************************************************************************************* /*----------------------------------------------------------------------------- * List Commands 列表命令 *----------------------------------------------------------------------------*/ 一般化的压入命令 void pushGenericCommand(client *c, int where) { int j, pushed = 0; robj *lobj = lookupKeyWrite(c->db,c->argv[1]); 库中查找对象是否存在 if (lobj && lobj->type != OBJ_LIST) { 存在对象但是不是列表对象 addReply(c,shared.wrongtypeerr); return; } for (j = 2; j < c->argc; j++) { if (!lobj) { 对象不存在,那需要创建新对象,设置初始化的默认值 lobj = createQuicklistObject(); quicklistSetOptions(lobj->ptr, server.list_max_ziplist_size, server.list_compress_depth); dbAdd(c->db,c->argv[1],lobj); 在数据库中添加键值 } listTypePush(lobj,c->argv[j],where); 压入一个元素 pushed++; 压入元素计数加1 } addReplyLongLong(c, (lobj ? listTypeLength(lobj) : 0)); 回复客户端 if (pushed) { char *event = (where == LIST_HEAD) ? "lpush" : "rpush"; 如果有压入数据,看看是什么事件 signalModifiedKey(c,c->db,c->argv[1]); 把修改键的信息发送给客户端 notifyKeyspaceEvent(NOTIFY_LIST,event,c->argv[1],c->db->id); 通知订阅的客户端 } server.dirty += pushed; 变动的键计数修改 } ********************************************************************************************************************* 左边压入 void lpushCommand(client *c) { pushGenericCommand(c,LIST_HEAD); } ********************************************************************************************************************* 右边压入 void rpushCommand(client *c) { pushGenericCommand(c,LIST_TAIL); } ********************************************************************************************************************* 将一个值插入到已经存在的列表中,如果列表不存在就不操作 void pushxGenericCommand(client *c, int where) { int j, pushed = 0; robj *subject; if ((subject = lookupKeyWriteOrReply(c,c->argv[1],shared.czero)) == NULL || 如果库中找不到 或者类型不是列表 checkType(c,subject,OBJ_LIST)) return; for (j = 2; j < c->argc; j++) { 正常情况,一个一个元素的压入 listTypePush(subject,c->argv[j],where); pushed++; 压入元素计数 } addReplyLongLong(c,listTypeLength(subject)); if (pushed) { 如果有压入新的元素,需要通知相关各方 char *event = (where == LIST_HEAD) ? "lpush" : "rpush"; signalModifiedKey(c,c->db,c->argv[1]); notifyKeyspaceEvent(NOTIFY_LIST,event,c->argv[1],c->db->id); } server.dirty += pushed; } ********************************************************************************************************************* 左压入 void lpushxCommand(client *c) { pushxGenericCommand(c,LIST_HEAD); } ********************************************************************************************************************* 右压入 void rpushxCommand(client *c) { pushxGenericCommand(c,LIST_TAIL); } ********************************************************************************************************************* 列表元素插入命令 void linsertCommand(client *c) { int where; robj *subject; listTypeIterator *iter; listTypeEntry entry; int inserted = 0; if (strcasecmp(c->argv[2]->ptr,"after") == 0) { 后面插入 where = LIST_TAIL; } else if (strcasecmp(c->argv[2]->ptr,"before") == 0) { 前面插入 where = LIST_HEAD; } else { addReply(c,shared.syntaxerr); return; } if ((subject = lookupKeyWriteOrReply(c,c->argv[1],shared.czero)) == NULL || 如果指定的键库中不存在 checkType(c,subject,OBJ_LIST)) return; /* Seek pivot from head to tail */ 在列表中从头到尾查找指定的元素 iter = listTypeInitIterator(subject,0,LIST_TAIL); 从头到尾进行遍历,初始的偏移量设置为0 while (listTypeNext(iter,&entry)) { if (listTypeEqual(&entry,c->argv[3])) { 如果找了指定的元素 listTypeInsert(&entry,c->argv[4],where); 在该元素前后或者后面插入新元素 inserted = 1; break; } } listTypeReleaseIterator(iter); 释放迭代器 if (inserted) { 如果有插入新的元素 signalModifiedKey(c,c->db,c->argv[1]); notifyKeyspaceEvent(NOTIFY_LIST,"linsert", c->argv[1],c->db->id); server.dirty++; } else { /* Notify client of a failed insert */ 通知客户端一次失败的插入操作 addReplyLongLong(c,-1); return; } addReplyLongLong(c,listTypeLength(subject)); } ********************************************************************************************************************* 返回列表长度 void llenCommand(client *c) { robj *o = lookupKeyReadOrReply(c,c->argv[1],shared.czero); if (o == NULL || checkType(c,o,OBJ_LIST)) return; addReplyLongLong(c,listTypeLength(o)); } ********************************************************************************************************************* 返回index所在位置的元素 void lindexCommand(client *c) { robj *o = lookupKeyReadOrReply(c,c->argv[1],shared.null[c->resp]); 查找列表 if (o == NULL || checkType(c,o,OBJ_LIST)) return; 如果库中不存在对应的键 或者 不是列表 long index; robj *value = NULL; if ((getLongFromObjectOrReply(c, c->argv[2], &index, NULL) != C_OK)) 获取索引的值 return; if (o->encoding == OBJ_ENCODING_QUICKLIST) { quicklistEntry entry; if (quicklistIndex(o->ptr, index, &entry)) { 根据索引位置获取值 if (entry.value) {字符串 value = createStringObject((char*)entry.value,entry.sz); } else {整型 value = createStringObjectFromLongLong(entry.longval); } addReplyBulk(c,value); decrRefCount(value); } else { addReplyNull(c); } } else { serverPanic("Unknown list encoding"); } } ********************************************************************************************************************* 通过索引设置元素的值 void lsetCommand(client *c) { robj *o = lookupKeyWriteOrReply(c,c->argv[1],shared.nokeyerr); 库中查找元素 if (o == NULL || checkType(c,o,OBJ_LIST)) return; long index; robj *value = c->argv[3]; if ((getLongFromObjectOrReply(c, c->argv[2], &index, NULL) != C_OK)) 获取传入索引 return; if (o->encoding == OBJ_ENCODING_QUICKLIST) { quicklist *ql = o->ptr; int replaced = quicklistReplaceAtIndex(ql, index, value->ptr, sdslen(value->ptr)); 取代索引所在位置的元素值 if (!replaced) { 没有发生取代,找不到索引所在元素的位置 addReply(c,shared.outofrangeerr); } else { 发生了取代,将消息通知相关各方 addReply(c,shared.ok); signalModifiedKey(c,c->db,c->argv[1]); notifyKeyspaceEvent(NOTIFY_LIST,"lset",c->argv[1],c->db->id); server.dirty++; } } else { serverPanic("Unknown list encoding"); } } ********************************************************************************************************************* 弹出元素的一般命令 void popGenericCommand(client *c, int where) { 确保库中存在对应键的值,而且值是列表对象 robj *o = lookupKeyWriteOrReply(c,c->argv[1],shared.null[c->resp]); if (o == NULL || checkType(c,o,OBJ_LIST)) return; robj *value = listTypePop(o,where); 获取弹出值 if (value == NULL) { addReplyNull(c); } else { char *event = (where == LIST_HEAD) ? "lpop" : "rpop"; 分析弹出事件 addReplyBulk(c,value); decrRefCount(value); 减少引用计数 notifyKeyspaceEvent(NOTIFY_LIST,event,c->argv[1],c->db->id); if (listTypeLength(o) == 0) { 如果对象长度为0 notifyKeyspaceEvent(NOTIFY_GENERIC,"del", c->argv[1],c->db->id); dbDelete(c->db,c->argv[1]); 将库中的键删除 } signalModifiedKey(c,c->db,c->argv[1]); server.dirty++; } } ********************************************************************************************************************* 左弹出 void lpopCommand(client *c) { popGenericCommand(c,LIST_HEAD); } ********************************************************************************************************************* 右弹出 void rpopCommand(client *c) { popGenericCommand(c,LIST_TAIL); } ********************************************************************************************************************* 返回列表区间元素 void lrangeCommand(client *c) { robj *o; long start, end, llen, rangelen; if ((getLongFromObjectOrReply(c, c->argv[2], &start, NULL) != C_OK) || 获取开始值位置 (getLongFromObjectOrReply(c, c->argv[3], &end, NULL) != C_OK)) return; 获取结束位置 if ((o = lookupKeyReadOrReply(c,c->argv[1],shared.emptyarray)) == NULL || checkType(c,o,OBJ_LIST)) return; llen = listTypeLength(o); 列表对象元素个数 /* convert negative indexes */ 转化负数的索引 if (start < 0) start = llen+start; if (end < 0) end = llen+end; if (start < 0) start = 0; 进过上面的处理如果还是负值,那么就从头开始 /* Invariant: start >= 0, so this test will be true when end < 0. * The range is empty when start > end or start >= length. */ 变量start大于等于0,所以如果end小于0,那么这个测试就是真的。 区间是空的,如果开始 比结束大 或者 开始 大于列表元素个数 if (start > end || start >= llen) { addReply(c,shared.emptyarray); return; } if (end >= llen) end = llen-1; 结束超过了元素个数,将结束位置设置到最后一个元素 rangelen = (end-start)+1; 给定区间的总元素 /* Return the result in form of a multi-bulk reply */ 通过多组回复的格式返回结果 addReplyArrayLen(c,rangelen); 返回总的个数 if (o->encoding == OBJ_ENCODING_QUICKLIST) { listTypeIterator *iter = listTypeInitIterator(o, start, LIST_TAIL);从头到尾 while(rangelen--) { 遍历范围区间 listTypeEntry entry; listTypeNext(iter, &entry);获取值 quicklistEntry *qe = &entry.entry; if (qe->value) { addReplyBulkCBuffer(c,qe->value,qe->sz); } else { addReplyBulkLongLong(c,qe->longval); } } listTypeReleaseIterator(iter); 释放迭代器 } else { serverPanic("List encoding is not QUICKLIST!"); } } ********************************************************************************************************************* 对列表进行修剪,只保留传入参数中间部分 void ltrimCommand(client *c) { robj *o; long start, end, llen, ltrim, rtrim; if ((getLongFromObjectOrReply(c, c->argv[2], &start, NULL) != C_OK) || 获取开始位置 (getLongFromObjectOrReply(c, c->argv[3], &end, NULL) != C_OK)) return; 获取结束位置 if ((o = lookupKeyWriteOrReply(c,c->argv[1],shared.ok)) == NULL || checkType(c,o,OBJ_LIST)) return; llen = listTypeLength(o); /* convert negative indexes */ if (start < 0) start = llen+start; if (end < 0) end = llen+end; if (start < 0) start = 0; /* Invariant: start >= 0, so this test will be true when end < 0. * The range is empty when start > end or start >= length. */ if (start > end || start >= llen) { /* Out of range start or start > end result in empty list */ start超过范围 或者 start 大于 end 那么结果就是空列表 ltrim = llen; 左边要删除的元素个数,整个列表的元素全部是 rtrim = 0; 右边要删除的元素个数 } else { if (end >= llen) end = llen-1; 如果结束位置大于列表元素个数,结束位置设置为最后一个元素 ltrim = start; 左边要删除的元素个数,从0到start-1 刚好start个 rtrim = llen-end-1; 右边要删除的元素个数 end后面的数据全部删除,刚好 llen-end-1个 } /* Remove list elements to perform the trim */ 移除列表元素 实现命令trim if (o->encoding == OBJ_ENCODING_QUICKLIST) { quicklistDelRange(o->ptr,0,ltrim); 删除左边 quicklistDelRange(o->ptr,-rtrim,rtrim); 删除右边 } else { serverPanic("Unknown list encoding"); } notifyKeyspaceEvent(NOTIFY_LIST,"ltrim",c->argv[1],c->db->id); if (listTypeLength(o) == 0) { 列表为空 dbDelete(c->db,c->argv[1]); 删除库中键值 notifyKeyspaceEvent(NOTIFY_GENERIC,"del",c->argv[1],c->db->id); } signalModifiedKey(c,c->db,c->argv[1]); server.dirty++; addReply(c,shared.ok); } ********************************************************************************************************************* 移除列表中的元素 同传入值一样的元素 删除个数也由传入值决定 void lremCommand(client *c) { robj *subject, *obj; obj = c->argv[3]; long toremove; long removed = 0; if ((getLongFromObjectOrReply(c, c->argv[2], &toremove, NULL) != C_OK)) return; subject = lookupKeyWriteOrReply(c,c->argv[1],shared.czero); if (subject == NULL || checkType(c,subject,OBJ_LIST)) return; listTypeIterator *li; if (toremove < 0) { 如果传入个数的值为负数,那么需要取绝对值 toremove = -toremove; li = listTypeInitIterator(subject,-1,LIST_HEAD);从尾到头,偏移量为-1 } else { li = listTypeInitIterator(subject,0,LIST_TAIL); 从头到尾,偏移量为0 } listTypeEntry entry; while (listTypeNext(li,&entry)) { 遍历列表,查找同样值的元素 if (listTypeEqual(&entry,obj)) { 找到就删除 listTypeDelete(li, &entry); server.dirty++; removed++; if (toremove && removed == toremove) break; } } listTypeReleaseIterator(li); 释放迭代列表 if (removed) { signalModifiedKey(c,c->db,c->argv[1]); notifyKeyspaceEvent(NOTIFY_LIST,"lrem",c->argv[1],c->db->id); } if (listTypeLength(subject) == 0) { dbDelete(c->db,c->argv[1]); 删除数据库键 notifyKeyspaceEvent(NOTIFY_GENERIC,"del",c->argv[1],c->db->id); } addReplyLongLong(c,removed); } ********************************************************************************************************************* /* This is the semantic of this command: 下面是这个命令的语义 * RPOPLPUSH srclist dstlist: 源列表 右边弹出 目标列表 左边压入 * IF LLEN(srclist) > 0 源列表还有元素 * element = RPOP srclist 从源列表右边弹出 * LPUSH dstlist element 在目标列表左边压入 * RETURN element 返回弹出元素 * ELSE * RETURN nil * END * END * * The idea is to be able to get an element from a list in a reliable way * since the element is not just returned but pushed against another list * as well. This command was originally proposed by Ezra Zygmuntowicz. */ 这样做的目的是能够以可靠的方式从一个列表中获取一个元素, 因为该元素不仅被返回,而且还被推到另一个列表中。这一命令最初是由以Ezra Zygmuntowicz提出的 void rpoplpushHandlePush(client *c, robj *dstkey, robj *dstobj, robj *value) { /* Create the list if the key does not exist */ 如果目标键值库中不存在 if (!dstobj) { dstobj = createQuicklistObject(); 创建 quicklistSetOptions(dstobj->ptr, server.list_max_ziplist_size, server.list_compress_depth); 设置默认参数 dbAdd(c->db,dstkey,dstobj); 新增 } signalModifiedKey(c,c->db,dstkey); listTypePush(dstobj,value,LIST_HEAD); 压入目标列表的头部 notifyKeyspaceEvent(NOTIFY_LIST,"lpush",dstkey,c->db->id); /* Always send the pushed value to the client. */ 发送压入的参数值到客户端 addReplyBulk(c,value); } ********************************************************************************************************************* void rpoplpushCommand(client *c) { robj *sobj, *value; if ((sobj = lookupKeyWriteOrReply(c,c->argv[1],shared.null[c->resp])) 检查源列表是否存在库中 以及 类型是否是列表 == NULL || checkType(c,sobj,OBJ_LIST)) return; if (listTypeLength(sobj) == 0) { 如果源列表没有元素了 /* This may only happen after loading very old RDB files. Recent * versions of Redis delete keys of empty lists. */ 发生这种情况只可能是加载旧版本的RDB文件了,因为新版本的redis会删除空的列表 addReplyNull(c); } else { robj *dobj = lookupKeyWrite(c->db,c->argv[2]); robj *touchedkey = c->argv[1]; if (dobj && checkType(c,dobj,OBJ_LIST)) return; 如果目标键存在而且不是列表 value = listTypePop(sobj,LIST_TAIL);弹出尾部元素 /* We saved touched key, and protect it, since rpoplpushHandlePush * may change the client command argument vector (it does not * currently). */ 我们保存了该键,并对其进行了保护,因为rpoplpushHandlePush函数可能会更改客户机命令参数向量(当前不会更改) incrRefCount(touchedkey); 增加键的引用,保护起来 rpoplpushHandlePush(c,c->argv[2],dobj,value);压入新值 /* listTypePop returns an object with its refcount incremented */ 函数listTypePop返回了一个引用计数加1的对象,这里需要减去 decrRefCount(value); /* Delete the source list when it is empty */ 删除源列表,如果列表已空 notifyKeyspaceEvent(NOTIFY_LIST,"rpop",touchedkey,c->db->id); if (listTypeLength(sobj) == 0) { dbDelete(c->db,touchedkey); notifyKeyspaceEvent(NOTIFY_GENERIC,"del", touchedkey,c->db->id); } signalModifiedKey(c,c->db,touchedkey); decrRefCount(touchedkey); 释放引用 server.dirty++; if (c->cmd->proc == brpoplpushCommand) { rewriteClientCommandVector(c,3,shared.rpoplpush,c->argv[1],c->argv[2]); } } } ********************************************************************************************************************* /*----------------------------------------------------------------------------- * Blocking POP operations 阻止POP操作 *----------------------------------------------------------------------------*/ /* This is a helper function for handleClientsBlockedOnKeys(). It's work * is to serve a specific client (receiver) that is blocked on 'key' * in the context of the specified 'db', doing the following: 这是一个handleClientsBlockedOnKeys的帮助函数。 它的工作是服务一个特定的客户端(接受者), 该客户端在被指定数据库的上下文中的键所阻塞。做下面的事情 * 1) Provide the client with the 'value' element. 提供给客户端值为value的元素 * 2) If the dstkey is not NULL (we are serving a BRPOPLPUSH) also push the * 'value' element on the destination list (the LPUSH side of the command). 如果目标键非空(我们在服务一个BRPOPLPUSH操作),同时把值为value的元素压入到目标列表(命令的LPUSH端) * 3) Propagate the resulting BRPOP, BLPOP and additional LPUSH if any into * the AOF and replication channel. 将生成的BRPOP、BLPOP和其他LPUSH(如果有)传播到AOF和复制通道 * The argument 'where' is LIST_TAIL or LIST_HEAD, and indicates if the * 'value' element was popped from the head (BLPOP) or tail (BRPOP) so that * we can propagate the command properly. 参数where是LIST_TAIL或LIST_HEAD,表明“value”元素是从head(BLPOP)还是tail(BRPOP)弹出的,这样我们可以正确地传播命令 * The function returns C_OK if we are able to serve the client, otherwise * C_ERR is returned to signal the caller that the list POP operation * should be undone as the client was not served: This only happens for * BRPOPLPUSH that fails to push the value to the destination key as it is * of the wrong type. */ 这个函数返回C_OK,如果我们能够服务客户端,否则返回C_ERR,给调用者发出信号,弹出操作应该被取消因为客户端不在服务中: 这个只会在函数BRPOPLPUSH中发生,发生在压入值到错误类型的目标键失败。 int serveClientBlockedOnList(client *receiver, robj *key, robj *dstkey, redisDb *db, robj *value, int where) { robj *argv[3]; if (dstkey == NULL) { /* Propagate the [LR]POP operation. */ 根据传入参数where 传播左边或右边操作 argv[0] = (where == LIST_HEAD) ? shared.lpop : 左边弹出 shared.rpop; 右边弹出 argv[1] = key; propagate((where == LIST_HEAD) ? 头部操作,即左边弹出命令 server.lpopCommand : server.rpopCommand, db->id,argv,2,PROPAGATE_AOF|PROPAGATE_REPL); /* BRPOP/BLPOP */ 左边或者右边弹出 addReplyArrayLen(receiver,2); addReplyBulk(receiver,key); addReplyBulk(receiver,value); /* Notify event. */ 通知事件 char *event = (where == LIST_HEAD) ? "lpop" : "rpop"; notifyKeyspaceEvent(NOTIFY_LIST,event,key,receiver->db->id); } else { /* BRPOPLPUSH */ robj *dstobj = lookupKeyWrite(receiver->db,dstkey); 查找数据库 if (!(dstobj && checkType(receiver,dstobj,OBJ_LIST))) { 如果 dstobj为空 或者 类型是列表对象 rpoplpushHandlePush(receiver,dstkey,dstobj, value); 将值压入到目标列表 /* Propagate the RPOPLPUSH operation. */ 传播RPOPLPUSH操作 argv[0] = shared.rpoplpush; argv[1] = key; argv[2] = dstkey; propagate(server.rpoplpushCommand, db->id,argv,3, PROPAGATE_AOF| PROPAGATE_REPL); /* Notify event ("lpush" was notified by rpoplpushHandlePush). */ 通知事件,lpush事件由函数rpoplpushHandlePush通知 notifyKeyspaceEvent(NOTIFY_LIST,"rpop",key,receiver->db->id); } else { /* BRPOPLPUSH failed because of wrong * destination type. */ BRPOPLPUSH操作失败 因为错误的目标类型 return C_ERR; } } return C_OK; } ********************************************************************************************************************* /* Blocking RPOP/LPOP */ 阻塞右边弹出或左边弹出 void blockingPopGenericCommand(client *c, int where) { robj *o; mstime_t timeout; int j; if (getTimeoutFromObjectOrReply(c,c->argv[c->argc-1],&timeout,UNIT_SECONDS) 获取对象超时时间 != C_OK) return; for (j = 1; j < c->argc-1; j++) { o = lookupKeyWrite(c->db,c->argv[j]); 根据传入的键查找数据库 (gdb调试用的打印键 p *(char *)(c->argv[1]).ptr@10) if (o != NULL) { 在库中 if (o->type != OBJ_LIST) { 非列表类型 addReply(c,shared.wrongtypeerr); return; } else { if (listTypeLength(o) != 0) { 列表长度不为0 /* Non empty list, this is like a non normal [LR]POP. */ 非空列表,就如一个非一般的左或右弹出 char *event = (where == LIST_HEAD) ? "lpop" : "rpop"; robj *value = listTypePop(o,where); 弹出元素 serverAssert(value != NULL); addReplyArrayLen(c,2); addReplyBulk(c,c->argv[j]); addReplyBulk(c,value); decrRefCount(value); 减少值的引用 notifyKeyspaceEvent(NOTIFY_LIST,event, c->argv[j],c->db->id); if (listTypeLength(o) == 0) { dbDelete(c->db,c->argv[j]); notifyKeyspaceEvent(NOTIFY_GENERIC,"del", c->argv[j],c->db->id); } signalModifiedKey(c,c->db,c->argv[j]); server.dirty++; /* Replicate it as an [LR]POP instead of B[LR]POP. */ 将其复制为[LR]POP而不是B[LR]POP事件 rewriteClientCommandVector(c,2, (where == LIST_HEAD) ? shared.lpop : shared.rpop, c->argv[j]); return; } } } } /* If we are inside a MULTI/EXEC and the list is empty the only thing * we can do is treating it as a timeout (even with timeout 0). */ 如果我们在MULTI/EXEC中,并且列表为空,那么我们唯一能做的就是将其视为超时(即使超时为0,即永不超时) if (c->flags & CLIENT_MULTI) { addReplyNullArray(c); return; } /* If the list is empty or the key does not exists we must block */ 如果列表是空的或者键不存在,我们必须为这个键阻塞 blockForKeys(c,BLOCKED_LIST,c->argv + 1,c->argc - 2,timeout,NULL,NULL); } ********************************************************************************************************************* 阻塞左弹出命令 void blpopCommand(client *c) { blockingPopGenericCommand(c,LIST_HEAD); } ********************************************************************************************************************* 阻塞右弹出命令 void brpopCommand(client *c) { blockingPopGenericCommand(c,LIST_TAIL); } ********************************************************************************************************************* 阻塞右弹出 左压入命令 void brpoplpushCommand(client *c) { mstime_t timeout; if (getTimeoutFromObjectOrReply(c,c->argv[3],&timeout,UNIT_SECONDS) != C_OK) return; 获取对象超时时间 robj *key = lookupKeyWrite(c->db, c->argv[1]); 根据键值查找数据库 if (key == NULL) { 数据中不存在 if (c->flags & CLIENT_MULTI) { /* Blocking against an empty list in a multi state * returns immediately. */ 阻塞对于一个在多状态客户端中的空列表来说,必须立刻返回 addReplyNull(c); } else { 单上下文,可以阻塞 /* The list is empty and the client blocks. */ 列表是空的,阻塞客户端(等待服务端返回) blockForKeys(c,BLOCKED_LIST,c->argv + 1,1,timeout,c->argv[2],NULL); } } else { 键非空 if (key->type != OBJ_LIST) { 不是列表类型 addReply(c, shared.wrongtypeerr); } else { /* The list exists and has elements, so * the regular rpoplpushCommand is executed. */ 列表存在并且有元素,因此执行常规rpoplpushCommand命令 serverAssertWithInfo(c,key,listTypeLength(key) > 0); rpoplpushCommand(c); } } } *********************************************************************************************************************
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