clusterCron 处理流程

轮训各个节点看是否节点可用

while((de = dictNext(di)) != NULL) {
clusterNode *node = dictGetVal(de);

    if (node->flags & (REDIS_NODE_MYSELF|REDIS_NODE_NOADDR)) continue;    /* A Node in HANDSHAKE state has a limited lifespan equal to the     * configured node timeout. */    if (nodeInHandshake(node) && now - node->ctime > handshake_timeout) {        clusterDelNode(node);        continue;    }    if (node->link == NULL) {        int fd;        mstime_t old_ping_sent;        clusterLink *link;        fd = anetTcpNonBlockBindConnect(server.neterr, node->ip,            node->port+REDIS_CLUSTER_PORT_INCR, REDIS_BIND_ADDR);        if (fd == -1) {            /* We got a synchronous error from connect before             * clusterSendPing() had a chance to be called.             * If node->ping_sent is zero, failure detection can't work,             * so we claim we actually sent a ping now (that will             * be really sent as soon as the link is obtained). */            if (node->ping_sent == 0) node->ping_sent = mstime();            redisLog(REDIS_DEBUG, "Unable to connect to "                "Cluster Node [%s]:%d -> %s", node->ip,                node->port+REDIS_CLUSTER_PORT_INCR,                server.neterr);            continue;        }        link = createClusterLink(node);        link->fd = fd;        node->link = link;        printf("yyyyyyyyyy cluster cron create fd  %d   port %d\n", fd, node->port + REDIS_CLUSTER_PORT_INCR);        aeCreateFileEvent(server.el,link->fd,AE_READABLE,                clusterReadHandler,link);        /* Queue a PING in the new connection ASAP: this is crucial         * to avoid false positives in failure detection.         *         * If the node is flagged as MEET, we send a MEET message instead         * of a PING one, to force the receiver to add us in its node         * table. */        old_ping_sent = node->ping_sent;        clusterSendPing(link, node->flags & REDIS_NODE_MEET ?                CLUSTERMSG_TYPE_MEET : CLUSTERMSG_TYPE_PING);        if (old_ping_sent) {            /* If there was an active ping before the link was             * disconnected, we want to restore the ping time, otherwise             * replaced by the clusterSendPing() call. */            node->ping_sent = old_ping_sent;        }        /* We can clear the flag after the first packet is sent.         * If we'll never receive a PONG, we'll never send new packets         * to this node. Instead after the PONG is received and we         * are no longer in meet/handshake status, we want to send         * normal PING packets. */        node->flags &= ~REDIS_NODE_MEET;        redisLog(REDIS_DEBUG,"Connecting with Node %.40s at %s:%d",                node->name, node->ip, node->port+REDIS_CLUSTER_PORT_INCR);    }}dictReleaseIterator(di);

随机找10个槽点进行测试 判断情况

if (!(iteration % 10)) {
int j;

    /* Check a few random nodes and ping the one with the oldest     * pong_received time. */    for (j = 0; j < 5; j++) {        de = dictGetRandomKey(server.cluster->nodes);        clusterNode *this = dictGetVal(de);        /* Don't ping nodes disconnected or with a ping currently active. */        if (this->link == NULL || this->ping_sent != 0) continue;        if (this->flags & (REDIS_NODE_MYSELF|REDIS_NODE_HANDSHAKE))            continue;        if (min_pong_node == NULL || min_pong > this->pong_received) {            min_pong_node = this;            min_pong = this->pong_received;        }    }    if (min_pong_node) {        redisLog(REDIS_DEBUG,"Pinging node %.40s", min_pong_node->name);        clusterSendPing(min_pong_node->link, CLUSTERMSG_TYPE_PING);    }}

3

1 查询是否有孤儿master
2 计算一个master 最大的slaves数量
3 如果是slave计算当前 master最大的slaves
4 同时进行状态检查 ping的发送 ，删除link的操作
orphaned_masters = 0;
max_slaves = 0;
this_slaves = 0;
di = dictGetSafeIterator(server.cluster->nodes);
while((de = dictNext(di)) != NULL) {
clusterNode *node = dictGetVal(de);
now = mstime(); /* Use an updated time at every iteration. */
mstime_t delay;

    if (node->flags &        (REDIS_NODE_MYSELF|REDIS_NODE_NOADDR|REDIS_NODE_HANDSHAKE))            continue;    /* Orphaned master check, useful only if the current instance     * is a slave that may migrate to another master. */    if (nodeIsSlave(myself) && nodeIsMaster(node) && !nodeFailed(node)) {        int okslaves = clusterCountNonFailingSlaves(node);        /* A master is orphaned if it is serving a non-zero number of         * slots, have no working slaves, but used to have at least one         * slave. */        if (okslaves == 0 && node->numslots > 0 && node->numslaves)            orphaned_masters++;        if (okslaves > max_slaves) max_slaves = okslaves;        if (nodeIsSlave(myself) && myself->slaveof == node)            this_slaves = okslaves;    }    /* If we are waiting for the PONG more than half the cluster     * timeout, reconnect the link: maybe there is a connection     * issue even if the node is alive. */    if (node->link && /* is connected */        now - node->link->ctime >        server.cluster_node_timeout && /* was not already reconnected */        node->ping_sent && /* we already sent a ping */        node->pong_received < node->ping_sent && /* still waiting pong */        /* and we are waiting for the pong more than timeout/2 */        now - node->ping_sent > server.cluster_node_timeout/2)    {        /* Disconnect the link, it will be reconnected automatically. */        freeClusterLink(node->link);    }    /* If we have currently no active ping in this instance, and the     * received PONG is older than half the cluster timeout, send     * a new ping now, to ensure all the nodes are pinged without     * a too big delay. */    if (node->link &&        node->ping_sent == 0 &&        (now - node->pong_received) > server.cluster_node_timeout/2)    {        clusterSendPing(node->link, CLUSTERMSG_TYPE_PING);        continue;    }    /* If we are a master and one of the slaves requested a manual     * failover, ping it continuously. */    if (server.cluster->mf_end &&        nodeIsMaster(myself) &&        server.cluster->mf_slave == node &&        node->link)    {        clusterSendPing(node->link, CLUSTERMSG_TYPE_PING);        continue;    }    /* Check only if we have an active ping for this instance. */    if (node->ping_sent == 0) continue;    /* Compute the delay of the PONG. Note that if we already received     * the PONG, then node->ping_sent is zero, so can't reach this     * code at all. */    delay = now - node->ping_sent;    if (delay > server.cluster_node_timeout) {        /* Timeout reached. Set the node as possibly failing if it is         * not already in this state. */        if (!(node->flags & (REDIS_NODE_PFAIL|REDIS_NODE_FAIL))) {            redisLog(REDIS_DEBUG,"*** NODE %.40s possibly failing",                node->name);            node->flags |= REDIS_NODE_PFAIL;            update_state = 1;        }    }}

4 一个salve 复制中断确保再次连接master

if (nodeIsSlave(myself) &&
server.masterhost == NULL &&
myself->slaveof &&
nodeHasAddr(myself->slaveof))
{
replicationSetMaster(myself->slaveof->ip, myself->slaveof->port);
}

5 孤儿master检查和node状态检查

/* Abourt a manual failover if the timeout is reached. */
manualFailoverCheckTimeout();

if (nodeIsSlave(myself)) {    clusterHandleManualFailover();    clusterHandleSlaveFailover();    /* If there are orphaned slaves, and we are a slave among the masters     * with the max number of non-failing slaves, consider migrating to     * the orphaned masters. Note that it does not make sense to try     * a migration if there is no master with at least *two* working     * slaves. */    if (orphaned_masters && max_slaves >= 2 && this_slaves == max_slaves)        clusterHandleSlaveMigration(max_slaves);}if (update_state || server.cluster->state == REDIS_CLUSTER_FAIL)    clusterUpdateState();