cluster.h

#ifndef __REDIS_CLUSTER_H
#define __REDIS_CLUSTER_H

/*-----------------------------------------------------------------------------
 * Redis cluster data structures, defines, exported API.
 *----------------------------------------------------------------------------*/

#define REDIS_CLUSTER_SLOTS 16384
#define REDIS_CLUSTER_OK 0          /* Everything looks ok */
#define REDIS_CLUSTER_FAIL 1        /* The cluster can't work */
#define REDIS_CLUSTER_NAMELEN 40    /* sha1 hex length */
#define REDIS_CLUSTER_PORT_INCR 10000 /* Cluster port = baseport + PORT_INCR */
#define REDIS_CLUSTER_IPLEN INET6_ADDRSTRLEN /* IPv6 address string length */

/* The following defines are amunt of time, sometimes expressed as
 * multiplicators of the node timeout value (when ending with MULT). */
#define REDIS_CLUSTER_DEFAULT_NODE_TIMEOUT 15
#define REDIS_CLUSTER_FAIL_REPORT_VALIDITY_MULT 2 /* Fail report validity. */
#define REDIS_CLUSTER_FAIL_UNDO_TIME_MULT 2 /* Undo fail if master is back. */
#define REDIS_CLUSTER_FAIL_UNDO_TIME_ADD 10 /* Some additional time. */
#define REDIS_CLUSTER_SLAVE_VALIDITY_MULT 10 /* Slave data validity. */
#define REDIS_CLUSTER_FAILOVER_AUTH_RETRY_MULT 4 /* Auth request retry time. */
#define REDIS_CLUSTER_FAILOVER_DELAY 5 /* Seconds */

struct clusterNode;

/* clusterLink encapsulates everything needed to talk with a remote node. */
typedef struct clusterLink {
    time_t ctime;               /* Link creation time */
    int fd;                     /* TCP socket file descriptor */
    sds sndbuf;                 /* Packet send buffer */
    sds rcvbuf;                 /* Packet reception buffer */
    struct clusterNode *node;   /* Node related to this link if any, or NULL */
} clusterLink;

/* Node flags */
#define REDIS_NODE_MASTER 1     /* The node is a master */
#define REDIS_NODE_SLAVE 2      /* The node is a slave */
#define REDIS_NODE_PFAIL 4      /* Failure? Need acknowledge */
#define REDIS_NODE_FAIL 8       /* The node is believed to be malfunctioning */
#define REDIS_NODE_MYSELF 16    /* This node is myself */
#define REDIS_NODE_HANDSHAKE 32 /* We have still to exchange the first ping */
#define REDIS_NODE_NOADDR   64  /* We don't know the address of this node */
#define REDIS_NODE_MEET 128     /* Send a MEET message to this node */
#define REDIS_NODE_PROMOTED 256 /* Master was a slave propoted by failover */
#define REDIS_NODE_NULL_NAME "\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000"

/* This structure represent elements of node->fail_reports. */
struct clusterNodeFailReport {
    struct clusterNode *node;  /* Node reporting the failure condition. */
    time_t time;               /* Time of the last report from this node. */
} typedef clusterNodeFailReport;

struct clusterNode {
    time_t ctime;   /* Node object creation time. */
    char name[REDIS_CLUSTER_NAMELEN]; /* Node name, hex string, sha1-size */
    int flags;      /* REDIS_NODE_... */
    uint64_t configEpoch; /* Last configEpoch observed for this node */
    unsigned char slots[REDIS_CLUSTER_SLOTS/8]; /* slots handled by this node */
    int numslots;   /* Number of slots handled by this node */
    int numslaves;  /* Number of slave nodes, if this is a master */
    struct clusterNode **slaves; /* pointers to slave nodes */
    struct clusterNode *slaveof; /* pointer to the master node */
    time_t ping_sent;       /* Unix time we sent latest ping */
    time_t pong_received;   /* Unix time we received the pong */
    time_t fail_time;       /* Unix time when FAIL flag was set */
    time_t voted_time;      /* Last time we voted for a slave of this master */
    char ip[REDIS_IP_STR_LEN];  /* Latest known IP address of this node */
    int port;                   /* Latest known port of this node */
    clusterLink *link;          /* TCP/IP link with this node */
    list *fail_reports;         /* List of nodes signaling this as failing */
};
typedef struct clusterNode clusterNode;

typedef struct clusterState {
    clusterNode *myself;  /* This node */
    uint64_t currentEpoch;
    int state;            /* REDIS_CLUSTER_OK, REDIS_CLUSTER_FAIL, ... */
    int size;             /* Num of master nodes with at least one slot */
    dict *nodes;          /* Hash table of name -> clusterNode structures */
    clusterNode *migrating_slots_to[REDIS_CLUSTER_SLOTS];
    clusterNode *importing_slots_from[REDIS_CLUSTER_SLOTS];
    clusterNode *slots[REDIS_CLUSTER_SLOTS];
    zskiplist *slots_to_keys;
    /* The following fields are used to take the slave state on elections. */
    mstime_t failover_auth_time;/* Time at which we'll try to get elected in ms*/
    int failover_auth_count;    /* Number of votes received so far. */
    int failover_auth_sent;     /* True if we already asked for votes. */
    uint64_t failover_auth_epoch; /* Epoch of the current election. */
    /* The followign fields are uesd by masters to take state on elections. */
    uint64_t last_vote_epoch;   /* Epoch of the last vote granted. */
    int todo_before_sleep; /* Things to do in clusterBeforeSleep(). */
    long long stats_bus_messages_sent;  /* Num of msg sent via cluster bus. */
    long long stats_bus_messages_received; /* Num of msg received via cluster bus. */
} clusterState;

/* clusterState todo_before_sleep flags. */
#define CLUSTER_TODO_HANDLE_FAILOVER (1<<0)
#define CLUSTER_TODO_UPDATE_STATE (1<<1)
#define CLUSTER_TODO_SAVE_CONFIG (1<<2)
#define CLUSTER_TODO_FSYNC_CONFIG (1<<3)

/* Redis cluster messages header */

/* Note that the PING, PONG and MEET messages are actually the same exact
 * kind of packet. PONG is the reply to ping, in the exact format as a PING,
 * while MEET is a special PING that forces the receiver to add the sender
 * as a node (if it is not already in the list). */
#define CLUSTERMSG_TYPE_PING 0          /* Ping */
#define CLUSTERMSG_TYPE_PONG 1          /* Pong (reply to Ping) */
#define CLUSTERMSG_TYPE_MEET 2          /* Meet "let's join" message */
#define CLUSTERMSG_TYPE_FAIL 3          /* Mark node xxx as failing */
#define CLUSTERMSG_TYPE_PUBLISH 4       /* Pub/Sub Publish propagation */
#define CLUSTERMSG_TYPE_FAILOVER_AUTH_REQUEST 5 /* May I failover? */
#define CLUSTERMSG_TYPE_FAILOVER_AUTH_ACK 6     /* Yes, you can failover. */

/* Initially we don't know our "name", but we'll find it once we connect
 * to the first node, using the getsockname() function. Then we'll use this
 * address for all the next messages. */
typedef struct {
    char nodename[REDIS_CLUSTER_NAMELEN];
    uint32_t ping_sent;
    uint32_t pong_received;
    char ip[16];    /* IP address last time it was seen */
    uint16_t port;  /* port last time it was seen */
    uint16_t flags;
    uint32_t notused; /* for 64 bit alignment */
} clusterMsgDataGossip;

typedef struct {
    char nodename[REDIS_CLUSTER_NAMELEN];
} clusterMsgDataFail;

typedef struct {
    uint32_t channel_len;
    uint32_t message_len;
    unsigned char bulk_data[8]; /* defined as 8 just for alignment concerns. */
} clusterMsgDataPublish;

union clusterMsgData {
    /* PING, MEET and PONG */
    struct {
        /* Array of N clusterMsgDataGossip structures */
        clusterMsgDataGossip gossip[1];
    } ping;

    /* FAIL */
    struct {
        clusterMsgDataFail about;
    } fail;

    /* PUBLISH */
    struct {
        clusterMsgDataPublish msg;
    } publish;
};

typedef struct {
    uint32_t totlen;    /* Total length of this message */
    uint16_t type;      /* Message type */
    uint16_t count;     /* Only used for some kind of messages. */
    uint64_t currentEpoch;  /* The epoch accordingly to the sending node. */
    uint64_t configEpoch;   /* The config epoch if it's a master, or the last epoch
                               advertised by its master if it is a slave. */
    char sender[REDIS_CLUSTER_NAMELEN]; /* Name of the sender node */
    unsigned char myslots[REDIS_CLUSTER_SLOTS/8];
    char slaveof[REDIS_CLUSTER_NAMELEN];
    char notused1[32];  /* 32 bytes reserved for future usage. */
    uint16_t port;      /* Sender TCP base port */
    uint16_t flags;     /* Sender node flags */
    unsigned char state; /* Cluster state from the POV of the sender */
    unsigned char notused2[3]; /* Reserved for future use. For alignment. */
    union clusterMsgData data;
} clusterMsg;

#define CLUSTERMSG_MIN_LEN (sizeof(clusterMsg)-sizeof(union clusterMsgData))

/* ----------------------- API exported outside cluster.c ------------------------- */
clusterNode *getNodeByQuery(redisClient *c, struct redisCommand *cmd, robj **argv, int argc, int *hashslot, int *ask);

#endif /* __REDIS_CLUSTER_H */