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sentinel.c
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sentinel.c
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/* Redis Sentinel implementation
*
* Copyright (c) 2009-2012, Salvatore Sanfilippo <antirez at gmail dot com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of Redis nor the names of its contributors may be used
* to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include "server.h"
#include "hiredis.h"
#ifdef USE_OPENSSL
#include "openssl/ssl.h"
#include "hiredis_ssl.h"
#endif
#include "async.h"
#include <ctype.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <fcntl.h>
extern char **environ;
#ifdef USE_OPENSSL
extern SSL_CTX *redis_tls_ctx;
extern SSL_CTX *redis_tls_client_ctx;
#endif
/* sentinel 默认端口号 */
#define REDIS_SENTINEL_PORT 26379
/* ======================== Sentinel global state =========================== */
/* Address object, used to describe an ip:port pair. */
/* 地址对象，用于保存主机名称，IP地址和端口号 */
typedef struct sentinelAddr {
char *hostname; /* Hostname OR address, as specified */
char *ip; /* Always a resolved address */
int port;
} sentinelAddr;
/* A Sentinel Redis Instance object is monitoring. */
/* 实例是一个主服务器 */
#define SRI_MASTER (1<<0)
/* 实例是一个从服务器 */
#define SRI_SLAVE (1<<1)
/* 实例是一个 Sentinel */
#define SRI_SENTINEL (1<<2)
/* 实例当前状态为: SDOWN，即哨兵单方面认为对方下线，是一个很主观的想法，主观下线 */
#define SRI_S_DOWN (1<<3) /* Subjectively down (no quorum). */
/* 实例当前状态为：ODOWN，即大多数（半数以上）哨兵认为对方主观下线，整个哨兵集群达成这个共识，标记为客观下线 */
#define SRI_O_DOWN (1<<4) /* Objectively down (confirmed by others). */
/* Sentinel 认为主服务器已下线 */
#define SRI_MASTER_DOWN (1<<5) /* A Sentinel with this flag set thinks that
its master is down. */
/* 正在对主服务器进行故障转移 */
#define SRI_FAILOVER_IN_PROGRESS (1<<6) /* Failover is in progress for
this master. */
/* 实例被选中为主服务器（当前仍是从服务器）*/
#define SRI_PROMOTED (1<<7) /* Slave selected for promotion. */
/* 哨兵向服务器发送了 SLAVEOF 命令，让其转向复制新主服务器 */
#define SRI_RECONF_SENT (1<<8) /* SLAVEOF <newmaster> sent. */
/* 从服务器正在和主服务器进行同步，INFO 响应中从服务器的主能对应上新主，从 SENT -> INPROG */
#define SRI_RECONF_INPROG (1<<9) /* Slave synchronization in progress. */
/* 从服务器与新服务器同步完毕，INFO 响应中 master_link_status 为 up，从 INPROG -> DONE */
#define SRI_RECONF_DONE (1<<10) /* Slave synchronized with new master. */
/* 主服务器强制执行故障转移操作，通过 SENTINEL FAILOVER <master-name> 命令主动触发而不用哨兵集群达成共识 */
#define SRI_FORCE_FAILOVER (1<<11) /* Force failover with master up. */
/* 已对返回 -BUSY 的服务器发送 SCRIPT KILL 命令 */
#define SRI_SCRIPT_KILL_SENT (1<<12) /* SCRIPT KILL already sent on -BUSY */
/* 主服务器正在重启 */
#define SRI_MASTER_REBOOT (1<<13) /* Master was detected as rebooting */
/* 时间常量，均以毫秒为单位 */
/* Note: times are in milliseconds. */
#define SENTINEL_PING_PERIOD 1000
/* 发送 INFO 命令的间隔 */
static mstime_t sentinel_info_period = 10000;
/* 发送 PING 命令的间隔 */
static mstime_t sentinel_ping_period = SENTINEL_PING_PERIOD;
/* 发送 ASK 命令的间隔，实际上是 SENTINEL is-master-down-by-addr 命令，询问对方某主服务器是否主观下线或者故障转移过程中用于拉票（哨兵 leader） */
static mstime_t sentinel_ask_period = 1000;
/* 发送 PUBLISH 命令的间隔 */
static mstime_t sentinel_publish_period = 2000;
/* 默认判断服务器主观下线所需要的时间，即失联多久才会认为对方主观下线 */
static mstime_t sentinel_default_down_after = 30000;
/* 默认 TILT 触发时长 */
static mstime_t sentinel_tilt_trigger = 2000;
/* 默认 TILT 环境时长（即哨兵正常工作多久后，才能退出 TITL 模式）*/
static mstime_t sentinel_tilt_period = SENTINEL_PING_PERIOD * 30;
/* 默认的从服务器配置修改超时时长 */
static mstime_t sentinel_slave_reconf_timeout = 10000;
/* 默认最少重连间隔 */
static mstime_t sentinel_min_link_reconnect_period = 15000;
/* 默认选举超时时长 */
static mstime_t sentinel_election_timeout = 10000;
/* 脚本最大执行时长 */
static mstime_t sentinel_script_max_runtime = 60000; /* 60 seconds max exec time. */
/* 脚本重试前的延迟时间 */
static mstime_t sentinel_script_retry_delay = 30000; /* 30 seconds between retries. */
/* 默认故障迁移执行时长 */
static mstime_t sentinel_default_failover_timeout = 60*3*1000;
/* 默认信息频道 */
#define SENTINEL_HELLO_CHANNEL "__sentinel__:hello"
/* 默认的从服务器优先级，用于新主选择，优先级越小被选为新主的概率越大，优先级为 0 不参与选择 */
#define SENTINEL_DEFAULT_SLAVE_PRIORITY 100
/* 默认同时对新主服务器进行复制的从服务器数量 */
#define SENTINEL_DEFAULT_PARALLEL_SYNCS 1
/* 默认最大积压命令数量 */
#define SENTINEL_MAX_PENDING_COMMANDS 100
/* 启动故障转移最大延迟时间 */
#define SENTINEL_MAX_DESYNC 1000
#define SENTINEL_DEFAULT_DENY_SCRIPTS_RECONFIG 1
#define SENTINEL_DEFAULT_RESOLVE_HOSTNAMES 0
#define SENTINEL_DEFAULT_ANNOUNCE_HOSTNAMES 0
/* 故障转移时的状态 */
/* Failover machine different states. */
/* 没在执行故障转移 */
#define SENTINEL_FAILOVER_STATE_NONE 0 /* No failover in progress. */
/* 正在等待故障转移的启动 */
#define SENTINEL_FAILOVER_STATE_WAIT_START 1 /* Wait for failover_start_time*/
/* 正在挑选将要提升作为新主服务器的从服务器 */
#define SENTINEL_FAILOVER_STATE_SELECT_SLAVE 2 /* Select slave to promote */
/* 向被选中的从服务器发送 SLAVEOF NO ONE 命令，将其提升为 master */
#define SENTINEL_FAILOVER_STATE_SEND_SLAVEOF_NOONE 3 /* Slave -> Master */
/* 等待从服务器转为主服务器 */
#define SENTINEL_FAILOVER_STATE_WAIT_PROMOTION 4 /* Wait slave to change role */
/* 向已下线主服务器的从属从服务器发送 SLAVEOF new_master_ip new_master_port 命令 */
/* 让它们向新主服务器建立主从复制，即向新主进行同步 */
#define SENTINEL_FAILOVER_STATE_RECONF_SLAVES 5 /* SLAVEOF newmaster */
/* 监视被升级的从服务器 */
#define SENTINEL_FAILOVER_STATE_UPDATE_CONFIG 6 /* Monitor promoted slave. */
/* 主从连接正常 */
#define SENTINEL_MASTER_LINK_STATUS_UP 0
/* 主从连接断开 */
#define SENTINEL_MASTER_LINK_STATUS_DOWN 1
/* 可用于多个函数的通用标识。
使用高位来避免与一般标识冲突。*/
/* Generic flags that can be used with different functions.
* They use higher bits to avoid colliding with the function specific
* flags. */
/* 没有标识 */
#define SENTINEL_NO_FLAGS 0
/* 生成事件 */
#define SENTINEL_GENERATE_EVENT (1<<16)
/* 领导 */
#define SENTINEL_LEADER (1<<17)
/* 观察者 */
#define SENTINEL_OBSERVER (1<<18)
/* 脚本执行状态与限制 */
/* Script execution flags and limits. */
/* 脚本目前没被执行 */
#define SENTINEL_SCRIPT_NONE 0
/* 脚本正在执行 */
#define SENTINEL_SCRIPT_RUNNING 1
/* 脚本队列保存脚本数量的最大值 */
#define SENTINEL_SCRIPT_MAX_QUEUE 256
/* 同一时间可执行脚本的最大数量 */
#define SENTINEL_SCRIPT_MAX_RUNNING 16
/* 脚本最大重试次数 */
#define SENTINEL_SCRIPT_MAX_RETRY 10
/* SENTINEL SIMULATE-FAILURE command flags. */
#define SENTINEL_SIMFAILURE_NONE 0
#define SENTINEL_SIMFAILURE_CRASH_AFTER_ELECTION (1<<0)
#define SENTINEL_SIMFAILURE_CRASH_AFTER_PROMOTION (1<<1)
/* The link to a sentinelRedisInstance. When we have the same set of Sentinels
* monitoring many masters, we have different instances representing the
* same Sentinels, one per master, and we need to share the hiredis connections
* among them. Otherwise if 5 Sentinels are monitoring 100 masters we create
* 500 outgoing connections instead of 5.
*
* So this structure represents a reference counted link in terms of the two
* hiredis connections for commands and Pub/Sub, and the fields needed for
* failure detection, since the ping/pong time are now local to the link: if
* the link is available, the instance is available. This way we don't just
* have 5 connections instead of 500, we also send 5 pings instead of 500.
*
* Links are shared only for Sentinels: master and slave instances have
* a link with refcount = 1, always. */
typedef struct instanceLink {
int refcount; /* Number of sentinelRedisInstance owners. */
int disconnected; /* Non-zero if we need to reconnect cc or pc. */
int pending_commands; /* Number of commands sent waiting for a reply. */
redisAsyncContext *cc; /* Hiredis context for commands. */
redisAsyncContext *pc; /* Hiredis context for Pub / Sub. */
mstime_t cc_conn_time; /* cc connection time. */
mstime_t pc_conn_time; /* pc connection time. */
mstime_t pc_last_activity; /* Last time we received any message. */
mstime_t last_avail_time; /* Last time the instance replied to ping with
a reply we consider valid. */
mstime_t act_ping_time; /* Time at which the last pending ping (no pong
received after it) was sent. This field is
set to 0 when a pong is received, and set again
to the current time if the value is 0 and a new
ping is sent. */
mstime_t last_ping_time; /* Time at which we sent the last ping. This is
only used to avoid sending too many pings
during failure. Idle time is computed using
the act_ping_time field. */
mstime_t last_pong_time; /* Last time the instance replied to ping,
whatever the reply was. That's used to check
if the link is idle and must be reconnected. */
mstime_t last_reconn_time; /* Last reconnection attempt performed when
the link was down. */
} instanceLink;
typedef struct sentinelRedisInstance {
int flags; /* See SRI_... defines */
char *name; /* Master name from the point of view of this sentinel. */
char *runid; /* Run ID of this instance, or unique ID if is a Sentinel.*/
uint64_t config_epoch; /* Configuration epoch. */
sentinelAddr *addr; /* Master host. */
instanceLink *link; /* Link to the instance, may be shared for Sentinels. */
mstime_t last_pub_time; /* Last time we sent hello via Pub/Sub. */
mstime_t last_hello_time; /* Only used if SRI_SENTINEL is set. Last time
we received a hello from this Sentinel
via Pub/Sub. */
mstime_t last_master_down_reply_time; /* Time of last reply to
SENTINEL is-master-down command. */
mstime_t s_down_since_time; /* Subjectively down since time. */
mstime_t o_down_since_time; /* Objectively down since time. */
mstime_t down_after_period; /* Consider it down after that period. */
mstime_t master_reboot_down_after_period; /* Consider master down after that period. */
mstime_t master_reboot_since_time; /* master reboot time since time. */
mstime_t info_refresh; /* Time at which we received INFO output from it. */
dict *renamed_commands; /* Commands renamed in this instance:
Sentinel will use the alternative commands
mapped on this table to send things like
SLAVEOF, CONFING, INFO, ... */
/* Role and the first time we observed it.
* This is useful in order to delay replacing what the instance reports
* with our own configuration. We need to always wait some time in order
* to give a chance to the leader to report the new configuration before
* we do silly things. */
int role_reported;
mstime_t role_reported_time;
mstime_t slave_conf_change_time; /* Last time slave master addr changed. */
/* Master specific. */
dict *sentinels; /* Other sentinels monitoring the same master. */
dict *slaves; /* Slaves for this master instance. */
unsigned int quorum;/* Number of sentinels that need to agree on failure. */
int parallel_syncs; /* How many slaves to reconfigure at same time. */
char *auth_pass; /* Password to use for AUTH against master & replica. */
char *auth_user; /* Username for ACLs AUTH against master & replica. */
/* Slave specific. */
mstime_t master_link_down_time; /* Slave replication link down time. */
int slave_priority; /* Slave priority according to its INFO output. */
int replica_announced; /* Replica announcing according to its INFO output. */
mstime_t slave_reconf_sent_time; /* Time at which we sent SLAVE OF <new> */
struct sentinelRedisInstance *master; /* Master instance if it's slave. */
char *slave_master_host; /* Master host as reported by INFO */
int slave_master_port; /* Master port as reported by INFO */
int slave_master_link_status; /* Master link status as reported by INFO */
unsigned long long slave_repl_offset; /* Slave replication offset. */
/* Failover */
char *leader; /* If this is a master instance, this is the runid of
the Sentinel that should perform the failover. If
this is a Sentinel, this is the runid of the Sentinel
that this Sentinel voted as leader. */
uint64_t leader_epoch; /* Epoch of the 'leader' field. */
uint64_t failover_epoch; /* Epoch of the currently started failover. */
int failover_state; /* See SENTINEL_FAILOVER_STATE_* defines. */
mstime_t failover_state_change_time;
mstime_t failover_start_time; /* Last failover attempt start time. */
mstime_t failover_timeout; /* Max time to refresh failover state. */
mstime_t failover_delay_logged; /* For what failover_start_time value we
logged the failover delay. */
struct sentinelRedisInstance *promoted_slave; /* Promoted slave instance. */
/* Scripts executed to notify admin or reconfigure clients: when they
* are set to NULL no script is executed. */
char *notification_script;
char *client_reconfig_script;
sds info; /* cached INFO output */
} sentinelRedisInstance;
/* Main state. */
struct sentinelState {
char myid[CONFIG_RUN_ID_SIZE+1]; /* This sentinel ID. */
uint64_t current_epoch; /* Current epoch. */
dict *masters; /* Dictionary of master sentinelRedisInstances.
Key is the instance name, value is the
sentinelRedisInstance structure pointer. */
int tilt; /* Are we in TILT mode? */
int running_scripts; /* Number of scripts in execution right now. */
mstime_t tilt_start_time; /* When TITL started. */
mstime_t previous_time; /* Last time we ran the time handler. */
list *scripts_queue; /* Queue of user scripts to execute. */
char *announce_ip; /* IP addr that is gossiped to other sentinels if
not NULL. */
int announce_port; /* Port that is gossiped to other sentinels if
non zero. */
unsigned long simfailure_flags; /* Failures simulation. */
int deny_scripts_reconfig; /* Allow SENTINEL SET ... to change script
paths at runtime? */
char *sentinel_auth_pass; /* Password to use for AUTH against other sentinel */
char *sentinel_auth_user; /* Username for ACLs AUTH against other sentinel. */
int resolve_hostnames; /* Support use of hostnames, assuming DNS is well configured. */
int announce_hostnames; /* Announce hostnames instead of IPs when we have them. */
} sentinel;
/* A script execution job. */
typedef struct sentinelScriptJob {
int flags; /* Script job flags: SENTINEL_SCRIPT_* */
int retry_num; /* Number of times we tried to execute it. */
char **argv; /* Arguments to call the script. */
mstime_t start_time; /* Script execution time if the script is running,
otherwise 0 if we are allowed to retry the
execution at any time. If the script is not
running and it's not 0, it means: do not run
before the specified time. */
pid_t pid; /* Script execution pid. */
} sentinelScriptJob;
/* ======================= hiredis ae.c adapters =============================
* Note: this implementation is taken from hiredis/adapters/ae.h, however
* we have our modified copy for Sentinel in order to use our allocator
* and to have full control over how the adapter works. */
typedef struct redisAeEvents {
redisAsyncContext *context;
aeEventLoop *loop;
int fd;
int reading, writing;
} redisAeEvents;
static void redisAeReadEvent(aeEventLoop *el, int fd, void *privdata, int mask) {
((void)el); ((void)fd); ((void)mask);
redisAeEvents *e = (redisAeEvents*)privdata;
redisAsyncHandleRead(e->context);
}
static void redisAeWriteEvent(aeEventLoop *el, int fd, void *privdata, int mask) {
((void)el); ((void)fd); ((void)mask);
redisAeEvents *e = (redisAeEvents*)privdata;
redisAsyncHandleWrite(e->context);
}
static void redisAeAddRead(void *privdata) {
redisAeEvents *e = (redisAeEvents*)privdata;
aeEventLoop *loop = e->loop;
if (!e->reading) {
e->reading = 1;
aeCreateFileEvent(loop,e->fd,AE_READABLE,redisAeReadEvent,e);
}
}
static void redisAeDelRead(void *privdata) {
redisAeEvents *e = (redisAeEvents*)privdata;
aeEventLoop *loop = e->loop;
if (e->reading) {
e->reading = 0;
aeDeleteFileEvent(loop,e->fd,AE_READABLE);
}
}
static void redisAeAddWrite(void *privdata) {
redisAeEvents *e = (redisAeEvents*)privdata;
aeEventLoop *loop = e->loop;
if (!e->writing) {
e->writing = 1;
aeCreateFileEvent(loop,e->fd,AE_WRITABLE,redisAeWriteEvent,e);
}
}
static void redisAeDelWrite(void *privdata) {
redisAeEvents *e = (redisAeEvents*)privdata;
aeEventLoop *loop = e->loop;
if (e->writing) {
e->writing = 0;
aeDeleteFileEvent(loop,e->fd,AE_WRITABLE);
}
}
static void redisAeCleanup(void *privdata) {
redisAeEvents *e = (redisAeEvents*)privdata;
redisAeDelRead(privdata);
redisAeDelWrite(privdata);
zfree(e);
}
static int redisAeAttach(aeEventLoop *loop, redisAsyncContext *ac) {
redisContext *c = &(ac->c);
redisAeEvents *e;
/* Nothing should be attached when something is already attached */
if (ac->ev.data != NULL)
return C_ERR;
/* Create container for context and r/w events */
e = (redisAeEvents*)zmalloc(sizeof(*e));
e->context = ac;
e->loop = loop;
e->fd = c->fd;
e->reading = e->writing = 0;
/* Register functions to start/stop listening for events */
ac->ev.addRead = redisAeAddRead;
ac->ev.delRead = redisAeDelRead;
ac->ev.addWrite = redisAeAddWrite;
ac->ev.delWrite = redisAeDelWrite;
ac->ev.cleanup = redisAeCleanup;
ac->ev.data = e;
return C_OK;
}
/* ============================= Prototypes ================================= */
void sentinelLinkEstablishedCallback(const redisAsyncContext *c, int status);
void sentinelDisconnectCallback(const redisAsyncContext *c, int status);
void sentinelReceiveHelloMessages(redisAsyncContext *c, void *reply, void *privdata);
sentinelRedisInstance *sentinelGetMasterByName(char *name);
char *sentinelGetSubjectiveLeader(sentinelRedisInstance *master);
char *sentinelGetObjectiveLeader(sentinelRedisInstance *master);
void instanceLinkConnectionError(const redisAsyncContext *c);
const char *sentinelRedisInstanceTypeStr(sentinelRedisInstance *ri);
void sentinelAbortFailover(sentinelRedisInstance *ri);
void sentinelEvent(int level, char *type, sentinelRedisInstance *ri, const char *fmt, ...);
sentinelRedisInstance *sentinelSelectSlave(sentinelRedisInstance *master);
void sentinelScheduleScriptExecution(char *path, ...);
void sentinelStartFailover(sentinelRedisInstance *master);
void sentinelDiscardReplyCallback(redisAsyncContext *c, void *reply, void *privdata);
int sentinelSendSlaveOf(sentinelRedisInstance *ri, const sentinelAddr *addr);
char *sentinelVoteLeader(sentinelRedisInstance *master, uint64_t req_epoch, char *req_runid, uint64_t *leader_epoch);
int sentinelFlushConfig(void);
void sentinelGenerateInitialMonitorEvents(void);
int sentinelSendPing(sentinelRedisInstance *ri);
int sentinelForceHelloUpdateForMaster(sentinelRedisInstance *master);
sentinelRedisInstance *getSentinelRedisInstanceByAddrAndRunID(dict *instances, char *ip, int port, char *runid);
void sentinelSimFailureCrash(void);
/* ========================= Dictionary types =============================== */
void releaseSentinelRedisInstance(sentinelRedisInstance *ri);
void dictInstancesValDestructor (dict *d, void *obj) {
UNUSED(d);
releaseSentinelRedisInstance(obj);
}
/* Instance name (sds) -> instance (sentinelRedisInstance pointer)
*
* also used for: sentinelRedisInstance->sentinels dictionary that maps
* sentinels ip:port to last seen time in Pub/Sub hello message. */
dictType instancesDictType = {
dictSdsHash, /* hash function */
NULL, /* key dup */
NULL, /* val dup */
dictSdsKeyCompare, /* key compare */
NULL, /* key destructor */
dictInstancesValDestructor,/* val destructor */
NULL /* allow to expand */
};
/* Instance runid (sds) -> votes (long casted to void*)
*
* This is useful into sentinelGetObjectiveLeader() function in order to
* count the votes and understand who is the leader. */
dictType leaderVotesDictType = {
dictSdsHash, /* hash function */
NULL, /* key dup */
NULL, /* val dup */
dictSdsKeyCompare, /* key compare */
NULL, /* key destructor */
NULL, /* val destructor */
NULL /* allow to expand */
};
/* Instance renamed commands table. */
dictType renamedCommandsDictType = {
dictSdsCaseHash, /* hash function */
NULL, /* key dup */
NULL, /* val dup */
dictSdsKeyCaseCompare, /* key compare */
dictSdsDestructor, /* key destructor */
dictSdsDestructor, /* val destructor */
NULL /* allow to expand */
};
/* =========================== Initialization =============================== */
void sentinelSetCommand(client *c);
void sentinelConfigGetCommand(client *c);
void sentinelConfigSetCommand(client *c);
/* this array is used for sentinel config lookup, which need to be loaded
* before monitoring masters config to avoid dependency issues */
const char *preMonitorCfgName[] = {
"announce-ip",
"announce-port",
"deny-scripts-reconfig",
"sentinel-user",
"sentinel-pass",
"current-epoch",
"myid",
"resolve-hostnames",
"announce-hostnames"
};
/* This function overwrites a few normal Redis config default with Sentinel
* specific defaults. */
void initSentinelConfig(void) {
server.port = REDIS_SENTINEL_PORT;
server.protected_mode = 0; /* Sentinel must be exposed. */
}
void freeSentinelLoadQueueEntry(void *item);
/* Perform the Sentinel mode initialization. */
void initSentinel(void) {
/* Initialize various data structures. */
sentinel.current_epoch = 0;
sentinel.masters = dictCreate(&instancesDictType);
sentinel.tilt = 0;
sentinel.tilt_start_time = 0;
sentinel.previous_time = mstime();
sentinel.running_scripts = 0;
sentinel.scripts_queue = listCreate();
sentinel.announce_ip = NULL;
sentinel.announce_port = 0;
sentinel.simfailure_flags = SENTINEL_SIMFAILURE_NONE;
sentinel.deny_scripts_reconfig = SENTINEL_DEFAULT_DENY_SCRIPTS_RECONFIG;
sentinel.sentinel_auth_pass = NULL;
sentinel.sentinel_auth_user = NULL;
sentinel.resolve_hostnames = SENTINEL_DEFAULT_RESOLVE_HOSTNAMES;
sentinel.announce_hostnames = SENTINEL_DEFAULT_ANNOUNCE_HOSTNAMES;
memset(sentinel.myid,0,sizeof(sentinel.myid));
server.sentinel_config = NULL;
}
/* This function is for checking whether sentinel config file has been set,
* also checking whether we have write permissions. */
void sentinelCheckConfigFile(void) {
if (server.configfile == NULL) {
serverLog(LL_WARNING,
"Sentinel needs config file on disk to save state. Exiting...");
exit(1);
} else if (access(server.configfile,W_OK) == -1) {
serverLog(LL_WARNING,
"Sentinel config file %s is not writable: %s. Exiting...",
server.configfile,strerror(errno));
exit(1);
}
}
/* This function gets called when the server is in Sentinel mode, started,
* loaded the configuration, and is ready for normal operations. */
void sentinelIsRunning(void) {
int j;
/* If this Sentinel has yet no ID set in the configuration file, we
* pick a random one and persist the config on disk. From now on this
* will be this Sentinel ID across restarts. */
for (j = 0; j < CONFIG_RUN_ID_SIZE; j++)
if (sentinel.myid[j] != 0) break;
if (j == CONFIG_RUN_ID_SIZE) {
/* Pick ID and persist the config. */
getRandomHexChars(sentinel.myid,CONFIG_RUN_ID_SIZE);
sentinelFlushConfig();
}
/* Log its ID to make debugging of issues simpler. */
serverLog(LL_WARNING,"Sentinel ID is %s", sentinel.myid);
/* We want to generate a +monitor event for every configured master
* at startup. */
sentinelGenerateInitialMonitorEvents();
}
/* ============================== sentinelAddr ============================== */
/* Create a sentinelAddr object and return it on success.
* On error NULL is returned and errno is set to:
* ENOENT: Can't resolve the hostname, unless accept_unresolved is non-zero.
* EINVAL: Invalid port number.
*/
sentinelAddr *createSentinelAddr(char *hostname, int port, int is_accept_unresolved) {
char ip[NET_IP_STR_LEN];
sentinelAddr *sa;
if (port < 0 || port > 65535) {
errno = EINVAL;
return NULL;
}
if (anetResolve(NULL,hostname,ip,sizeof(ip),
sentinel.resolve_hostnames ? ANET_NONE : ANET_IP_ONLY) == ANET_ERR) {
serverLog(LL_WARNING, "Failed to resolve hostname '%s'", hostname);
if (sentinel.resolve_hostnames && is_accept_unresolved) {
ip[0] = '\0';
}
else {
errno = ENOENT;
return NULL;
}
}
sa = zmalloc(sizeof(*sa));
sa->hostname = sdsnew(hostname);
sa->ip = sdsnew(ip);
sa->port = port;
return sa;
}
/* Return a duplicate of the source address. */
sentinelAddr *dupSentinelAddr(sentinelAddr *src) {
sentinelAddr *sa;
sa = zmalloc(sizeof(*sa));
sa->hostname = sdsnew(src->hostname);
sa->ip = sdsnew(src->ip);
sa->port = src->port;
return sa;
}
/* Free a Sentinel address. Can't fail. */
void releaseSentinelAddr(sentinelAddr *sa) {
sdsfree(sa->hostname);
sdsfree(sa->ip);
zfree(sa);
}
/* Return non-zero if two addresses are equal. */
int sentinelAddrIsEqual(sentinelAddr *a, sentinelAddr *b) {
return a->port == b->port && !strcasecmp(a->ip,b->ip);
}
/* Return non-zero if the two addresses are equal, either by address
* or by hostname if they could not have been resolved.
*/
int sentinelAddrOrHostnameEqual(sentinelAddr *a, sentinelAddr *b) {
return a->port == b->port &&
(!strcmp(a->ip, b->ip) ||
!strcasecmp(a->hostname, b->hostname));
}
/* Return non-zero if a hostname matches an address. */
int sentinelAddrEqualsHostname(sentinelAddr *a, char *hostname) {
char ip[NET_IP_STR_LEN];
/* We always resolve the hostname and compare it to the address */
if (anetResolve(NULL, hostname, ip, sizeof(ip),
sentinel.resolve_hostnames ? ANET_NONE : ANET_IP_ONLY) == ANET_ERR)
return 0;
return !strcasecmp(a->ip, ip);
}
const char *announceSentinelAddr(const sentinelAddr *a) {
return sentinel.announce_hostnames ? a->hostname : a->ip;
}
/* Return an allocated sds with hostname/address:port. IPv6
* addresses are bracketed the same way anetFormatAddr() does.
*/
sds announceSentinelAddrAndPort(const sentinelAddr *a) {
const char *addr = announceSentinelAddr(a);
if (strchr(addr, ':') != NULL)
return sdscatprintf(sdsempty(), "[%s]:%d", addr, a->port);
else
return sdscatprintf(sdsempty(), "%s:%d", addr, a->port);
}
/* =========================== Events notification ========================== */
/* Send an event to log, pub/sub, user notification script.
*
* 'level' is the log level for logging. Only LL_WARNING events will trigger
* the execution of the user notification script.
*
* 'type' is the message type, also used as a pub/sub channel name.
*
* 'ri', is the redis instance target of this event if applicable, and is
* used to obtain the path of the notification script to execute.
*
* The remaining arguments are printf-alike.
* If the format specifier starts with the two characters "%@" then ri is
* not NULL, and the message is prefixed with an instance identifier in the
* following format:
*
* <instance type> <instance name> <ip> <port>
*
* If the instance type is not master, than the additional string is
* added to specify the originating master:
*
* @ <master name> <master ip> <master port>
*
* Any other specifier after "%@" is processed by printf itself.
*/
void sentinelEvent(int level, char *type, sentinelRedisInstance *ri,
const char *fmt, ...) {
va_list ap;
char msg[LOG_MAX_LEN];
robj *channel, *payload;
/* Handle %@ */
if (fmt[0] == '%' && fmt[1] == '@') {
sentinelRedisInstance *master = (ri->flags & SRI_MASTER) ?
NULL : ri->master;
if (master) {
snprintf(msg, sizeof(msg), "%s %s %s %d @ %s %s %d",
sentinelRedisInstanceTypeStr(ri),
ri->name, announceSentinelAddr(ri->addr), ri->addr->port,
master->name, announceSentinelAddr(master->addr), master->addr->port);
} else {
snprintf(msg, sizeof(msg), "%s %s %s %d",
sentinelRedisInstanceTypeStr(ri),
ri->name, announceSentinelAddr(ri->addr), ri->addr->port);
}
fmt += 2;
} else {
msg[0] = '\0';
}
/* Use vsprintf for the rest of the formatting if any. */
if (fmt[0] != '\0') {
va_start(ap, fmt);
vsnprintf(msg+strlen(msg), sizeof(msg)-strlen(msg), fmt, ap);
va_end(ap);
}
/* Log the message if the log level allows it to be logged. */
if (level >= server.verbosity)
serverLog(level,"%s %s",type,msg);
/* Publish the message via Pub/Sub if it's not a debugging one. */
if (level != LL_DEBUG) {
channel = createStringObject(type,strlen(type));
payload = createStringObject(msg,strlen(msg));
pubsubPublishMessage(channel,payload,0);
decrRefCount(channel);
decrRefCount(payload);
}
/* Call the notification script if applicable. */
if (level == LL_WARNING && ri != NULL) {
sentinelRedisInstance *master = (ri->flags & SRI_MASTER) ?
ri : ri->master;
if (master && master->notification_script) {
sentinelScheduleScriptExecution(master->notification_script,
type,msg,NULL);
}
}
}
/* This function is called only at startup and is used to generate a
* +monitor event for every configured master. The same events are also
* generated when a master to monitor is added at runtime via the
* SENTINEL MONITOR command. */
void sentinelGenerateInitialMonitorEvents(void) {
dictIterator *di;
dictEntry *de;
di = dictGetIterator(sentinel.masters);
while((de = dictNext(di)) != NULL) {
sentinelRedisInstance *ri = dictGetVal(de);
sentinelEvent(LL_WARNING,"+monitor",ri,"%@ quorum %d",ri->quorum);
}
dictReleaseIterator(di);
}
/* ============================ script execution ============================ */
/* Release a script job structure and all the associated data. */
void sentinelReleaseScriptJob(sentinelScriptJob *sj) {
int j = 0;
while(sj->argv[j]) sdsfree(sj->argv[j++]);
zfree(sj->argv);
zfree(sj);
}
#define SENTINEL_SCRIPT_MAX_ARGS 16
void sentinelScheduleScriptExecution(char *path, ...) {
va_list ap;
char *argv[SENTINEL_SCRIPT_MAX_ARGS+1];
int argc = 1;
sentinelScriptJob *sj;
va_start(ap, path);
while(argc < SENTINEL_SCRIPT_MAX_ARGS) {
argv[argc] = va_arg(ap,char*);
if (!argv[argc]) break;
argv[argc] = sdsnew(argv[argc]); /* Copy the string. */
argc++;
}
va_end(ap);
argv[0] = sdsnew(path);
sj = zmalloc(sizeof(*sj));
sj->flags = SENTINEL_SCRIPT_NONE;
sj->retry_num = 0;
sj->argv = zmalloc(sizeof(char*)*(argc+1));
sj->start_time = 0;
sj->pid = 0;
memcpy(sj->argv,argv,sizeof(char*)*(argc+1));
listAddNodeTail(sentinel.scripts_queue,sj);
/* Remove the oldest non running script if we already hit the limit. */
if (listLength(sentinel.scripts_queue) > SENTINEL_SCRIPT_MAX_QUEUE) {
listNode *ln;
listIter li;
listRewind(sentinel.scripts_queue,&li);
while ((ln = listNext(&li)) != NULL) {
sj = ln->value;
if (sj->flags & SENTINEL_SCRIPT_RUNNING) continue;
/* The first node is the oldest as we add on tail. */
listDelNode(sentinel.scripts_queue,ln);
sentinelReleaseScriptJob(sj);
break;
}
serverAssert(listLength(sentinel.scripts_queue) <=
SENTINEL_SCRIPT_MAX_QUEUE);
}
}
/* Lookup a script in the scripts queue via pid, and returns the list node
* (so that we can easily remove it from the queue if needed). */
listNode *sentinelGetScriptListNodeByPid(pid_t pid) {
listNode *ln;
listIter li;
listRewind(sentinel.scripts_queue,&li);
while ((ln = listNext(&li)) != NULL) {
sentinelScriptJob *sj = ln->value;
if ((sj->flags & SENTINEL_SCRIPT_RUNNING) && sj->pid == pid)
return ln;
}
return NULL;
}
/* Run pending scripts if we are not already at max number of running
* scripts. */
void sentinelRunPendingScripts(void) {
listNode *ln;
listIter li;
mstime_t now = mstime();
/* Find jobs that are not running and run them, from the top to the
* tail of the queue, so we run older jobs first. */
listRewind(sentinel.scripts_queue,&li);
while (sentinel.running_scripts < SENTINEL_SCRIPT_MAX_RUNNING &&
(ln = listNext(&li)) != NULL)
{
sentinelScriptJob *sj = ln->value;
pid_t pid;
/* Skip if already running. */
if (sj->flags & SENTINEL_SCRIPT_RUNNING) continue;
/* Skip if it's a retry, but not enough time has elapsed. */
if (sj->start_time && sj->start_time > now) continue;
sj->flags |= SENTINEL_SCRIPT_RUNNING;
sj->start_time = mstime();
sj->retry_num++;
pid = fork();
if (pid == -1) {
/* Parent (fork error).
* We report fork errors as signal 99, in order to unify the
* reporting with other kind of errors. */
sentinelEvent(LL_WARNING,"-script-error",NULL,
"%s %d %d", sj->argv[0], 99, 0);
sj->flags &= ~SENTINEL_SCRIPT_RUNNING;
sj->pid = 0;
} else if (pid == 0) {
/* Child */
tlsCleanup();
execve(sj->argv[0],sj->argv,environ);
/* If we are here an error occurred. */
_exit(2); /* Don't retry execution. */
} else {
sentinel.running_scripts++;
sj->pid = pid;
sentinelEvent(LL_DEBUG,"+script-child",NULL,"%ld",(long)pid);
}
}
}
/* How much to delay the execution of a script that we need to retry after
* an error?
*
* We double the retry delay for every further retry we do. So for instance
* if RETRY_DELAY is set to 30 seconds and the max number of retries is 10
* starting from the second attempt to execute the script the delays are:
* 30 sec, 60 sec, 2 min, 4 min, 8 min, 16 min, 32 min, 64 min, 128 min. */
mstime_t sentinelScriptRetryDelay(int retry_num) {
mstime_t delay = sentinel_script_retry_delay;
while (retry_num-- > 1) delay *= 2;
return delay;
}
/* Check for scripts that terminated, and remove them from the queue if the
* script terminated successfully. If instead the script was terminated by
* a signal, or returned exit code "1", it is scheduled to run again if
* the max number of retries did not already elapsed. */
void sentinelCollectTerminatedScripts(void) {
int statloc;
pid_t pid;
while ((pid = waitpid(-1, &statloc, WNOHANG)) > 0) {
int exitcode = WEXITSTATUS(statloc);
int bysignal = 0;
listNode *ln;
sentinelScriptJob *sj;
if (WIFSIGNALED(statloc)) bysignal = WTERMSIG(statloc);
sentinelEvent(LL_DEBUG,"-script-child",NULL,"%ld %d %d",
(long)pid, exitcode, bysignal);
ln = sentinelGetScriptListNodeByPid(pid);
if (ln == NULL) {
serverLog(LL_WARNING,"waitpid() returned a pid (%ld) we can't find in our scripts execution queue!", (long)pid);
continue;
}
sj = ln->value;
/* If the script was terminated by a signal or returns an
* exit code of "1" (that means: please retry), we reschedule it
* if the max number of retries is not already reached. */
if ((bysignal || exitcode == 1) &&
sj->retry_num != SENTINEL_SCRIPT_MAX_RETRY)
{
sj->flags &= ~SENTINEL_SCRIPT_RUNNING;
sj->pid = 0;
sj->start_time = mstime() +
sentinelScriptRetryDelay(sj->retry_num);
} else {
/* Otherwise let's remove the script, but log the event if the
* execution did not terminated in the best of the ways. */
if (bysignal || exitcode != 0) {
sentinelEvent(LL_WARNING,"-script-error",NULL,
"%s %d %d", sj->argv[0], bysignal, exitcode);
}
listDelNode(sentinel.scripts_queue,ln);
sentinelReleaseScriptJob(sj);
}
sentinel.running_scripts--;
}
}
/* Kill scripts in timeout, they'll be collected by the
* sentinelCollectTerminatedScripts() function. */
void sentinelKillTimedoutScripts(void) {
listNode *ln;
listIter li;
mstime_t now = mstime();
listRewind(sentinel.scripts_queue,&li);
while ((ln = listNext(&li)) != NULL) {
sentinelScriptJob *sj = ln->value;
if (sj->flags & SENTINEL_SCRIPT_RUNNING &&
(now - sj->start_time) > sentinel_script_max_runtime)
{
sentinelEvent(LL_WARNING,"-script-timeout",NULL,"%s %ld",
sj->argv[0], (long)sj->pid);
kill(sj->pid,SIGKILL);