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arcus_zk.c
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/* -*- Mode: C; tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/*
* arcus-memcached - Arcus memory cache server
* Copyright 2010-2014 NAVER Corp.
* Copyright 2015 JaM2in Co., Ltd.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
Arcus incorporates memcached instance as a ephemeral entity
Here's how memcached participates in Arcus cluster
1. get local IP address
2. connect to Zookeeper ensemble
3. sync "/arcus/cache_server_mapping"
for latest provisioned cache server
4. get child of "/arcus/cache_server_mapping/{ip}:{port}" znode
to get service code
this service code is a string that indicates which service this
cache server belongs to
ie. /arcus/cache_server_mapping/10.0.0.1:11211/{svc}
5. create an ephemeral "/arcus/cache_list/{svc}/{ip}:{port}-{hostname}" znode
to indicate that this server is participating in Arcus {svc} cluster
{port} is the memcached listen port
hostname is a redudant information to easily identify the server
the memcached memory capacity is stored in the znode's data
6. create "/arcus/cache_server_log/{date}/{ip}:{port}-{hostname}-" sequential znode
this is to log join and leave activity for later debugging or post-mortem
In global watcher callback routine, we chose not to restart/reconnect to
Zookeeper ensemble (when session expires), because this may create stale cache
entry access. We need to restart the whole memcached process to flush its content
before rejoin the Arcus cluster. We need to force restart of memcached (/etc/inittab)
*/
#include <config.h>
#ifdef ENABLE_ZK_INTEGRATION
#include <assert.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <time.h>
#include <unistd.h>
#include <string.h>
#include <zookeeper.h>
#include <errno.h>
#include <fcntl.h>
#include <pthread.h>
#include <stdbool.h>
#include <sysexits.h>
#include <limits.h>
#include "arcus_zk.h"
#ifdef ENABLE_CLUSTER_AWARE
#include "cluster_config.h"
#endif
/* zookeeper.h unfortunately includes a lot of other headers. One of
* them (recordio.h) unconditionally defines htonll. memcached.h also
* includes so many headers. util.h defines htonll, which conflicts
* with the one in zookeeper.h. As a workaround, define HAVE_HTONLL
* here to prevent util.h from defining htonll again.
*
* All we need from memcached.h is ADMIN_CLIENT_IP...
*/
#define HAVE_HTONLL 1
#include "memcached.h"
/* Kill server if disconnected from zookeeper for too long */
//#define ENABLE_SUICIDE_UPON_DISCONNECT 1
// Recv. timeout governs ZK heartbeat period, reconnect timeout
// as well as ZK session timeout
//
// Below sets 30 sec. session timeout, 20 sec Zookeeper ensemble timeout,
// and 10 second heartbeat period
#define DEFAULT_ZK_TO 30000 // ZK session timeout in msec (server tick time is 2 sec, min is 4 sec)
#define MAX_ZK_TO 300 // Max allowable session timeout in sec
#define MIN_ZK_TO 10 // Min 10 seconds, in line with the current heartbeat timeout
#define ZK_WATCH 1
#define ZK_NOWATCH 0
#define SYSLOGD_PORT 514 // UDP syslog port #
/* One heartbeat every 3 seconds. */
#define HEART_BEAT_PERIOD 3 /* sec */
/* If consecutive heartbeats fail, consider memcached dead and commit
* suicide. If the accumulated latency of consecutive heartbeats is
* over the following HEART_BEAT_FAILSTOP value, it does fail-stop.
*/
#define HEART_BEAT_MIN_FAILSTOP 3000 /* msec */
#define HEART_BEAT_DFT_FAILSTOP 60000 /* msec */
#define HEART_BEAT_MAX_FAILSTOP 300000 /* msec */
/* If hearbeat takes more than timeout msec, consider it failed. */
#define HEART_BEAT_MIN_TIMEOUT 50 /* msec */
#define HEART_BEAT_DFT_TIMEOUT 10000 /* msec */
#define HEART_BEAT_MAX_TIMEOUT HEART_BEAT_MAX_FAILSTOP /* msec */
#define MAX_SERVICECODE_LENGTH 128
#define MAX_HOSTNAME_LENGTH 128
static const char *zk_root = NULL;
static const char *zk_map_dir = "cache_server_mapping";
static const char *zk_log_dir = "cache_server_log";
static const char *zk_cache_dir = "cache_list";
static const char *mc_hb_command = "set arcus:zk-ping 1 0 1\r\n1\r\n";
typedef struct {
char *ensemble_list; /* ZK ensemble IP:port list */
zhandle_t *zh; /* ZK handle */
clientid_t myid;
} zk_info_t;
static zk_info_t zk_info;
static zk_info_t *main_zk=NULL;
static int last_rc=ZOK;
#ifdef ENABLE_SUICIDE_UPON_DISCONNECT
static bool zk_connected = false;
#endif
/* this is to indicate if we get shutdown signal during ZK initialization
* ZK shutdown is done at the end of arcus_zk_init() to simplify synchronization
*/
volatile sig_atomic_t arcus_zk_shutdown=0;
/* This flag is now used to indicate graceful shutdown. See hb_thread for
* more comment.
*/
/* placeholder for zookeeper and memcached settings */
typedef struct {
char *svc; // Service code name
char *mc_ipport; // this memcached ip:port string
char *mc_hostnameport; // this memcached hostname:port string
char *hostip; // localhost server IP
int port; // memcached port number
bool zk_failstop; // memcached automatic failstop on/off
int hb_failstop; // memcached heartbeat failstop
int hb_timeout; // memcached heartbeat timeout
int zk_timeout; // Zookeeper session timeout
bool auto_scrub; // automactic scrub_stale
char *znode_name; // Ephemeral ZK node name for this mc identification
int znode_ver; // Ephemeral ZK node version
bool znode_created; // Ephemeral ZK node is created ?
int verbose; // verbose output
size_t maxbytes; // mc -M option
EXTENSION_LOGGER_DESCRIPTOR *logger; // mc logger
union {
ENGINE_HANDLE *v0;
ENGINE_HANDLE_V1 *v1;
} engine; // mc engine
char *cluster_path; // cluster path for this memcached
#ifdef PROXY_SUPPORT
char *proxy; // proxy server ip:port
#endif
#ifdef ENABLE_CLUSTER_AWARE
struct cluster_config *ch; // cluster configuration handle
#endif
pthread_mutex_t lock;
bool init; // is this structure initialized?
} arcus_zk_conf;
arcus_zk_conf arcus_conf = {
.svc = NULL,
.mc_ipport = NULL,
.mc_hostnameport = NULL,
.hostip = NULL,
.zk_failstop = true,
.hb_failstop = HEART_BEAT_DFT_FAILSTOP,
.hb_timeout = HEART_BEAT_DFT_TIMEOUT,
.zk_timeout = DEFAULT_ZK_TO,
.auto_scrub = true,
.znode_name = NULL,
.znode_ver = -1,
.znode_created = false,
.verbose = -1,
.port = -1,
.maxbytes = -1,
.logger = NULL,
.cluster_path = NULL,
#ifdef PROXY_SUPPORT
.proxy = NULL,
#endif
#ifdef ENABLE_CLUSTER_AWARE
.ch = NULL,
#endif
.lock = PTHREAD_MUTEX_INITIALIZER,
.init = false
};
/* Arcus ZK stats */
arcus_zk_stats azk_stat;
// context struct to pass to app_ping
typedef struct {
struct sockaddr_in addr; // cache this for use in L7 ping routine
struct timeval to; // mc_hb may block for up to this long (give or take)
} app_ping_t;
static app_ping_t mc_ping_context;
// static declaration
static void arcus_zk_watcher(zhandle_t *wzh, int type, int state,
const char *path, void *cxt);
static void arcus_cache_list_watcher(zhandle_t *zh, int type, int state,
const char *path, void *ctx);
static void arcus_zk_sync_cb(int rc, const char *name, const void *data);
static void arcus_zk_log(zhandle_t *zh, const char *);
static void arcus_exit(zhandle_t *zh, int err);
int mc_hb(void *context); // memcached self-heartbeat
/* State machine thread.
* It performs all blocking ZK operations including cluster_config.
* We don't do blocking operations in the context of watcher callback
* any more.
*/
/* sm request structure */
struct sm_request {
bool update_cache_list;
};
/* sm structure */
struct sm {
/* sm requests by other threads */
struct sm_request request;
/* Cache of the latest version we pulled from ZK */
struct String_vector sv_cache_list; /* from /cache_list/{svc} */
/* Current # of nodes in cluster */
int cluster_node_count;
/* the time a new node was added to the cluster */
volatile uint64_t node_added_time;
volatile bool mc_pause;
/* Used to wake up the thread */
pthread_mutex_t lock;
pthread_cond_t cond;
bool notification;
volatile bool state_running;
#ifdef ENABLE_SUICIDE_UPON_DISCONNECT
volatile bool timer_running;
#endif
pthread_t state_tid;
#ifdef ENABLE_SUICIDE_UPON_DISCONNECT
/* A timer thread to fail-stop the server
* when it is disconnected from the ZK ensemble.
*/
pthread_t timer_tid;
#endif
} sm_info;
/* sm functions */
static int sm_init(void);
static void sm_lock(void);
static void sm_unlock(void);
static void sm_wakeup(bool locked);
/* async routine synchronization */
static pthread_cond_t azk_cond = PTHREAD_COND_INITIALIZER;
static pthread_mutex_t azk_mtx = PTHREAD_MUTEX_INITIALIZER;
static int azk_count;
/* zookeeper close synchronization */
static pthread_mutex_t zk_lock = PTHREAD_MUTEX_INITIALIZER;
/* memcached heartheat thread */
static volatile bool hb_thread_running = false;
static bool hb_thread_sleep = false;
static pthread_mutex_t hb_thread_lock;
static pthread_cond_t hb_thread_cond;
static void *hb_thread(void *arg);
static int start_hb_thread(app_ping_t *data);
static int
arcus_memcached_scrub_stale(void)
{
ENGINE_ERROR_CODE ret;
ret = arcus_conf.engine.v1->scrub_stale(arcus_conf.engine.v0);
return ret == ENGINE_SUCCESS ? 0 : -1;
}
/* Some znode names use '^' as a delimiter.
* Return pointers to the starting and ending ('^') characters.
*/
static int
breakup_string(char *str, char *start[], char *end[], int vec_len)
{
char *c = str;
int i = 0;
while (i < vec_len) {
start[i] = c;
while (*c != '\0') {
if (*c == '^')
break;
c++;
}
if (*c == '\0') {
end[i] = c;
i++;
break;
}
if (start[i] == c)
break; /* empty */
end[i] = c++;
i++;
}
if (*c != '\0') {
/* There are leftover characters. Ignore them. */
}
return i; /* i <= vec_len */
}
/* mutex for async operations */
static void inc_count(int delta)
{
pthread_mutex_lock(&azk_mtx);
azk_count += delta;
pthread_cond_broadcast(&azk_cond);
pthread_mutex_unlock(&azk_mtx);
}
static int wait_count(int timeout)
{
struct timeval tv;
struct timespec ts;
int rc = 0;
pthread_mutex_lock(&azk_mtx);
while (azk_count > 0 && rc == 0) {
if (timeout == 0) {
rc = pthread_cond_wait(&azk_cond, &azk_mtx);
} else {
gettimeofday(&tv, NULL);
ts.tv_sec = tv.tv_sec;
ts.tv_nsec = tv.tv_usec*1000;
//clock_gettime(CLOCK_REALTIME, &ts);
ts.tv_sec += timeout/1000; /* timeout: msec */
rc = pthread_cond_timedwait(&azk_cond, &azk_mtx, &ts);
}
}
pthread_mutex_unlock(&azk_mtx);
return rc;
}
static int
arcus_zk_client_init(zk_info_t *zinfo)
{
inc_count(1);
zinfo->zh = zookeeper_init(zinfo->ensemble_list, arcus_zk_watcher,
arcus_conf.zk_timeout, &zinfo->myid, zinfo, 0);
if (!zinfo->zh) {
arcus_conf.logger->log(EXTENSION_LOG_WARNING, NULL,
"zookeeper_init() failed (%s error)\n", strerror(errno));
return EX_PROTOCOL;
}
/* wait until above init callback is called
* We need to wait until ZOO_CONNECTED_STATE
*/
if (wait_count(arcus_conf.zk_timeout) != 0) {
/* zoo_state(zh) != ZOO_CONNECTED_STATE */
arcus_conf.logger->log(EXTENSION_LOG_WARNING, NULL,
"cannot to be ZOO_CONNECTED_STATE\n");
zookeeper_close(zinfo->zh);
zinfo->zh = NULL;
inc_count(-1);
return EX_PROTOCOL;
}
return 0;
}
// Arcus zookeeper global watch callback routine
static void
arcus_zk_watcher(zhandle_t *wzh, int type, int state, const char *path, void *cxt)
{
if (type != ZOO_SESSION_EVENT) {
return;
}
if (state == ZOO_CONNECTED_STATE) {
const clientid_t *id = zoo_client_id(wzh);
zk_info_t *zinfo = cxt;
if (arcus_conf.verbose > 2) {
arcus_conf.logger->log(EXTENSION_LOG_DEBUG, NULL,
"ZK ensemble connected. session id: 0x%llx\n",
(long long) zinfo->myid.client_id);
}
if (zinfo->myid.client_id == 0 || zinfo->myid.client_id != id->client_id) {
if (arcus_conf.verbose > 2)
arcus_conf.logger->log(EXTENSION_LOG_DEBUG, NULL,
"A old session id: 0x%llx\n", (long long) zinfo->myid.client_id);
zinfo->myid = *id;
}
// finally connected to one of ZK ensemble. signal go.
inc_count(-1);
#ifdef ENABLE_SUICIDE_UPON_DISCONNECT
zk_connected = true;
#endif
}
else if (state == ZOO_AUTH_FAILED_STATE) {
// authorization failure
arcus_conf.logger->log(EXTENSION_LOG_WARNING, NULL, "Auth failure. shutting down\n");
arcus_exit(wzh, EX_NOPERM);
}
else if (state == ZOO_EXPIRED_SESSION_STATE) {
if (arcus_conf.zk_failstop) {
// very likely that memcached process exited and restarted within
// session timeout
arcus_conf.logger->log(EXTENSION_LOG_WARNING, NULL, "Expired state. shutting down\n");
// send SMS here??
arcus_exit(wzh, EX_TEMPFAIL);
} else {
arcus_conf.logger->log(EXTENSION_LOG_WARNING, NULL, "Expired state. pausing memcached (zk_failstop: off)\n");
sm_lock();
sm_info.mc_pause = true;
sm_wakeup(true);
sm_unlock();
}
}
else if (state == ZOO_ASSOCIATING_STATE || state == ZOO_CONNECTING_STATE) {
/* we get these when connection to Ensemble is dropped and retrying
* this happens emsemble failover as well
* since this is not memcached operation issue, we will allow reconnecting
* but it is possible that app_ping fails and zk server may have disconnected
* and if that's the case, we let heartbeat timeout algorithm decide
* what to do.
*/
arcus_conf.logger->log(EXTENSION_LOG_DEBUG, NULL, "CONNECTING.... \n");
#ifdef ENABLE_SUICIDE_UPON_DISCONNECT
/* The server is disconnected from ZK. But we do not know how much
* time has elapsed from the last successful ZK ping. A connection
* timeout (session timeout * 2/3) might have occurred. Or, the
* TCP connection might have reset/closed (immediate).
* See sm_timer_thread. For now, it is being conservative and dies
* in session timeout * 1/3. Perhaps we should do our own ping, not
* rely on ZK session notifications. FIXME
*/
zk_connected = false;
#endif
}
}
/* cache_list zk watcher */
static void
arcus_cache_list_watcher(zhandle_t *zh, int type, int state, const char *path, void *ctx)
{
if (type == ZOO_CHILD_EVENT) {
/* The ZK library has two threads of its own. The completion thread
* calls watcher functions.
*
* Do not do operations that may block or fail in the watcher context.
*/
arcus_conf.logger->log(EXTENSION_LOG_INFO, NULL,
"ZOO_CHILD_EVENT from ZK cache list: state=%d, path=%s\n",
state, (path ? path : "null"));
} else {
/* an unexpected event has been occurred */
arcus_conf.logger->log(EXTENSION_LOG_WARNING, NULL,
"Unexpected event(%d) gotten by cache_list_watcher: state=%d path=%s\n",
type, state, (path ? path : "null"));
}
/* Just wake up the sm thread and update the hash ring.
* This may be a false positive (session event or others).
* But it is harmless.
*
* Should we do this only in ZOO_CHILD_EVENT ? FIXME.
*/
sm_lock();
sm_info.request.update_cache_list = true;
sm_wakeup(true);
sm_unlock();
}
static int
arcus_read_ZK_children(zhandle_t *zh, const char *zpath, watcher_fn watcher,
struct String_vector *strv)
{
int rc = zoo_wget_children(zh, zpath, watcher, NULL, strv);
if (rc != ZOK) {
arcus_conf.logger->log(EXTENSION_LOG_WARNING, NULL,
"Failed to read children(znode list) of zpath=%s: "
"error=%d(%s)\n", zpath, rc, zerror(rc));
return (rc == ZNONODE ? 0 : -1);
}
return 1; /* The caller must free strv */
}
static bool
check_znode_existence(struct String_vector *strv, char *znode_name)
{
for (int i = 0; i < strv->count; i++) {
if (strcmp(strv->data[i], znode_name) == 0)
return true;
}
return false;
}
#ifdef ENABLE_CLUSTER_AWARE
/* update cluster config, that is ketama hash ring. */
static int
update_cluster_config(struct String_vector *strv)
{
if (strv->count == 0) { /* cache_list can be empty. */
sm_info.cluster_node_count = 0;
return 0;
}
arcus_conf.logger->log(EXTENSION_LOG_INFO, NULL, "update cluster config...\n");
if (arcus_conf.verbose > 0) {
for (int i = 0; i < strv->count; i++) {
arcus_conf.logger->log(EXTENSION_LOG_INFO, NULL, "server[%d] = %s\n",
i, strv->data[i]);
}
}
/* reconfigure arcus-memcached cluster */
if (cluster_config_reconfigure(arcus_conf.ch, strv->data, strv->count) < 0) {
return -1;
}
sm_info.cluster_node_count = strv->count;
return 0;
}
#endif
/* callback for sync command */
static void
arcus_zk_sync_cb(int rc, const char *name, const void *data)
{
if (arcus_conf.verbose > 2) {
arcus_conf.logger->log(EXTENSION_LOG_DEBUG, NULL, "arcus_zk_sync cb\n");
}
// signal cond var
inc_count(-1);
last_rc = rc;
}
/* Log memcached join/leave acvitivity for debugging purpose
* We cannot log in case of memcached crash
*/
static void
arcus_zk_log(zhandle_t *zh, const char *action)
{
int rc;
char zpath[200] = "";
char rcbuf[200] = "";
char sbuf[200] = "";
struct timeval now;
struct tm *ltm;
struct Stat zstat;
if (!zh || zoo_state(zh) != ZOO_CONNECTED_STATE || !arcus_conf.init)
return;
gettimeofday(&now, 0);
ltm = localtime (&now.tv_sec);
strftime(sbuf, sizeof(sbuf), "%Y-%m-%d", ltm);
snprintf(zpath, sizeof(zpath), "%s/%s/%s", zk_root, zk_log_dir, sbuf);
rc = zoo_exists(zh, zpath, ZK_NOWATCH, &zstat);
if (rc == ZNONODE) {
// if this "date" directory does not exist, create one
rc = zoo_create(zh, zpath, NULL, 0, &ZOO_OPEN_ACL_UNSAFE,
0, rcbuf, sizeof(rcbuf));
if (rc == ZOK && arcus_conf.verbose > 2) {
arcus_conf.logger->log(EXTENSION_LOG_DEBUG, NULL,
"znode %s does not exist. created\n", rcbuf);
}
}
if (rc == ZOK || rc == ZNODEEXISTS) {
// if this znode already exist or the creation was successful
snprintf(zpath, sizeof(zpath), "%s/%s/%s/%s-",
zk_root, zk_log_dir, sbuf, arcus_conf.znode_name);
snprintf(sbuf, sizeof(sbuf), "%s", action);
rc = zoo_create(zh, zpath, sbuf, strlen(sbuf), &ZOO_OPEN_ACL_UNSAFE,
ZOO_SEQUENCE, rcbuf, sizeof(rcbuf));
if (arcus_conf.verbose > 2)
arcus_conf.logger->log(EXTENSION_LOG_DEBUG, NULL, "znode \"%s\" created\n", rcbuf);
}
if (rc) {
arcus_conf.logger->log(EXTENSION_LOG_DEBUG, NULL,
"cannot log this acvitiy (%s error)\n", zerror(rc));
}
}
static void
arcus_exit(zhandle_t *zh, int err)
{
if (zh)
zookeeper_close(zh);
arcus_conf.logger->log(EXTENSION_LOG_WARNING, NULL, "shutting down\n");
exit(err);
}
static void arcus_adjust_ping_timeout(app_ping_t *ping_data, int timeout)
{
/* +50 msec so that the caller can detect the timeout */
uint64_t usec = timeout * 1000 + 50000;
ping_data->to.tv_sec = usec / 1000000;
ping_data->to.tv_usec = usec % 1000000;
}
static void arcus_prepare_ping_context(app_ping_t *ping_data, int port)
{
/* prepare app_ping context data:
* sockaddr for memcached connection in app ping
*/
memset(ping_data, 0, sizeof(app_ping_t));
ping_data->addr.sin_family = AF_INET;
ping_data->addr.sin_port = htons(port);
/* Use the admin ip (currently localhost) to avoid competing with
* regular clients for connections.
*/
ping_data->addr.sin_addr.s_addr = inet_addr(ADMIN_CLIENT_IP);
arcus_adjust_ping_timeout(ping_data, arcus_conf.hb_timeout);
}
/* This is L7 application ping callback
* only one app ping per ZK ping period if successful
* In this case, we make a TCP connection to self memcached port, and
* try to set a key.
*
* Make sure that successful app heartbeat completes in 2/3 of recv timeout,
* otherwise it is very possible have expired state in the end.
* This retries 2 twice at every 1/3 of ZK recv timeout
*/
int mc_hb(void *context)
{
app_ping_t *data = (app_ping_t *) context;
struct linger linger;
struct timeval tv_timeo;
char buf[32];
int flags;
int sock;
int err=0;
/* make a tcp connection to this memcached itself,
* and try "set arcus:zk-ping".
*/
sock = socket(AF_INET, SOCK_STREAM, IPPROTO_IP);
if (sock == -1) {
arcus_conf.logger->log(EXTENSION_LOG_WARNING, NULL,
"mc_hb: cannot create a socket (error=%s)\n", strerror(errno));
return 0; /* Allow ZK ping by returning 0 even if socket() fails. */
}
flags = 1;
setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &flags, sizeof(flags)); /* fast port recycle */
setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, &flags, sizeof(flags));
/* send()/recv() could be blocked forever when all memcached worker threads are deadlocked
* while the acceptor thread is still alive.
* Blocked in L7 health check, ZK ping fails, then ZK ensemble gives up the connection.
* However, as the blocked ZK ping runs on ZK client's I/O thread
* the client cannot receive the events from ZK ensemble. So memcached fails to fail-stop.
* To prevent this situation we set timeouts to send()/recv().
*/
tv_timeo = data->to;
setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO, &tv_timeo, sizeof(tv_timeo));
setsockopt(sock, SOL_SOCKET, SO_SNDTIMEO, &tv_timeo, sizeof(tv_timeo));
linger.l_onoff = 1;
linger.l_linger = 0; /* flush buffers upon close() and send TCP RST */
setsockopt(sock, SOL_SOCKET, SO_LINGER, &linger, sizeof(linger));
arcus_conf.logger->log(EXTENSION_LOG_DEBUG, NULL,
"mc_hb: connecting to memcached at %s:%d...\n",
inet_ntoa(data->addr.sin_addr), arcus_conf.port);
err = connect(sock, (struct sockaddr *) &data->addr, sizeof(struct sockaddr));
if (err) {
arcus_conf.logger->log(EXTENSION_LOG_WARNING, NULL,
"mc_hb: cannot connect to local memcached (error=%s)\n", strerror(errno));
close(sock);
return 0; /* Allow ZK ping by returning 0 even if socket() fails. */
}
/* Try to set a key "arcus:zk-ping"
* we need to be careful here. Since we can make a connection, basic
* memcached event loop works and system resources are enough. if we can an
* error during send()/recv(), it may not be a memcached failure at all.
* We may get slab memory shortage for slab class 0 for above key.
* For now, we simply return here without ping error or intentional delay
*/
err = send(sock, mc_hb_command, 28, 0);
if (err > 0) {
// expects "STORED\r\n"
err = recv(sock, buf, 8, 0);
if (err < 0) {
arcus_conf.logger->log(EXTENSION_LOG_WARNING, NULL,
"mc_hb: recv failed (error=%s)\n", strerror(errno));
}
} else {
if (err < 0) {
arcus_conf.logger->log(EXTENSION_LOG_WARNING, NULL,
"mc_hb: send failed (error=%s)\n", strerror(errno));
}
}
close(sock);
return 0;
}
static void hb_wakeup(void)
{
pthread_mutex_lock(&hb_thread_lock);
if (hb_thread_sleep == true)
pthread_cond_signal(&hb_thread_cond);
pthread_mutex_unlock(&hb_thread_lock);
}
static void *hb_thread(void *arg)
{
app_ping_t *ping_data = arg;
int cur_hb_failstop = arcus_conf.hb_failstop;
int cur_hb_timeout = arcus_conf.hb_timeout;
int acc_hb_latency = 0;
bool shutdown_by_me = false;
struct timeval tv;
struct timespec ts;
struct timeval start_time;
struct timeval end_time;
uint64_t elapsed_msec, start_msec, end_msec;
arcus_conf.logger->log(EXTENSION_LOG_WARNING, NULL,
"Heartbeat thread is running.\n");
/* We consider 3 types of shutdowns.
*
* 1. control-c
* The user wants a graceful shutdown. The main thread wakes up all
* the worker threads and wait for them to terminate. It also calls
* the engine destroy function. In this case, heartbeat should just stop.
* arcus_zk_shutdown = 1 indicates this case. So, we check that flag
* in this function.
*
* 2. kill -KILL
* Something is very wrong, and the user wants to kill the process right
* away. For example, control-c/graceful shutdown might hang due to bugs.
* And, the user wants to forcefully kill the process. There is nothing
* we can do here.
*
* 3. Heartbeat failure
* memcached is not working properly. We attempt to close the ZK session
* and then forcefully terminate. This is NOT a graceful shutdown. We
* do not wait for worker threads to terminate. We do not call the engine
* destroy function.
*/
hb_thread_running = true;
while (!arcus_zk_shutdown) {
/* If the last hearbeat timed out, do not wait and try another
* right away.
*/
if (acc_hb_latency == 0) {
/* sleep HEART_BEAT_PERIOD seconds */
gettimeofday(&tv, NULL);
ts.tv_sec = tv.tv_sec + HEART_BEAT_PERIOD;
ts.tv_nsec = tv.tv_usec*1000;
/* sleep with spurious wakeups checking */
while (tv.tv_sec < ts.tv_sec && !arcus_zk_shutdown) {
pthread_mutex_lock(&hb_thread_lock);
hb_thread_sleep = true;
pthread_cond_timedwait(&hb_thread_cond, &hb_thread_lock, &ts);
hb_thread_sleep = false;
pthread_mutex_unlock(&hb_thread_lock);
gettimeofday(&tv, NULL);
}
}
/* Graceful shutdown was requested while sleeping. */
if (arcus_zk_shutdown)
break;
/* check if hb_failstop is changed */
if (cur_hb_failstop != arcus_conf.hb_failstop) {
arcus_conf.logger->log(EXTENSION_LOG_WARNING, NULL,
"Heartbeat failstop has changed. old(%d) => new(%d)\n",
cur_hb_failstop, arcus_conf.hb_failstop);
cur_hb_failstop = arcus_conf.hb_failstop;
acc_hb_latency = 0; /* reset accumulated hb latency */
}
/* check if hb_timeout is changed */
if (cur_hb_timeout != arcus_conf.hb_timeout) {
arcus_conf.logger->log(EXTENSION_LOG_WARNING, NULL,
"Heartbeat timeout has changed. old(%d) => new(%d)\n",
cur_hb_timeout, arcus_conf.hb_timeout);
cur_hb_timeout = arcus_conf.hb_timeout;
acc_hb_latency = 0; /* reset accumulated hb latency */
/* adjust ping timeout */
arcus_adjust_ping_timeout(ping_data, cur_hb_timeout);
}
/* Do one ping and measure how long it takes. */
gettimeofday(&start_time, NULL);
mc_hb((void *)ping_data);
gettimeofday(&end_time, NULL);
/* Graceful shutdown was requested while doing heartbeat.
* When worker threads die, there is no one to process heartbeat
* request, and we would see a timeout. Ignore the false alarm.
*/
if (arcus_zk_shutdown)
break;
/* Paranoid. Check if the clock had gone backwards. */
start_msec = start_time.tv_sec * 1000 + start_time.tv_usec / 1000;
end_msec = end_time.tv_sec * 1000 + end_time.tv_usec / 1000;
if (start_msec <= end_msec) {
elapsed_msec = end_msec - start_msec;
azk_stat.hb_count += 1;
azk_stat.hb_latency += elapsed_msec;
} else {
elapsed_msec = 0; /* Ignore this heartbeat */
arcus_conf.logger->log(EXTENSION_LOG_WARNING, NULL,
"hb_thread: Clock has gone backwards? start_msec=%"PRIu64
" end_msec=%"PRIu64"\n", start_msec, end_msec);
}
if (elapsed_msec > cur_hb_timeout) {
if (cur_hb_failstop > 0) {
acc_hb_latency += elapsed_msec;
} else {
/* Reset the acc_hb_latency */
acc_hb_latency = 0;
}
/* Print a message for every failure to help debugging, postmortem
* analysis, etc.
*/
arcus_conf.logger->log(EXTENSION_LOG_WARNING, NULL,
"Heartbeat failure. hb_timeout=%d hb_latency=%"PRIu64
" accumulated_hb_latency=%d\n", cur_hb_timeout,
elapsed_msec, acc_hb_latency);
if (acc_hb_latency > cur_hb_failstop) {
/* Do not bother calling memcached.c:shutdown_server.
* Call arcus_zk_final directly. shutdown_server just sets
* memcached_shutdown = arcus_zk_shutdown = 1 and calls
* arcus_zk_final. These flags are used for graceful shutdown.
* We do not need them here. Besides, arcus_zk_final kills
* the process right away, assuming the zookeeper library
* still functions.
*/
/*
SERVER_HANDLE_V1 *api = arcus_conf.get_server_api();
api->core->shutdown();
*/
arcus_conf.logger->log(EXTENSION_LOG_WARNING, NULL,
"consecutive heartbeat failures. Shutting down...\n");
shutdown_by_me = true;
break;
}
} else {
/* Reset the acc_hb_latency */
acc_hb_latency = 0;
}
}
hb_thread_running = false;
if (shutdown_by_me) {
arcus_zk_shutdown = 1;
arcus_zk_final("Heartbeat failure");
arcus_zk_destroy();
exit(0);
}
return NULL;
}
static int start_hb_thread(app_ping_t *data)
{
pthread_t tid;
pthread_attr_t attr;
int ret;
pthread_attr_init(&attr);
pthread_mutex_init(&hb_thread_lock, NULL);
pthread_cond_init(&hb_thread_cond, NULL);
if ((ret = pthread_create(&tid, &attr, hb_thread, (void *)data)) != 0) {
arcus_conf.logger->log(EXTENSION_LOG_WARNING, NULL,
"Cannot create hb thread: %s\n", strerror(ret));
}
return ret;
}
static int arcus_build_znode_name(char *ensemble_list)
{
int sock, rc;
socklen_t socklen=16;
struct in_addr inaddr;
struct sockaddr_in saddr, myaddr;
struct hostent *zkhost, *hp;
char *zip, *hlist;
char *sep1=",";
char *sep2=":";
char myip[50];
char rcbuf[200];
// Need to figure out local IP. first create a dummy udp socket
if ((sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP)) == -1) {
arcus_conf.logger->log(EXTENSION_LOG_WARNING, NULL,
"socket() failed: %s\n", strerror(errno));
return EX_OSERR;
}
saddr.sin_family = AF_INET;
saddr.sin_port = htons(SYSLOGD_PORT); // what if this is not open? XXX
// loop through all ensemble IP in case ensemble failure
zip = strtok_r(ensemble_list, sep1, &hlist); // separate IP:PORT tuple
while (zip)
{
zip = strtok(zip, sep2); // extract the first IP
// try to convert IP -> network IP format
if (inet_aton(zip, &inaddr)) {
// just use the IP
saddr.sin_addr = inaddr;
if (arcus_conf.verbose > 2) {
arcus_conf.logger->log(EXTENSION_LOG_DEBUG, NULL,
"Trying ensemble IP: %s\n", zip);
}
} else {
// Must be hostname, not IP. Convert hostname to IP first
zkhost = gethostbyname(zip);
if (!zkhost) {
arcus_conf.logger->log(EXTENSION_LOG_DEBUG, NULL,
"Invalid IP/hostname in arg: %s\n", zip);
// get next token: separate IP:PORT tuple
zip = strtok_r(NULL, sep1, &hlist);
continue;
}
memcpy((char *)&saddr.sin_addr,
zkhost->h_addr_list[0], zkhost->h_length);
inet_ntop(AF_INET, &saddr.sin_addr, rcbuf, sizeof(rcbuf));
if (arcus_conf.verbose > 2) {
arcus_conf.logger->log(EXTENSION_LOG_DEBUG, NULL,
"Trying converted IP of hostname(%s): %s\n", zip, rcbuf);
}
}
// try to connect to ensemble' arcus_conf.logger->logd UDP port
// this is dummy code that simply is used to get local IP address
int flags = fcntl(sock, F_GETFL, 0);
fcntl(sock, F_SETFL, flags | O_NONBLOCK);
rc = connect(sock, (struct sockaddr*) &saddr, sizeof(struct sockaddr_in));
fcntl(sock, F_SETFL, flags);
if (rc == 0) { // connect immediately
if (arcus_conf.verbose > 2) {
arcus_conf.logger->log(EXTENSION_LOG_DEBUG, NULL,
"connected to ensemble \"%s\" syslogd UDP port\n", zip);
}
break;
}
// if cannot connect immediately, try other ensemble
arcus_conf.logger->log(EXTENSION_LOG_WARNING, NULL,
"Cannot connect to ensemble %s (%s error)\n", zip, strerror(errno));
zip = strtok_r(NULL, sep1, &hlist); // get next token: separate IP:PORT tuple
}
if (!zip) { // failed to connect to all ensemble host. fail
arcus_conf.logger->log(EXTENSION_LOG_WARNING, NULL,
"not able to connect any Ensemble server\n");
close(sock); sock = -1;
return EX_UNAVAILABLE;
}
// finally, what's my local IP?
if (getsockname(sock, (struct sockaddr *) &myaddr, &socklen)) {
arcus_conf.logger->log(EXTENSION_LOG_WARNING, NULL,
"getsockname failed: %s\n", strerror(errno));
close(sock); sock = -1;
return EX_NOHOST;
}
close(sock); sock = -1;
// Finally local IP
inet_ntop(AF_INET, &myaddr.sin_addr, myip, sizeof(myip));
arcus_conf.hostip = strdup(myip);