zabbix原始碼閱讀--zabbix_agent

        zabbix是一個實時監控系統,可以監控伺服器的執行狀態(cpu,記憶體,埠),並且可以傳送報警郵件和簡訊,或者執行遠端命令.由於工作上需要對zabbix進行二次開發,所以藉此機會閱讀了一下zabbix的原始碼.zabbix前臺是php實現的,後臺是用c寫的,按功能分為幾個部分:agent,server,proxy,sender. zabbix_agent負責收集機器上的資料（比如cpu利用率，記憶體剩餘量等）傳送給zabbix_server,zabbix_server負責收集zabbix_agent或者zabbix_proxy傳送過來的資料，更新資料庫，而前臺的php程式碼就可以從資料庫內拿出這些資料進行顯示。

先看zabbix_agent，它預設會啟動三個程式：collector_thread、listener_thread、active_checks_thread

/* start the collector thread */
thread_args = (zbx_thread_args_t *)zbx_malloc(NULL, sizeof(zbx_thread_args_t));
thread_args->thread_num = thread_num;
thread_args->args = NULL;
threads[thread_num++] = zbx_thread_start(collector_thread, thread_args);
/* start listeners */
for (i = 0; i < CONFIG_ZABBIX_FORKS; i++)
{
	thread_args = (zbx_thread_args_t *)zbx_malloc(NULL, sizeof(zbx_thread_args_t));
	thread_args->thread_num = thread_num;
	thread_args->args = &listen_sock;
	threads[thread_num++] = zbx_thread_start(listener_thread, thread_args);
}
/* start active check */
if (0 == CONFIG_DISABLE_ACTIVE)
{
	activechk_args.host = CONFIG_HOSTS_ALLOWED;
	activechk_args.port = (unsigned short)CONFIG_SERVER_PORT;
	thread_args = (zbx_thread_args_t *)zbx_malloc(NULL, sizeof(zbx_thread_args_t));
	thread_args->thread_num = thread_num;
	thread_args->args = &activechk_args;
	threads[thread_num++] = zbx_thread_start(active_checks_thread, thread_args);
}

其中collector_thread會每隔1s收集本機的cpu狀態存入結構體ZBX_CPUS_STAT_DATA中，將磁碟的狀態存入結構體ZBX_DISKDEVICES_DATA

typedef struct
{
	zbx_uint64_t	h_counter[ZBX_CPU_STATE_COUNT][MAX_COLLECTOR_HISTORY];
	unsigned char	h_status[MAX_COLLECTOR_HISTORY];
	int		h_first;
	int		h_count;
	int		cpu_num;
}
ZBX_SINGLE_CPU_STAT_DATA;

typedef struct
{
	ZBX_SINGLE_CPU_STAT_DATA	*cpu;
	int				count;
}
ZBX_CPUS_STAT_DATA;

 

typedef struct c_single_diskdevice_data
{
	char		name[32];
	int		index;
	time_t		clock[MAX_COLLECTOR_HISTORY];
	zbx_uint64_t	r_sect[MAX_COLLECTOR_HISTORY];
	zbx_uint64_t	r_oper[MAX_COLLECTOR_HISTORY];
	zbx_uint64_t	r_byte[MAX_COLLECTOR_HISTORY];
	zbx_uint64_t	w_sect[MAX_COLLECTOR_HISTORY];
	zbx_uint64_t	w_oper[MAX_COLLECTOR_HISTORY];
	zbx_uint64_t	w_byte[MAX_COLLECTOR_HISTORY];
	double		r_sps[ZBX_AVG_COUNT];
	double		r_ops[ZBX_AVG_COUNT];
	double		r_bps[ZBX_AVG_COUNT];
	double		w_sps[ZBX_AVG_COUNT];
	double		w_ops[ZBX_AVG_COUNT];
	double		w_bps[ZBX_AVG_COUNT];
} ZBX_SINGLE_DISKDEVICE_DATA;

typedef struct c_diskdevices_data
{
	int				count;
	ZBX_SINGLE_DISKDEVICE_DATA	device[MAX_DISKDEVICES];
} ZBX_DISKDEVICES_DATA;

zabbix_agent和zabbix_server通訊有兩種方式：主動和被動，即它可以主動的傳送資訊給zabbix_server，也可以等zabbix_server請求時在傳送相關的資訊進行響應。預設情況這兩個方式都開啟了。另外，zabbix_server和zabbix_agent通訊的協議是json格式的，詳細格式請查閱官網文件。

    listener_thread程式是負責被動方式，它負責監聽10050埠，然後等待server端的請求並進行響應，請看下面的程式碼（listener.c）

static void	process_listener(zbx_sock_t *s)
{
	AGENT_RESULT	result;
	char		*command;
	char		**value = NULL;
	int		ret;

	if (SUCCEED == (ret = zbx_tcp_recv_to(s, &command, CONFIG_TIMEOUT)))
	{
		zbx_rtrim(command, "\r\n");

		zabbix_log(LOG_LEVEL_DEBUG, "Requested [%s]", command);

		init_result(&result);
		process(command, 0, &result);

		if (NULL == (value = GET_TEXT_RESULT(&result)))
			value = GET_MSG_RESULT(&result);

		if (NULL != value)
		{
			zabbix_log(LOG_LEVEL_DEBUG, "Sending back [%s]", *value);
			ret = zbx_tcp_send_to(s, *value, CONFIG_TIMEOUT);
		}

		free_result(&result);
	}

	if (FAIL == ret)
		zabbix_log(LOG_LEVEL_DEBUG, "Process listener error: %s", zbx_tcp_strerror());
}

值得一提的是從伺服器接收的變數command，它其實就是我們在前臺頁面新增item時填的key，接下來有這麼一個結構

ZBX_METRIC	parameters_common[] =
/*      KEY                     FLAG		FUNCTION        ADD_PARAM       TEST_PARAM */
{
	{"agent.ping",		0,		AGENT_PING, 		0,	0},
	{"agent.version",	0,		AGENT_VERSION,		0,	0},

	{"system.localtime",	0,		SYSTEM_LOCALTIME,	0,	0},
	{"system.run",		CF_USEUPARAM,	SYSTEM_RUN,	 	0,	"echo test"},

	{"web.page.get",	CF_USEUPARAM,	WEB_PAGE_GET,	 	0,	"localhost,,80"},
	{"web.page.perf",	CF_USEUPARAM,	WEB_PAGE_PERF,	 	0,	"localhost,,80"},
	{"web.page.regexp",	CF_USEUPARAM,	WEB_PAGE_REGEXP,	0,	"localhost,,80,OK"},
｝

這個結構體將key和agent接收到key後執行的function聯絡到了一起

    active_checks_thread程式是負責主動傳送收集到的資訊給zabbix_server的。除此之外，他還負責傳送心跳包已經更新自己維護的一個active_checks條目表，部分程式碼（active.c：ZBX_THREAD_ENTRY(active_checks_thread, args)）如下：

while (ZBX_IS_RUNNING())
{
	if (time(NULL) >= nextsend)
	{
		send_buffer(activechk_args.host, activechk_args.port); //負責傳送心跳包
		nextsend = (int)time(NULL) + 1;
	}
	if (time(NULL) >= nextrefresh)
	{
		zbx_setproctitle("poller [getting list of active checks]");

		if (FAIL == refresh_active_checks(activechk_args.host, activechk_args.port))  //更新自己維護的一個active_checks條目表
		{
			nextrefresh = (int)time(NULL) + 60;
		}
		else
		{
			nextrefresh = (int)time(NULL) + CONFIG_REFRESH_ACTIVE_CHECKS;
		}
	}

	if (time(NULL) >= nextcheck && CONFIG_BUFFER_SIZE / 2 > buffer.pcount)
	{
		zbx_setproctitle("poller [processing active checks]");

		process_active_checks(activechk_args.host, activechk_args.port); //主動傳送收集到的資訊給zabbix_server
		if (CONFIG_BUFFER_SIZE / 2 <= buffer.pcount) /* failed to complete processing active checks */
			continue;

		nextcheck = get_min_nextcheck();
		if (FAIL == nextcheck)
			nextcheck = (int)time(NULL) + 60;
	}
	else
	{
		zabbix_log(LOG_LEVEL_DEBUG, "Sleeping for %d second(s)", 1);
		zbx_setproctitle("poller [sleeping for %d second(s)]", 1);
		zbx_sleep(1);
	}
}

 轉載請註明出處：http://blog.csdn.net/liujian0616/article/details/7932323