Netdata - daemon
学习Netdata中的相关技术。
Version
netdata v1.14.0-71-ga5e952c
Option
定义opiton 。
struct option_def option_definitions[] = {
265 // opt description arg name default value
266 { 'c', "Configuration file to load.", "filename", CONFIG_DIR "/" CONFIG_FILENAME},
267 { 'D', "Do not fork. Run in the foreground.", NULL, "run in the background"},
268 { 'd', "Fork. Run in the background.", NULL, "run in the background"},
269 { 'h', "Display this help message.", NULL, NULL},
270 { 'P', "File to save a pid while running.", "filename", "do not save pid to a file"},
271 { 'i', "The IP address to listen to.", "IP", "all IP addresses IPv4 and IPv6"},
272 { 'p', "API/Web port to use.", "port", "19999"},
273 { 's', "Prefix for /proc and /sys (for containers).", "path", "no prefix"},
274 { 't', "The internal clock of netdata.", "seconds", "1"},
275 { 'u', "Run as user.", "username", "netdata"},
276 { 'v', "Print netdata version and exit.", NULL, NULL},
277 { 'V', "Print netdata version and exit.", NULL, NULL},
278 { 'W', "See Advanced options below.", "options", NULL},
默认的启动脚本：
ExecStart=/usr/sbin/net data -P /var/run/netdata/netdata.pid -D -W set global 'process scheduling policy' 'keep' -W set global 'OOM score' 'keep'
多了几个参数，使用 -W 进行设置。待补充
配置文件解析
section
配置包含了以下几个section
85#define CONFIG_SECTION_GLOBAL "global"
86#define CONFIG_SECTION_WEB "web"
87#define CONFIG_SECTION_STATSD "statsd"
88#define CONFIG_SECTION_PLUGINS "plugins"
89#define CONFIG_SECTION_CLOUD "cloud"
90#define CONFIG_SECTION_REGISTRY "registry"
91#define CONFIG_SECTION_HEALTH "health"
92#define CONFIG_SECTION_BACKEND "backend"
93#define CONFIG_SECTION_STREAM "stream"
94#define CONFIG_SECTION_EXPORTING "exporting:global"
95#define CONFIG_SECTION_PROMETHEUS "prometheus:exporter"
96#define CONFIG_SECTION_HOST_LABEL "host labels"
97#define EXPORTING_CONF "exporting.conf"
每个section下有若干key-value组成。
结构
配置文件由一个avl树来进行维护。
143struct config {
144 struct section *first_section;
145 struct section *last_section; // optimize inserting at the end
146 netdata_mutex_t mutex;
147 avl_tree_lock index;
148};
mutex 是一个 pthread_mutex_t互斥量，主要用来做写锁 。另一个锁是avl的锁，主要用来读锁。
126struct section {
127 avl avl; // the index entry of this section - this has to be first!
128
129 uint32_t hash; // a simple hash to speed up searching
130 // we first compare hashes, and only if the hashes are equal we do string comparisons
131
132 char *name;
133
134 struct section *next; // gloabl config_mutex protects just this
135
136 struct config_option *values;
137 avl_tree_lock values_index;
138
139 netdata_mutex_t mutex; // this locks only the writers, to ensure atomic updates
140 // readers are protected using the rwlock in avl_tree_lock
141};
hash使用的是FNV hash算法。
比较
112static int appconfig_option_compare(void *a, void *b) {
113 if(((struct config_option *)a)->hash < ((struct config_option *)b)->hash) return -1;
114 else if(((struct config_option *)a)->hash > ((struct config_option *)b)->hash) return 1;
115 else return strcmp(((struct config_option *)a)->name, ((struct config_option *)b)->name);
116}
这里先比较hash ，再比较name。
【未完待续】
来源：oschina
链接：https://my.oschina.net/guopei/blog/3235888