MEMCACHED源码之main初始化
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一．启动memcached
1.memcached启动选项：
-p TCP监听端口 (default: 11211)
-U UDP 监听端口 (default: 11211, 0 is off)
-s UNIX socket监听路径，不支持网络
-a UNIX socket访问掩码, 八进制 (default: 0700)
-l <ip_addr> 监听的服务器IP地址 (default: all addresses)
-d 启动一个守护进程
-r 最大限度利用核心文件限制
-u 运行memcached用户
-m 最大的内存使用 (default: 64 MB)
-M 内存耗尽返回错误
-c 最大并发连接 (default: 1024)
-k 锁定所有分页内存
-v 输出警告和错误信息
-vv 同时打印客户端请求和返回信息
-vvv 打印内部状态转换信息
-i 打印memcached 和 libevent 版本信息
-P 设置保存pid文件, only used with -d option
-f 块大小增长倍数 (default: 1.25)
-n key+value+flags最小分配空间(default: 48)
-L 如何有效，尝试使用大内存页。增加内存页大小可以减少失误的TLB数量，提高性能。
-D 指定key和IDs的分隔符 default is ":" (colon). 如果指定此选项，统计信息收集自动开启;
-t 使用的线程数量 (default: 4)
-R 每个事件的最大请求数 (default: 20)
-C 禁止使用 CAS
-b 设置积压队列数限制 (default: 1024)
-B 绑定协议 - one of ascii, binary, or auto (default)
-I 分配给每个slab页(default: 1mb, min: 1k, max: 128m)
2.启动
# ./memcached -d -m 500 -u root -l 192.168.50.10 -p 12000 -c 256 -P /tmp/memcached.pid -vvv
slab class 1: chunk size 96 perslab 10922
slab class 2: chunk size 120 perslab 8738
slab class 3: chunk size 152 perslab 6898
slab class 4: chunk size 192 perslab 5461
slab class 5: chunk size 240 perslab 4369
slab class 6: chunk size 304 perslab 3449
slab class 7: chunk size 384 perslab 2730
slab class 8: chunk size 480 perslab 2184
slab class 9: chunk size 600 perslab 1747
slab class 10: chunk size 752 perslab 1394
slab class 11: chunk size 944 perslab 1110
slab class 12: chunk size 1184 perslab 885
slab class 13: chunk size 1480 perslab 708
slab class 14: chunk size 1856 perslab 564
slab class 15: chunk size 2320 perslab 451
slab class 16: chunk size 2904 perslab 361
slab class 17: chunk size 3632 perslab 288
slab class 18: chunk size 4544 perslab 230
slab class 19: chunk size 5680 perslab 184
slab class 20: chunk size 7104 perslab 147
slab class 21: chunk size 8880 perslab 118
slab class 22: chunk size 11104 perslab 94
slab class 23: chunk size 13880 perslab 75
slab class 24: chunk size 17352 perslab 60
slab class 25: chunk size 21696 perslab 48
slab class 26: chunk size 27120 perslab 38
slab class 27: chunk size 33904 perslab 30
slab class 28: chunk size 42384 perslab 24
slab class 29: chunk size 52984 perslab 19
slab class 30: chunk size 66232 perslab 15
slab class 31: chunk size 82792 perslab 12
slab class 32: chunk size 103496 perslab 10
slab class 33: chunk size 129376 perslab 8
slab class 34: chunk size 161720 perslab 6
slab class 35: chunk size 202152 perslab 5
slab class 36: chunk size 252696 perslab 4
slab class 37: chunk size 315872 perslab 3
slab class 38: chunk size 394840 perslab 2
slab class 39: chunk size 493552 perslab 2
slab class 40: chunk size 616944 perslab 1
slab class 41: chunk size 771184 perslab 1
slab class 42: chunk size 1048576 perslab 1
使用12000端口，root用户，最大使用500M内存，253个并发连接，输出详细信息，以守护进程方式运行。
从输出信息可看出memcached分配内存的过程。
在入口main中 初始化阶段 while循环 接受处理这些参数：
int main (int argc, char **argv) { .....若干变量声明.... if (!sanitycheck()) { return EX_OSERR; } /* handle SIGINT */ signal(SIGINT, sig_handler); /* init settings */ settings_init(); /* set stderr non-buffering (for running under, say, daemontools) */ setbuf(stderr, NULL); /* process arguments */ /* arguments 后不跟值 arguments: 后跟值 */ while (-1 != (c = getopt(argc, argv, "a:" /* access mask for unix socket */ /* UNIX socket访问掩码, 八进制 (default: 0700) */ "A" /* enable admin shutdown commannd */ "p:" /* TCP port number to listen on */ /* TCP监听端口 (default: 11211) */ "s:" /* unix socket path to listen on */ /* UNIX socket监听路径, 不支持网络 */ "U:" /* UDP port number to listen on */ /* UDP监听端口 (default: 11211, 0 is off) */ "m:" /* max memory to use for items in megabytes */ /* 最大的内存使用 (default: 64 MB) */ "M" /* return error on memory exhausted */ /* 内存耗尽返回错误 */ "c:" /* max simultaneous connections */ /* 最大并发连接 (default: 1024) */ "k" /* lock down all paged memory */ /* 锁定所有分页内存 */ "hi" /* help, licence info */ "r" /* maximize core file limit */ /* 最大限度利用核心文件限制 */ "v" /* verbose */ /* 输出警告和错误信息 */ "d" /* daemon mode */ /* 启动一个守护进程 */ "l:" /* interface to listen on */ /* <ip_addr> 监听的服务器IP地址 (default: all addresses) */ "u:" /* user identity to run as */ /* 运行memcached用户 */ "P:" /* save PID in file */ /* 设置保存pid文件, only used with -d option */ "f:" /* factor? */ /* 块大小增长倍数 (default: 1.25) */ "n:" /* minimum space allocated for key+value+flags */ /* key+value+flags最小分配空间(default: 48) */ "t:" /* threads */ /* 使用的线程数量 (default: 4) */ "D:" /* prefix delimiter? */ /* 指定key和IDs的分隔符 default is ":" (colon). 如果指定此选项，统计信息收集自动开启; */ "L" /* Large memory pages */ /* 如何有效，尝试使用大内存页。增加内存页大小可以减少失误的TLB数量，提高性能。 */ "R:" /* max requests per event */ /* 每个事件的最大请求数 (default: 20) */ "C" /* Disable use of CAS */ /* 禁止使用 CAS */ "b:" /* backlog queue limit */ /* 设置积压队列数限制 (default: 1024) */ "B:" /* Binding protocol */ /* 绑定协议 - one of ascii, binary, or auto (default) */ "I:" /* Max item size */ /* 分配给每个slab页(default: 1mb, min: 1k, max: 128m) */ "S" /* Sasl ON */ "F" /* Disable flush_all */ "o:" /* Extended generic options */ ))) { switch (c) { case 'A': /* enables "shutdown" command */ settings.shutdown_command = true; break; case 'a': /* access for unix domain socket, as octal mask (like chmod)*/ settings.access= strtol(optarg,NULL,8); break; case 'U': /* UDP port number to listen on */ settings.udpport = atoi(optarg); udp_specified = true; break; case 'p': /* TCP port number to listen on */ settings.port = atoi(optarg); tcp_specified = true; break; case 's': /* unix socket path to listen on */ settings.socketpath = optarg; break; case 'm': /* max memory to use for items in megabytes */ settings.maxbytes = ((size_t)atoi(optarg)) * 1024 * 1024; break; case 'M': /* return error on memory exhausted */ settings.evict_to_free = 0; break; case 'c': /* max simultaneous connections */ settings.maxconns = atoi(optarg); break; case 'h': /* help, licence info */ usage(); exit(EXIT_SUCCESS); case 'i': /* help, licence info */ usage_license(); exit(EXIT_SUCCESS); case 'k': /* lock down all paged memory */ lock_memory = true; break; case 'v': /* verbose */ settings.verbose++; break; case 'l': /* interface to listen on */ if (settings.inter != NULL) { size_t len = strlen(settings.inter) + strlen(optarg) + 2; char *p = malloc(len); if (p == NULL) { fprintf(stderr, "Failed to allocate memory\n"); return 1; } snprintf(p, len, "%s,%s", settings.inter, optarg); free(settings.inter); settings.inter = p; } else { settings.inter= strdup(optarg); } break; case 'd': do_daemonize = true; break; case 'r': maxcore = 1; break; case 'R': settings.reqs_per_event = atoi(optarg); if (settings.reqs_per_event == 0) { fprintf(stderr, "Number of requests per event must be greater than 0\n"); return 1; } break; case 'u': /* user identity to run as */ username = optarg; break; case 'P': pid_file = optarg; break; case 'f': settings.factor = atof(optarg); if (settings.factor <= 1.0) { fprintf(stderr, "Factor must be greater than 1\n"); return 1; } break; case 'n': settings.chunk_size = atoi(optarg); if (settings.chunk_size == 0) { fprintf(stderr, "Chunk size must be greater than 0\n"); return 1; } break; case 't': settings.num_threads = atoi(optarg); if (settings.num_threads <= 0) { fprintf(stderr, "Number of threads must be greater than 0\n"); return 1; } /* There're other problems when you get above 64 threads. * In the future we should portably detect # of cores for the * default. */ if (settings.num_threads > 64) { fprintf(stderr, "WARNING: Setting a high number of worker" "threads is not recommended.\n" " Set this value to the number of cores in" " your machine or less.\n"); } break; case 'D': if (! optarg || ! optarg[0]) { fprintf(stderr, "No delimiter specified\n"); return 1; } settings.prefix_delimiter = optarg[0]; settings.detail_enabled = 1; break; case 'L' : if (enable_large_pages() == 0) { preallocate = true; } else { fprintf(stderr, "Cannot enable large pages on this system\n" "(There is no Linux support as of this version)\n"); return 1; } break; case 'C' : settings.use_cas = false; break; case 'b' : settings.backlog = atoi(optarg); break; case 'B': protocol_specified = true; if (strcmp(optarg, "auto") == 0) { settings.binding_protocol = negotiating_prot; } else if (strcmp(optarg, "binary") == 0) { settings.binding_protocol = binary_prot; } else if (strcmp(optarg, "ascii") == 0) { settings.binding_protocol = ascii_prot; } else { fprintf(stderr, "Invalid value for binding protocol: %s\n" " -- should be one of auto, binary, or ascii\n", optarg); exit(EX_USAGE); } break; case 'I': buf = strdup(optarg); unit = buf[strlen(buf)-1]; if (unit == 'k' || unit == 'm' || unit == 'K' || unit == 'M') { buf[strlen(buf)-1] = '\0'; size_max = atoi(buf); if (unit == 'k' || unit == 'K') size_max *= 1024; if (unit == 'm' || unit == 'M') size_max *= 1024 * 1024; settings.item_size_max = size_max; } else { settings.item_size_max = atoi(buf); } if (settings.item_size_max < 1024) { fprintf(stderr, "Item max size cannot be less than 1024 bytes.\n"); return 1; } if (settings.item_size_max > 1024 * 1024 * 128) { fprintf(stderr, "Cannot set item size limit higher than 128 mb.\n"); return 1; } if (settings.item_size_max > 1024 * 1024) { fprintf(stderr, "WARNING: Setting item max size above 1MB is not" " recommended!\n" " Raising this limit increases the minimum memory requirements\n" " and will decrease your memory efficiency.\n" ); } free(buf); break; case 'S': /* set Sasl authentication to true. Default is false */#ifndef ENABLE_SASL fprintf(stderr, "This server is not built with SASL support.\n"); exit(EX_USAGE);#endif settings.sasl = true; break; case 'F' : settings.flush_enabled = false; break; case 'o': /* It's sub-opts time! */ subopts = optarg; while (*subopts != '\0') { switch (getsubopt(&subopts, subopts_tokens, &subopts_value)) { case MAXCONNS_FAST: settings.maxconns_fast = true; break; case HASHPOWER_INIT: if (subopts_value == NULL) { fprintf(stderr, "Missing numeric argument for hashpower\n"); return 1; } settings.hashpower_init = atoi(subopts_value); if (settings.hashpower_init < 12) { fprintf(stderr, "Initial hashtable multiplier of %d is too low\n", settings.hashpower_init); return 1; } else if (settings.hashpower_init > 64) { fprintf(stderr, "Initial hashtable multiplier of %d is too high\n" "Choose a value based on \"STAT hash_power_level\" from a running instance\n", settings.hashpower_init); return 1; } break; case SLAB_REASSIGN: settings.slab_reassign = true; break; case SLAB_AUTOMOVE: if (subopts_value == NULL) { settings.slab_automove = 1; break; } settings.slab_automove = atoi(subopts_value); if (settings.slab_automove < 0 || settings.slab_automove > 2) { fprintf(stderr, "slab_automove must be between 0 and 2\n"); return 1; } break; case TAIL_REPAIR_TIME: if (subopts_value == NULL) { fprintf(stderr, "Missing numeric argument for tail_repair_time\n"); return 1; } settings.tail_repair_time = atoi(subopts_value); if (settings.tail_repair_time < 10) { fprintf(stderr, "Cannot set tail_repair_time to less than 10 seconds\n"); return 1; } break; case HASH_ALGORITHM: if (subopts_value == NULL) { fprintf(stderr, "Missing hash_algorithm argument\n"); return 1; }; if (strcmp(subopts_value, "jenkins") == 0) { hash_type = JENKINS_HASH; } else if (strcmp(subopts_value, "murmur3") == 0) { hash_type = MURMUR3_HASH; } else { fprintf(stderr, "Unknown hash_algorithm option (jenkins, murmur3)\n"); return 1; } break; case LRU_CRAWLER: if (start_item_crawler_thread() != 0) { fprintf(stderr, "Failed to enable LRU crawler thread\n"); return 1; } break; case LRU_CRAWLER_SLEEP: settings.lru_crawler_sleep = atoi(subopts_value); if (settings.lru_crawler_sleep > 1000000 || settings.lru_crawler_sleep < 0) { fprintf(stderr, "LRU crawler sleep must be between 0 and 1 second\n"); return 1; } break; case LRU_CRAWLER_TOCRAWL: if (!safe_strtoul(subopts_value, &tocrawl)) { fprintf(stderr, "lru_crawler_tocrawl takes a numeric 32bit value\n"); return 1; } settings.lru_crawler_tocrawl = tocrawl; break; default: printf("Illegal suboption \"%s\"\n", subopts_value); return 1; } } break; default: fprintf(stderr, "Illegal argument \"%c\"\n", c); return 1; } }- MEMCACHED源码之main初始化
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