\u672c\u6587\u5c06\u4e3a\u4f60\u8bf4\u660eIPC\u7684\u53e6\u4e00\u79cd\u65b9\u5f0f\uff1a\u4fe1\u53f7\u91cf\u3002\u5728\u64cd\u4f5c\u7cfb\u7edf\u539f\u7406\u8bfe\u7a0b\u4e2d\uff0c\u6211\u4eec\u5bf9\u4fe1\u53f7\u91cf\u673a\u5236\u6709\u6240\u4e86\u89e3\uff0c\u5373\u5b9e\u73b0\u8fdb\u7a0b\u5bf9\u5171\u4eab\u8d44\u6e90\u7684\u4e92\u65a5\u8bbf\u95ee\u4ee5\u53ca\u8fdb\u7a0b\u95f4\u7684\u540c\u6b65\u3002\u4e0e\u5176\u4ed6\u51e0\u79cd\u901a\u4fe1\u65b9\u5f0f\u76f8\u6bd4\uff0c\u4fe1\u53f7\u91cf\u66f4\u7a81\u51fa\u7684\u662f\u5bf9\u5171\u4eab\u8d44\u6e90\u7684\u8bbf\u95ee\u63a7\u5236\u3002\u63a5\u4e0b\u6765\uff0c\u6211\u4eec\u4e00\u8fb9\u56de\u5fc6\u4ee5\u524d\u5b66\u8fc7\u7684\u4fe1\u53f7\u91cf\u673a\u5236\uff0c\u4e00\u8fb9\u5b66\u4e60\u5982\u4f55\u7528\u7cfb\u7edf\u8c03\u7528\u51fd\u6570\u6765\u5b9e\u73b0\u76f8\u5173\u64cd\u4f5c\u3002<\/p>\n
1.\u521b\u5efa\u4fe1\u53f7\u91cf\u96c6<\/p>\n
\u6ce8\u610f\u8fd9\u91cc\u4f7f\u7528\u7684\u662f\u4fe1\u53f7\u91cf\u96c6\uff0c\u800c\u4e0d\u662f\u521b\u5efa\u4e00\u4e2a\u4fe1\u53f7\u91cf\u3002\u901a\u5e38\u6211\u4eec\u7528\u4f2a\u4ee3\u7801\u5b9e\u73b0\u8fdb\u7a0b\u95f4\u7684\u4e92\u65a5\u6216\u540c\u6b65\u65f6\uff0c\u90fd\u5b9a\u4e49\u4e00\u4e2a\u6574\u5f62\u53d8\u91cf\u4f5c\u4e3a\u4fe1\u53f7\u91cf\uff0c\u521d\u503c\u4e00\u822c\u90fd\u4e3a0\u62161\u3002\u5b9e\u9645\u5e94\u7528\u65f6\uff0c\u6211\u4eec\u6bcf\u6b21\u90fd\u9700\u8981\u521b\u5efa\u4e00\u4e2a\u4fe1\u53f7\u91cf\u96c6\uff0c\u5373\u4f7f\u6b64\u96c6\u5408\u53ea\u5305\u542b\u4e00\u4e2a\u4fe1\u53f7\u91cf\u3002\u4e00\u822c\u6211\u4eec\u901a\u8fc7\u4e0b\u9762\u51fd\u6570\u53bb\u521b\u5efa\u6216\u8005\u6253\u5f00\u4e00\u4e2a\u4fe1\u53f7\u91cf\u96c6\u3002<\/p>\n
int semget(key_t key,int nsems,int semflg);<\/pre>\n\u6211\u4eec\u8fd9\u91cc\u9700\u8981\u6ce8\u610f\u7684\u662f\uff0c\u6b64\u51fd\u6570\u4f55\u65f6\u521b\u5efa\u4e00\u4e2a\u4fe1\u53f7\u91cf\u96c6\uff0c\u4f55\u65f6\u6253\u5f00\u4e00\u4e2a\u4fe1\u53f7\u91cf\u96c6\u3002\u5f53semflg=IPC_CREATE\u65f6\uff0c\u5982\u679c\u5f53\u524d\u7cfb\u7edf\u4e2d\u4e0d\u5b58\u5728\u6b64\u4fe1\u53f7\u91cf\u96c6\u5408\uff08key\u503c\u4e0d\u5b58\u5728\uff09\uff0c\u90a3\u4e48semget\u51fd\u6570\u5b8c\u6210\u4e00\u4e2a\u4fe1\u53f7\u91cf\u7684\u521b\u5efa\uff1b\u5426\u5219\uff0csemget\u51fd\u6570\u6253\u5f00\u8fd9\u4e2a\u5df2\u5b58\u5728\u7684\u4fe1\u53f7\u91cf\u96c6\u3002\u5f53semflg=IPC_CREATE|IPC_EXCL\u65f6\uff0c\u53ea\u4f1a\u5b8c\u6210\u521b\u5efa\uff0c\u5982\u679ckey\u503c\u5bf9\u5e94\u7684\u4fe1\u53f7\u91cf\u96c6\u5408\u4ee5\u5b58\u5728\uff0c\u90a3\u4e48\u76f4\u63a5\u8fd4\u56de\u9519\u8bef\uff0c\u9519\u8bef\u4ee3\u7801\u4e3aEEXIST\u3002\u8fd9\u5e76\u4e0d\u96be\u7406\u89e3\uff0c\u548copen\u6587\u4ef6\u7684\u60c5\u51b5\u7c7b\u4f3c\u3002\u6b64\u51fd\u6570\u6210\u529f\u6267\u884c\u8fd4\u56de\u4fe1\u53f7\u91cf\u96c6\u7684\u6807\u793a\u7b26\uff0c\u5426\u5219\u4e3a-1\u3002<\/p>\n
\u53e6\u5916\u5173\u4e8e\u6211\u4eec\u6240\u521b\u5efa\u7684\u8fd9\u4e2a\u4fe1\u53f7\u91cf\u96c6\uff0c\u6709\u7ed3\u6784\u4f53struct semid_ds\u4e0e\u4e4b\u5bf9\u5e94\uff0c\u8fd9\u4e2a\u7ed3\u6784\u4f53\u4e2d\u5b58\u50a8\u4fe1\u53f7\u91cf\u96c6\u4e2d\u7684\u76f8\u5173\u5c5e\u6027\u3002<\/p>\n
2.PV\u64cd\u4f5c\u7684\u5b9e\u73b0<\/p>\n
\u5bf9\u4e8e\u4fe1\u53f7\u91cf\u673a\u5236\uff0c\u6211\u4eec\u6700\u719f\u6089\u7684\u5e94\u8be5\u4fbf\u662fPV\u64cd\u4f5c\u4e86\u3002\u4ee5\u524d\u6211\u4eec\u5728\u5199\u8fdb\u7a0b\u4e92\u65a5\u6216\u540c\u6b65\u7684\u4f2a\u4ee3\u7801\u65f6\uff0c\u90fd\u662f\u76f4\u63a5\u6765\u4f7f\u7528P(semaphore)\u548cV(semaphore)\u3002\u90a3\u4e48\u6211\u4eec\u5982\u4f55\u5177\u4f53\u5b9e\u73b0\uff1f<\/p>\n
int semop(int semid,struct sembuf *sops,size_t nsops);<\/pre>\n\u73b0\u5728\u6211\u8981\u544a\u8bc9\u4f60\uff0cP\u548cV\u64cd\u4f5c\u5747\u901a\u8fc7\u4e0a\u8ff0\u51fd\u6570\u6765\u5b8c\u6210\u3002\u4f60\u80af\u5b9a\u9a6c\u4e0a\u4f1a\u60f3\uff0cP\u548cV\u4e24\u4e2a\u622a\u7136\u4e0d\u540c\u7684\u64cd\u4f5c\u5982\u4f55\u4f7f\u7528\u4e0a\u8ff0\u51fd\u6570\u6765\u5b8c\u6210\uff1f\u8fd9\u5176\u5b9e\u53d6\u51b3\u4e8esops\u53c2\u6570\u3002\u8bf7\u5148\u770b\u8fd9\u4e2a\u53c2\u6570\u7684\u7c7b\u578b\uff1a<\/p>\n
struct sembuf\r\n{\r\n\tushort sem_num;\/*\u4fe1\u53f7\u5728\u4fe1\u53f7\u91cf\u96c6\u4e2d\u7684\u7d22\u5f15*\/\r\n\tshort sem_op; \/*\u64cd\u4f5c\u7c7b\u578b\uff0c\u662fP\u8fd8\u662fV*\/\r\n\tshort sem_flg;\/*\u64cd\u4f5c\u6807\u5fd7*\/\r\n}<\/pre>\n\u6211\u4eec\u53ef\u4ee5\u53d1\u73b0\uff0c\u901a\u8fc7semid\u548csem_num\u4e24\u4e2a\u5b57\u6bb5\u5c31\u53ef\u4ee5\u786e\u5b9a\u4fe1\u53f7\u91cf\u96c6\u4e2d\u7684\u6307\u5b9a\u4fe1\u53f7\u91cf\u3002sem_op\u53d6\u4e0d\u540c\u7684\u503c\u5c31\u4f1a\u4ea7\u751f\u4e0d\u540c\u7684\u64cd\u4f5c\u3002\u7279\u522b\u7684\uff0c\u5982\u679c\u5176\u503c\u4e3a0\uff0c\u5219\u6b64\u65f6semop\u64cd\u4f5c\u7684\u4f5c\u7528\u662f\u6d4b\u8bd5\u4fe1\u53f7\u91cf\u7684\u503c\u662f\u5426\u4e3a0\u3002\u4e0b\u9762\u7684\u4ee3\u7801\u662f\u7ecf\u5178PV\u64cd\u4f5c\u7684\u5b9e\u73b0\u65b9\u6cd5\u3002<\/p>\n
int p(int semid,int index)\r\n{\r\n\tstruct sembuf buf={0,-1,IPC_NOWAIT};\r\n\r\n\tif(index<0)\r\n\t{\r\n\t\tprintf(\"error:index of the semaphore is invalid\\n\");\r\n\t\texit(1);\r\n\t}\r\n\tbuf.sem_num=index;\r\n\tif(semop(semid,&buf,1)==-1)\r\n\t{\r\n\t\tprintf(\"P operation failed\\n\");\r\n\t\texit(1);\r\n\t}\r\n\treturn 0;\r\n}\r\n\r\nint v(int semid,int index)\r\n{\r\n\tstruct sembuf buf={0,+1,IPC_NOWAIT};\r\n\r\n\tif(index<0)\r\n\t{\r\n\t\tprintf(\"error:index of the semaphore is invalid\\n\");\r\n\t\texit(1);\r\n\t}\r\n\tbuf.sem_num=index;\r\n\tif(semop(semid,&buf,1)==-1)\r\n\t{\r\n\t\tprintf(\"V operation failed\\n\");\r\n\t\texit(1);\r\n\t}\r\n\treturn 0;\r\n}<\/pre>\n\u6211\u4eec\u8fd9\u91cc\u7279\u522b\u8981\u8bf4\u660e\u7684\u662fstruct sembuf\u7ed3\u6784\u4e2d\u7684sem_flg\u5b57\u6bb5\uff0c\u5982\u679c\u5176\u503c\u4e3aIPC_NOWAIT\uff0c\u6839\u636esem_op\u7684\u4e0d\u540c\u610f\u4e49\u4e5f\u4e0d\u540c\u3002\u5f53sem_op\u4e3a0\u65f6\uff0c\u5982\u679c\u8bbe\u7f6eIPC_NOWAIT\uff0c\u90a3\u4e48\u8c03\u7528\u8fdb\u7a0b\u76f4\u63a5\u8fd4\u56de\uff1b\u5426\u5219\u8c03\u7528\u8fdb\u7a0b\u8fdb\u5165\u7761\u7720\u72b6\u6001\u76f4\u81f3\u4fe1\u53f7\u91cf\u4e3a0\u3002\u5f53sem_op<0\u65f6\uff0c\u8868\u793a\u7533\u8bf7\u8d44\u6e90\uff0c\u5982\u679c\u6ca1\u6709\u8bbe\u7f6eIPC_NOWAIT,\u90a3\u4e48\u8c03\u7528\u8fdb\u7a0b\u963b\u585e\u81f3\u6b64\u8d44\u6e90\u88ab\u91ca\u653e\uff1b\u5426\u5219\u8fdb\u7a0b\u76f4\u63a5\u8fd4\u56de\u3002<\/p>\n
3.\u4fe1\u53f7\u91cf\u7684\u63a7\u5236<\/p>\n
\u4e0a\u8ff0\u4e24\u90e8\u5206\u5185\u5bb9\u2014\u2014\u5982\u4f55\u521b\u5efa\u4fe1\u53f7\u91cf\u96c6\uff0c\u5982\u4f55PV\u64cd\u4f5c\u2014\u2014\u4f3c\u4e4e\u5df2\u7ecf\u53ef\u4ee5\u8be0\u91ca\u4fe1\u53f7\u91cf\u4e86\uff0c\u4f46\u662f\u8fd9\u6bd5\u7adf\u4e0d\u662f\u6211\u4eec\u5199\u4f2a\u4ee3\u7801\uff0c\u6211\u4eec\u5fc5\u987b\u5bf9\u4fe1\u53f7\u91cf\u8fdb\u884c\u76f8\u5173\u63a7\u5236\uff0c\u6bd4\u5982\u5982\u4f55\u5bf9\u4fe1\u53f7\u91cf\u8bbe\u7f6e\u521d\u503c\uff0c\u5982\u4f55\u5f97\u5230\u4fe1\u53f7\u91cf\u5f53\u524d\u7684\u503c\u7b49\u7b49\u3002\u56e0\u6b64\u638c\u63e1\u597d\u63a7\u5236\u51fd\u6570semctl\u5c24\u4e3a\u91cd\u8981\u3002<\/p>\n
int semctl(int semid,int semnum,int cmd,union semun);<\/pre>\n\u6ce8\u610f\u7b2c\u56db\u4e2a\u53c2\u6570\u7c7b\u578b\u662f\u4e0d\u786e\u5b9a\u7684\uff0c\u7531cmd\u7684\u7c7b\u578b\u6765\u786e\u5b9a\u3002\u7b2c\u56db\u4e2a\u53c2\u6570\u6240\u6709\u53ef\u80fd\u4f1a\u7528\u5230\u7684\u53d8\u91cf\u90fd\u88ab\u5b9a\u4e49\u5728\u4e00\u4e2a\u5171\u7528\u4f53\u4e2d\u3002<\/p>\n
union semun\r\n{\r\n\tint val;\r\n\tstruct semid_ds *buf;\r\n\tushort *array;\r\n\tvoid *pad;\r\n}<\/pre>\n\u4e0b\u9762\u6211\u4eec\u5bf9\u51e0\u79cd\u5e38\u7528\u7684cmd\u8fdb\u884c\u8bf4\u660e\u3002<\/p>\n
\u5982\u679c\u6211\u4eec\u60f3\u6253\u5370\u67d0\u4e2a\u5df2\u5b58\u5728\u4fe1\u53f7\u91cf\u96c6\u7684\u5404\u4e2a\u5c5e\u6027\u4fe1\u606f\u65f6\uff0c\u90a3\u4e48\u53ef\u4ee5\u53c2\u8003\u4e0b\u9762\u4ee3\u7801\u3002<\/p>\n
union semun semop;\r\nstruct semid_ds seminfo;\r\nsemop.buf=&seminfo;\r\nif(semctl(semid,0,IPC_STAT,semop)==-1)\r\n{\r\n\tprintf(\"error:get the info of semaphroe failed\\n\");\r\n\texit(1);\r\n}<\/pre>\n\u56e0\u4e3a\u6b64\u65f6\u5019cmd\u4e3aIPC_STAT\uff0c\u90a3\u4e48semctl\u4f1a\u81ea\u52a8\u4ecesemop\u4e2d\u53d6\u8d70buf\u5b57\u6bb5\u3002\u6b64\u64cd\u4f5c\u6210\u529f\u5b8c\u6210\u540e\uff0c\u4fe1\u53f7\u91cf\u96c6\u7684\u4fe1\u606f\u4fbf\u5b58\u50a8\u5728seminfo\u4e2d\u3002\u6ce8\u610f\uff0c\u5728\u4f7f\u7528\u6b64\u64cd\u4f5c\u524d\uff0c\u4e00\u5b9a\u8981\u5c06buf\u6307\u5411\u4e00\u4e2astruct semid_ds\u7c7b\u578b\u7684\u53d8\u91cf\uff0c\u5426\u5219buf\u5c06\u662f\u4e00\u4e2a”\u91ce\u6307\u9488”\u3002<\/p>\n
\u5982\u679c\u60f3\u4e3a\u67d0\u4e2a\u6307\u5b9a\u7684\u4fe1\u53f7\u91cf\u8bbe\u7f6e\u521d\u503c\uff0c\u90a3\u4e48\u4e0b\u9762\u4ee3\u7801\u5c31\u662f\u5b9e\u73b0\u5c06\u6807\u793a\u7b26\u4e3asemid\u7684\u4fe1\u53f7\u91cf\u96c6\u4e2d\u7d22\u5f15\u4e3aindex\u7684\u4fe1\u53f7\u91cf\u8d4b\u503c\u4e3a5\u3002<\/p>\n
union semnu semop;\r\nsemop.val=5;\r\nsemctl(semid,index,SETVAL,semop);<\/pre>\n\u60f3\u5f97\u5230\u67d0\u4e2a\u4fe1\u53f7\u91cf\u5f53\u524d\u7684\u503c\u65f6\uff0c\u5c31\u53ef\u4ee5\u53c2\u8003\u4e0b\u9762\u4ee3\u7801\uff0c\u6ce8\u610f\u7b2c\u56db\u4e2a\u53c2\u6570\u4e3a0\uff0c\u56e0\u4e3acmd\u4e3aGETVAL\uff0c\u6240\u4ee5semctl\u51fd\u6570\u4f1a\u5ffd\u7565\u7b2c\u56db\u4e2a\u53c2\u6570\u7684\u53d6\u503c\u3002<\/p>\n
int semval;\r\nsemval=semctl(semid,index,GETVAL,0);<\/pre>\n\u5173\u4e8e\u4fe1\u53f7\u91cf\u7684\u57fa\u672c\u77e5\u8bc6\u5c31\u662f\u8fd9\u4e9b\uff0c\u4e0b\u7bc7\u6587\u7ae0\u5c06\u7528\u4e0a\u8ff0\u5185\u5bb9\u6765\u5b9e\u73b0\u4e00\u4e2a\u8fdb\u7a0b\u4e92\u65a5\u7684\u4f8b\u5b50\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u672c\u6587\u5c06\u4e3a\u4f60\u8bf4\u660eIPC\u7684\u53e6\u4e00\u79cd\u65b9\u5f0f\uff1a\u4fe1\u53f7\u91cf\u3002\u5728\u64cd\u4f5c\u7cfb\u7edf\u539f\u7406\u8bfe\u7a0b\u4e2d\uff0c\u6211\u4eec\u5bf9\u4fe1\u53f7\u91cf\u673a\u5236\u6709\u6240\u4e86\u89e3\uff0c\u5373\u5b9e\u73b0\u8fdb\u7a0b\u5bf9\u5171\u4eab\u8d44\u6e90 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[140],"tags":[139,108,142,402],"class_list":["post-1199","post","type-post","status-publish","format-standard","hentry","category-140","tag-ipc","tag-linux","tag-142","tag-402"],"views":9185,"_links":{"self":[{"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/posts\/1199","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/comments?post=1199"}],"version-history":[{"count":0,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/posts\/1199\/revisions"}],"wp:attachment":[{"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/media?parent=1199"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/categories?post=1199"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/tags?post=1199"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}