資源簡介
教材中對讀者寫者問題算法均有描述，但這個算法在不斷地有讀者流的情況下，寫者會被阻塞。編寫一個寫者優先解決讀者寫者問題的程序，其中讀者和寫者均是多個進程，用信號量作為同步互斥機制。
代碼片段和文件信息
#include?
#include?
#include?
#include?
#include?
#include?
#include?
#include?
#include?
#include?
#define?maxn?15
struct?shared{
?????????????char?*?text;
?????????????int?rnwn;
};
union?semun{
int?val;
struct?semid_ds?*buf;
unsigned?short?*arry;
};
int?Vsem（int?semid）{
struct?sembuf?buf={0+1SEM_UNDO};
if（semop（semid&buf1）==-1）{
perror（“semop“）;
return?0;
}
return?1;
}
int?Psem（int?semid）{
struct?sembuf?buf={0-1SEM_UNDO};
if（semop（semid&buf1）==-1）{
perror（“semop“）;
return?0;
}
return?1;
}
void?creader（int?rn_mutexint?wn_mutexint?w_firstint?readint?writestruct?shared?*?share）{
????????int?k=20;
????????while（k--）{
????????????????Psem（read）;
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