银行家算法1文档格式.docx

1、Request当进程pi提出资源申请时，系统执行下列步骤：（1）若RequestNeed,转（2）；否则错误返回（2）若RequestAvailable,转（3）；否则进程等待（3）假设系统分配了资源，则有：=Available-Request;=Allocation+Request;=Need-Request若系统新状态是安全的，则分配完成若系统新状态是不安全的，则恢复原状态，进程等待为进行安全性检查，定义数据结构：Work:ARRAY【1.m】 of integer;Finish:ARRAY【1.n】 of Boolean;安全性检查的步骤：（1） Work:=Available;=fal

2、se;（2） 寻找满足条件的i：a.Finish=false;b.NeedWork;如果不存在，则转（4）（3） Work:=Work+Allocation;=true;转（2）（4） 若对所有i,Finish=true,则系统处于安全状态，否则处于不安全状态/* 银行家算法，操作系统概念（OS concepts Six Edition）作者：ctu_85*/#include malloc.hstdio.h#define alloclen sizeof（struct allocation）#define maxlen sizeof（struct max）#define avalen sizeo

3、f（struct available）#define needlen sizeof（struct need）#define finilen sizeof（struct finish）#define pathlen sizeof（struct path）struct allocationint value;struct allocation *next;struct maxstruct max *next;struct availablestruct available *next;struct needstruct need *next;struct pathstruct path *next

4、;struct finishint stat;struct finish *next;int main（）int row,colum,status=0,i,j,t,temp,processtest;struct allocation *allochead,*alloc1,*alloc2,*alloctemp;struct max *maxhead,*maxium1,*maxium2,*maxtemp;struct available *avahead,*available1,*available2,*availabletemp,*workhead,*work1,*work2,*worktemp

5、,*worktemp1;struct need *needhead,*need1,*need2,*needtemp;struct finish *finihead,*finish1,*finish2,*finishtemp;struct path *pathhead,*path1,*path2,*pathtemp;char c;printf（nPlease enter the type of sources the system has:n）;scanf（%d,&colum）;Please enter the number of processes now in the memory:row）

6、;Please enter the allocation array:for（i=0;irow;i+）The allocation for process p%d:,i）;for （j=0;jnext=alloc2-next=NULL;allochead-value）;status+;elsealloc2=（struct allocation *）malloc（alloclen）;%d,%dalloc2-if（status=1）allochead-next=alloc2;alloc1=alloc2;alloc2-status=0;Please enter the max array:The m

7、ax needed from process p%d:The type %c maxium system resource may needed:maxhead=maxium1=maxium2=（struct max*）malloc（maxlen）;maxium1-next=maxium2-maxium1-maxium2=（struct max *）malloc（maxlen）;maxium2-maxhead-next=maxium2;maxium1=maxium2;maxium2-Please enter the available array now exists in the syste

8、m:The type %c available system resource number:avahead=available1=available2=（struct available*）malloc（avalen）;workhead=work1=work2=（struct available*）malloc（avalen）;available1-next=available2-work1-next=work2-available1-value=available1-value;available2=（struct available*）malloc（avalen）;work2=（stru

9、ct available*）malloc（avalen）;available2-work2-value=available2-avahead-next=available2;workhead-next=work2;available1=available2;work1=work2;available2-alloctemp=allochead;maxtemp=maxhead;needhead=need1=need2=（struct need*）malloc（needlen）;need1-next=need2-value=maxtemp-value-alloctemp-need2=（struct

10、need *）malloc（needlen）;need2-value=（maxtemp-value）-（alloctemp-needhead-next=need2;need1=need2;maxtemp=maxtemp-next;alloctemp=alloctemp-finihead=finish1=finish2=（struct finish*）malloc（finilen）;finish1-next=finish2-stat=0;finish2=（struct finish*）malloc（finilen）;finish2-finihead-next=finish2;finish1=fi

11、nish2; /*Initialization compleated*/processtest=0;for（temp=0;tempstat=0）for（j=0;j+,needtemp=needtemp-next,worktemp=worktemp-next）if（needtemp-valuevalue）processtest+;if（processtest=colum）worktemp1-value+=alloctemp-worktemp1=worktemp1-pathhead=path1=path2=（struct path*）malloc（pathlen）;path1-next=path2-value=i;path2=（struct path*）malloc（pathlen）;path2-pathhead-next=path2;path1=path2;finishtemp-stat=1;for（t=0;tfinishtemp=finishtemp-value=0）nWARNING,the system is in nonsafe status!exit（0）;nThe system is in safe status!nThe safe sequence is:dop%d ,pathhead-while（pathhead=pathhead-next）;