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online exercise -4 Version 0
👤 Author: by writer 2020-11-03 02:25:01 last modified by writer

The Customers and Barbers Problem (real case in a barbershop near a University).
A barbershop consists of n waiting chairs and has a chief barber B0(expensive cost) and two ordinary barbers(B1,B2). The customers are classified into three classes. Class A only asks chief barber's service, Class B only asks ordinary barber's service , Class C asks barber' service no matter the barber is chief or not. When a customer enters the barbershop, if all waiting chairs are occupied, the customer leaves the shop , otherwise the customer sits in one free chair at the end of queue. When any barber is free, he calls a customer in the queue who matches him in the way "first come first serve" and serve this customer. If there are more than one barber who are free, the way which barber calls customer first is according to the order(B0,B1,B2). If a barber is free and there are no customers who match him , he takes a rest. If waiting customers see their matched barbers are taking a rest, they arouse the barbers' attention. Write a program to coordinate the barbers and customers.

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1756894282qqcom • 2020-11-03 15:34:20

The shared data structure is:
var barber,wait:semaphore;{initial value=0}
entry:semaphore;{initial value=A}
couter:integer; {initial value=0}
Code snippet about the barber:
repeat
p(barber);
"share"
until false;
About customer code snippet:
p(entry);
if count=n then exit;
count:=count+A;
if count＞A then
begin
v(eatry);
p(wait);
end
else
begin
v(entry);
v(barber);
"share"
p(entry);
count:=count-A;
if count＞0 then v(wait);
v(entry);
end PostVer 0

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1079513613qqcom • 2020-11-03 15:40:08

<p class="p1"><span class="s1">var barber,</span></p>
<p class="p1"><span class="s1">wait:semaphore;</span></p>
<p class="p1"><span class="s1">{</span></p>
<p class="p1"><span class="s1">initial value=0</span></p>
<p class="p1"><span class="s1">} </span></p>
<p class="p1"><span class="s1">entry:semaphore;</span></p>
<p class="p1"><span class="s1">{</span></p>
<p class="p1"><span class="s1">initial value=A</span></p>
<p class="p1"><span class="s1">} </span></p>
<p class="p1"><span class="s1">couter:integer;</span></p>
<p class="p1"><span class="s1"> {</span></p>
<p class="p1"><span class="s1">initial value=0</span></p>
<p class="p1"><span class="s1">}</span></p>
<p class="p1"><span class="s1"> Code snippet about the barber: repeat p(barber);</span></p>
<p class="p1"><span class="s1"> "share" until false; </span></p>
<p class="p1"><span class="s1">About customer code snippet: p(entry); </span></p>
<p class="p1"><span class="s1">if count=n </span></p>
<p class="p1"><span class="s1">then exit; </span></p>
<p class="p1"><span class="s1">count:=count+A; </span></p>
<p class="p1"><span class="s1">if count</span><span class="s2">＞</span><span class="s1">A </span></p>
<p class="p1"><span class="s1">then begin v(eatry); </span></p>
<p class="p1"><span class="s1">p(wait); </span></p>
<p class="p1"><span class="s1">end</span></p>
<p class="p1"><span class="s1">else </span></p>
<p class="p1"><span class="s1">begin v(entry); </span></p>
<p class="p1"><span class="s1">v(barber); </span></p>
<p class="p1"><span class="s1">"share" p(entry); </span></p>
<p class="p1"><span class="s1">count:=count-A; </span></p>
<p class="p1"><span class="s1">if count</span><span class="s2">＞</span><span class="s1">0 then v(wait); </span></p>
<p class="p1"><span class="s1">v(entry); </span></p>
<p class="p1"><span class="s1">end</span></p> PostVer 0

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804824950qqcom • 2020-11-03 15:47:13

The shared data structure is:
var barber,wait:semaphore;{initial value=0}
entry:semaphore;{initial value=A}
couter:integer; {initial value=0}

Code snippet about the barber:
repeat
p(barber);
"share"
until false;
About customer code snippet:
p(entry);
if count=n then exit;
count:=count+A;
if count＞A then
begin
v(eatry);
p(wait);
end
else
begin
v(entry);
v(barber);
"share"
p(entry);
count:=count-A;
if count＞0 then v(wait);
v(entry);
end PostVer 0

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1720650158qqcom • 2020-11-03 17:27:44

<a href="http://www.yvsou.com/wp-content/uploads/sites/30/2020/11/Barber.jpg"><img class="alignnone size-medium wp-image-8773" src="http://www.yvsou.com/wp-content/uploads/sites/30/2020/11/Barber-300x100.jpg" alt="" width="300" height="100" /></a><a href="http://www.yvsou.com/wp-content/uploads/sites/30/2020/11/customer.jpg"><img class="alignnone size-medium wp-image-8774" src="http://www.yvsou.com/wp-content/uploads/sites/30/2020/11/customer-300x192.jpg" alt="" width="300" height="192" /></a> PostVer 0

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cfeshete97gmailcom • 2020-11-04 01:08:50

Name:<strong> FESHETE CHARLES DE-GAULLE 2018529627022</strong>

 

Problem:<strong> Sleeping Barber in Synchr</strong><strong>onization</strong>

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244766935qqcom • 2020-11-06 20:41:33

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997371991qqcom • 2020-11-06 22:28:17

2018329621069 张时敏

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653968106qqcom • 2020-11-07 18:17:01

2018329621008徐天然

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1730854984qqcom • 2020-11-08 14:12:56

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512858048qqcom • 2020-11-09 12:11:15

The program is :

int waiting=0; //等候理发顾客数 int CHAIRS=N; //为顾客准备的椅子数 semaphore customers,barbers,mutex; customers=0;barbers=0;mutex=1; cobegin process barber( ) { while(true) { P(customers); //有顾客吗？若无顾客，理发师睡眠 P(mutex); //若有顾客时，进入临界区 waiting--; //等候顾客数少一个 V(barbers); //理发师准备为顾客理发 V(mutex); //退出临界区 cut_hair(); //理发师正在理发(非临界区) } } process customer_i( ) { P(mutex); //进入临界区 if(waiting<CHAIRS) { //有空椅子吗 waiting++; //等候顾客数加1 V(customers); //唤醒理发师 V(mutex); //退出临界区 P(barbers); //理发师忙，顾客坐下等待 get_haircut(); //否则顾客坐下理发 } else V(mutex); //人满了，离开！ } coend PostVer 0

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2470994471qqcom • 2020-11-09 12:43:47

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1210775967qqcom • 2020-11-09 19:54:12

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hokyeejaufoxmailcom • 2020-11-09 20:52:51

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1403861656qqcom • 2020-11-09 22:37:55

The Shared data structure is:

var barber,wait:semaphore; {initial value =0}

entry:semaphore; {initial value =A}

couter:integer; {initial value =0}

Code snippet about barber:

repeat

p(barber);

"share"

until false;

Code snippet about the customer:

p(entry);

if count=n then exit;

count:=count+A;

If count > A then

begin

v(eatry);

p(wait);

end

else

begin

v(entry);

v(barber);

"share"

p(entry);

count:=count-A;

If count > 0 then v(wait);

v(entry);

en PostVer 0

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454234624qqcom • 2020-11-10 00:21:58

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wx287_oz26ft1wt2_isbggtha4lgepaasa • 2020-11-17 14:34:47

2018529627050-DAVID BUKEDI DIELA

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450766287qqcom • 2020-11-17 15:31:19

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439731491qqcom • 2021-01-05 17:11:44

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1119833189qqcom • 2021-01-06 22:11:24

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1224532347qqcom • 2021-01-07 13:31:58

理发师操作：

Barber(){

while(1){

P(wait); //唤醒等待的一位顾客

P(mutex); //顾客被唤醒，准备理发，没有顾客，则睡觉

custNum--; //当前店里顾客数减1

V(barber); //有顾客来了，醒来理发

V(mettux): //释放互斥信号量

}

}

顾客操作：

Customer(){

while(1){

P(mutex); //顾客想要理发

if(custNum<N){ //店里人没有满

custNum++；

V(wait); //理发师睡觉的话，唤醒他理发

V(mutex); //释放互斥量，理发这一动作成功

P(baber); //理发师进行理发操作

}

else

{

V(metux); //释放互斥量，打消进店理发的举动

}

}

} PostVer 0

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962305148qqcom • 2021-01-07 22:07:04

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1285795916qqcom • 2021-01-07 22:10:46

邱锐鹏 2018329621199

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2736689890qqcom • 2021-01-08 00:38:26

2018329621239-严宇豪
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indigo203outlookcom • 2021-01-08 04:24:59

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shatino94163com • 2021-01-08 19:22:54

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