return(item); } { count=0; in=0; out=0; } ½ø³Ì£º
producer,consumer producer£¨Éú²úÕß½ø³Ì£©; Item_Type item; {
while(true) {
produce(&item); buffer.enter( ); buffer.deposit(item); buffer.leave( ); } }
consumer£¨Ïû·ÑÕß½ø³Ì£©; Item_Type item; {
while(true) {
buffer.enter( ); item=buffer.fetch( ); buffer.leave( ); consume(&item); }
}
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Ò³ºÅp=INT(0/2048)=0¡ Ò³ÄÚÆ«ÒÆw=mod(0/2048)¡0
ÒÔÒ³ºÅΪË÷ÒýËÑË÷Ò³±íµÃµ½0ºÅÒ³ÃæËùÔÚµÄÎïÀí¿éºÅΪ2 ÎïÀíµØÖ·=ÎïÀí¿éºÅ*¿é´óС+Ò³ÄÚÆ«ÒÆ=2*£¨2*1024£©+0=4096
Æß¡¢Ð´³öʹÓüǼÐÍÐźÅÁ¿µÄwait(s)ºÍsignal(s)²Ù×÷µÄʵÏÖ£¬ËµÃ÷ÓëʹÓÃÕûÐÍÐźÅÁ¿Ïà±È£¬Ê¹ÓüǼÐÍÐźÅÁ¿ÓÐʲôÓŵ㡣 procedure wait(s) var s:semaphore begin
s.value:=s.value-1; if s.value<0 then block(s.L) end.
procedure signal(s) var s:semaphore begin
s.value:=s.value+1; if s.value<=0 then wakeup(s.L)
end.
¼Ç¼ÐÍÐźÅÁ¿½â¾öÉú²úÕß-Ïû·ÑÕßͬ²½ÎÊÌâµÄËã·¨£º
ÉèÖÃÒ»¸ö»¥³âÐźÅÁ¿£¬mutexÓÃÓÚʵÏÖ¶Ô¹«¹²»º³å³ØµÄ»¥³â·ÃÎÊ£¬³õֵΪ1¡£ ÉèÖÃÁ½¸öͬ²½ÐźÅÁ¿£¬·Ö±ð±íʾ¿ÉÓÃ×ÊÔ´Êý¡£ empty£º±íʾ¿Õ»º³åÇøÊý,³õֵΪn
full£º±íʾװÓвúÆ·µÄ»º³åÇøÊý£¬³õֵΪ0£¬(Ò»¸ö»º³åÇøÖзÅÒ»¸ö²úÆ·)
Producer: begin repeat ? produce an item in nextp; wait(empty); wait(mutex); buffer(in):=nextp; in:=(in+1)mod n
signal(mutex); signal(full)£» until false£¨3·Ö£©
Consumer: begin repeat ¡ wait(full); wait(mutex); nextc:=buffer(out); out:=(out+1)mod n; signal(mutex);
signal(empty)£» consume item in nextc; until false;