1. (Signal-PV)Writer-Reader Problem
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| void Reader(){
// operate count
// 1. lock count
// 2. if <read counter> == 0 then lock<writer> // if current reader is the first one to read the file, then it needs see if there is writers, and lock them.
// 3. unlock count
// 4. custom read operation
// 5. lock count
// 6. if <read counter> == 0 then unlock<writer> // if current reader is the first one to read the file, then it needs see if there is writers, and unlock them.
// 7. unlock count
}
void Writer(){
// 1. lock writer
// 2. custom write operations
// 3. wakeUp writer
}
// SYSTEM FUNCTIONS BELOW
void wait(value){
// 1. value = value - 1
// 2. if value < 0 then block value queue
}
void signal(value){
// 1. value = value + 1
// 2. if value <= 0 then wakeUp value queue
}
|
2. (Monitors)
Monitors handle all the P-V Operations, although cut down the complicated P-V Operations in user’s applications, it may cause less efficiency.
- Only One Process in One Exact Time, use Queue to row requests.
- User’s Applications can access synchronized devices using interface provided by Monitors.
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| void put(item){
// 1. if count>=0 then cwait(notFull)
// 2. add item in queue
// 3. if notEmpty then csignal(notEmpty)
}
void producer(){
// 1. produce
// 2. put
}
void consumer(){
// 1. get
// 2. consume
}
|
