Metered concurrency: Difference between revisions
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m →{{header|Tcl}}: metadata improvement |
Go solution |
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work(i, 2000, semaphore, timer, println) |
work(i, 2000, semaphore, timer, println) |
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}</lang> |
}</lang> |
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=={{header|Go}}== |
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Implementation using Go channels. |
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<lang go>package main |
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import ( |
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"fmt" |
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"time" |
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) |
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func main() { |
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// three operations per task description |
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acquire := make(chan int) |
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release := make(chan int) |
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count := make(chan chan int) |
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// library analogy per WP article |
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go librarian(acquire, release, count, 10) |
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nStudents := 20 |
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studied := make(chan int) // done channel |
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for i := 0; i < nStudents; i++ { |
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go student(acquire, release, studied) |
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} |
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// wait until all students are done |
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for i := 0; i < nStudents; i++ { |
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<-studied |
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} |
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} |
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func librarian(a, r chan int, c chan chan int, count int) { |
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p := a // accquire operation is served or not depending on count |
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for { |
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select { |
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case <-p: // accquire/p/wait operation |
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count-- |
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if count == 0 { |
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p = nil |
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} |
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case <-r: // release operation |
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count++ |
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p = a |
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case cc := <-c: // count operation |
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cc <- count |
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} |
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} |
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} |
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func student(a, r, s chan int) { |
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a <- 0 // accquire |
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fmt.Println("Studying...") // report per task descrption |
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time.Sleep(2e9) // sleep per task description |
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r <- 0 // release |
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s <- 0 // signal done |
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}</lang> |
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Output shows 10 students studying immediately, about a 2 second pause, 10 more students studying, then another pause of about 2 seconds before returning to the command prompt. |
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=={{header|Haskell}}== |
=={{header|Haskell}}== |
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