Data update

Task/Synchronous-concurrency/Fortran/synchronous-concurrency.f

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+program concurrent_line_printer
+    ! Uses OpenMP to create 2 threads and manage the communication between them.
+    use omp_lib
+    implicit none
+
+    character(len=256) :: shared_line
+    integer :: shared_count
+    integer :: state  ! 0=ready, 1=line_available, 2=reading_done, 3=count_available
+
+    state = 0
+    shared_count = 0
+
+    !$omp parallel sections num_threads(2)
+
+    !$omp section
+    call reader_thread()
+
+    !$omp section
+    call printer_thread()
+
+    !$omp end parallel sections
+
+contains
+
+    subroutine reader_thread()
+        integer :: io_stat, unit_num, final_count
+        character(len=256) :: line
+
+        open(newunit=unit_num, file='input.txt', status='old', action='read', iostat=io_stat)
+        if (io_stat /= 0) then
+            print *, "Error: Cannot open input.txt"
+            !$omp atomic write
+            state = 2
+            return
+        end if
+
+        ! Read and send each line
+        do
+            read(unit_num, '(A)', iostat=io_stat) line
+            if (io_stat /= 0) exit
+
+            ! Wait for printer to be ready
+            do while (state /= 0)
+                !$omp flush(state)
+            end do
+
+            ! Send line to printer
+            shared_line = line
+            !$omp flush(shared_line)
+            !$omp atomic write
+            state = 1
+        end do
+
+        close(unit_num)
+
+        ! Wait for last line to be processed
+        do while (state == 1)
+            !$omp flush(state)
+        end do
+
+        ! Signal reading is done
+        !$omp atomic write
+        state = 2
+
+        ! Wait for count to be available
+        do while (state /= 3)
+            !$omp flush(state)
+        end do
+
+        !$omp flush(shared_count)
+        final_count = shared_count
+
+        print *, "Number of lines printed by printer thread:", final_count
+
+    end subroutine reader_thread
+
+    subroutine printer_thread()
+        character(len=256) :: line
+        integer :: count, current_state
+
+        count = 0
+
+        do
+            ! Wait for line or done signal
+            do
+                !$omp flush(state)
+                current_state = state
+                if (current_state /= 0) exit
+            end do
+
+            if (current_state == 2) exit  ! Reading done
+
+            ! Get and print line
+            !$omp flush(shared_line)
+            line = shared_line
+            count = count + 1
+            print *, trim(line)
+
+            ! Signal line processed
+            !$omp atomic write
+            state = 0
+        end do
+
+        ! Send count back to reader
+        shared_count = count
+        !$omp flush(shared_count)
+        !$omp atomic write
+        state = 3
+
+    end subroutine printer_thread
+
+end program concurrent_line_printer