1 files changed, 90 insertions, 0 deletions
diff --git a/chan.go b/chan.go
new file mode 100644
index 0000000..65c79ba
--- /dev/null
+++ b/chan.go
@@ -0,0 +1,90 @@
+package gui
+
+// channel communication to the plugins
+// https://github.com/sourcegraph/conc
+// https://www.reddit.com/r/golang/comments/11x1oek/hello_gophers_show_me_your_concurrent_code/
+
+import (
+	// "regexp"
+	// "git.wit.org/wit/gui/toolkit"
+	"sync"
+	"github.com/sourcegraph/conc"
+	"github.com/sourcegraph/conc/stream"
+)
+
+func makeConc() {
+	var wg conc.WaitGroup
+	defer wg.Wait()
+
+	startTheThing(&wg)
+}
+
+func startTheThing(wg *conc.WaitGroup) {
+	wg.Go(func() {
+		log(debugNow, "startTheThing()")
+	})
+}
+
+func mapStream(
+    in chan int,
+    out chan int,
+    f func(int) int,
+) {
+    tasks := make(chan func())
+    taskResults := make(chan chan int)
+
+    // Worker goroutines
+    var workerWg sync.WaitGroup
+    for i := 0; i < 10; i++ {
+        workerWg.Add(1)
+        go func() {
+            defer workerWg.Done()
+            for task := range tasks {
+                task()
+            }
+        }()
+    }
+
+    // Ordered reader goroutines
+    var readerWg sync.WaitGroup
+    readerWg.Add(1)
+    go func() {
+        defer readerWg.Done()
+        for result := range taskResults {
+            item := <-result
+            out <- item
+        }
+    }()
+
+    // Feed the workers with tasks
+    for elem := range in {
+        resultCh := make(chan int, 1)
+        taskResults <- resultCh
+        tasks <- func() {
+            resultCh <- f(elem)
+        }
+    }
+
+    // We've exhausted input.
+    // Wait for everything to finish
+    close(tasks)
+    workerWg.Wait()
+    close(taskResults)
+    readerWg.Wait()
+}
+
+func mapStream2(
+    in chan int,
+    out chan int,
+    f func(int) int,
+) {
+    s := stream.New().WithMaxGoroutines(10)
+    for elem := range in {
+        elem := elem
+        s.Go(func() stream.Callback {
+            res := f(elem)
+            return func() { out <- res }
+        })
+    }
+    s.Wait()
+}