1 files changed, 40 insertions, 0 deletions
diff --git a/weed/util/limiter.go b/weed/util/limiter.go
index 2e5168d3d..ccdaa701e 100644
--- a/weed/util/limiter.go
+++ b/weed/util/limiter.go
@@ -7,6 +7,46 @@ import (
 	"sync/atomic"
 )
 
+// initial version comes from https://github.com/korovkin/limiter/blob/master/limiter.go
+
+// LimitedConcurrentExecutor object
+type LimitedConcurrentExecutor struct {
+	limit     int
+	tokenChan chan int
+}
+
+func NewLimitedConcurrentExecutor(limit int) *LimitedConcurrentExecutor {
+
+	// allocate a limiter instance
+	c := &LimitedConcurrentExecutor{
+		limit:     limit,
+		tokenChan: make(chan int, limit),
+	}
+
+	// allocate the tokenChan:
+	for i := 0; i < c.limit; i++ {
+		c.tokenChan <- i
+	}
+
+	return c
+}
+
+// Execute adds a function to the execution queue.
+// if num of go routines allocated by this instance is < limit
+// launch a new go routine to execute job
+// else wait until a go routine becomes available
+func (c *LimitedConcurrentExecutor) Execute(job func()) {
+	token := <-c.tokenChan
+	go func() {
+		defer func() {
+			c.tokenChan <- token
+		}()
+		// run the job
+		job()
+	}()
+}
+
+// a different implementation, but somehow more "conservative"
 type OperationRequest func()
 
 type LimitedOutOfOrderProcessor struct {