Merge pull request #31 from chrislusf/master

sync

2 files changed, 53 insertions, 0 deletions

diff --git a/weed/util/bytes.go b/weed/util/bytes.go
index 67e6876fa..c2a4df108 100644
--- a/weed/util/bytes.go
+++ b/weed/util/bytes.go
@@ -1,6 +1,7 @@
 package util
 
 import (
+	"bytes"
 	"crypto/md5"
 	"crypto/rand"
 	"encoding/base64"
@@ -148,3 +149,15 @@ func RandomBytes(byteCount int) []byte {
 	rand.Read(buf)
 	return buf
 }
+
+type BytesReader struct {
+	Bytes []byte
+	*bytes.Reader
+}
+
+func NewBytesReader(b []byte) *BytesReader {
+	return &BytesReader{
+		Bytes:  b,
+		Reader: bytes.NewReader(b),
+	}
+}
diff --git a/weed/util/limiter.go b/weed/util/limiter.go
new file mode 100644
index 000000000..91499632c
--- /dev/null
+++ b/weed/util/limiter.go
@@ -0,0 +1,40 @@
+package util
+
+// 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()
+	}()
+}