thread number spec

.gitignore

@@ -0,0 +1,2 @@
+test/
+lazy-rebuild

lazy-rebuild.go

@@ -10,6 +10,8 @@ import (
 	"strings"
 	//"log"
 	"os"
+	"sync"
+	"strconv"
 )
 
 var keepLongExt bool = false
@@ -64,13 +66,21 @@ func dofile(i int, y string) {
 		fmt.Printf("(%d) %s -> %s\n", i, y, newname)
 	}
 }
+var maxThreads int = 0
 func main() {
 	ar := os.Args[1:];
+	var wg sync.WaitGroup
+	
 	if (len(ar) < 1) {
-		fmt.Printf("Usage: %s [--long] [--fake] [--recurse] [-quiet] <file ...>\n\t--long\tKeep long file extensions\n\t--fake\tDo not rename files.\n\t--recurse\tWalk path recursively.\n\t--quiet\tDo not show (some) errors.\n", os.Args[0])
+		fmt.Printf("Usage: %s [--long] [--fake] [--recurse] [-quiet] [--threads <number>] <file ...>\n\t--long\tKeep long file extensions\n\t--fake\tDo not rename files.\n\t--recurse\tWalk path recursively.\n\t--quiet\tDo not show (some) errors.\n", os.Args[0])
 		return;
 	}
+	var ignore = false
 	for i, x := range ar {
+		if ignore {
+			ignore=false
+			continue
+		}
 		if( strings.HasPrefix(x, "--")) {
 			switch x[2:] {
 			case "long":
@@ -81,6 +91,17 @@ func main() {
 				recurse = !recurse
 			case "quiet":
 				noErr = !noErr
+			case "threads":
+				if i<len(ar)-1 {
+					if th, err := strconv.Atoi(ar[i+1]); err ==nil {
+						maxThreads = th
+						ignore = true
+					} else {
+						fmt.Printf("Bad threads flag");
+					}
+				} else {
+					fmt.Printf("No threads flag")
+				}
 			default:
 				fmt.Printf("Unknown flag \"%s\"\n", x)
 			}
@@ -88,23 +109,50 @@ func main() {
 			if fi, err:= os.Stat(x); os.IsNotExist(err) {
 				fmt.Printf("(%d) %s does not exist.\n", i, x)	
 			} else {
+				var sem chan bool
+
+				if maxThreads >0 {
+					sem = make(chan bool, maxThreads)
+				}else {
+					sem = make(chan bool)
+				}
+
+				var _dofile = func(i int, s string) {
+					if maxThreads == 1 {
+						dofile(i,s)
+						return
+					}
+					wg.Add(1)
+					if(maxThreads>0) {
+						sem <- true
+					}
+					
+					go func() {
+						defer wg.Done()
+						dofile(i,s)
+						if(maxThreads>0) {
+							<-sem
+						}
+					}()
+				}
+
 				if(fi.Mode().IsDir()) {
 					if(recurse) {
 						filepath.Walk(x, func(path string, f os.FileInfo, err error) error {
 							if(!f.Mode().IsDir()) {
-								dofile(i,path)
+								_dofile(i,path)
 							}
 							return nil
 						})
 					} else {
 						files, err := ioutil.ReadDir(x)
 						if err != nil {
-							fmt.Printf("E: Error enumerating files: %s\n", err)
+							fmt.Printf("E: Error enumerating files in %s: %s\n", x, err)
 						} else {
 							for _, f := range files {
 								if(!f.Mode().IsDir()) {
 									fl := fmt.Sprintf("%s/%s", x, f.Name())
-									dofile(i,fl)
+									_dofile(i,fl)
 								} else {
 									fmt.Printf("!: Ignoring %s (is directory)\n", f.Name())
 								}
@@ -113,11 +161,14 @@ func main() {
 					}
 				} else {
 					
-					dofile(i, x)
+					_dofile(i, x)
 				}
+				close(sem)
+
 			}
 		}
 	}
+	wg.Wait()
 	return;
 	
 }