implements new video update using lazy lists

lists.go

@@ -6,6 +6,7 @@ type listLazy struct {
 	dry     bool
 	state   int
 	content []*videoContainer
+	par     int
 }
 
 // listUpdateChunk concurrently runs the lists update function and
@@ -18,9 +19,19 @@ func (l *listLazy) listUpdateChunk(state int) chan []*videoContainer {
 	return chn
 }
 
-// listNew creates a new lazy list with the given update function.
+// listNew creates a new lazy list with the given update function and a
+// parallel update count of 5.
 func listNew(update func(int) []*videoContainer) *listLazy {
-	return &listLazy{update, false, 0, []*videoContainer{}}
+	return &listLazy{update, false, 0, []*videoContainer{}, 5}
+}
+
+// listPar sets the number of parallel update functions to be executed on each
+// triggered list update. The count is always >= 1.
+func (l *listLazy) listPar(count int) {
+	if count < 1 {
+		count = 1
+	}
+	l.par = count
 }
 
 // listGet returns the element with the given index from the list. If
@@ -28,9 +39,8 @@ func listNew(update func(int) []*videoContainer) *listLazy {
 // the requested element is available. If the element could not be acquired
 // nil is returned.
 func (l *listLazy) listGet(index int) *videoContainer {
-	par := 5 // parallel update count
 	for index >= len(l.content) && !l.dry {
-		temp := make([]chan []*videoContainer, par)
+		temp := make([]chan []*videoContainer, l.par)
 
 		for i, _ := range temp {
 			temp[i] = l.listUpdateChunk(l.state + i)
@@ -53,7 +63,12 @@ func (l *listLazy) listGet(index int) *videoContainer {
 	return nil
 }
 
-// listLazy tries to return the requested slice from the list. If the
+// listCached returns all cached entries of the underlying list slice.
+func (l *listLazy) listCached() []*videoContainer {
+	return l.content
+}
+
+// listSlice tries to return the requested slice from the list. If the
 // list is too short the lists update function will be called until
 // the length is sufficient. If the list is too small, a smaller slice
 // then requested may be returned.

logic.go

@@ -9,7 +9,6 @@ import (
 	"sort"
 	"strconv"
 	"strings"
-	"sync"
 )
 
 // maps user input to events
@@ -266,43 +265,25 @@ func logicUserPage(user string, page int) {
 func logicNew(none string) {
 	logicVarWindow = logicWindowSearch
 	logicVarSearch = ""
-	videos := []*videoContainer{}
 	users := logicGetUsers()
-	lock := &sync.Mutex{}
-	barrier := &sync.WaitGroup{}
-	barrier.Add(len(users))
-
-	for i, user := range users {
-
-		// put into scope
-		user := user
-		i := i
-		go func() {
-			list := videoListUser(user)
-			cliHome()
-			fmt.Println()
-			lock.Lock()
-
-			cliStatus("updating users (" + strconv.Itoa(i+1) + "/" + strconv.Itoa(len(users)) + ")")
-			videos = append(videos, list...)
-
-			lock.Unlock()
-			barrier.Done()
-		}()
+
+	upd := func(state int) []*videoContainer {
+		if state < len(users) {
+			return videoListUser(users[state])
+		}
+		return nil // all users updated (wont occur in reality)
 	}
-	barrier.Wait()
+
+	logicVarLazy = listNew(upd)
+	cliStatus("updating users ...")
+	logicVarLazy.listPar(len(users))
+	logicVarLazy.listGet(0) // downloads all user pages as par = len(users)
 
 	cliHome()
 	fmt.Println()
 	cliStatus("sorting ...")
-	sort.Sort(&videoSort{videos})
+	sort.Sort(&videoSort{logicVarLazy.listCached()})
 
-	upd := func(state int) []*videoContainer {
-		all := videos
-		videos = nil
-		return all
-	}
-	logicVarLazy = listNew(upd)
 	logicSearchPage("new videos", 0)
 }