add parallelism [pre] section run before all other | update readme accordingly

README.md

@@ -235,17 +235,13 @@ $ nix-amer -p apt-get myserver.build
 _myserver.build_
 
 ```
-[ comment starts with opening brackets '['
-
-[aliases]
-alias sshd  /etc/ssh/sshd_config
+# [pre] is executed before launching everything else
+[pre]
+install nginx ssh sslh
 alias nginx /etc/nginx/nginx.conf
+alias sshd  /etc/ssh/sshd_config
 alias sslh  /etc/default/sslh
 
-[install packages]
-install nginx ssh
-install sslh
-
 [nginx]
 set nginx@http.gzip           off
 service enable nginx

internal/buildfile/reader.go

@@ -9,6 +9,7 @@ import (
 	"io"
 	"regexp"
 	"strings"
+	"sync"
 	"time"
 )
 
@@ -125,10 +126,18 @@ func (r *Reader) Execute() error {
 	// 	return fmt.Errorf("cannot upgrade | %s", err)
 	// }
 	refresh := make(chan bool, 1)
+	wg := new(sync.WaitGroup)
+	wgstatus := new(sync.WaitGroup)
 
-	// 1. create status table
+	// 1. create status table + extract [pre] section if one
 	table := make([]tableSection, 0)
+	index := make(map[string]int, 0)
+
+	var pre *[]instruction.T = nil
+	var preTable *tableSection = nil
+
 	for secname, sec := range r.Content {
+
 		tableSec := tableSection{
 			name:         secname,
 			instructions: make([]execStatus, len(*sec), len(*sec)+1),
@@ -137,39 +146,69 @@ func (r *Reader) Execute() error {
 		// for each instruction
 		for i, inst := range *sec {
 			tableSec.instructions[i].name = inst.Raw()
-			tableSec.instructions[i].start = time.Now()
 		}
 
 		table = append(table, tableSec)
-		go execSection(sec, *r.Context, refresh, &table[len(table)-1])
+		index[secname] = len(table) - 1
+
+		// [pre] section
+		if secname == "pre" {
+			pre = sec
+			preTable = &tableSec
+		}
+
+		// add one section
+		wg.Add(len(*sec))
 
 	}
 
-	// 2. create status updater
-	go status(refresh, table)
-	time.Sleep(time.Second * 10)
+	// 2. launch status updater
+	wgstatus.Add(1)
+	go status(table, refresh, wgstatus)
+
+	// 3. launch [pre] (it set)
+	if pre != nil {
+		execSection(pre, *r.Context, preTable, refresh, wg)
+		time.Sleep(time.Second * 2)
+	}
+
+	// 4. launch each other section
+	for secname, sec := range r.Content {
+		// do not launch pre again
+		if secname == "pre" {
+			continue
+		}
+		i, ok := index[secname]
+		if !ok {
+			continue
+		}
+		go execSection(sec, *r.Context, &table[i], refresh, wg)
+	}
+
+	wg.Wait()
 	close(refresh)
+	wgstatus.Wait()
 
 	return nil
 }
 
-func execSection(section *[]instruction.T, ctx instruction.ExecutionContext, refresher chan<- bool, tsec *tableSection) {
+func execSection(section *[]instruction.T, ctx instruction.ExecutionContext, tsec *tableSection, refresher chan<- bool, wg *sync.WaitGroup) {
 
 	for i, inst := range *section {
+		tsec.instructions[i].start = time.Now()
 		_, err := inst.Exec(ctx)
 		tsec.instructions[i].stop = time.Now()
 		tsec.instructions[i].stopped = true
 		tsec.instructions[i].err = err
 		refresher <- true
+		wg.Done()
 	}
 
 }
 
-func status(refresher chan bool, table []tableSection) {
-	fmt.Printf("status\n")
-	remain := false
+func status(table []tableSection, refresher <-chan bool, wg *sync.WaitGroup) {
 
-	for <-refresher {
+	for opened := true; true; _, opened = <-refresher {
 
 		// 1. clean screen
 		fmt.Printf("\033[H\033[2J")
@@ -185,7 +224,6 @@ func status(refresher chan bool, table []tableSection) {
 				if !inst.stopped {
 					clifmt.Align(fmt.Sprintf("(%d) %s", i, clifmt.Color(0, inst.name)))
 					fmt.Printf("%s\n", clifmt.Color(33, "processing"))
-					remain = true
 					continue
 				}
 
@@ -201,11 +239,12 @@ func status(refresher chan bool, table []tableSection) {
 			}
 		}
 
-		// 4. close refresher if no remaining task
-		if !remain {
+		if !opened {
 			break
 		}
 
 	}
 
+	wg.Done()
+
 }