Made Building happen async and in multiple process (#53)

* Use startprocess and async to make building faster
* write log file on error
* Logged error files should be chronological.
* Clean up async dispatch for building

.gitignore

@@ -2,4 +2,5 @@ docs/*
 examplebook/my*
 nbook
 nbook.exe
-x_*
+x_*
+*.log

src/nimibook/builds.nim

@@ -1,17 +1,28 @@
-import std / [os, strutils]
+import std / [os, strutils, asyncdispatch, osproc, streams, sugar]
 import nimibook / [types, commands, themes]
 import nimib
 
-proc buildNim*(entry: Entry, srcDir: string, nimOptions: seq[string]): bool =
+proc buildNim*(entry: Entry, srcDir: string, nimOptions: seq[string]): Future[bool] {.async.} =
   let
     cmd = "nim"
     args = @["r"] & nimOptions & @[srcDir / entry.path]
   # "-d:release", "-f", "--verbosity:0", "--hints:off"
   debugEcho "[Executing] ", cmd, " ", args.join(" ")
-  if execShellCmd(cmd & " " & args.join(" ")) != 0:
-    echo "[nimibook.error] error while processing ", entry.path
-    return false
-  return true
+
+  let process = startProcess(cmd, args = args, options = {poUsePath, poStdErrToStdOut})
+  defer: process.close()
+  while process.running():
+    await sleepAsync(10)
+
+  result = process.peekexitCode == 0
+  if not result:
+    # Process failed so we write a '.log'
+    let logPath = entry.path.changeFileExt("log")
+    discard tryRemoveFile(logPath)
+    let fs = openFileStream(logPath, fmWrite)
+    defer: fs.close()
+    for line in process.lines:
+      fs.writeLine(line)
 
 proc buildMd*(entry: Entry): bool =
   try:
@@ -24,25 +35,36 @@ proc buildMd*(entry: Entry): bool =
     echo "[nimibook.error] error while processing ", entry.path
     return false
 
-proc build*(entry: Entry, srcDir: string, nimOptions: seq[string]): bool =
+proc build*(entry: Entry, srcDir: string, nimOptions: seq[string]): Future[bool] {.async.} =
   let splitted = entry.path.splitFile()
-  if splitted.ext == ".nim":
-    return buildNim(entry, srcDir, nimOptions)
-  elif splitted.ext == ".md":
+  case splitted.ext
+  of ".nim":
+    return await buildNim(entry, srcDir, nimOptions)
+  of ".md":
     return buildMd(entry)
   else:
     echo "[nimibook.error] invalid file extension (must be one of .nim, .md): ", splitted.ext
     return false
 
 proc build*(book: Book, nimOptions: seq[string] = @[]) =
-  var buildErrors: seq[string]
+  var
+    buildErrors: seq[string]
+    buildFutures: seq[Future[bool]]
   dump book
-  for entry in book.toc.entries:
+  for i in 0..book.toc.entries.high:
+    let entry = book.toc.entries[i] # use index since `items` returns `lent` in `1.7.x+`
     if entry.isDraft:
       continue
     echo "[nimibook] build entry: ", entry.path
-    if not build(entry, book.srcDir, nimOptions):
-      buildErrors.add entry.path
+    buildFutures.add build(entry, book.srcDir, nimOptions)
+    closureScope:
+      let path = entry.path
+      buildFutures[^1].addCallback do (f: Future[bool]):
+        if not f.read():
+          buildErrors.add path
+
+  discard waitFor all buildFutures
+
   if len(buildErrors) > 0:
     echo "[nimibook.error] ", len(buildErrors), " build errors:"
     for err in buildErrors:

src/nimibook/commands.nim

@@ -4,6 +4,7 @@ import jsony
 
 proc dump*(book: Book) =
   var book = book
+  discard existsOrCreateDir(book.homeDir())
   let uri = normalizedPath(book.homeDir / "book.json")
   echo "[nimibook] dumping ", uri
   writeFile(uri, book.toJson)