added option to not start async process immediately

src/misc/async_process.nim

@@ -5,6 +5,7 @@ logCategory "asyncprocess"
 
 type AsyncChannel*[T] = ref object
   chan: ptr Channel[T]
+  closed: bool
 
 type AsyncProcess* = ref object
   name: string
@@ -137,6 +138,42 @@ proc recvLine*[T: char](achan: AsyncChannel[T]): Future[string] {.async.} =
 
   return ""
 
+proc tryRecvLine*[T: char](achan: AsyncChannel[T]): Future[Option[string]] {.async.} =
+  if achan.closed:
+    return string.none
+
+  var buffer = ""
+
+  var cr = false
+  while not achan.chan.isNil:
+    while not achan.chan.isNil:
+      let (hasData, c) = achan.chan[].tryRecv
+      if not hasData:
+        continue
+
+      if c == '\0':
+        achan.closed = true
+
+        if buffer.len > 0:
+          return buffer.some
+        else:
+          return string.none
+
+      if c != '\r' and c != '\n':
+        cr = false
+        buffer.add c
+      elif c == '\r':
+        cr = true
+      elif c == '\n':
+        if cr and buffer.len == 0:
+          return "\r\n".some
+        cr = false
+        return buffer.some
+
+    await sleepAsync 1
+
+  return string.none
+
 proc send*[T](achan: AsyncChannel[Option[T]], data: T) {.async.} =
   while not achan.chan[].trySend(data.some):
     await sleepAsync 1
@@ -155,6 +192,11 @@ proc recvLine*(process: AsyncProcess): Future[string] =
     return result
   return process.input.recvLine()
 
+proc tryRecvLine*(process: AsyncProcess): Future[Option[string]] {.async.} =
+  if process.input.isNil or process.input.chan.isNil:
+    return string.none
+  return process.input.tryRecvLine().await
+
 proc recvErrorLine*(process: AsyncProcess): Future[string] =
   if process.error.isNil or process.error.chan.isNil:
     result = newFuture[string]("recvError")
@@ -225,6 +267,25 @@ proc writeOutput(chan: ptr Channel[Stream], data: ptr Channel[Option[string]]):
 
   return true
 
+proc start*(process: AsyncProcess): bool =
+  log(lvlInfo, fmt"start process {process.name} {process.args}")
+  try:
+    process.process = startProcess(process.name, args=process.args, options={poUsePath, poDaemon})
+  except CatchableError as e:
+    log(lvlError, fmt"Failed to start {process.name}: {e.msg}")
+    return false
+
+  process.readerFlowVar = spawn(readInput(process.inputStreamChannel, process.serverDiedNotifications, process.input.chan, process.output.chan))
+  process.inputStreamChannel[].send process.process.outputStream()
+
+  process.errorReaderFlowVar = spawn(readInput(process.errorStreamChannel, process.serverDiedNotifications, process.error.chan, process.output.chan))
+  process.errorStreamChannel[].send process.process.errorStream()
+
+  process.writerFlowVar = spawn(writeOutput(process.outputStreamChannel, process.output.chan))
+  process.outputStreamChannel[].send process.process.inputStream()
+
+  return true
+
 proc restartServer(process: AsyncProcess) {.async.} =
   var startCounter = 0
 
@@ -243,26 +304,14 @@ proc restartServer(process: AsyncProcess) {.async.} =
 
     inc startCounter
 
-    log(lvlInfo, fmt"start process {process.name} {process.args}")
-    try:
-      process.process = startProcess(process.name, args=process.args, options={poUsePath, poDaemon})
-    except CatchableError as e:
-      log(lvlError, fmt"Failed to start {process.name}: {e.msg}")
+    if not process.start():
       break
 
-    process.readerFlowVar = spawn(readInput(process.inputStreamChannel, process.serverDiedNotifications, process.input.chan, process.output.chan))
-    process.inputStreamChannel[].send process.process.outputStream()
-
-    process.errorReaderFlowVar = spawn(readInput(process.errorStreamChannel, process.serverDiedNotifications, process.error.chan, process.output.chan))
-    process.errorStreamChannel[].send process.process.errorStream()
-
-    process.writerFlowVar = spawn(writeOutput(process.outputStreamChannel, process.output.chan))
-    process.outputStreamChannel[].send process.process.inputStream()
-
     if not process.onRestarted.isNil:
       process.onRestarted().await
 
-proc startAsyncProcess*(name: string, args: seq[string] = @[], autoRestart = true): AsyncProcess =
+
+proc startAsyncProcess*(name: string, args: seq[string] = @[], autoRestart = true, autoStart = true): AsyncProcess =
   let process = AsyncProcess()
   process.name = name
   process.args = @args
@@ -283,7 +332,8 @@ proc startAsyncProcess*(name: string, args: seq[string] = @[], autoRestart = tru
   process.serverDiedNotifications = cast[ptr Channel[bool]](allocShared0(sizeof(Channel[bool])))
   process.serverDiedNotifications[].open()
 
-  asyncCheck process.restartServer()
-  process.serverDiedNotifications[].send true
+  if autoStart:
+    asyncCheck process.restartServer()
+    process.serverDiedNotifications[].send true
 
-  return process
+  return process