add: ipc: groundwork for graceful exits

Author: xTrayambak

src/components/ipc/shared.nim

@@ -270,6 +270,16 @@ type
     ## feJSWebSocketEvent
     feJSWebSocketEvent
 
+    ## feShutdown
+    ## The IPC server sends this to a process when it needs to close. The process doesn't need to actually close during the scenarios below:
+    ## - the renderer is busy laying out content during the exit
+    ## - the JavaScript runtime is executing an unrecoverable loop
+    ## - the HTML/CSS parser is deadlocked due to a bug
+    ## - the network process is fetching some content
+    ## 
+    ## It's more of a hint to start cleaning up, as the IPC server will soonly after call `kill(2)` on the process.
+    feGoodbye
+
   DataTransferRequest* = ref object
     kind: FerusMagic = feDataTransferRequest
 
@@ -281,11 +291,14 @@ type
 
     success*: bool
     data*: string
-
+  
   # TODO: might wanna move these into their own file
   HandshakePacket* = ref object
     kind: FerusMagic = feHandshake
     process*: FerusProcess
+  
+  GoodbyePacket* = object
+    kind: FerusMagic = feGoodbye
 
   ExitReason* = enum
     erUnknown ## Unhandled crash, most likely.

src/components/master/master.nim

@@ -1,4 +1,4 @@
-import std/[os, logging, osproc, strutils, options, base64, net, sets, terminal, tables]
+import std/[os, logging, osproc, strutils, options, base64, net, sets, terminal, posix, tables]
 import ../../components/ipc/server/prelude
 import jsony
 import ./summon
@@ -408,6 +408,20 @@ proc onConsoleLog*(
     resetStyle,
   )
 
+proc requestShutdown*(master: MasterProcess, process: FerusProcess) =
+  info "Requesting shutdown for "  & $process.kind & " process (PID " & $process.pid & ")"
+  master.server.send(process.socket, GoodbyePacket())
+
+proc cleanupAllProcesses*(master: MasterProcess) =
+  for group in master.server.groups:
+    for process in group:
+      master.requestShutdown(process)
+
+  for group in master.server.groups:
+    for process in group:
+      if kill(process.pid.Pid, SIGKILL) != 0:
+        error "An error occured whilst killing child process: " & $strerror(errno)
+
 proc packetHandler*(
     master: MasterProcess, process: FerusProcess, kind: FerusMagic, data: string
 ) =
@@ -493,6 +507,15 @@ proc packetHandler*(
       return
 
     master.server.send(process.socket, &resp)
+  of feRendererExit:
+    if process.kind != Renderer:
+      master.server.reportBadMessage(
+        process,
+        "Non-renderer process sent `feRendererExit` opcode",
+        High
+      )
+
+    debug "The renderer has shut down."
   else:
     warn "Unhandled IPC protocol magic: " & $kind
     return

src/components/renderer/core.nim

@@ -62,6 +62,7 @@ proc close*(renderer: FerusRenderer) {.inline.} =
   info "Closing renderer."
 
   destroy renderer.window
+  renderer.ipc.send(RendererExit()) # tell the IPC server we're exiting.
   glfw.terminate()
 
 proc setWindowTitle*(renderer: FerusRenderer, title: string) {.inline.} =

src/components/renderer/ipc.nim

@@ -1,8 +1,8 @@
 import std/base64
-
-import ../../components/ipc/shared, vmath
-from ferusgfx import Scene
-import ferusgfx/displaylist
+import ../../components/ipc/shared
+import pkg/vmath
+from pkg/ferusgfx import Scene
+import pkg/ferusgfx/displaylist
 
 import ../parsers/html/document
 
@@ -23,25 +23,28 @@ type
     of GIFNode:
       gifContent*: string
 
-  RendererMutationPacket* = ref object
+  RendererMutationPacket* = object
     kind: FerusMagic = feRendererMutation
     list*: IPCDisplayList
 
-  RendererLoadFontPacket* = ref object
+  RendererLoadFontPacket* = object
     kind: FerusMagic = feRendererLoadFont
     name*, content*, format*: string
 
-  RendererSetWindowTitle* = ref object
+  RendererSetWindowTitle* = object
     kind: FerusMagic = feRendererSetWindowTitle
     title*: string
 
-  RendererRenderDocument* = ref object
+  RendererRenderDocument* = object
     kind: FerusMagic = feRendererRenderDocument
     document*: HTMLDocument
 
-  RendererGotoURL* = ref object
+  RendererGotoURL* = object
     kind: FerusMagic = feRendererGotoURL
     url*: string
+  
+  RendererExit* = object
+    kind: FerusMagic = feRendererExit
 
   IPCDisplayList* = GDisplayList[Drawable] ## IPC display list
 

src/components/renderer/process.nim

@@ -163,5 +163,5 @@ proc renderProcessLogic*(client: var IPCClient, process: FerusProcess) {.inline.
   while not renderer.shouldClose:
     client.talk(renderer, process)
     renderer.tick()
-
+  
   close renderer