From 37415a15e43d9b087e860f8223188ac4c2070c73 Mon Sep 17 00:00:00 2001
From: Martin <mautner@vrvis.at>
Date: Thu, 6 Jul 2023 11:33:42 +0200
Subject: [PATCH] [Debugger] Enable file watchers on demand due to inotify
 limit on Linux

---
 src/Libs/FShade.Debug/Debugger.fs     |  4 +++-
 src/Libs/FShade.Debug/FileWatchers.fs | 21 ++++++++++++++++++++-
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/src/Libs/FShade.Debug/Debugger.fs b/src/Libs/FShade.Debug/Debugger.fs
index b974c13..4f22e97 100644
--- a/src/Libs/FShade.Debug/Debugger.fs
+++ b/src/Libs/FShade.Debug/Debugger.fs
@@ -235,7 +235,9 @@ module ShaderDebugger =
                                 Report.Line(2, $"{definition} - {definition.Location}")
 
                                 success <- true
-                                projects.[definition.Project].Callbacks.Add update
+                                let project = projects.[definition.Project]
+                                project.Callbacks.Add update
+                                FileWatchers.activate project.Data
                                 shaderCache.[id] <- (definition, cval)
                                 string definition, cval
 
diff --git a/src/Libs/FShade.Debug/FileWatchers.fs b/src/Libs/FShade.Debug/FileWatchers.fs
index 4312929..cda96b4 100644
--- a/src/Libs/FShade.Debug/FileWatchers.fs
+++ b/src/Libs/FShade.Debug/FileWatchers.fs
@@ -2,6 +2,7 @@
 
 open System.IO
 open System.Collections.Generic
+open Aardvark.Base
 
 module internal FileWatchers =
 
@@ -19,7 +20,6 @@ module internal FileWatchers =
                 | (true, w) -> w
                 | _ ->
                     let w = new FileSystemWatcher(dir)
-                    w.EnableRaisingEvents <- true
                     watchers.[dir] <- w
                     w
 
@@ -27,6 +27,25 @@ module internal FileWatchers =
             watcher.Renamed.Add (fun e -> if Set.contains e.FullPath files then callback e.FullPath)
             watcher.Created.Add (fun e -> if Set.contains e.FullPath files then callback e.FullPath)
 
+    // Enables the file watchers for the given project.
+    // On Linux there is a limit on how many file watcher can be active so we only activate them on demand.
+    // See: https://travisgosselin.com/configured-user-limit-inotify-instances/
+    let activate (project : ProjectData) =
+        let directories =
+            project.Files
+            |> List.map Path.GetDirectoryName
+            |> List.distinct
+
+        for dir in directories do
+            match watchers.TryGetValue dir with
+            | (true, w) ->
+                try
+                    w.EnableRaisingEvents <- true
+                with exn ->
+                    Log.warn "[FShade] Could not enable file watcher for directory '%s': %s" dir exn.Message
+            | _ ->
+                Log.warn "[FShade] File watcher for directory '%s' not found" dir
+
     let dispose() =
         for w in watchers.Values do w.Dispose()
         watchers.Clear()
\ No newline at end of file