move writing to REPL history file to behind a PID lock (#45450)

Should fix #37015

---------

Co-authored-by: KristofferC <[email protected]>
Co-authored-by: Ian Butterworth <[email protected]>
Co-authored-by: Matt Bauman <[email protected]>

Author: 4 people

stdlib/REPL/Project.toml

@@ -3,6 +3,7 @@ uuid = "3fa0cd96-eef1-5676-8a61-b3b8758bbffb"
 version = "1.11.0"
 
 [deps]
+FileWatching = "7b1f6079-737a-58dc-b8bc-7a2ca5c1b5ee"
 InteractiveUtils = "b77e0a4c-d291-57a0-90e8-8db25a27a240"
 JuliaSyntaxHighlighting = "ac6e5ff7-fb65-4e79-a425-ec3bc9c03011"
 Markdown = "d6f4376e-aef5-505a-96c1-9c027394607a"

stdlib/REPL/src/REPL.jl

@@ -41,6 +41,7 @@ end
 using Base.Meta, Sockets, StyledStrings
 using JuliaSyntaxHighlighting
 import InteractiveUtils
+import FileWatching
 
 export
     AbstractREPL,
@@ -927,7 +928,6 @@ function add_history(hist::REPLHistoryProvider, s::PromptState)
     # mode: $mode
     $(replace(str, r"^"ms => "\t"))
     """
-    # TODO: write-lock history file
     try
         seekend(hist.history_file)
     catch err
@@ -936,8 +936,15 @@ function add_history(hist::REPLHistoryProvider, s::PromptState)
         # If this doesn't fix it (e.g. when file is deleted), we'll end up rethrowing anyway
         hist_open_file(hist)
     end
-    print(hist.history_file, entry)
-    flush(hist.history_file)
+    if isfile(hist.file_path)
+        FileWatching.mkpidlock(hist.file_path  * ".pid", stale_age=3) do
+            print(hist.history_file, entry)
+            flush(hist.history_file)
+        end
+    else # handle eg devnull
+        print(hist.history_file, entry)
+        flush(hist.history_file)
+    end
     nothing
 end