From 92944be3c3718095efa38e2a8db94844b1c7f739 Mon Sep 17 00:00:00 2001
From: Benoit Germain <benoit.germain@ubisoft.com>
Date: Tue, 28 May 2024 18:01:55 +0200
Subject: New Lanes finalizer API lanes.finally()

---
 tests/basic.lua     |  6 ++---
 tests/finalizer.lua | 70 ++++++++++++++++++++++++++++++++---------------------
 2 files changed, 46 insertions(+), 30 deletions(-)

(limited to 'tests')

diff --git a/tests/basic.lua b/tests/basic.lua
index cfe6fd5..ab8a080 100644
--- a/tests/basic.lua
+++ b/tests/basic.lua
@@ -485,6 +485,6 @@ end
 
 local nameof_type, nameof_name = lanes.nameof(print)
 PRINT("name of " .. nameof_type .. " print = '" .. nameof_name .. "'")
-
---
-io.stderr:write "Done! :)\n"
+-- install a finalizer that gets called upon Lanes's internal Universe is GCed.
+-- that way, we print our message after anything that can be output by lanes that are still running at that point
+lanes.finally(function() io.stderr:write "\n=======================================\nTEST OK\n" end)
diff --git a/tests/finalizer.lua b/tests/finalizer.lua
index 060e0a6..2acc39d 100644
--- a/tests/finalizer.lua
+++ b/tests/finalizer.lua
@@ -10,20 +10,22 @@
 
 local lanes = require "lanes"
 lanes.configure{with_timers=false}
+local finally = lanes.finally
 
-local FN= "finalizer-test.tmp"
+local FN = "finalizer-test.tmp"
 
 local cleanup
 
-local which= os.time() % 2  -- 0/1
-
-local function lane()
-
+local function lane(error_)
     set_finalizer(cleanup)
 
-    local f,err= io.open(FN,"w")
+    local st,err = pcall(finally, cleanup) -- should cause an error because called from a lane
+    assert(not st, "finally() should have thrown an error")
+    io.stderr:write("finally() raised error '", err, "'\n")
+
+    local f,err = io.open(FN,"w")
     if not f then
-        error( "Could not create "..FN..": "..err )
+        error( "Could not create "..FN..": "..err)
     end
 
     f:write( "Test file that should get removed." )
@@ -32,11 +34,10 @@ local function lane()
     -- don't forget to close the file immediately, else we won't be able to delete it until f is collected
     f:close()
 
-    if which==0 then
-        print "you loose"
-        error("aa")    -- exception here; the value needs NOT be a string
+    if error_ then
+        io.stderr:write("Raising ", tostring(error_), "\n")
+        error(error_, 0)    -- exception here; the value needs NOT be a string
     end
-
     -- no exception
 end
 
@@ -44,8 +45,8 @@ end
 -- This is called at the end of the lane; whether succesful or not.
 -- Gets the 'error()' parameter as parameter ('nil' if normal return).
 --
-cleanup= function(err)
-
+cleanup = function(err)
+    io.stderr:write "------------------------ In Worker Finalizer -----------------------\n"
     -- An error in finalizer will override an error (or success) in the main
     -- chunk.
     --
@@ -57,30 +58,45 @@ cleanup= function(err)
         io.stderr:write( "Cleanup after normal return\n" )
     end
         
-    local _,err2= os.remove(FN)
-    print( "file removal result: ", tostring( err2))
+    local _,err2 = os.remove(FN)
+    io.stderr:write( "file removal result: ", tostring(err2), "\n")
     assert(not err2)    -- if this fails, it will be shown in the calling script
                         -- as an error from the lane itself
     
     io.stderr:write( "Removed file "..FN.."\n" )
 end
 
-local lgen = lanes.gen("*", lane)
+-- we need error_trace_level above "minimal" to get a stack trace out of h:join()
+local lgen = lanes.gen("*", {error_trace_level = "basic"}, lane)
+
+local do_test = function(error_)
 
-io.stderr:write "Launching the lane!\n"
+    io.stderr:write "======================== Launching the lane! =======================\n"
 
-local h= lgen()
+    local h = lgen(error_)
 
-local _,err,stack= h:join()   -- wait for the lane (no automatic error propagation)
-if err then
-    assert(stack)
-    io.stderr:write( "Lane error: "..tostring(err).."\n" )
-    io.stderr:write( "\t", table.concat(stack,"\t\n"), "\n" )
+    local _,err,stack = h:join()   -- wait for the lane (no automatic error propagation)
+    if err then
+        assert(stack, "no stack trace on error, check 'error_trace_level'")
+        io.stderr:write( "Lane error: "..tostring(err).."\n" )
+        io.stderr:write( "\t", table.concat(stack,"\t\n"), "\n" )
+    end
 end
 
-local f= io.open(FN,"r")
-if f then
-    error( "CLEANUP DID NOT WORK: "..FN.." still exists!" )
+do_test(nil)
+do_test("An error")
+
+local on_exit = function()
+    finally(nil)
+    io.stderr:write "=========================In Lanes Finalizer! =======================\n"
+    local f = io.open(FN,"r")
+    if f then
+        error( "CLEANUP DID NOT WORK: "..FN.." still exists!" )
+    else
+        io.stderr:write(FN .. " was successfully removed\n")
+    end
+    io.stderr:write "Finished!\n"
 end
 
-io.stderr:write "Finished!\n"
+-- this function is called after script exit, when the state is closed
+lanes.finally(on_exit)
-- 
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