5 files changed, 23 insertions, 25 deletions

diff --git a/src/cancel.cpp b/src/cancel.cpp
index 755215f..15a2c83 100644
--- a/src/cancel.cpp
+++ b/src/cancel.cpp
@@ -95,6 +95,8 @@ CancelOp WhichCancelOp(std::string_view const& opString_)
         _op = CancelOp::MaskLine;
     } else if (opString_ == "count") {
         _op = CancelOp::MaskCount;
+    } else if (opString_ == "all") {
+        _op = CancelOp::MaskAll;
     }
     return _op;
 }
diff --git a/src/cancel.h b/src/cancel.h
index 93fae4d..e62cf0a 100644
--- a/src/cancel.h
+++ b/src/cancel.h
@@ -29,6 +29,7 @@ enum class CancelOp
     MaskRet = LUA_MASKRET,
     MaskLine = LUA_MASKLINE,
     MaskCount = LUA_MASKCOUNT,
+    MaskAll = LUA_MASKCALL | LUA_MASKRET | LUA_MASKLINE | LUA_MASKCOUNT
 };
 
 // xxh64 of string "kCancelError" generated at https://www.pelock.com/products/hash-calculator
diff --git a/src/lanes.lua b/src/lanes.lua
index 48ebeb6..d28fcf4 100644
--- a/src/lanes.lua
+++ b/src/lanes.lua
@@ -98,7 +98,6 @@ local default_params =
     keepers_gc_threshold = -1,
     nb_user_keepers = 0,
     on_state_create = nil,
-    shutdown_mode = "hard",
     shutdown_timeout = 0.25,
     strip_functions = true,
     track_lanes = false,
@@ -159,14 +158,6 @@ local param_checkers =
         end
         return true
     end,
-    shutdown_mode = function(val_)
-        local valid_hooks = { soft = true, hard = true, call = true, ret = true, line = true, count = true }
-        -- shutdown_mode should be a known hook mask
-        if not valid_hooks[val_] then
-            return nil, "unknown value"
-        end
-        return true
-    end,
     shutdown_timeout = function(val_)
         -- shutdown_timeout should be a number in [0,3600]
         if type(val_) ~= "number" then
diff --git a/src/universe.cpp b/src/universe.cpp
index 1cb4fd0..5fda29a 100644
--- a/src/universe.cpp
+++ b/src/universe.cpp
@@ -147,8 +147,7 @@ void Universe::callOnStateCreate(lua_State* const L_, lua_State* const from_, Lo
     DEBUGSPEW_CODE(DebugSpewIndentScope _scope{ _U });
     lua_createtable(L_, 0, 1);                                                                     // L_: settings universe {mt}
     std::ignore = luaG_getfield(L_, 1, "shutdown_timeout");                                        // L_: settings universe {mt} shutdown_timeout
-    std::ignore = luaG_getfield(L_, 1, "shutdown_mode");                                           // L_: settings universe {mt} shutdown_timeout shutdown_mode
-    lua_pushcclosure(L_, LG_universe_gc, 2);                                                       // L_: settings universe {mt} LG_universe_gc
+    lua_pushcclosure(L_, LG_universe_gc, 1);                                                       // L_: settings universe {mt} LG_universe_gc
     lua_setfield(L_, -2, "__gc");                                                                  // L_: settings universe {mt}
     lua_setmetatable(L_, -2);                                                                      // L_: settings universe
     lua_pop(L_, 1);                                                                                // L_: settings
@@ -352,7 +351,7 @@ lanes::AllocatorDefinition Universe::resolveAllocator(lua_State* const L_, std::
 
 // #################################################################################################
 
-void Universe::terminateFreeRunningLanes(lua_State* const L_, lua_Duration const shutdownTimeout_, CancelOp const op_)
+bool Universe::terminateFreeRunningLanes(lua_Duration const shutdownTimeout_, CancelOp const op_)
 {
     if (selfdestructFirst != SELFDESTRUCT_END) {
         // Signal _all_ still running threads to exit (including the timer thread)
@@ -404,15 +403,8 @@ void Universe::terminateFreeRunningLanes(lua_State* const L_, lua_Duration const
         }
     }
 
-    // If after all this, we still have some free-running lanes, it's an external user error, they should have stopped appropriately
-    {
-        std::lock_guard<std::mutex> _guard{ selfdestructMutex };
-        Lane* _lane{ selfdestructFirst };
-        if (_lane != SELFDESTRUCT_END) {
-            // this causes a leak because we don't call U's destructor (which could be bad if the still running lanes are accessing it)
-            raise_luaL_error(L_, "Zombie thread '%s' refuses to die!", _lane->debugName.data());
-        }
-    }
+    // are all lanes successfully terminated?
+    return selfdestructFirst == SELFDESTRUCT_END;
 }
 
 // #################################################################################################
@@ -421,15 +413,21 @@ void Universe::terminateFreeRunningLanes(lua_State* const L_, lua_Duration const
 LUAG_FUNC(universe_gc)
 {
     lua_Duration const _shutdown_timeout{ lua_tonumber(L_, lua_upvalueindex(1)) };
-    std::string_view const _op_string{ luaG_tostring(L_, lua_upvalueindex(2)) };
     STACK_CHECK_START_ABS(L_, 1);
     Universe* const _U{ luaG_tofulluserdata<Universe>(L_, 1) };                                    // L_: U
-    _U->terminateFreeRunningLanes(L_, _shutdown_timeout, WhichCancelOp(_op_string));
+
+    // attempt to terminate all lanes with increasingly stronger cancel methods
+    bool const _allLanesTerminated{ 
+        _U->terminateFreeRunningLanes(_shutdown_timeout, CancelOp::Soft)
+        || _U->terminateFreeRunningLanes(_shutdown_timeout, CancelOp::Hard)
+        || _U->terminateFreeRunningLanes(_shutdown_timeout, CancelOp::MaskAll)
+    };
 
     // invoke the function installed by lanes.finally()
     kFinalizerRegKey.pushValue(L_);                                                                // L_: U finalizer|nil
     if (!lua_isnil(L_, -1)) {
-        lua_pcall(L_, 0, 0, 0);                                                                    // L_: U
+        lua_pushboolean(L_, _allLanesTerminated);                                                  // L_: U finalizer bool
+        lua_pcall(L_, 1, 0, 0);                                                                    // L_: U
         // discard any error that might have occured
         lua_settop(L_, 1);
     } else {
@@ -438,6 +436,12 @@ LUAG_FUNC(universe_gc)
     // in case of error, the message is pushed on the stack
     STACK_CHECK(L_, 1);
 
+    // if some lanes are still running here, we have no other choice than crashing and let the client figure out what's wrong
+    while (_U->selfdestructFirst != SELFDESTRUCT_END) {
+        throw std::logic_error{ "Some lanes are still running at shutdown" };
+        //std::this_thread::yield();
+    }
+
     // no need to mutex-protect this as all threads in the universe are gone at that point
     if (_U->timerLinda != nullptr) { // test in case some early internal error prevented Lanes from creating the deep timer
         [[maybe_unused]] int const _prev_ref_count{ _U->timerLinda->refcount.fetch_sub(1, std::memory_order_relaxed) };
diff --git a/src/universe.h b/src/universe.h
index 6374648..dc8940f 100644
--- a/src/universe.h
+++ b/src/universe.h
@@ -139,7 +139,7 @@ class Universe
     void initializeOnStateCreate(lua_State* const L_);
     lanes::AllocatorDefinition resolveAllocator(lua_State* const L_, std::string_view const& hint_) const;
     static inline void Store(lua_State* L_, Universe* U_);
-    void terminateFreeRunningLanes(lua_State* L_, lua_Duration shutdownTimeout_, CancelOp op_);
+    [[nodiscard]] bool terminateFreeRunningLanes(lua_Duration shutdownTimeout_, CancelOp op_);
 };
 
 // #################################################################################################