From 4695cbe96514e6b174fb5050bb2e9a41514091f3 Mon Sep 17 00:00:00 2001
From: Benoit Germain <benoit.germain@ubisoft.com>
Date: Tue, 4 Jun 2024 15:00:06 +0200
Subject: Refactored keeper implementation of linda:limit()

---
 src/keeper.cpp | 54 +++++++++++++++++++++++++++++++-----------------------
 1 file changed, 31 insertions(+), 23 deletions(-)

diff --git a/src/keeper.cpp b/src/keeper.cpp
index 1779ab3..a546868 100644
--- a/src/keeper.cpp
+++ b/src/keeper.cpp
@@ -77,17 +77,31 @@ class KeyUD
     // can't actually delete the operator because the compiler generates stack unwinding code that could call it in case of exception
     static void operator delete([[maybe_unused]] void* p_, [[maybe_unused]] KeeperState L_) { LUA_ASSERT(L_, !"should never be called"); }
 
-    [[nodiscard]] static KeyUD* GetPtr(KeeperState K_, int idx_);
+    [[nodiscard]] bool changeLimit(int limit_);
     [[nodiscard]] static KeyUD* Create(KeeperState K_);
-    void prepareAccess(KeeperState K_);
+    [[nodiscard]] static KeyUD* GetPtr(KeeperState K_, int idx_);
     void peek(KeeperState K_, int count_);
     void pop(KeeperState K_, int count_);
+    void prepareAccess(KeeperState K_);
     void push(KeeperState K_, int count_);
     [[nodiscard]] bool reset(KeeperState K_);
 };
 
 // #################################################################################################
 
+bool KeyUD::changeLimit(int const limit_)
+{
+    bool const _newSlackAvailable{
+        ((limit >= 0) && (count >= limit)) // then: the key was full if limited and count exceeded the previous limit
+        && ((limit_ < 0) || (count < limit_)) // now: the key is not full if unlimited or count is lower than the new limit
+    };
+    // set the new limit
+    limit = limit_;
+    return _newSlackAvailable;
+}
+
+// #################################################################################################
+
 // in: nothing
 // out: { first = 1, count = 0, limit = -1}
 KeyUD* KeyUD::Create(KeeperState const K_)
@@ -111,18 +125,6 @@ KeyUD* KeyUD::GetPtr(KeeperState const K_, int idx_)
 
 // #################################################################################################
 
-// expects 'this' on top of the stack
-// replaces it by its uservalue on the stack
-void KeyUD::prepareAccess(KeeperState const K_)
-{
-    LUA_ASSERT(K_, KeyUD::GetPtr(K_, -1) == this);
-    // we can replace the key userdata in the stack without fear of it being GCed, there are other references around
-    lua_getiuservalue(K_, -1, kContentsTableIndex);
-    lua_replace(K_, -2);
-}
-
-// #################################################################################################
-
 // in: fifo
 // out: ...|nothing
 // pops the fifo, push as much data as is available (up to the specified count) without consuming it
@@ -182,6 +184,18 @@ void KeyUD::pop(KeeperState const K_, int const count_)
 
 // #################################################################################################
 
+// expects 'this' on top of the stack
+// replaces it by its uservalue on the stack
+void KeyUD::prepareAccess(KeeperState const K_)
+{
+    LUA_ASSERT(K_, KeyUD::GetPtr(K_, -1) == this);
+    // we can replace the key userdata in the stack without fear of it being GCed, there are other references around
+    lua_getiuservalue(K_, -1, kContentsTableIndex);
+    lua_replace(K_, -2);
+}
+
+// #################################################################################################
+
 // in: expect fifo args... on top of the stack
 // out: nothing, removes all pushed values from the stack
 void KeyUD::push(KeeperState const K_, int const count_)
@@ -432,17 +446,11 @@ int keepercall_limit(lua_State* const L_)
     }
     // remove any clutter on the stack
     lua_settop(_K, 0);                                                                             // _K:
-    // return true if we decide that blocked threads waiting to write on that key should be awakened
-    // this is the case if we detect the key was full but it is no longer the case
-    // TODO: make this KeyUD::changeLimit() -> was full (bool)
-    if (
-        ((_key->limit >= 0) && (_key->count >= _key->limit)) // the key was full if limited and count exceeded the previous limit
-        && ((_limit < 0) || (_key->count < _limit))          // the key is not full if unlimited or count is lower than the new limit
-    ) {
+    if (_key->changeLimit(_limit)) {
+        // return true if we decide that blocked threads waiting to write on that key should be awakened
+        // this is the case if we detect the key was full but it is no longer the case
         lua_pushboolean(_K, 1);                                                                    // _K: true
     }
-    // set the new limit
-    _key->limit = _limit;
     // return 0 or 1 value
     return lua_gettop(_K);
 }
-- 
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