From 1524f8eb8ca237ad8c02ae348cc8cb60276dbb15 Mon Sep 17 00:00:00 2001
From: Nicolas Noble <pixel@nobis-crew.org>
Date: Tue, 30 Jul 2013 18:25:31 -0700
Subject: Saving some memory by having the LuaTasks being stackless when
 possible.

---
 includes/LuaTask.h |  8 ++++++--
 src/LuaTask.cc     | 22 +++++++++++++---------
 2 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/includes/LuaTask.h b/includes/LuaTask.h
index 1f7a0b5..85ce1f8 100644
--- a/includes/LuaTask.h
+++ b/includes/LuaTask.h
@@ -3,6 +3,8 @@
 #include <c++11-surrogates.h>
 #include <BLua.h>
 #include <Task.h>
+#include <StacklessTask.h>
+#include <Buffer.h>
 
 namespace Balau {
 
@@ -19,6 +21,7 @@ class LuaExecCell {
     void throwError() throw (GeneralException);
   protected:
     virtual void run(Lua &) = 0;
+    virtual bool needsStack() { return false; }
     void setError() { m_gotError = true; }
   private:
     Events::Async m_event;
@@ -43,6 +46,7 @@ class LuaExecFile : public LuaExecCell {
   public:
       LuaExecFile(IO<Handle> file) : m_file(file) { }
   private:
+    virtual bool needsStack() { return !m_file.isA<Buffer>(); }
     virtual void run(Lua &);
     IO<Handle> m_file;
 };
@@ -52,14 +56,14 @@ class LuaTask : public Task {
       ~LuaTask() { L.weaken(); }
     virtual const char * getName() const { return "LuaTask"; }
   private:
-      LuaTask(Lua && __L, LuaExecCell * cell) : L(Move(__L)), m_cell(cell) { }
+      LuaTask(Lua && __L, LuaExecCell * cell) : L(Move(__L)), m_cell(cell) { if (!cell->needsStack()) setStackless(); }
     virtual void Do();
     Lua L;
     LuaExecCell * m_cell;
     friend class LuaMainTask;
 };
 
-class LuaMainTask : public Task {
+class LuaMainTask : public StacklessTask {
   public:
       LuaMainTask();
       ~LuaMainTask();
diff --git a/src/LuaTask.cc b/src/LuaTask.cc
index 5075c36..30fdef2 100644
--- a/src/LuaTask.cc
+++ b/src/LuaTask.cc
@@ -42,18 +42,22 @@ void Balau::LuaMainTask::stop() {
 }
 
 void Balau::LuaMainTask::Do() {
+    LuaExecCell * cell = NULL;
     for (;;) {
-        LuaExecCell * cell;
         Printer::elog(E_TASK, "LuaMainTask at %p tries to pop an ExecCell", this);
-        while ((cell = m_queue.pop())) {
-            Printer::elog(E_TASK, "LuaMainTask at %p popped %p", this, cell);
-            if (dynamic_cast<LuaTaskStopper *>(cell)) {
-                Printer::elog(E_TASK, "LuaMainTask at %p is stopping", this);
-                delete cell;
-                return;
-            }
-            TaskMan::registerTask(new LuaTask(L.thread(), cell), this);
+        try {
+            cell = m_queue.pop();
+        }
+        catch (Balau::EAgain & e) {
+            taskSwitch();
+        }
+        Printer::elog(E_TASK, "LuaMainTask at %p popped %p", this, cell);
+        if (dynamic_cast<LuaTaskStopper *>(cell)) {
+            Printer::elog(E_TASK, "LuaMainTask at %p is stopping", this);
+            delete cell;
+            return;
         }
+        TaskMan::registerTask(new LuaTask(L.thread(), cell), this);
     }
 }
 
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