From b7ff56db631be7416cf228dff89cb23d753e4ec8 Mon Sep 17 00:00:00 2001
From: Robin Haberkorn <robin.haberkorn@googlemail.com>
Date: Sun, 20 Nov 2016 09:00:50 +0100
Subject: fixed glib warnings about using g_mem_set_vtable() and revised memory
 limiting

 * we were basing the glib allocators on throwing std::bad_alloc just like
   the C++ operators. However, this always was unsafe since we were throwing
   exceptions across plain-C frames (Glib).
   Also, the memory vtable has been deprecated in Glib, resulting in
   ugly warnings.
 * Instead, we now let the C++ new/delete operators work like Glib
   by basing them on g_malloc/g_slice.
   This means they will assert and the application will terminate
   abnormally in case of OOM. OOMs cannot be handled properly anyway, so it is
   more important to have a good memory limiting mechanism.
 * Memory limiting has been completely revised.
   Instead of approximating undo stack sizes using virtual methods
   (which is unprecise and comes with a performance penalty),
   we now use a common base class SciTECO::Object to count the memory
   required by all objects allocated within SciTECO.
   This is less precise than using global replacement new/deletes
   which would allow us to control allocations in all C++ code including
   Scintilla, but they are only supported as of C++14 (GCC 5) and adding compile-time
   checks would be cumbersome.
   In any case, we're missing Glib allocations (esp. strings).
 * As a platform-specific extension, on Linux/glibc we use mallinfo()
   to count the exact memory usage of the process.
   On Windows, we use GetProcessMemoryInfo() -- the latter implementation
   is currently UNTESTED.
 * We use g_malloc() for new/delete operators when there is
   malloc_trim() since g_slice does not free heap chunks properly
   (probably does its own mmap()ing), rendering malloc_trim() ineffective.
   We've also benchmarked g_slice on Linux/glib (malloc_trim() shouldn't
   be available elsewhere) and found that it brings no significant
   performance benefit.
   On all other platforms, we use g_slice since it is assumed
   that it at least does not hurt.
   The new g_slice based allocators should be tested on MSVCRT
   since I assume that they bring a significant performance benefit
   on Windows.
 * Memory limiting does now work in batch mode as well and is still
   enabled by default.
 * The old UndoTokenWithSize CRTP hack could be removed.
   UndoStack operations should be a bit faster now.
   But on the other hand, there will be an overhead due to repeated
   memory limit checking on every processed character.
---
 src/main.cpp | 57 ++-------------------------------------------------------
 1 file changed, 2 insertions(+), 55 deletions(-)

(limited to 'src/main.cpp')

diff --git a/src/main.cpp b/src/main.cpp
index e9be929..bc82093 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -23,7 +23,6 @@
 #include <string.h>
 #include <stdlib.h>
 #include <signal.h>
-#include <new>
 
 #include <glib.h>
 #include <glib/gprintf.h>
@@ -81,12 +80,10 @@ static gboolean mung_profile = TRUE;
 sig_atomic_t sigint_occurred = FALSE;
 
 extern "C" {
-static gpointer g_malloc_exception(gsize n_bytes);
-static gpointer g_calloc_exception(gsize n_blocks, gsize n_block_bytes);
-static gpointer g_realloc_exception(gpointer mem, gsize n_bytes);
 
 static void sigint_handler(int signal);
-}
+
+} /* extern "C" */
 
 #if defined(G_OS_UNIX) || defined(G_OS_HAIKU)
 
@@ -342,45 +339,6 @@ initialize_environment(const gchar *program)
  * Callbacks
  */
 
-class g_bad_alloc : public std::bad_alloc {
-public:
-	const char *
-	what() const throw()
-	{
-		return "glib allocation";
-	}
-};
-
-static gpointer
-g_malloc_exception(gsize n_bytes)
-{
-	gpointer p = malloc(n_bytes);
-
-	if (!p)
-		throw g_bad_alloc();
-	return p;
-}
-
-static gpointer
-g_calloc_exception(gsize n_blocks, gsize n_block_bytes)
-{
-	gpointer p = calloc(n_blocks, n_block_bytes);
-
-	if (!p)
-		throw g_bad_alloc();
-	return p;
-}
-
-static gpointer
-g_realloc_exception(gpointer mem, gsize n_bytes)
-{
-	gpointer p = realloc(mem, n_bytes);
-
-	if (!p)
-		throw g_bad_alloc();
-	return p;
-}
-
 static void
 sigint_handler(int signal)
 {
@@ -403,15 +361,6 @@ main(int argc, char **argv)
 	static GotoTable	cmdline_goto_table;
 	static QRegisterTable	local_qregs;
 
-	static GMemVTable vtable = {
-		g_malloc_exception,	/* malloc */
-		g_realloc_exception,	/* realloc */
-		free,			/* free */
-		g_calloc_exception,	/* calloc */
-		malloc,			/* try_malloc */
-		realloc			/* try_realloc */
-	};
-
 	gchar *mung_filename;
 
 #ifdef DEBUG_PAUSE
@@ -422,8 +371,6 @@ main(int argc, char **argv)
 	signal(SIGINT, sigint_handler);
 	signal(SIGTERM, sigint_handler);
 
-	g_mem_set_vtable(&vtable);
-
 	mung_filename = process_options(argc, argv);
 	/*
 	 * All remaining arguments in argv are arguments
-- 
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