remove sys_alloca (difficult to wrap in a sysdep function) and eliminate the need for it

debug: when building error message, use mmap instead of alloca
scheduler: remove reference to deleted header

This was SVN commit r5019.

source/lib/debug.cpp

@@ -26,11 +26,12 @@
 #include <stdarg.h>
 #include <string.h>
 
-#include "lib/posix/posix_pthread.h"
 #include "lib.h"
 #include "app_hooks.h"
 #include "path_util.h"
 #include "debug_stl.h"
+#include "allocators.h"
+#include "lib/posix/posix_pthread.h"
 #include "lib/sysdep/cpu.h"	// CAS
 #include "lib/sysdep/sysdep.h"
 #include "lib/res/file/file.h"	// FILE_ACCESS
@@ -504,45 +505,12 @@ static bool should_suppress_error(u8* suppress)
 	return false;
 }
 
-static wchar_t* alloc_mem(void* alloca_buf, size_t alloca_buf_size,
-	void*& heap_mem, size_t& max_chars)
-{
-	void* chosen_buf;
-	size_t chosen_size;
-
-	// rationale:
-	// - this needs to be quite large, so preallocating is undesirable.
-	// - prefer malloc to alloca because it allows returning larger
-	//   buffers (stack space may be quite limited).
-	// - do not rely on malloc because we might be called upon to report
-	//   heap corruption errors. therefore, the caller should allocate some
-	//   scratch memory via alloca, which is used as an (optional) backup.
-	// - note: we can't alloca here because it'd be lost after
-	//   function return, but must be passed on to debug_display_error.
-
-	// try allocating from heap.
-	chosen_size = 500*KiB;	// 'enough'
-	chosen_buf = heap_mem = malloc(chosen_size);
-	// .. failed; use alloca_buf.
-	if(!chosen_buf)
-	{
-		// caller didn't set it up => we have no memory to return; abort.
-		if(!alloca_buf)
-			return 0;
-
-		chosen_buf  = alloca_buf;
-		chosen_size = alloca_buf_size;
-	}
-
-	max_chars = chosen_size / sizeof(wchar_t);
-	return (wchar_t*)chosen_buf;
-}
 
+static const size_t message_size_bytes = 256*KiB;	// enough
 
 void debug_error_message_free(ErrorMessageMem* emm)
 {
-	// note: no-op if wasn't allocated from heap.
-	free(emm->heap_mem);
+	page_aligned_free(emm->pa_mem, message_size_bytes);
 }
 
 // split out of debug_display_error because it's used by the self-test.
@@ -552,10 +520,12 @@ const wchar_t* debug_error_message_build(
 	uint skip, void* context,
 	ErrorMessageMem* emm)
 {
-	size_t max_chars;
-	wchar_t* buf = alloc_mem(emm->alloca_buf, emm->alloca_buf_size, emm->heap_mem, max_chars);
-	if(!buf)
+	// rationale: see ErrorMessageMem
+	emm->pa_mem = page_aligned_alloc(message_size_bytes);
+	if(!emm->pa_mem)
 		return L"(insufficient memory to generate error message)";
+	wchar_t* const buf = (wchar_t*)emm->pa_mem;
+	const size_t max_chars = size_bytes / sizeof(wchar_t);
 	wchar_t* pos = buf; size_t chars_left = max_chars; int len;
 
 	// header
@@ -700,8 +670,6 @@ ErrorReaction debug_display_error(const wchar_t* description,
 
 
 	ErrorMessageMem emm;
-	emm.alloca_buf_size = 50000;
-	emm.alloca_buf = sys_alloca(emm.alloca_buf_size);
 	const wchar_t* text = debug_error_message_build(description,
 		fn_only, line, func, skip, context, &emm);
 

source/lib/debug.h

@@ -650,12 +650,16 @@ extern const char* debug_get_thread_name();
  **/
 struct ErrorMessageMem
 {
-	// passed to debug_error_message_build from caller
-	void* alloca_buf;
-	size_t alloca_buf_size;
-
-	// allocated within debug_error_message_build
-	void* heap_mem;
+	// rationale:
+	// - error messages with stack traces require a good deal of memory
+	//   (dozens of KB). static buffers of that size are undesirable.
+ 	// - the heap may be corrupted, so don't use malloc. allocator.h's
+	//   page_aligned_malloc (implemented via mmap) should be safe.
+	// - alloca is a bit iffy (the stack may be maxed out), non-portable and
+	//   complicates the code because it can't be allocated by a subroutine.
+	// - this method is probably slow, but error messages aren't built often.
+	//   if necessary, first try malloc and use mmap if that fails.
+	void* pa_mem;
 };
 
 /**

source/lib/lockfree.cpp

@@ -284,7 +284,7 @@ static void smr_release_unreferenced_nodes(TLS* tls)
 retry:
 	const size_t max_hps = (active_threads+3) * NUM_HPS;
 		// allow for creating a few additional threads during the loop
-	void** hps = (void**)sys_alloca(max_hps * sizeof(void*));
+	void** hps = (void**)alloca(max_hps * sizeof(void*));
 	size_t num_hps = 0;
 	// for each participating thread:
 	for(TLS* t = tls_list; t; t = t->next)
@@ -561,7 +561,7 @@ retry:
 // or 0 if not found in the list.
 void* lfl_find(LFList* list, uintptr_t key)
 {
-	ListPos* pos = (ListPos*)sys_alloca(sizeof(ListPos));
+	ListPos* pos = (ListPos*)alloca(sizeof(ListPos));
 	if(!list_lookup(list, key, pos))
 		return 0;
 	return node_user_data(pos->cur);
@@ -579,7 +579,7 @@ void* lfl_insert(LFList* list, uintptr_t key, size_t additional_bytes, int* was_
 		// if this triggers, tls_alloc called from lfl_init failed due to
 		// lack of memory and the caller didn't check its return value.
 
-	ListPos* pos = (ListPos*)sys_alloca(sizeof(ListPos));
+	ListPos* pos = (ListPos*)alloca(sizeof(ListPos));
 
 	Node* node = 0;
 	if(was_inserted)
@@ -632,7 +632,7 @@ LibError lfl_erase(LFList* list, uintptr_t key)
 		// if this triggers, tls_alloc called from lfl_init failed due to
 		// lack of memory and the caller didn't check its return value.
 
-	ListPos* pos = (ListPos*)sys_alloca(sizeof(ListPos));
+	ListPos* pos = (ListPos*)alloca(sizeof(ListPos));
 
 retry:
 	// not found in list - abort.

source/lib/sysdep/sysdep.h

@@ -106,11 +106,6 @@ extern LibError sys_cursor_free(void* cursor);
 extern int sys_vsnprintf(char* buffer, size_t count, const char* format, va_list argptr);
 
 
-/**
- * allocate on stack, automatically free when current function returns.
- **/
-extern void* sys_alloca(size_t size);
-
 // describe the current OS error state.
 //
 // err: if not 0, use that as the error code to translate; otherwise,

source/lib/sysdep/win/wsysdep.cpp

@@ -46,24 +46,6 @@ void sys_display_msgw(const wchar_t* caption, const wchar_t* msg)
 }
 
 
-void* sys_alloca(size_t size)
-{
-	void* ret;
-	__try
-	{
-		ret = _alloca(size);
-	}
-	// if stack overflow, handle it; otherwise, continue handler search.
-	__except(GetExceptionCode() == STATUS_STACK_OVERFLOW)
-	{
-		// restore guard page - necessary on XP, works everywhere.
-		_resetstkoflw();
-		ret = 0;
-	}
-	return ret;
-}
-
-
 //-----------------------------------------------------------------------------
 // "program error" dialog (triggered by debug_assert and exception)
 //-----------------------------------------------------------------------------

source/simulation/Scheduler.h

@@ -12,7 +12,6 @@
 #include <list>
 #include <set>
 
-#include "EntityMessage.h"
 #include "EntityHandles.h"
 #include "ps/Singleton.h"
 #include "ps/CStr.h"