make backtrace in timeout's logs with recursion (VKCOM#940)

common/fast-backtrace.cpp

@@ -39,17 +39,20 @@ int fast_backtrace(void **buffer, int size) {
     stack_end = static_cast<char *>(__libc_stack_end);
   }
 #endif
+  return fast_backtrace_by_bp(get_bp(), stack_end, buffer, size);
+}
 
-  auto *bp = static_cast<stack_frame *>(get_bp());
+int fast_backtrace_by_bp(void *bp, void *stack_end_, void **buffer, int size) {
+  stack_frame *current_bp = static_cast<stack_frame *>(bp);
   int i = 0;
-  while (i < size && reinterpret_cast<char *>(bp) <= stack_end && !(reinterpret_cast<long>(bp) & (sizeof(long) - 1))) {
-    void *ip = bp->ip;
+  while (i < size && reinterpret_cast<char *>(current_bp) <= stack_end_ && !(reinterpret_cast<long>(current_bp) & (sizeof(long) - 1))) {
+    void *ip = current_bp->ip;
     buffer[i++] = ip;
-    stack_frame *p = bp->bp;
-    if (p <= bp) {
+    stack_frame *p = current_bp->bp;
+    if (p <= current_bp) {
       break;
     }
-    bp = p;
+    current_bp = p;
   }
   return i;
 }

common/fast-backtrace.h

@@ -14,6 +14,7 @@ extern char *stack_end;
 }
 
 int fast_backtrace (void **buffer, int size) __attribute__ ((noinline));
+int fast_backtrace_by_bp (void *bp, void *stack_end_, void **buffer, int size) __attribute__ ((noinline));
 int fast_backtrace_without_recursions(void **buffer, int size) noexcept;
 int fast_backtrace_without_recursions_by_bp(void *bp, void *stack_end_, void **buffer, int size) noexcept;
 

server/json-logger.cpp

@@ -97,7 +97,7 @@ int script_backtrace(void **buffer, int size) {
 #endif
   char *stack_start = PhpScript::current_script->script_stack.get_stack_ptr();
   char *stack_end = stack_start + PhpScript::current_script->script_stack.get_stack_size();
-  return fast_backtrace_without_recursions_by_bp(rbp, stack_end, buffer, size);
+  return fast_backtrace_by_bp(rbp, stack_end, buffer, size);
 }
 
 } // namespace