From 0a2617527c9b46a587a8f34571a54347cd5c4b5a Mon Sep 17 00:00:00 2001
From: Simon Ruderich <simon@ruderich.org>
Date: Mon, 10 Jun 2013 06:08:35 +0200
Subject: [PATCH] Inline fast part of tracked_fds_find().

---
 configure.ac   |  1 +
 src/compiler.h | 11 +++++++++++
 src/trackfds.h | 15 +++++++++++++++
 3 files changed, 27 insertions(+)

diff --git a/configure.ac b/configure.ac
index ec5b658..3b007c5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -43,6 +43,7 @@ AC_TYPE_SIZE_T
 AC_TYPE_SSIZE_T
 
 AC_C_INLINE
+AX_C___ATTRIBUTE__
 
 AC_FUNC_FORK
 AC_CHECK_FUNCS([dup2 memmove setenv strdup])
diff --git a/src/compiler.h b/src/compiler.h
index 3d92f2f..9e23e23 100644
--- a/src/compiler.h
+++ b/src/compiler.h
@@ -20,6 +20,17 @@
 #ifndef COMPILER_H
 #define COMPILER_H 1
 
+/* Prevent/force inlining. Used to improve performance. */
+#undef __noinline
+#undef __always_inline
+#ifdef HAVE___ATTRIBUTE__
+# define __noinline      __attribute__((noinline))
+# define __always_inline __attribute__((always_inline))
+#else
+# define __noinline
+# define __always_inline
+#endif
+
 /* Branch prediction information for the compiler. */
 #ifdef HAVE___BUILTIN_EXPECT
 # define likely(x)   __builtin_expect(!!(x), 1)
diff --git a/src/trackfds.h b/src/trackfds.h
index 9b2aaa6..175f1e3 100644
--- a/src/trackfds.h
+++ b/src/trackfds.h
@@ -299,10 +299,25 @@ static int tracked_fds_remove(int fd) {
     /* Not found. */
     return 0;
 }
+
+static int tracked_fds_find_slow(int fd);
+/*
+ * tracked_fds_find() is called for each hook call and should be as fast as
+ * possible. As most file descriptors are < TRACKFDS_STATIC_COUNT, force the
+ * compiler to inline that part which is almost exclusively used.
+ *
+ * Inlining tracked_fds_add()/tracked_fds_remove() isn't worth the effort as
+ * they are not called often enough.
+ */
+inline static int tracked_fds_find(int fd) __always_inline;
 static int tracked_fds_find(int fd) {
     if (fd < TRACKFDS_STATIC_COUNT) {
         return tracked_fds[fd];
     }
+
+    return tracked_fds_find_slow(fd);
+}
+static int tracked_fds_find_slow(int fd) {
     if (tracked_fds_list_count == 0) {
         return 0;
     }
-- 
2.43.2