From e7b3f5745cd92c3d02a7cc8b8f8ae8a469975f49 Mon Sep 17 00:00:00 2001
From: Jan Kanis <jan.code@jankanis.nl>
Date: Thu, 24 Jan 2013 14:29:13 +0100
Subject: [PATCH] replace compiler-supported TLS with pthread_get/setspecific;
 remove GPLv3 code from two commits ago

---
 configure.ac | 32 --------------------------------
 reader.cpp   | 24 ++++++++++++------------
 2 files changed, 12 insertions(+), 44 deletions(-)

diff --git a/configure.ac b/configure.ac
index 0b4ba0dea..bf3defcff 100644
--- a/configure.ac
+++ b/configure.ac
@@ -40,38 +40,6 @@ AC_SUBST(XSEL_BIN)
 AC_SUBST(XSEL_MAN_PATH)
 
 
-# Copied from http://git.savannah.gnu.org/gitweb/?p=autoconf-archive.git;a=blob_plain;f=m4/ax_tls.m4, 
-# This definition is licenced under GPLv3+. 
-AC_DEFUN([AX_TLS], [
-  AC_MSG_CHECKING(for thread local storage (TLS) class)
-  AC_CACHE_VAL(ac_cv_tls, [
-    ax_tls_keywords="__thread __declspec(thread) none"
-    for ax_tls_keyword in $ax_tls_keywords; do
-       AS_CASE([$ax_tls_keyword],
-          [none], [ac_cv_tls=none ; break],
-          [AC_TRY_COMPILE(
-              [#include <stdlib.h>
-               static void
-               foo(void) {
-               static ] $ax_tls_keyword [ int bar;
-               exit(1);
-               }],
-               [],
-               [ac_cv_tls=$ax_tls_keyword ; break],
-               ac_cv_tls=none
-           )])
-    done
-  ])
-  AC_MSG_RESULT($ac_cv_tls)
-
-  AS_IF([test "$ac_cv_tls" != "none"],
-    AC_DEFINE_UNQUOTED([TLS], $ac_cv_tls, [If the compiler supports a TLS storage class define it to that here])
-      m4_ifnblank([$1], [$1]),
-    m4_ifnblank([$2], [$2])
-  )
-])
-
-AX_TLS
 
 #
 # If needed, run autoconf to regenerate the configure file
diff --git a/reader.cpp b/reader.cpp
index 6caca362b..244fe28de 100644
--- a/reader.cpp
+++ b/reader.cpp
@@ -45,6 +45,7 @@ commence.
 #include <unistd.h>
 #include <wctype.h>
 #include <stack>
+#include <pthread.h>
 
 #if HAVE_NCURSES_H
 #include <ncurses.h>
@@ -183,10 +184,8 @@ commence.
 /* Any time the contents of a buffer changes, we update the generation count. This allows for our background highlighting thread to notice it and skip doing work that it would otherwise have to do. */
 static volatile unsigned int s_generation_count;
 
-/* This threadlocal generation count is set when an autosuggestion background thread starts up, so it can easily check if the work it is doing is no longer useful. */
-#ifdef TLS
-static TLS unsigned int thread_generation_count;
-#endif
+/* This pthreads generation count is set when an autosuggestion background thread starts up, so it can easily check if the work it is doing is no longer useful. */
+static pthread_key_t generation_count_key;
 
 /* A color is an int */
 typedef int color_t;
@@ -674,12 +673,8 @@ int reader_reading_interrupted()
 
 bool reader_cancel_thread()
 {
-#ifdef TLS
     ASSERT_IS_BACKGROUND_THREAD();
-    return s_generation_count != thread_generation_count;
-#else
-    return 0;
-#endif
+    return ((size_t) s_generation_count) != (size_t) pthread_getspecific(generation_count_key);
 }
 
 void reader_write_title()
@@ -800,6 +795,10 @@ static void exec_prompt()
 
 void reader_init()
 {
+    // We store unsigned ints cast to size_t's cast to void* in pthreads tls storage
+    assert(sizeof(size_t) >= sizeof(unsigned int));
+    assert(sizeof(void*) >= sizeof(size_t));
+    VOMIT_ON_FAILURE(pthread_key_create(&generation_count_key, NULL));
 
     tcgetattr(0,&shell_modes);        /* get the current terminal modes */
     memcpy(&saved_modes,
@@ -826,6 +825,7 @@ void reader_init()
 void reader_destroy()
 {
     tcsetattr(0, TCSANOW, &saved_modes);
+    pthread_key_delete(generation_count_key);
 }
 
 
@@ -1240,9 +1240,9 @@ struct autosuggestion_context_t
             return 0;
         }
 
-#ifdef TLS
-        thread_generation_count = generation_count;
-#endif
+        // The manpage doesn't list any errors pthread_setspecific can return, 
+        // so I'm assuming it can not fail. 
+        pthread_setspecific(generation_count_key, (void*)(size_t) generation_count);
 
         /* Let's make sure we aren't using the empty string */
         if (search_string.empty())