migrate per-thread magazine caches from single-thread scenario to first

Thu Jul 12 15:46:40 2007  Tim Janik  <timj@imendio.com>

        * glib/gslice.c: migrate per-thread magazine caches from single-thread
        scenario to first thread using GSlice after g_thread_init(); based on
        a patch by Tor Lillqvist, fixes #331853.
        removed warning about g_thread_init() being called after other glib
        functions (in particular g_slice* calls), because GSlice can cope
        with this now and the rest of glib is believed to cope as well.

        * tests/slice-threadinit.c: new test program which tests GSlice working
        across g_thread_init() calls.



svn path=/trunk/; revision=5629

ChangeLog

@@ -1,3 +1,15 @@
+Thu Jul 12 15:46:40 2007  Tim Janik  <timj@imendio.com>
+
+	* glib/gslice.c: migrate per-thread magazine caches from single-thread
+	scenario to first thread using GSlice after g_thread_init(); based on
+	a patch by Tor Lillqvist, fixes #331853.
+	removed warning about g_thread_init() being called after other glib
+	functions (in particular g_slice* calls), because GSlice can cope
+	with this now and the rest of glib is believed to cope as well.
+
+	* tests/slice-threadinit.c: new test program which tests GSlice working
+	across g_thread_init() calls.
+
 2007-07-10  Matthias Clasen  <mclasen@redhat.com>
 
 	* glib/pltcheck.sh: Add g_once_init_enter to the whitelist of

glib/gslice.c

@@ -372,20 +372,14 @@ void
 _g_slice_thread_init_nomessage (void)
 {
   /* we may not use g_error() or friends here */
-  if (sys_page_size)
-    {
-      const char *pname;
-
-      /* mem_error ("g_thread_init() must be called before GSlice is used, memory corrupted..."); */
-      fputs ("\n***MEMORY-WARNING***: ", stderr);
-      pname = g_get_prgname();
-      fprintf (stderr, "%s[%u]: GSlice: ", pname ? pname : "", getpid());
-      fputs ("g_thread_init() must be called before all other GLib functions; "
-             "memory corruption due to late invocation of g_thread_init() has been detected; "
-             "this program is likely to crash, leak or unexpectedly abort soon...\n", stderr);
-    }
   if (!sys_page_size)
     g_slice_init_nomessage();
+  else
+    {
+      /* g_slice_init_nomessage() has been called already, probably due
+       * to a g_slice_alloc1() before g_thread_init().
+       */
+    }
   private_thread_memory = g_private_new (private_thread_memory_cleanup);
   allocator->magazine_mutex = g_mutex_new();
   allocator->slab_mutex = g_mutex_new();
@@ -428,12 +422,39 @@ thread_memory_from_self (void)
 {
   ThreadMemory *tmem = g_private_get (private_thread_memory);
   if (G_UNLIKELY (!tmem))
+    {
+      static ThreadMemory *single_thread_memory = NULL;   /* remember single-thread info for multi-threaded case */
+      if (single_thread_memory && g_thread_supported ())
+        {
+          g_mutex_lock (allocator->slab_mutex);
+          if (single_thread_memory)
+            {
+              /* GSlice has been used before g_thread_init(), and now
+               * we are running threaded. to cope with it, use the saved
+               * thread memory structure from when we weren't threaded.
+               */
+              tmem = single_thread_memory;
+              single_thread_memory = NULL;      /* slab_mutex protected when multi-threaded */
+            }
+          g_mutex_unlock (allocator->slab_mutex);
+        }
+      if (!tmem)
 	{
           const guint n_magazines = MAX_SLAB_INDEX (allocator);
 	  tmem = g_malloc0 (sizeof (ThreadMemory) + sizeof (Magazine) * 2 * n_magazines);
 	  tmem->magazine1 = (Magazine*) (tmem + 1);
 	  tmem->magazine2 = &tmem->magazine1[n_magazines];
+	}
+      /* g_private_get/g_private_set works in the single-threaded xor the multi-
+       * threaded case. but not *across* g_thread_init(), after multi-thread
+       * initialization it returns NULL for previously set single-thread data.
+       */
       g_private_set (private_thread_memory, tmem);
+      /* save single-thread thread memory structure, in case we need to
+       * pick it up again after multi-thread initialization happened.
+       */
+      if (!single_thread_memory && !g_thread_supported ())
+        single_thread_memory = tmem;            /* no slab_mutex created yet */
     }
   return tmem;
 }

tests/Makefile.am

@@ -104,6 +104,7 @@ test_programs =					\
 	slist-test				\
 	slice-test				\
 	slice-color				\
+	slice-threadinit			\
 	spawn-test				\
 	$(spawn_test_win32_gui)			\
 	strfunc-test				\
@@ -175,6 +176,8 @@ slice_test_SOURCES = slice-test.c memchunks.c
 slice_test_LDADD = $(thread_ldadd)
 slice_color_SOURCES = slice-color.c memchunks.c
 slice_color_LDADD = $(thread_ldadd)
+slice_threadinit_SOURCES = slice-threadinit.c
+slice_threadinit_LDADD = $(thread_ldadd)
 spawn_test_LDADD = $(progs_ldadd)
 strfunc_test_LDADD = $(progs_ldadd)
 string_test_LDADD = $(progs_ldadd)

tests/slice-threadinit.c

@@ -0,0 +1,166 @@
+/* slice-threadinit.c - test GSlice across g_thread_init
+ * Copyright (C) 2007 Tim Janik
+ *
+ * This work is provided "as is"; redistribution and modification
+ * in whole or in part, in any medium, physical or electronic is
+ * permitted without restriction.
+ *
+ * This work is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * In no event shall the authors or contributors be liable for any
+ * direct, indirect, incidental, special, exemplary, or consequential
+ * damages (including, but not limited to, procurement of substitute
+ * goods or services; loss of use, data, or profits; or business
+ * interruption) however caused and on any theory of liability, whether
+ * in contract, strict liability, or tort (including negligence or
+ * otherwise) arising in any way out of the use of this software, even
+ * if advised of the possibility of such damage.
+ */
+#include <glib.h>
+
+#define N_PAGES                 (101)                   /* number of pages to sample */
+#define SAMPLE_SIZE             (7)
+#define PAGE_SIZE               (128)                   /* must be <= minimum GSlice alignment block */
+#define MAGAZINE_PROBES         { 77, 265, 347 }        /* block sizes hopefully unused by g_thread_init */
+#define MAX_PROBE_TRIALS        (1031)                  /* must be >= maximum magazine size */
+
+#define ALIGN(size, base)       ((base) * (gsize) (((size) + (base) - 1) / (base)))
+
+static struct {
+  void *page;
+  void *sample;
+} pages[N_PAGES] = { { NULL, }, };
+
+static const guint magazine_probes[] = MAGAZINE_PROBES;
+#define N_MAGAZINE_PROBES       G_N_ELEMENTS (magazine_probes)
+
+static void
+release_trash_list (GSList **trash_list,
+                    gsize    block_size)
+{
+  while (*trash_list)
+    {
+      g_slice_free1 (block_size, (*trash_list)->data);
+      *trash_list = g_slist_delete_link (*trash_list, *trash_list);
+    }
+}
+
+static GSList *free_list = NULL;
+
+static gboolean
+allocate_from_known_page (void)
+{
+  guint i, j, n_trials = N_PAGES * PAGE_SIZE / SAMPLE_SIZE; /* upper bound */
+  for (i = 0; i < n_trials; i++)
+    {
+      void *b = g_slice_alloc (SAMPLE_SIZE);
+      void *p = (void*) (PAGE_SIZE * ((gsize) b / PAGE_SIZE));
+      free_list = g_slist_prepend (free_list, b);
+      /* find page */
+      for (j = 0; j < N_PAGES; j++)
+        if (pages[j].page == p)
+          return TRUE;
+    }
+  return FALSE;
+}
+
+int
+main (int   argc,
+      char *argv[])
+{
+  int j, n_pages = 0;
+  void *mps[N_MAGAZINE_PROBES];
+
+  /* probe some magazine sizes */
+  for (j = 0; j < N_MAGAZINE_PROBES; j++)
+    mps[j] = g_slice_alloc (magazine_probes[j]);
+  /* mps[*] now contains pointers to allocated slices */
+
+  /* allocate blocks from N_PAGES different pages */
+  while (n_pages < N_PAGES)
+    {
+      void *b = g_slice_alloc (SAMPLE_SIZE);
+      void *p = (void*) (PAGE_SIZE * ((gsize) b / PAGE_SIZE));
+      for (j = 0; j < N_PAGES; j++)
+        if (pages[j].page == p)
+          break;
+      if (j < N_PAGES)  /* known page */
+        free_list = g_slist_prepend (free_list, b);
+      else              /* new page */
+        {
+          j = n_pages++;
+          pages[j].page = p;
+          pages[j].sample = b;
+        }
+    }
+  /* release intermediate allocations */
+  release_trash_list (&free_list, SAMPLE_SIZE);
+
+  /* ensure that we can allocate from known pages */
+  if (!allocate_from_known_page())
+    g_error ("failed to allocate from magazine/page cache (before g_thread_init)");
+  /* release intermediate allocations */
+  release_trash_list (&free_list, SAMPLE_SIZE);
+
+  /* release magazine probes to be retained */
+  for (j = 0; j < N_MAGAZINE_PROBES; j++)
+    g_slice_free1 (magazine_probes[j], mps[j]);
+  /* mps[*] now contains pointers to releaed slices */
+
+  /* ensure probes were retained */
+  for (j = 0; j < N_MAGAZINE_PROBES; j++)
+    {
+      GSList *trash = NULL;
+      guint k;
+      for (k = 0; k < MAX_PROBE_TRIALS; k++)
+        {
+          void *mem = g_slice_alloc (magazine_probes[j]);
+          if (mem == mps[j])
+            break;      /* reallocated previously freed slice */
+          trash = g_slist_prepend (trash, mem);
+        }
+      release_trash_list (&trash, magazine_probes[j]);
+      if (k >= MAX_PROBE_TRIALS)        /* failed to reallocate slice */
+        g_error ("failed to reallocate slice from magazine (before g_thread_init): size=%d", magazine_probes[j]);
+    }
+  /* mps[*] now contains pointers to reallocated slices */
+
+  /* release magazine probes to be retained across g_thread_init */
+  for (j = 0; j < N_MAGAZINE_PROBES; j++)
+    g_slice_free1 (magazine_probes[j], mps[j]);
+  /* mps[*] now contains pointers to releaed slices */
+
+  /* initialize threading (should retain allocator state) */
+  g_thread_init (NULL);
+
+  /* ensure probes were retained */
+  for (j = 0; j < N_MAGAZINE_PROBES; j++)
+    {
+      GSList *trash = NULL;
+      guint k;
+      for (k = 0; k < MAX_PROBE_TRIALS; k++)
+        {
+          void *mem = g_slice_alloc (magazine_probes[j]);
+          if (mem == mps[j])
+            break;      /* reallocated previously freed slice */
+          trash = g_slist_prepend (trash, mem);
+        }
+      release_trash_list (&trash, magazine_probes[j]);
+      if (k >= MAX_PROBE_TRIALS)        /* failed to reallocate slice */
+        g_error ("failed to reallocate slice from magazine (after g_thread_init): size=%d", magazine_probes[j]);
+    }
+  /* mps[*] now contains pointers to reallocated slices */
+
+  /* ensure that we can allocate from known pages */
+  if (!allocate_from_known_page())
+    g_error ("failed to allocate from magazine/page cache (after g_thread_init)");
+
+  /* some cleanups */
+  for (j = 0; j < N_MAGAZINE_PROBES; j++)
+    g_slice_free1 (magazine_probes[j], mps[j]);
+  release_trash_list (&free_list, SAMPLE_SIZE);
+
+  return 0;
+}