erts: Fix race bug in ets:all/0

causing recently created/deleted tables to not be included/excluded.

3 files changed, 38 insertions, 10 deletions

diff --git a/erts/emulator/beam/erl_db.c b/erts/emulator/beam/erl_db.c
index 41e64fcd4f..a5d67571e2 100644
--- a/erts/emulator/beam/erl_db.c
+++ b/erts/emulator/beam/erl_db.c
@@ -1,7 +1,7 @@
 /*
  * %CopyrightBegin%
  *
- * Copyright Ericsson AB 1996-2013. All Rights Reserved.
+ * Copyright Ericsson AB 1996-2014. All Rights Reserved.
  *
  * The contents of this file are subject to the Erlang Public License,
  * Version 1.1, (the "License"); you may not use this file except in
@@ -125,6 +125,7 @@ get_meta_main_tab_lock(unsigned slot)
 static erts_smp_spinlock_t meta_main_tab_main_lock;
 static Uint meta_main_tab_first_free;   /* Index of first free slot */
 static int meta_main_tab_cnt;		/* Number of active tables */
+static int meta_main_tab_top;           /* Highest ever used slot + 1 */
 static Uint meta_main_tab_slot_mask;    /* The slot index part of an unnamed table id */
 static Uint meta_main_tab_seq_incr;
 static Uint meta_main_tab_seq_cnt = 0;  /* To give unique(-ish) table identifiers */
@@ -1469,6 +1470,10 @@ BIF_RETTYPE ets_new_2(BIF_ALIST_2)
     ASSERT(slot>=0 && slot<db_max_tabs);
     meta_main_tab_first_free = GET_NEXT_FREE_SLOT(slot);
     meta_main_tab_cnt++;
+    if (slot >= meta_main_tab_top) {
+	ASSERT(slot == meta_main_tab_top);
+	meta_main_tab_top = slot + 1;
+    }
 
     if (is_named) {
 	ret = BIF_ARG_1;
@@ -2058,27 +2063,31 @@ BIF_RETTYPE ets_all_0(BIF_ALIST_0)
 {
     DbTable* tb;
     Eterm previous;
-    int i, j;
+    int i;
     Eterm* hp;
     Eterm* hendp;
     int t_tabs_cnt;
-    int t_max_tabs;
+    int t_top;
 
     erts_smp_spin_lock(&meta_main_tab_main_lock);
     t_tabs_cnt = meta_main_tab_cnt;
-    t_max_tabs = db_max_tabs;
+    t_top = meta_main_tab_top;
     erts_smp_spin_unlock(&meta_main_tab_main_lock);
 
     hp = HAlloc(BIF_P, 2*t_tabs_cnt);
     hendp = hp + 2*t_tabs_cnt;
 
     previous = NIL;
-    j = 0;
-    for(i = 0; (i < t_max_tabs && j < t_tabs_cnt); i++) {
+    for(i = 0; i < t_top; i++) {
 	erts_smp_rwmtx_t *mmtl = get_meta_main_tab_lock(i);
 	erts_smp_rwmtx_rlock(mmtl);
 	if (IS_SLOT_ALIVE(i)) {
-	    j++;
+	    if (hp == hendp) {
+		/* Racing table creator, grab some more heap space */
+		t_tabs_cnt = 10;
+		hp = HAlloc(BIF_P, 2*t_tabs_cnt);
+		hendp = hp + 2*t_tabs_cnt;
+	    }
 	    tb = meta_main_tab[i].u.tb;
 	    previous = CONS(hp, tb->common.id, previous);
 	    hp += 2;
@@ -2849,6 +2858,7 @@ void init_db(void)
     ERTS_ETS_MISC_MEM_ADD(size);
 
     meta_main_tab_cnt = 0;
+    meta_main_tab_top = 0;
     for (i=1; i<db_max_tabs; i++) {
 	SET_NEXT_FREE_SLOT(i-1,i);
     }
diff --git a/lib/stdlib/doc/src/ets.xml b/lib/stdlib/doc/src/ets.xml
index 21cf8e4149..3df24bf688 100644
--- a/lib/stdlib/doc/src/ets.xml
+++ b/lib/stdlib/doc/src/ets.xml
@@ -4,7 +4,7 @@
 <erlref>
   <header>
     <copyright>
-      <year>1996</year><year>2013</year>
+      <year>1996</year><year>2014</year>
       <holder>Ericsson AB. All Rights Reserved.</holder>
     </copyright>
     <legalnotice>
@@ -171,6 +171,10 @@
         <p>Returns a list of all tables at the node. Named tables are
           given by their names, unnamed tables are given by their
           table identifiers.</p>
+	<p>There is no guarantee of consistency in the returned list. Tables created
+	or deleted by other processes "during" the ets:all() call may or may
+	not be included in the list. Only tables created/deleted <em>before</em>
+	ets:all() is called are guaranteed to be included/excluded.</p>
       </desc>
     </func>
     <func>
diff --git a/lib/stdlib/test/ets_SUITE.erl b/lib/stdlib/test/ets_SUITE.erl
index 82c3e7ecaf..8dc8b2c291 100644
--- a/lib/stdlib/test/ets_SUITE.erl
+++ b/lib/stdlib/test/ets_SUITE.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %%
-%% Copyright Ericsson AB 1996-2013. All Rights Reserved.
+%% Copyright Ericsson AB 1996-2014. All Rights Reserved.
 %%
 %% The contents of this file are subject to the Erlang Public License,
 %% Version 1.1, (the "License"); you may not use this file except in
@@ -75,6 +75,7 @@
 -export([otp_9932/1]).
 -export([otp_9423/1]).
 -export([otp_10182/1]).
+-export([ets_all/1]).
 -export([memory_check_summary/1]).
 
 -export([init_per_testcase/2, end_per_testcase/2]).
@@ -151,6 +152,7 @@ all() ->
      otp_10182,
      otp_9932,
      otp_9423,
+     ets_all,
      
      memory_check_summary]. % MUST BE LAST
 
@@ -5565,7 +5567,19 @@ otp_10182(Config) when is_list(Config) ->
     ets:delete(Db),
     In = Out.
 
-    
+%% Test that ets:all include/exclude tables that we know are created/deleted
+ets_all(Config) when is_list(Config) ->
+    Pids = [spawn_link(fun() -> ets_all_run() end) || _ <- [1,2]],
+    receive after 3*1000 -> ok end,
+    [begin unlink(P), exit(P,kill) end || P <- Pids],
+    ok.
+
+ets_all_run() ->
+    Table = ets:new(undefined, []),
+    true = lists:member(Table, ets:all()),
+    ets:delete(Table),
+    false = lists:member(Table, ets:all()),
+    ets_all_run().
     
 
 %