add system_info(ets_limit)

Add system_info(ets_limit) to provide a way to retrieve the runtime's
maximum number of ETS tables. Add tests and documentation for it too.

Also repair the alphabetical order of system_info/1 argument descriptions
in the documentation and in the erlang.erl clauses. Add new preloaded
erlang.erl due to that change. Also ensure all system_info/1 clauses are
represented in the erlang.xml source documentation -- a couple had been
inadvertently dropped in previous commits when other clauses were added.

7 files changed, 84 insertions, 9 deletions

diff --git a/erts/doc/src/erl.xml b/erts/doc/src/erl.xml
index c16b45856d..528a2d95aa 100644
--- a/erts/doc/src/erl.xml
+++ b/erts/doc/src/erl.xml
@@ -524,7 +524,7 @@
 	<p>Calling <c>erlang:halt/1</c> with a string argument will still
 	produce a crash dump.</p>
       </item>
-      <tag><c><![CDATA[+e Number]]></c></tag>
+      <tag><marker id="+e"><c><![CDATA[+e Number]]></c></marker></tag>
       <item>
         <p>Set max number of ETS tables.</p>
       </item>
diff --git a/erts/doc/src/erlang.xml b/erts/doc/src/erlang.xml
index 5ee40823bc..d3b21de8cf 100644
--- a/erts/doc/src/erlang.xml
+++ b/erts/doc/src/erlang.xml
@@ -5500,6 +5500,9 @@ ok
       <name name="system_info" arity="1" clause_i="49"/>
       <name name="system_info" arity="1" clause_i="50"/>
       <name name="system_info" arity="1" clause_i="51"/>
+      <name name="system_info" arity="1" clause_i="52"/>
+      <name name="system_info" arity="1" clause_i="53"/>
+      <name name="system_info" arity="1" clause_i="54"/>
       <fsummary>Information about the system</fsummary>
       <desc>
         <p>Returns various information about the current system
@@ -5576,6 +5579,13 @@ ok
               information see the <seealso marker="erts:crash_dump">"How to interpret the Erlang crash dumps"</seealso>
               chapter in the ERTS User's Guide.</p>
           </item>
+          <tag><marker id="system_info_dist_buf_busy_limit"><c>dist_buf_busy_limit</c></marker></tag>
+          <item>
+            <p>Returns the value of the distribution buffer busy limit
+	    in bytes. This limit can be set on startup by passing the
+	    <seealso marker="erts:erl#+zdbbl">+zdbbl</seealso> command line
+	    flag to <c>erl</c>.</p>
+          </item>
           <tag><c>dist_ctrl</c></tag>
           <item>
             <p>Returns a list of tuples
@@ -5622,12 +5632,14 @@ ok
 	      The return value will always be <c>false</c> since
 	      the elib_malloc allocator has been removed.</p>
           </item>
-          <tag><marker id="system_info_dist_buf_busy_limit"><c>dist_buf_busy_limit</c></marker></tag>
+          <tag><c>ets_limit</c></tag>
           <item>
-            <p>Returns the value of the distribution buffer busy limit
-	    in bytes. This limit can be set on startup by passing the
-	    <seealso marker="erts:erl#+zdbbl">+zdbbl</seealso> command line
-	    flag to <c>erl</c>.</p>
+            <p>Returns the maximum number of ETS tables allowed. This limit
+              can be increased on startup by passing the <seealso
+              marker="erts:erl#+e">+e</seealso> command line flag to
+              <c>erl</c> or by setting the environment variable
+              <c>ERL_MAX_ETS_TABLES</c> before starting the Erlang runtime
+              system.</p>
           </item>
           <tag><c>fullsweep_after</c></tag>
           <item>
diff --git a/erts/emulator/beam/erl_bif_info.c b/erts/emulator/beam/erl_bif_info.c
index 673dfc658c..3b25efd9af 100755
--- a/erts/emulator/beam/erl_bif_info.c
+++ b/erts/emulator/beam/erl_bif_info.c
@@ -2636,6 +2636,9 @@ BIF_RETTYPE system_info_1(BIF_ALIST_1)
 
 	BIF_RET(res);
     }
+    else if (ERTS_IS_ATOM_STR("ets_limit",BIF_ARG_1)) {
+        BIF_RET(make_small(erts_db_get_max_tabs()));
+    }
 
     BIF_ERROR(BIF_P, BADARG);
 }
diff --git a/erts/emulator/beam/erl_db.c b/erts/emulator/beam/erl_db.c
index 98c2988323..40b8eaf8fb 100644
--- a/erts/emulator/beam/erl_db.c
+++ b/erts/emulator/beam/erl_db.c
@@ -3811,6 +3811,13 @@ erts_db_foreach_offheap(DbTable *tb,
     tb->common.meth->db_foreach_offheap(tb, func, arg);
 }
 
+/* retrieve max number of ets tables */
+Uint
+erts_db_get_max_tabs()
+{
+    return db_max_tabs;
+}
+
 /*
  * For testing of meta tables only.
  *
diff --git a/erts/emulator/beam/erl_db.h b/erts/emulator/beam/erl_db.h
index 6b62e10eb7..5b4681fc90 100644
--- a/erts/emulator/beam/erl_db.h
+++ b/erts/emulator/beam/erl_db.h
@@ -79,6 +79,8 @@ extern erts_smp_atomic_t erts_ets_misc_mem_size;
 
 Eterm erts_ets_colliding_names(Process*, Eterm name, Uint cnt);
 
+Uint erts_db_get_max_tabs(void);
+
 #endif
 
 #if defined(ERTS_WANT_DB_INTERNAL__) && !defined(ERTS_HAVE_DB_INTERNAL__)
diff --git a/erts/emulator/test/system_info_SUITE.erl b/erts/emulator/test/system_info_SUITE.erl
index 0350eb671d..ceb4afb5cf 100644
--- a/erts/emulator/test/system_info_SUITE.erl
+++ b/erts/emulator/test/system_info_SUITE.erl
@@ -37,7 +37,8 @@
 	 init_per_group/2,end_per_group/2, 
 	 init_per_testcase/2, end_per_testcase/2]).
 
--export([process_count/1, system_version/1, misc_smoke_tests/1, heap_size/1, wordsize/1, memory/1]).
+-export([process_count/1, system_version/1, misc_smoke_tests/1, heap_size/1, wordsize/1, memory/1,
+         ets_limit/1]).
 
 -define(DEFAULT_TIMEOUT, ?t:minutes(2)).
 
@@ -45,7 +46,7 @@ suite() -> [{ct_hooks,[ts_install_cth]}].
 
 all() -> 
     [process_count, system_version, misc_smoke_tests,
-     heap_size, wordsize, memory].
+     heap_size, wordsize, memory, ets_limit].
 
 groups() -> 
     [].
@@ -496,3 +497,52 @@ mapn(_Fun, 0) ->
     [];
 mapn(Fun, N) ->
     [Fun(N) | mapn(Fun, N-1)].
+
+ets_limit(doc) ->
+    "Verify system_info(ets_limit) reflects max ETS table settings.";
+ets_limit(suite) -> [];
+ets_limit(Config0) when is_list(Config0) ->
+    Config = [{testcase,ets_limit}|Config0],
+    true = is_integer(get_ets_limit(Config)),
+    12345 = get_ets_limit(Config, 12345),
+    ok.
+
+get_ets_limit(Config) ->
+    get_ets_limit(Config, 0).
+get_ets_limit(Config, EtsMax) ->
+    Envs = case EtsMax of
+               0 -> [];
+               _ -> [{"ERL_MAX_ETS_TABLES", integer_to_list(EtsMax)}]
+           end,
+    {ok, Node} = start_node(Config, Envs),
+    Me = self(),
+    Ref = make_ref(),
+    spawn_link(Node,
+               fun() ->
+                       Res = erlang:system_info(ets_limit),
+                       unlink(Me),
+                       Me ! {Ref, Res}
+               end),
+    receive
+        {Ref, Res} ->
+            Res
+    end,
+    stop_node(Node),
+    Res.
+
+start_node(Config, Envs) when is_list(Config) ->
+    Pa = filename:dirname(code:which(?MODULE)),
+    {A, B, C} = now(),
+    Name = list_to_atom(atom_to_list(?MODULE)
+                        ++ "-"
+                        ++ atom_to_list(?config(testcase, Config))
+                        ++ "-"
+                        ++ integer_to_list(A)
+                        ++ "-"
+                        ++ integer_to_list(B)
+                        ++ "-"
+                        ++ integer_to_list(C)),
+    ?t:start_node(Name, peer, [{args, "-pa "++Pa}, {env, Envs}]).
+
+stop_node(Node) ->
+    ?t:stop_node(Node).
diff --git a/erts/preloaded/src/erlang.erl b/erts/preloaded/src/erlang.erl
index a969ef91dc..d40ee7c59a 100644
--- a/erts/preloaded/src/erlang.erl
+++ b/erts/preloaded/src/erlang.erl
@@ -2099,13 +2099,14 @@ tuple_to_list(_Tuple) ->
          (creation) -> integer();
          (debug_compiled) -> boolean();
          (dist) -> binary();
+         (dist_buf_busy_limit) -> non_neg_integer();
          (dist_ctrl) -> {Node :: node(),
                          ControllingEntity :: port() | pid()};
          (driver_version) -> string();
 	 (dynamic_trace) -> none | dtrace | systemtap;
          (dynamic_trace_probes) -> boolean();
          (elib_malloc) -> false;
-         (dist_buf_busy_limit) -> non_neg_integer();
+         (ets_limit) -> pos_integer();
          (fullsweep_after) -> {fullsweep_after, non_neg_integer()};
          (garbage_collection) -> [{atom(), integer()}];
          (heap_sizes) -> [non_neg_integer()];