Add erlang:external_size/2 BIF

This BIF's second parameter is a list of options.
Currently the only allowed option is {minor_version, Version}
where version is either 0 (default) or 1.

5 files changed, 116 insertions, 2 deletions

diff --git a/erts/doc/src/erlang.xml b/erts/doc/src/erlang.xml
index ad7a57bd73..84d4160e6a 100644
--- a/erts/doc/src/erlang.xml
+++ b/erts/doc/src/erlang.xml
@@ -1035,6 +1035,56 @@ b</pre>
       </desc>
     </func>
     <func>
+      <name>erlang:external_size(Term) -> integer() >= 0</name>
+      <fsummary>Calculate the maximum size for a term encoded in the Erlang
+        external term format</fsummary>
+      <type>
+        <v>Term = term()</v>
+      </type>
+      <desc>
+        <p>Calculates, without doing the encoding, the maximum byte size for
+          a term encoded in the Erlang external term format. The following
+          condition applies always:</p>
+        <p>
+          <pre>
+> <input>Size1 = byte_size(term_to_binary(Term)),</input>
+> <input>Size2 = erlang:external_size(Term),</input>
+> <input>true = Size1 =&lt; Size2.</input>
+true
+          </pre>
+        </p>
+        <p>This is equivalent to a call to: <code>erlang:external_size(Term, [])
+          </code></p>
+      </desc>
+    </func>
+    <func>
+      <name>erlang:external_size(Term, [Option]) -> integer() >= 0</name>
+      <fsummary>Calculate the maximum size for a term encoded in the Erlang
+        external term format</fsummary>
+      <type>
+        <v>Term = term()</v>
+        <v>Option = {minor_version, Version}</v>
+      </type>
+      <desc>
+        <p>Calculates, without doing the encoding, the maximum byte size for
+          a term encoded in the Erlang external term format. The following
+          condition applies always:</p>
+        <p>
+          <pre>
+> <input>Size1 = byte_size(term_to_binary(Term, Options)),</input>
+> <input>Size2 = erlang:external_size(Term, Options),</input>
+> <input>true = Size1 =&lt; Size2.</input>
+true
+          </pre>
+        </p>
+        <p>The option <c>{minor_version, Version}</c> specifies how floats
+          are encoded. See
+          <seealso marker="#term_to_binary/2">term_to_binary/2</seealso> for
+          a more detailed description.
+        </p>
+      </desc>
+    </func>
+    <func>
       <name>float(Number) -> float()</name>
       <fsummary>Convert a number to a float</fsummary>
       <type>
diff --git a/erts/emulator/beam/bif.tab b/erts/emulator/beam/bif.tab
index b171e99e03..831c0b1ce6 100644
--- a/erts/emulator/beam/bif.tab
+++ b/erts/emulator/beam/bif.tab
@@ -87,6 +87,8 @@ bif erlang:exit/2
 bif 'erl.lang.proc':signal/2		ebif_signal_2 exit_2
 bif erlang:external_size/1
 bif 'erl.lang.term':external_size/1	ebif_external_size_1
+bif erlang:external_size/2
+bif 'erl.lang.term':external_size/2	ebif_external_size_2
 ubif erlang:float/1
 ubif 'erl.lang.number':to_float/1	ebif_to_float_1 float_1
 bif erlang:float_to_list/1
diff --git a/erts/emulator/beam/external.c b/erts/emulator/beam/external.c
index 1a102f7187..6953e7fe7d 100644
--- a/erts/emulator/beam/external.c
+++ b/erts/emulator/beam/external.c
@@ -459,6 +459,12 @@ Uint erts_encode_ext_size(Eterm term)
 	+ 1 /* VERSION_MAGIC */;
 }
 
+Uint erts_encode_ext_size_2(Eterm term, unsigned dflags)
+{
+    return encode_size_struct2(NULL, term, TERM_TO_BINARY_DFLAGS|dflags)
+        + 1 /* VERSION_MAGIC */;
+}
+
 Uint erts_encode_ext_size_ets(Eterm term)
 {
     return encode_size_struct2(NULL, term, TERM_TO_BINARY_DFLAGS|DFLAGS_INTERNAL_TAGS);
@@ -1262,6 +1268,49 @@ external_size_1(Process* p, Eterm Term)
 }
 
 Eterm
+external_size_2(Process* p, Eterm Term, Eterm Flags)
+{
+    Uint size;
+    Uint flags = TERM_TO_BINARY_DFLAGS;
+
+    while (is_list(Flags)) {
+        Eterm arg = CAR(list_val(Flags));
+        Eterm* tp;
+
+        if (is_tuple(arg) && *(tp = tuple_val(arg)) == make_arityval(2)) {
+            if (tp[1] == am_minor_version && is_small(tp[2])) {
+                switch (signed_val(tp[2])) {
+                case 0:
+                    break;
+                case 1:
+                    flags |= DFLAG_NEW_FLOATS;
+                    break;
+                default:
+                    goto error;
+                }
+            } else {
+                goto error;
+            }
+        } else {
+        error:
+            BIF_ERROR(p, BADARG);
+        }
+        Flags = CDR(list_val(Flags));
+    }
+    if (is_not_nil(Flags)) {
+        goto error;
+    }
+
+    size = erts_encode_ext_size_2(Term, flags);
+    if (IS_USMALL(0, size)) {
+        BIF_RET(make_small(size));
+    } else {
+        Eterm* hp = HAlloc(p, BIG_UINT_HEAP_SIZE);
+        BIF_RET(uint_to_big(size, hp));
+    }
+}
+
+Eterm
 erts_term_to_binary(Process* p, Eterm Term, int level, Uint flags)
 {
     Uint size;
diff --git a/erts/emulator/beam/external.h b/erts/emulator/beam/external.h
index d8287b96a4..72fe74baf2 100644
--- a/erts/emulator/beam/external.h
+++ b/erts/emulator/beam/external.h
@@ -160,6 +160,7 @@ Uint erts_encode_dist_ext_size(Eterm, Uint32, ErtsAtomCacheMap *);
 void erts_encode_dist_ext(Eterm, byte **, Uint32, ErtsAtomCacheMap *);
 
 Uint erts_encode_ext_size(Eterm);
+Uint erts_encode_ext_size_2(Eterm, unsigned);
 Uint erts_encode_ext_size_ets(Eterm);
 void erts_encode_ext(Eterm, byte **);
 byte* erts_encode_ext_ets(Eterm, byte *, struct erl_off_heap_header** ext_off_heap);
diff --git a/erts/emulator/test/binary_SUITE.erl b/erts/emulator/test/binary_SUITE.erl
index 4e82381fba..fed5854112 100644
--- a/erts/emulator/test/binary_SUITE.erl
+++ b/erts/emulator/test/binary_SUITE.erl
@@ -478,6 +478,11 @@ terms(Config) when is_list(Config) ->
 			  Sz when is_integer(Sz), size(Bin) =< Sz ->
 			      ok
 		      end,
+              Bin1 = term_to_binary(Term, [{minor_version, 1}]),
+              case erlang:external_size(Bin1, [{minor_version, 1}]) of
+              Sz1 when is_integer(Sz1), size(Bin1) =< Sz1 ->
+                  ok
+              end,
 		      Term = binary_to_term(Bin),
 		      Term = binary_to_term(Bin, [safe]),
 		      Unaligned = make_unaligned_sub_binary(Bin),
@@ -510,7 +515,12 @@ terms_float(Config) when is_list(Config) ->
 			      Term = binary_to_term(Bin0),
 			      Bin1 = term_to_binary(Term, [{minor_version,1}]),
 			      Term = binary_to_term(Bin1),
-			      true = size(Bin1) < size(Bin0)
+			      true = size(Bin1) < size(Bin0),
+                  Size0 = erlang:external_size(Term),
+                  Size00 = erlang:external_size(Term, [{minor_version, 0}]),
+                  Size1 = erlang:external_size(Term, [{minor_version, 1}]),
+                  true = (Size0 =:= Size00),
+                  true = Size1 < Size0
 		      end).
 
 external_size(Config) when is_list(Config) ->
@@ -526,7 +536,9 @@ external_size(Config) when is_list(Config) ->
 	    io:format("  Aligned size: ~p\n", [Sz1]),
 	    io:format("Unaligned size: ~p\n", [Sz2]),
 	    ?line ?t:fail()
-    end.
+    end,
+    ?line erlang:external_size(Bin) =:= erlang:external_size(Bin, [{minor_version, 1}]),
+    ?line erlang:external_size(Unaligned) =:= erlang:external_size(Unaligned, [{minor_version, 1}]).
 
 external_size_1(Term, Size0, Limit) when Size0 < Limit ->
     case erlang:external_size(Term) of