SERVER-9564 When libabigail utils are present, minimize relinking

SConstruct

@@ -564,6 +564,9 @@ env_vars = Variables(
     args=ARGUMENTS
 )
 
+env_vars.Add('ABIDW',
+    help="Configures the path to the 'abidw' (a libabigail) utility")
+
 env_vars.Add('ARFLAGS',
     help='Sets flags for the archiver',
     converter=variable_shlex_converter)
@@ -1028,6 +1031,13 @@ env['_LIBDEPS'] = '$_LIBDEPS_OBJS' if link_model == "object" else '$_LIBDEPS_LIB
 
 if link_model.startswith("dynamic"):
 
+    # Add in the abi linking tool if the user requested and it is
+    # supported on this platform.
+    if env.get('ABIDW'):
+        abilink = Tool('abilink')
+        if abilink.exists(env):
+            abilink(env)
+
     # Redirect the 'Library' target, which we always use instead of 'StaticLibrary' for things
     # that can be built in either mode, to point to SharedLibrary.
     env['BUILDERS']['Library'] = env['BUILDERS']['SharedLibrary']

site_scons/libdeps.py

@@ -235,7 +235,9 @@ def libdeps_emitter(target, source, env):
             file_name = '${LIBPREFIX}' + file_name
         if not file_name.endswith(lib_suffix):
             file_name += '${LIBSUFFIX}'
-        libdep_files.append(env.File(os.path.join(dir_name, file_name)))
+
+        node_factory = env['BUILDERS']['StaticLibrary'].target_factory or env.File
+        libdep_files.append(node_factory(os.path.join(dir_name, file_name)))
 
     for t in target:
         # target[0] must be a Node and not a string, or else libdeps will fail to
@@ -276,7 +278,9 @@ def shlibdeps_emitter(target, source, env):
             file_name = '${SHLIBPREFIX}' + file_name
         if not file_name.endswith(lib_suffix):
             file_name += '${SHLIBSUFFIX}'
-        libdep_files.append(env.File(os.path.join(dir_name, file_name)))
+
+        node_factory = env['BUILDERS']['SharedLibrary'].target_factory or env.File
+        libdep_files.append(node_factory(os.path.join(dir_name, file_name)))
 
     for t in target:
         # target[0] must be a Node and not a string, or else libdeps will fail to

site_scons/site_tools/abilink.py

@@ -0,0 +1,66 @@
+# Copyright (C) 2015 MongoDB Inc.
+#
+# This program is free software: you can redistribute it and/or  modify
+# it under the terms of the GNU Affero General Public License, version 3,
+# as published by the Free Software Foundation.
+#
+# This program 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.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import SCons
+import subprocess
+
+def _detect(env):
+    try:
+        abidw = env['ABIDW']
+        if not abidw:
+            return None
+    except KeyError:
+        pass
+
+    return env.WhereIs('abidw')
+
+def generate(env):
+
+    class AbilinkNode(SCons.Node.FS.File):
+        def __init__(self, name, directory, fs):
+            SCons.Node.FS.File.__init__(self, name, directory, fs)
+
+        def get_contents(self):
+            if not self.rexists():
+                return ''
+            fname = self.rfile().abspath
+            try:
+                # TODO: If there were python bindings for libabigail, we
+                # could avoid the shell out (and probably be faster, as we
+                # could get exactly the information we want).
+                contents = subprocess.check_output([env.subst('$ABIDW'), fname])
+            except EnvironmentError, e:
+                if not e.filename:
+                    e.filename = fname
+                raise
+            return contents
+
+        def get_content_hash(self):
+            return SCons.Util.MD5signature(self.get_contents())
+
+    env['ABIDW'] = _detect(env)
+
+    def ShlibNode(env, name, directory = None, create = 1):
+        return env.fs._lookup(env.subst(name), directory, AbilinkNode, create)
+
+    env.AddMethod(ShlibNode, 'ShlibNode')
+
+    def shlib_target_factory(arg):
+        return env.ShlibNode(arg)
+
+    env['BUILDERS']['SharedLibrary'].target_factory = shlib_target_factory
+
+def exists(env):
+    result = _detect(env) != None
+    return result