Added caching of the 'module' detection result.

lib/spack/spack/test/module_parsing.py

@@ -180,7 +180,7 @@ def test_get_module_cmd_returns_the_same(tmpdir):
         with open('module_list.txt') as f:
             module_list = f.read()
 
-    module_cmd = get_module_cmd()
+    module_cmd = get_module_cmd(True)
     module_cmd_list = module_cmd('list', output=str, error=str)
 
     # Lmod command reprints some env variables on every invocation.
@@ -287,7 +287,7 @@ def test_get_module_cmd_detect_order(backup_restore_env, tmpdir):
                            'echo $0 $*')
     which_executable.chmod(0o770)
 
-    module_cmd = get_module_cmd()
+    module_cmd = get_module_cmd(True)
     module_cmd_list = module_cmd('list', output=str)
 
     assert module_cmd_list == (str(user_definition) + ' python list\n')
@@ -296,7 +296,7 @@ def test_get_module_cmd_detect_order(backup_restore_env, tmpdir):
     # definition from the bash initialization scripts.
     user_definition.write('exit 1')
 
-    module_cmd = get_module_cmd()
+    module_cmd = get_module_cmd(True)
     module_cmd_list = module_cmd('list', output=str)
 
     assert module_cmd_list == (str(init_definition) + ' python list\n')
@@ -305,7 +305,7 @@ def test_get_module_cmd_detect_order(backup_restore_env, tmpdir):
     # incorrectly, Spack should use the 'modulecmd' executable.
     init_definition.write('exit 1')
 
-    module_cmd = get_module_cmd()
+    module_cmd = get_module_cmd(True)
     module_cmd_list = module_cmd('list', output=str)
 
     assert module_cmd_list == (str(which_executable) + ' python list\n')
@@ -315,7 +315,7 @@ def test_get_module_cmd_detect_order(backup_restore_env, tmpdir):
                            'exit 1')
 
     with pytest.raises(ModuleError) as e:
-        get_module_cmd()
+        get_module_cmd(True)
     assert str(e.value).startswith('Spack requires \'modulecmd\' executable ')
 
 
@@ -358,12 +358,12 @@ def write_modulecmd(f, version):
 
     # The script must be modified.
     write_modulecmd(modulecmd, '3.3.0')
-    module_cmd = get_module_cmd()
+    module_cmd = get_module_cmd(True)
     script = module_cmd('load', 'mod', output=str)
     assert script == 'exec(open(\'modulescript_12345_00\').read())'
 
     # The script must not be modified.
     write_modulecmd(modulecmd, '4.0.0')
-    module_cmd = get_module_cmd()
+    module_cmd = get_module_cmd(True)
     script = module_cmd('load', 'mod', output=str)
     assert script == 'exec \'modulescript_12345_00\''

lib/spack/spack/util/module_cmd.py

@@ -33,8 +33,15 @@
 import llnl.util.tty as tty
 from spack.util.executable import which
 
+_module_cmd_cache = None
+
+
+def get_module_cmd(update_cache=False):
+    global _module_cmd_cache
+
+    if not update_cache and _module_cmd_cache:
+        return _module_cmd_cache
 
-def get_module_cmd():
     result = None
 
     # Unset BASH_ENV to prevent possible redefinition of the function.
@@ -45,10 +52,10 @@ def get_module_cmd():
             os.environ.pop('BASH_ENV')
 
         result = get_module_cmd_from_bash()
-    except ModuleError:
-        tty.warn('Could not detect module function as a shell function in the '
-                 'current environment. Trying to detect in the interactive '
-                 'login environment.')
+    except ModuleError as e:
+        tty.warn('Failed to detect module function as a shell function in the '
+                 'current environment: ' + str(e) + ' Trying to detect in the '
+                 'interactive login shell.')
     finally:
         if env_bu:
             os.environ.clear()
@@ -60,10 +67,10 @@ def get_module_cmd():
             # all, it should be available at least in the case of the
             # interactive login shell.
             result = get_module_cmd_from_bash(['-i', '-l'])
-        except ModuleError:
-            tty.warn('Could not detect module function in the interactive '
-                     'login environment. Trying to find \'modulecmd\' in the '
-                     '$PATH.')
+        except ModuleError as e:
+            tty.warn('Failed to detect module function in the interactive '
+                     'login shell: ' + str(e) + ' Trying to find '
+                     '\'modulecmd\' in the $PATH.')
 
     if result is None:
         try:
@@ -81,6 +88,8 @@ def get_module_cmd():
                 result(error=str)) is not None:
         result.post_processor = old_tcl_postprocessor
 
+    _module_cmd_cache = result
+
     return result