add set_procfs_pathset_procfs_path

3 files changed, 42 insertions, 5 deletions

diff --git a/psutil/__init__.py b/psutil/__init__.py
index 7a170937..d6a66de2 100644
--- a/psutil/__init__.py
+++ b/psutil/__init__.py
@@ -2270,6 +2270,13 @@ def users():
     return _psplatform.users()
 
 
+def set_procfs_path(path):
+    """Set an alternative path for /proc filesystem on Linux, Solaris
+    and AIX. This superseds PROCFS_PATH variable which is deprecated.
+    """
+    _psplatform.PROCFS_PATH = path
+
+
 # =====================================================================
 # --- Windows services
 # =====================================================================
diff --git a/psutil/_pslinux.py b/psutil/_pslinux.py
index b57adb34..b9b43346 100644
--- a/psutil/_pslinux.py
+++ b/psutil/_pslinux.py
@@ -68,6 +68,7 @@ __extra__all__ = [
 # =====================================================================
 
 
+PROCFS_PATH = None
 POWER_SUPPLY_PATH = "/sys/class/power_supply"
 HAS_SMAPS = os.path.exists('/proc/%s/smaps' % os.getpid())
 HAS_PRLIMIT = hasattr(cext, "linux_prlimit")
@@ -210,8 +211,36 @@ else:
 
 
 def get_procfs_path():
-    """Return updated psutil.PROCFS_PATH constant."""
-    return sys.modules['psutil'].PROCFS_PATH
+    """Return updated PROCFS_PATH constant.
+    Return value is cached after 10 calls.
+    """
+    global PROCFS_PATH
+
+    if PROCFS_PATH is not None:
+        return PROCFS_PATH
+
+    path = sys.modules['psutil'].PROCFS_PATH
+    if path != "/proc":
+        msg = \
+            "you used `psutil.PROCFS_PATH = %s` somewhere in your code; " \
+            "that is deprecated and will be ignored in the future; replace " \
+            "it with `set_procfs_path(%r)`" % (path, path)
+        warnings.warn(msg, category=FutureWarning, stacklevel=2)
+        PROCFS_PATH = path
+
+    # Cache the value if path remained the same after 10 calls.
+    # This means that from now on any change to psutil.PROCFS_PATH
+    # will be ignored.
+    # This is based on the assumption that it's likely that the user
+    # does "psutil.PROCFS_PATH" at import time, not later.
+    get_procfs_path.ncalls += 1
+    if get_procfs_path.ncalls >= 10:
+        PROCFS_PATH = path
+
+    return path
+
+
+get_procfs_path.ncalls = 0
 
 
 def readlink(path):
diff --git a/psutil/tests/test_linux.py b/psutil/tests/test_linux.py
index 6ba17b25..5d345ae0 100755
--- a/psutil/tests/test_linux.py
+++ b/psutil/tests/test_linux.py
@@ -1058,7 +1058,7 @@ class TestMisc(unittest.TestCase):
                 self.assertRaises(
                     IOError, psutil.cpu_times_percent, percpu=True)
 
-                psutil.PROCFS_PATH = my_procfs
+                psutil.set_procfs_path(my_procfs)
 
                 self.assertEqual(psutil.cpu_percent(), 0)
                 self.assertEqual(sum(psutil.cpu_times_percent()), 0)
@@ -1085,6 +1085,7 @@ class TestMisc(unittest.TestCase):
                 self.assertNotEqual(
                     sum(map(sum, psutil.cpu_times_percent(percpu=True))), 0)
         finally:
+            psutil.set_procfs_path("/proc")
             shutil.rmtree(my_procfs)
             reload_module(psutil)
 
@@ -1120,7 +1121,7 @@ class TestMisc(unittest.TestCase):
     def test_procfs_path(self):
         tdir = tempfile.mkdtemp()
         try:
-            psutil.PROCFS_PATH = tdir
+            psutil.set_procfs_path(tdir)
             self.assertRaises(IOError, psutil.virtual_memory)
             self.assertRaises(IOError, psutil.cpu_times)
             self.assertRaises(IOError, psutil.cpu_times, percpu=True)
@@ -1133,7 +1134,7 @@ class TestMisc(unittest.TestCase):
             self.assertRaises(IOError, psutil.disk_partitions)
             self.assertRaises(psutil.NoSuchProcess, psutil.Process)
         finally:
-            psutil.PROCFS_PATH = "/proc"
+            psutil.set_procfs_path("/proc")
             os.rmdir(tdir)
 
     def test_sector_size_mock(self):