Replace functions in utils with oslo.fileutils

The following functions have moved to oslo.
remove_path_on_error
file_open
delete_if_exists

Replaced/removed overlapping functions with the ones in fileutils

Change-Id: I41a19d76a777b6f899843bb0cc0582630accbd5c

8 files changed, 89 insertions, 49 deletions

diff --git a/nova/openstack/common/fileutils.py b/nova/openstack/common/fileutils.py
index b988ad03d..53e07a2a5 100644
--- a/nova/openstack/common/fileutils.py
+++ b/nova/openstack/common/fileutils.py
@@ -16,9 +16,18 @@
 #    under the License.
 
 
+import contextlib
 import errno
 import os
 
+from nova.openstack.common import excutils
+from nova.openstack.common.gettextutils import _
+from nova.openstack.common import log as logging
+
+LOG = logging.getLogger(__name__)
+
+_FILE_CACHE = {}
+
 
 def ensure_tree(path):
     """Create a directory (and any ancestor directories required)
@@ -33,3 +42,69 @@ def ensure_tree(path):
                 raise
         else:
             raise
+
+
+def read_cached_file(filename, force_reload=False):
+    """Read from a file if it has been modified.
+
+    :param force_reload: Whether to reload the file.
+    :returns: A tuple with a boolean specifying if the data is fresh
+              or not.
+    """
+    global _FILE_CACHE
+
+    if force_reload and filename in _FILE_CACHE:
+        del _FILE_CACHE[filename]
+
+    reloaded = False
+    mtime = os.path.getmtime(filename)
+    cache_info = _FILE_CACHE.setdefault(filename, {})
+
+    if not cache_info or mtime > cache_info.get('mtime', 0):
+        LOG.debug(_("Reloading cached file %s") % filename)
+        with open(filename) as fap:
+            cache_info['data'] = fap.read()
+        cache_info['mtime'] = mtime
+        reloaded = True
+    return (reloaded, cache_info['data'])
+
+
+def delete_if_exists(path):
+    """Delete a file, but ignore file not found error.
+
+    :param path: File to delete
+    """
+
+    try:
+        os.unlink(path)
+    except OSError as e:
+        if e.errno == errno.ENOENT:
+            return
+        else:
+            raise
+
+
+@contextlib.contextmanager
+def remove_path_on_error(path):
+    """Protect code that wants to operate on PATH atomically.
+    Any exception will cause PATH to be removed.
+
+    :param path: File to work with
+    """
+    try:
+        yield
+    except Exception:
+        with excutils.save_and_reraise_exception():
+            delete_if_exists(path)
+
+
+def file_open(*args, **kwargs):
+    """Open file
+
+    see built-in file() documentation for more details
+
+    Note: The reason this is kept in a separate module is to easily
+    be able to provide a stub module that doesn't alter system
+    state at all (for unit tests)
+    """
+    return file(*args, **kwargs)
diff --git a/nova/tests/test_configdrive2.py b/nova/tests/test_configdrive2.py
index a71a01f8f..490edc4ed 100644
--- a/nova/tests/test_configdrive2.py
+++ b/nova/tests/test_configdrive2.py
@@ -22,6 +22,7 @@ import tempfile
 
 from nova import test
 
+from nova.openstack.common import fileutils
 from nova import utils
 from nova.virt import configdrive
 
@@ -53,7 +54,7 @@ class ConfigDriveTestCase(test.TestCase):
 
         finally:
             if imagefile:
-                utils.delete_if_exists(imagefile)
+                fileutils.delete_if_exists(imagefile)
 
     def test_create_configdrive_vfat(self):
         imagefile = None
@@ -87,4 +88,4 @@ class ConfigDriveTestCase(test.TestCase):
 
         finally:
             if imagefile:
-                utils.delete_if_exists(imagefile)
+                fileutils.delete_if_exists(imagefile)
diff --git a/nova/tests/virt/libvirt/test_libvirt.py b/nova/tests/virt/libvirt/test_libvirt.py
index 2f5f9c857..b6f2a3d8a 100644
--- a/nova/tests/virt/libvirt/test_libvirt.py
+++ b/nova/tests/virt/libvirt/test_libvirt.py
@@ -4745,7 +4745,7 @@ disk size: 4.4M''', ''))
         self.stubs.Set(os, 'unlink', fake_unlink)
         self.stubs.Set(images, 'fetch', lambda *_: None)
         self.stubs.Set(images, 'qemu_img_info', fake_qemu_img_info)
-        self.stubs.Set(utils, 'delete_if_exists', fake_rm_on_errror)
+        self.stubs.Set(fileutils, 'delete_if_exists', fake_rm_on_errror)
 
         context = 'opaque context'
         image_id = '4'
diff --git a/nova/utils.py b/nova/utils.py
index 9067488d5..41d18b3cb 100644
--- a/nova/utils.py
+++ b/nova/utils.py
@@ -21,7 +21,6 @@
 
 import contextlib
 import datetime
-import errno
 import functools
 import hashlib
 import inspect
@@ -439,18 +438,6 @@ def to_bytes(text, default=0):
         return default
 
 
-def delete_if_exists(pathname):
-    """delete a file, but ignore file not found error."""
-
-    try:
-        os.unlink(pathname)
-    except OSError as e:
-        if e.errno == errno.ENOENT:
-            return
-        else:
-            raise
-
-
 def get_from_path(items, path):
     """Returns a list of items matching the specified path.
 
@@ -733,18 +720,6 @@ def timefunc(func):
     return inner
 
 
-@contextlib.contextmanager
-def remove_path_on_error(path):
-    """Protect code that wants to operate on PATH atomically.
-    Any exception will cause PATH to be removed.
-    """
-    try:
-        yield
-    except Exception:
-        with excutils.save_and_reraise_exception():
-            delete_if_exists(path)
-
-
 def make_dev_path(dev, partition=None, base='/dev'):
     """Return a path to a particular device.
 
@@ -803,18 +778,6 @@ def read_cached_file(filename, cache_info, reload_func=None):
     return cache_info['data']
 
 
-def file_open(*args, **kwargs):
-    """Open file
-
-    see built-in file() documentation for more details
-
-    Note: The reason this is kept in a separate module is to easily
-          be able to provide a stub module that doesn't alter system
-          state at all (for unit tests)
-    """
-    return file(*args, **kwargs)
-
-
 def hash_file(file_like_object):
     """Generate a hash for the contents of a file."""
     checksum = hashlib.sha1()
diff --git a/nova/virt/configdrive.py b/nova/virt/configdrive.py
index 57e5155c8..173dd457b 100644
--- a/nova/virt/configdrive.py
+++ b/nova/virt/configdrive.py
@@ -169,7 +169,7 @@ class ConfigDriveBuilder(object):
 
     def cleanup(self):
         if self.imagefile:
-            utils.delete_if_exists(self.imagefile)
+            fileutils.delete_if_exists(self.imagefile)
 
         try:
             shutil.rmtree(self.tempdir)
diff --git a/nova/virt/images.py b/nova/virt/images.py
index b40f566a6..08d275bc6 100755
--- a/nova/virt/images.py
+++ b/nova/virt/images.py
@@ -28,6 +28,7 @@ from oslo.config import cfg
 
 from nova import exception
 from nova.image import glance
+from nova.openstack.common import fileutils
 from nova.openstack.common import log as logging
 from nova import utils
 
@@ -197,7 +198,7 @@ def fetch(context, image_href, path, _user_id, _project_id):
     #             checked before we got here.
     (image_service, image_id) = glance.get_remote_image_service(context,
                                                                 image_href)
-    with utils.remove_path_on_error(path):
+    with fileutils.remove_path_on_error(path):
         with open(path, "wb") as image_file:
             image_service.download(context, image_id, image_file)
 
@@ -206,7 +207,7 @@ def fetch_to_raw(context, image_href, path, user_id, project_id):
     path_tmp = "%s.part" % path
     fetch(context, image_href, path_tmp, user_id, project_id)
 
-    with utils.remove_path_on_error(path_tmp):
+    with fileutils.remove_path_on_error(path_tmp):
         data = qemu_img_info(path_tmp)
 
         fmt = data.file_format
@@ -223,7 +224,7 @@ def fetch_to_raw(context, image_href, path, user_id, project_id):
         if fmt != "raw" and CONF.force_raw_images:
             staged = "%s.converted" % path
             LOG.debug("%s was %s, converting to raw" % (image_href, fmt))
-            with utils.remove_path_on_error(staged):
+            with fileutils.remove_path_on_error(staged):
                 convert_image(path_tmp, staged, 'raw')
                 os.unlink(path_tmp)
 
diff --git a/nova/virt/libvirt/driver.py b/nova/virt/libvirt/driver.py
index c0cec7a43..135791f3d 100755
--- a/nova/virt/libvirt/driver.py
+++ b/nova/virt/libvirt/driver.py
@@ -2932,7 +2932,7 @@ class LibvirtDriver(driver.ComputeDriver):
         return os.path.exists(data['filename'])
 
     def check_instance_shared_storage_cleanup(self, ctxt, data):
-        utils.delete_if_exists(data["filename"])
+        fileutils.delete_if_exists(data["filename"])
 
     def check_can_live_migrate_destination(self, ctxt, instance_ref,
                                            src_compute_info, dst_compute_info,
diff --git a/nova/virt/libvirt/imagebackend.py b/nova/virt/libvirt/imagebackend.py
index 844d9dfde..c564d2d24 100755
--- a/nova/virt/libvirt/imagebackend.py
+++ b/nova/virt/libvirt/imagebackend.py
@@ -166,7 +166,7 @@ class Image(object):
         if can_fallocate is None:
             _out, err = utils.trycmd('fallocate', '-n', '-l', '1',
                                      self.path + '.fallocate_test')
-            utils.delete_if_exists(self.path + '.fallocate_test')
+            fileutils.delete_if_exists(self.path + '.fallocate_test')
             can_fallocate = not err
             self.__class__.can_fallocate = can_fallocate
             if not can_fallocate:
@@ -215,7 +215,7 @@ class Raw(Image):
         else:
             prepare_template(target=base, *args, **kwargs)
             if not os.path.exists(self.path):
-                with utils.remove_path_on_error(self.path):
+                with fileutils.remove_path_on_error(self.path):
                     copy_raw_image(base, self.path, size)
         self.correct_format()
 
@@ -273,7 +273,7 @@ class Qcow2(Image):
         # Create the legacy backing file if necessary.
         if legacy_backing_size:
             if not os.path.exists(legacy_base):
-                with utils.remove_path_on_error(legacy_base):
+                with fileutils.remove_path_on_error(legacy_base):
                     libvirt_utils.copy_image(base, legacy_base)
                     disk.extend(legacy_base, legacy_backing_size)
 
@@ -285,7 +285,7 @@ class Qcow2(Image):
                       (base, size))
             raise exception.InstanceTypeDiskTooSmall()
         if not os.path.exists(self.path):
-            with utils.remove_path_on_error(self.path):
+            with fileutils.remove_path_on_error(self.path):
                 copy_qcow2_image(base, self.path, size)
 
     def snapshot_create(self):