[OE-core] package: Add cachedpath optimisation
Richard Purdie
richard.purdie at linuxfoundation.org
Fri Mar 15 01:57:43 UTC 2013
Currently, various standard library operations like os.walk(),
os.path.isdir() and os.path.islink() each call stat or lstat which
involves a syscall into the kernel. There is no caching since they could
conceivably have changed on disk. The result is that for something like
the do_package task of the kernel we're spending over two minutes making
868,000 individual stat calls for 23,000 files. This is suboptimal.
This patch adds lib/oe/cachedpath.py which are a set of replacement
functions for these operations which use cached stat data rather than
hitting the kernel each time. It gives a nice performance improvement
halving the build time of the kernel do_package.
Signed-off-by: Richard Purdie <richard.purdie at linuxfoundation.org>
---
diff --git a/meta/classes/base.bbclass b/meta/classes/base.bbclass
index 4d69caf..9d5b0ad 100644
--- a/meta/classes/base.bbclass
+++ b/meta/classes/base.bbclass
@@ -10,7 +10,7 @@ inherit utility-tasks
inherit metadata_scm
inherit logging
-OE_IMPORTS += "os sys time oe.path oe.utils oe.data oe.package oe.packagegroup oe.sstatesig oe.lsb"
+OE_IMPORTS += "os sys time oe.path oe.utils oe.data oe.package oe.packagegroup oe.sstatesig oe.lsb oe.cachedpath"
OE_IMPORTS[type] = "list"
def oe_import(d):
diff --git a/meta/classes/package.bbclass b/meta/classes/package.bbclass
index 1625ebd..720e2b1 100644
--- a/meta/classes/package.bbclass
+++ b/meta/classes/package.bbclass
@@ -729,7 +729,7 @@ python split_and_strip_files () {
baselibdir = os.path.abspath(dvar + os.sep + d.getVar("base_libdir", True))
if (d.getVar('INHIBIT_PACKAGE_DEBUG_SPLIT', True) != '1') and \
(d.getVar('INHIBIT_PACKAGE_STRIP', True) != '1'):
- for root, dirs, files in os.walk(dvar):
+ for root, dirs, files in oe.cachedpath.walk(dvar):
for f in files:
file = os.path.join(root, f)
if file.endswith(".ko") and file.find("/lib/modules/") != -1:
@@ -743,7 +743,7 @@ python split_and_strip_files () {
continue
try:
- ltarget = oe.path.realpath(file, dvar, False)
+ ltarget = oe.cachedpath.realpath(file, dvar, False)
s = os.lstat(ltarget)
except OSError, (err, strerror):
if err != errno.ENOENT:
@@ -969,7 +969,7 @@ python populate_packages () {
os.chdir(workdir)
unshipped = []
- for root, dirs, files in os.walk(dvar):
+ for root, dirs, files in oe.cachedpath.walk(dvar):
dir = root[len(dvar):]
if not dir:
dir = os.sep
@@ -1003,7 +1003,7 @@ python package_fixsymlinks () {
for path in pkgfiles[pkg]:
rpath = path[len(inst_root):]
pkg_files[pkg].append(rpath)
- rtarget = oe.path.realpath(path, inst_root, True, assume_dir = True)
+ rtarget = oe.cachedpath.realpath(path, inst_root, True, assume_dir = True)
if not os.path.lexists(rtarget):
dangling_links[pkg].append(os.path.normpath(rtarget[len(inst_root):]))
@@ -1775,6 +1775,9 @@ python do_package () {
# as any change to rpmdeps requires this to be rerun.
# PACKAGE_BBCLASS_VERSION = "1"
+ # Init cachedpath
+ oe.cachedpath.initcache()
+
###########################################################################
# Sanity test the setup
###########################################################################
@@ -1835,7 +1838,7 @@ python do_package () {
pkgdest = d.getVar('PKGDEST', True)
for pkg in packages:
pkgfiles[pkg] = []
- for walkroot, dirs, files in os.walk(pkgdest + "/" + pkg):
+ for walkroot, dirs, files in oe.cachedpath.walk(pkgdest + "/" + pkg):
for file in files:
pkgfiles[pkg].append(walkroot + os.sep + file)
diff --git a/meta/lib/oe/cachedpath.py b/meta/lib/oe/cachedpath.py
new file mode 100644
index 0000000..bc65665
--- /dev/null
+++ b/meta/lib/oe/cachedpath.py
@@ -0,0 +1,190 @@
+#
+# Based on standard python library functions but avoid
+# repeated stat calls. Its assumed the files will not change from under us
+# so we can cache stat calls.
+#
+cachedpathstatcache = {}
+cachedpathlstatcache = {}
+
+import os
+import errno
+import stat
+
+def initcache():
+ global cachedpathstatcache
+ global cachedpathlstatcache
+ cachedpathstatcache = {}
+ cachedpathlstatcache = {}
+
+def callstat(path):
+ if path in cachedpathstatcache:
+ return cachedpathstatcache[path]
+ #bb.error("Statpath:" + path)
+ try:
+ st = os.stat(path)
+ cachedpathstatcache[path] = st
+ return st
+ except os.error:
+ cachedpathstatcache[path] = False
+ return False
+
+def calllstat(path):
+ if path in cachedpathlstatcache:
+ return cachedpathlstatcache[path]
+ #bb.error("LStatpath:" + path)
+ try:
+ st = os.lstat(path)
+ cachedpathlstatcache[path] = st
+ return st
+ except (os.error, AttributeError):
+ cachedpathlstatcache[path] = False
+ return False
+
+# This follows symbolic links, so both islink() and isdir() can be true
+# for the same path ono systems that support symlinks
+def isfile(path):
+ """Test whether a path is a regular file"""
+ st = callstat(path)
+ if not st:
+ return False
+ return stat.S_ISREG(st.st_mode)
+
+# Is a path a directory?
+# This follows symbolic links, so both islink() and isdir()
+# can be true for the same path on systems that support symlinks
+def isdir(s):
+ """Return true if the pathname refers to an existing directory."""
+ st = callstat(s)
+ if not st:
+ return False
+ return stat.S_ISDIR(st.st_mode)
+
+def islink(path):
+ """Test whether a path is a symbolic link"""
+ st = calllstat(path)
+ if not st:
+ return False
+ return stat.S_ISLNK(st.st_mode)
+
+def walk(top, topdown=True, onerror=None, followlinks=False):
+ # Matches os.walk, not os.path.walk()
+
+ # We may not have read permission for top, in which case we can't
+ # get a list of the files the directory contains. os.path.walk
+ # always suppressed the exception then, rather than blow up for a
+ # minor reason when (say) a thousand readable directories are still
+ # left to visit. That logic is copied here.
+ try:
+ # Note that listdir and error are globals in this module due
+ # to earlier import-*.
+ names = os.listdir(top)
+ except error, err:
+ if onerror is not None:
+ onerror(err)
+ return
+
+ dirs, nondirs = [], []
+ for name in names:
+ if isdir(os.path.join(top, name)):
+ dirs.append(name)
+ else:
+ nondirs.append(name)
+
+ if topdown:
+ yield top, dirs, nondirs
+ for name in dirs:
+ new_path = os.path.join(top, name)
+ if followlinks or not islink(new_path):
+ for x in walk(new_path, topdown, onerror, followlinks):
+ yield x
+ if not topdown:
+ yield top, dirs, nondirs
+
+
+
+## realpath() related functions
+def __is_path_below(file, root):
+ return (file + os.path.sep).startswith(root)
+
+def __realpath_rel(start, rel_path, root, loop_cnt, assume_dir):
+ """Calculates real path of symlink 'start' + 'rel_path' below
+ 'root'; no part of 'start' below 'root' must contain symlinks. """
+ have_dir = True
+
+ for d in rel_path.split(os.path.sep):
+ if not have_dir and not assume_dir:
+ raise OSError(errno.ENOENT, "no such directory %s" % start)
+
+ if d == os.path.pardir: # '..'
+ if len(start) >= len(root):
+ # do not follow '..' before root
+ start = os.path.dirname(start)
+ else:
+ # emit warning?
+ pass
+ else:
+ (start, have_dir) = __realpath(os.path.join(start, d),
+ root, loop_cnt, assume_dir)
+
+ assert(__is_path_below(start, root))
+
+ return start
+
+def __realpath(file, root, loop_cnt, assume_dir):
+ while islink(file) and len(file) >= len(root):
+ if loop_cnt == 0:
+ raise OSError(errno.ELOOP, file)
+
+ loop_cnt -= 1
+ target = os.path.normpath(os.readlink(file))
+
+ if not os.path.isabs(target):
+ tdir = os.path.dirname(file)
+ assert(__is_path_below(tdir, root))
+ else:
+ tdir = root
+
+ file = __realpath_rel(tdir, target, root, loop_cnt, assume_dir)
+
+ try:
+ is_dir = isdir(file)
+ except:
+ is_dir = False
+
+ return (file, is_dir)
+
+def realpath(file, root, use_physdir = True, loop_cnt = 100, assume_dir = False):
+ """ Returns the canonical path of 'file' with assuming a
+ toplevel 'root' directory. When 'use_physdir' is set, all
+ preceding path components of 'file' will be resolved first;
+ this flag should be set unless it is guaranteed that there is
+ no symlink in the path. When 'assume_dir' is not set, missing
+ path components will raise an ENOENT error"""
+
+ root = os.path.normpath(root)
+ file = os.path.normpath(file)
+
+ if not root.endswith(os.path.sep):
+ # letting root end with '/' makes some things easier
+ root = root + os.path.sep
+
+ if not __is_path_below(file, root):
+ raise OSError(errno.EINVAL, "file '%s' is not below root" % file)
+
+ try:
+ if use_physdir:
+ file = __realpath_rel(root, file[(len(root) - 1):], root, loop_cnt, assume_dir)
+ else:
+ file = __realpath(file, root, loop_cnt, assume_dir)[0]
+ except OSError, e:
+ if e.errno == errno.ELOOP:
+ # make ELOOP more readable; without catching it, there will
+ # be printed a backtrace with 100s of OSError exceptions
+ # else
+ raise OSError(errno.ELOOP,
+ "too much recursions while resolving '%s'; loop in '%s'" %
+ (file, e.strerror))
+
+ raise
+
+ return file
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