[Patch V2 3/3] .pytool/Plugin/EccCheck: Add performance optimizations

["Michael D Kinney" <michael.d.kinney@intel.com>]

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2986

Improve the performance of EccCheck by using a temp file
instead of stdout to capture the results of the git diff
commands. If a large patch set is passed into EccCheck,
using stdout could be slow and also added the large diff
content to the build log that is redundant information.

A second performance improvement is to filter the
modified directories to remove duplicate directories.
Complex libraries and modules that have subdirectories
with sources would be scanned twice if there were source
changes in both the main directory and subdirectories.
Filter out the subdirectories from the modified directory
list when this case is detected.

Cc: Sean Brogan <sean.brogan@microsoft.com>
Cc: Bret Barkelew <Bret.Barkelew@microsoft.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Michael Kubacki <michael.kubacki@microsoft.com>
Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
---
 .pytool/Plugin/EccCheck/EccCheck.py | 121 +++++++++++++++++++++-------
 1 file changed, 94 insertions(+), 27 deletions(-)

diff --git a/.pytool/Plugin/EccCheck/EccCheck.py b/.pytool/Plugin/EccCheck/EccCheck.py
index de766d984f7c..4fbc67765fdf 100644
--- a/.pytool/Plugin/EccCheck/EccCheck.py
+++ b/.pytool/Plugin/EccCheck/EccCheck.py
@@ -30,7 +30,6 @@ class EccCheck(ICiBuildPlugin):
     },
     """
 
-    ReModifyFile = re.compile(r'[B-Q,S-Z]+[\d]*\t(.*)')
     FindModifyFile = re.compile(r'\+\+\+ b\/(.*)')
     LineScopePattern = (r'@@ -\d*\,*\d* \+\d*\,*\d* @@.*')
     LineNumRange = re.compile(r'@@ -\d*\,*\d* \+(\d*)\,*(\d*) @@.*')
@@ -87,10 +86,12 @@ class EccCheck(ICiBuildPlugin):
               os.path.join(basetools_path, "Source", "Python", "Ecc", "exception.xml"),
               os.path.join(temp_path, "exception.xml")
               )
+            # Output file to use for git diff operations
+            temp_diff_output = os.path.join (temp_path, 'diff.txt')
 
             self.ApplyConfig(pkgconfig, temp_path, packagename)
-            modify_dir_list = self.GetModifyDir(packagename)
-            patch = self.GetDiff(packagename)
+            modify_dir_list = self.GetModifyDir(packagename, temp_diff_output)
+            patch = self.GetDiff(packagename, temp_diff_output)
             ecc_diff_range = self.GetDiffRange(patch, packagename, temp_path)
             #
             # Use temp_path as working directory when running ECC tool
@@ -129,37 +130,103 @@ class EccCheck(ICiBuildPlugin):
             raise
             return 1
 
-    def GetDiff(self, pkg: str) -> List[str]:
-        return_buffer = StringIO()
-        params = "diff --unified=0 origin/master HEAD"
-        RunCmd("git", params, outstream=return_buffer)
-        p = return_buffer.getvalue().strip()
-        patch = p.split("\n")
-        return_buffer.close()
-
+    def GetDiff(self, pkg: str, temp_diff_output: str) -> List[str]:
+        patch = []
+        #
+        # Generate unified diff between origin/master and HEAD.
+        #
+        params = "diff --output={} --unified=0 origin/master HEAD".format(temp_diff_output)
+        RunCmd("git", params)
+        with open(temp_diff_output) as file:
+            patch = file.read().strip().split('\n')
         return patch
 
-    def GetModifyDir(self, pkg: str) -> List[str]:
-        return_buffer = StringIO()
-        params = "diff --name-status" + ' HEAD' + ' origin/master'
-        RunCmd("git", params, outstream=return_buffer)
-        p1 = return_buffer.getvalue().strip()
-        dir_list = p1.split("\n")
-        return_buffer.close()
+    def GetModifyDir(self, pkg: str, temp_diff_output: str) -> List[str]:
+        #
+        # Generate diff between origin/master and HEAD using --diff-filter to
+        # exclude deleted and renamed files that do not need to be scanned by
+        # ECC.  Also use --name-status to only generate the names of the files
+        # with differences.  The output format of this git diff command is a
+        # list of files with the change status and the filename.  The filename
+        # is always at the end of the line.  Examples:
+        #
+        #   M       MdeModulePkg/Application/CapsuleApp/CapsuleApp.h
+        #   M       MdeModulePkg/Application/UiApp/FrontPage.h
+        #
+        params = "diff --output={} --diff-filter=dr --name-status origin/master HEAD".format(temp_diff_output)
+        RunCmd("git", params)
+        dir_list = []
+        with open(temp_diff_output) as file:
+            dir_list = file.read().strip().split('\n')
+
         modify_dir_list = []
         for modify_dir in dir_list:
-            file_path = self.ReModifyFile.findall(modify_dir)
-            if file_path:
-                file_dir = os.path.dirname(file_path[0])
-            else:
+            #
+            # Parse file name from the end of the line
+            #
+            file_path = modify_dir.strip().split()
+            #
+            # Skip lines that do not have at least 2 elements (status and file name)
+            #
+            if len(file_path) < 2:
                 continue
-            if pkg in file_dir and file_dir != pkg:
-                modify_dir_list.append('%s' % file_dir)
-            else:
+            #
+            # Parse the directory name from the file name
+            #
+            file_dir = os.path.dirname(file_path[-1])
+            #
+            # Skip directory names that do not start with the package being scanned.
+            #
+            if file_dir.split('/')[0] != pkg:
                 continue
+            #
+            # Skip directory names that are identical to the package being scanned.
+            # The assumption here is that there are no source files at the package
+            # root.  Instead, the only expected files in the package root are
+            # EDK II meta data files (DEC, DSC, FDF).
+            #
+            if file_dir == pkg:
+                continue
+            #
+            # Skip directory names that are already in the modified dir list
+            #
+            if file_dir in modify_dir_list:
+                continue
+            #
+            # Add the candidate directory to scan to the modified dir list
+            #
+            modify_dir_list.append(file_dir)
 
-        modify_dir_list = list(set(modify_dir_list))
-        return modify_dir_list
+        #
+        # Remove duplicates from modify_dir_list
+        # Given a folder path, ECC performs a recursive scan of that folder.
+        # If a parent and child folder are both present in modify_dir_list,
+        # then ECC will perform redudanct scans of source files.  In order
+        # to prevent redundant scans, if a parent and child folder are both
+        # present, then remove all the child folders.
+        #
+        # For example, if modified_dir_list contains the following elements:
+        #   MdeModulePkg/Core/Dxe
+        #   MdeModulePkg/Core/Dxe/Hand
+        #   MdeModulePkg/Core/Dxe/Mem
+        #
+        # Then MdeModulePkg/Core/Dxe/Hand and MdeModulePkg/Core/Dxe/Mem should
+        # be removed because the files in those folders are covered by a scan
+        # of MdeModulePkg/Core/Dxe.
+        #
+        filtered_list = []
+        for dir1 in modify_dir_list:
+            Append = True
+            for dir2 in modify_dir_list:
+                if dir1 == dir2:
+                    continue
+                common = os.path.commonpath([dir1, dir2])
+                if os.path.normpath(common) == os.path.normpath(dir2):
+                    Append = False
+                    break
+            if Append and dir1 not in filtered_list:
+                filtered_list.append(dir1)
+        return filtered_list
 
     def GetDiffRange(self, patch_diff: List[str], pkg: str, temp_path: str) -> Dict[str, List[Tuple[int, int]]]:
         IsDelete = True
-- 
2.32.0.windows.1