lit/TestRunner.py: [Win32] Introduce WinWaitReleased(f), to wait for file handles to be released by children.

When wait() has finished, opened handles (especially writing stdout to file) might not be released immediately.
To wait for released, poll to attempt renaming.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@145222 91177308-0d34-0410-b5e6-96231b3b80d8

utils/lit/lit/TestRunner.py

@@ -23,6 +23,41 @@ kUseCloseFDs = not kIsWindows
 # Use temporary files to replace /dev/null on Windows.
 kAvoidDevNull = kIsWindows
 
+def RemoveForce(f):
+    try:
+        os.remove(f)
+    except OSError:
+        pass
+
+def WinRename(f_o, f_n):
+    import time
+    retry_cnt = 256
+    while (True):
+        try:
+            os.rename(f_o, f_n)
+            break
+        except WindowsError, (winerror, strerror):
+            retry_cnt = retry_cnt - 1
+            if retry_cnt <= 0:
+                raise
+            elif winerror == 32: # ERROR_SHARING_VIOLATION
+                time.sleep(0.01)
+            else:
+                raise
+
+def WinWaitReleased(f):
+    import random
+    t = "%s%06d" % (f, random.randint(0, 999999))
+    RemoveForce(t)
+    try:
+        WinRename(f, t) # rename
+        WinRename(t, f) # restore
+    except WindowsError, (winerror, strerror):
+        if winerror == 3: # ERROR_PATH_NOT_FOUND
+            pass
+        else:
+            raise
+
 def executeCommand(command, cwd=None, env=None):
     p = subprocess.Popen(command, cwd=cwd,
                          stdin=subprocess.PIPE,
@@ -68,6 +103,7 @@ def executeShCmd(cmd, cfg, cwd, results):
     input = subprocess.PIPE
     stderrTempFiles = []
     opened_files = []
+    written_files = []
     named_temp_files = []
     # To avoid deadlock, we use a single stderr stream for piped
     # output. This is null until we have seen some output using
@@ -124,6 +160,8 @@ def executeShCmd(cmd, cfg, cwd, results):
                     if r[1] == 'a':
                         r[2].seek(0, 2)
                     opened_files.append(r[2])
+                    if r[1] in 'aw':
+                        written_files.append(r[0])
                 result = r[2]
             final_redirects.append(result)
 
@@ -224,6 +262,11 @@ def executeShCmd(cmd, cfg, cwd, results):
         else:
             exitCode = res
 
+    # Make sure written_files is released by other (child) processes.
+    if (kIsWindows):
+        for f in written_files:
+            WinWaitReleased(f)
+
     # Remove any named temporary files we created.
     for f in named_temp_files:
         try: