Darwin - fix intermitent crashes in import crashinfo

[vharron]

Summary

"import crashinfo" was probably failing because multiple dotest invocations
are all trying to compile crashinfo.so at the same time.

I've put a mutex around the compile step to prevent this.

[clayborg]

Looks good.

[amccarth]

lldb/trunk/test/lock.py

5

fcntl doesn't seem to be available on Windows. Is there a more platform-neutral way to accomplish this?

lldb/trunk/test/dotest.py

 ./dotest.py -h
 
 for available options.
 """
 
 import commands
 import os
 import errno
+import lock
 import platform
 import progress
 import signal
 import subprocess
 import sys
 import textwrap
 import time
 import inspect

 
 def setupCrashInfoHook():
     global setCrashInfoHook
     setCrashInfoHook = setCrashInfoHook_NonMac # safe default
     if platform.system() == "Darwin":
         test_dir = os.environ['LLDB_TEST']
         if not test_dir or not os.path.exists(test_dir):
             return
+        dylib_lock = os.path.join(test_dir,"crashinfo.lock")
         dylib_src = os.path.join(test_dir,"crashinfo.c")
         dylib_dst = os.path.join(test_dir,"crashinfo.so")
+        try:
+            compile_lock = lock.Lock(dylib_lock)
+            compile_lock.acquire()
+            if not os.path.isfile(dylib_dst) or os.path.getmtime(dylib_dst) < os.path.getmtime(dylib_src):
+                # we need to compile
                 cmd = "SDKROOT= xcrun clang %s -o %s -framework Python -Xlinker -dylib -iframework /System/Library/Frameworks/ -Xlinker -F /System/Library/Frameworks/" % (dylib_src,dylib_dst)
-        if subprocess.call(cmd,shell=True) == 0 and os.path.exists(dylib_dst):
-            setCrashInfoHook = setCrashInfoHook_Mac
+                if subprocess.call(cmd,shell=True) != 0 or not os.path.isfile(dylib_dst):
+                    raise Exception('command failed: "{}"'.format(cmd))
+        finally:
+            compile_lock.release()
+            del compile_lock
+
+
     else:
         pass
 
 def parseOptionsAndInitTestdirs():
     """Initialize the list of directories containing our unittest scripts.
 
     '-h/--help as the first option prints out usage info and exit the program.
     """

lldb/trunk/test/lock.py

+"""
+Interprocess mutex based on file locks
+"""
+
+import fcntl
+import os
+
+class Lock:
+
+    def __init__(self, filename):
+        self.filename = filename
+        # This will create it if it does not exist already
+        self.handle = open(filename, 'w')
+
+    # Bitwise OR fcntl.LOCK_NB if you need a non-blocking lock
+    def acquire(self):
+        fcntl.flock(self.handle, fcntl.LOCK_EX)
+
+    def release(self):
+        fcntl.flock(self.handle, fcntl.LOCK_UN)
+
+    def __del__(self):
+        self.handle.close()