copyOrLink race condition

.gitattributes

@@ -0,0 +1 @@
+* text eol=crlf

integrationtests.py

@@ -18,6 +18,8 @@
 import sys
 import tempfile
 import unittest
+import time
+import concurrent.futures
 
 import clcache
 
@@ -1071,6 +1073,44 @@ def testHitsViaMpConcurrent(self):
                 self.assertEqual(stats.numCacheMisses(), 2)
                 self.assertEqual(stats.numCacheEntries(), 2)
 
+class TestConcurrent(unittest.TestCase):
+    @staticmethod
+    def runCompiler():
+        with cd(os.path.join(ASSETS_DIR, "hits-and-misses")):
+            cmd = CLCACHE_CMD + ["/nologo", "/EHsc", "/c", 'hit.cpp']
+            return subprocess.check_call(cmd)
+
+    def testRaceAddingAnObject(self):
+        """ This tests attempts to expose a race condition when two clcache invocations decide to add an object to the
+        cache at the same time """
+
+        # object cache key
+        cachekey = '5080f03ed6fda8fecd7562c0fad99926'
+
+        # Obtain final object lock and write the object file
+        cache = clcache.Cache()
+        section = cache.compilerArtifactsRepository.section(cachekey)
+        section.lock.acquire()
+
+        executor = concurrent.futures.ThreadPoolExecutor(max_workers=1)
+        compilerTask = executor.submit(TestConcurrent.runCompiler)
+
+        # Give the clcache process time to get locked acquiring the artifactsSection lock
+        time.sleep(5)
+
+        # Replacing artifacts
+        print('Replacing artifacts')
+        artifactsPath = lambda objectName: os.path.join(section.cacheEntryDir(cachekey), objectName)
+        artifacts = [artifactsPath('object'), artifactsPath('output.txt'), artifactsPath('stderr.txt')]
+        clcache.ensureDirectoryExists(section.cacheEntryDir(cachekey))
+        for artifact in artifacts:
+            with open(artifact, 'w+') as f:
+                f.write('dummy')
+
+        section.lock.release()
+
+        timeoutSeconds = 5
+        self.assertEqual(0, compilerTask.result(timeout=timeoutSeconds))
 
 class TestBasedir(unittest.TestCase):
     def testBasedir(self):