Fixed flakiness of BuildSessionLoggerTest

libraries/tools/kotlin-gradle-plugin/src/test/kotlin/org/jetbrains/kotlin/gradle/statistics/BuildSessionLoggerTest.kt

@@ -21,7 +21,7 @@ class BuildSessionLoggerTest {
 
     private lateinit var rootFolder: File
 
-    private fun statFilesCount() = rootFolder.listFiles().single().listFiles().size
+    private fun statFilesCount() = rootFolder.listFiles()?.single()?.listFiles()?.size ?: 0
 
     @Before
     fun prepareFolder() {
@@ -56,7 +56,7 @@ class BuildSessionLoggerTest {
         logger1.finishBuildSession("", null)
         logger2.finishBuildSession("", null)
 
-        rootFolder.listFiles().first().listFiles().forEach { file ->
+        rootFolder.listFiles()?.first()?.listFiles()?.forEach { file ->
             assertTrue(
                 file.name.matches(BuildSessionLogger.STATISTICS_FILE_NAME_PATTERN.toRegex()),
                 "Check that file name ${file.name} matches pattern ${BuildSessionLogger.STATISTICS_FILE_NAME_PATTERN}"
@@ -73,7 +73,7 @@ class BuildSessionLoggerTest {
 
         assertEquals(1, statFilesCount())
 
-        val file2edit = rootFolder.listFiles().first().listFiles().first()
+        val file2edit = rootFolder.listFiles()?.first()?.listFiles()?.first() ?: fail("Could not find single stat file")
 
         logger.startBuildSession(0, 0)
         logger.finishBuildSession("", null)
@@ -97,8 +97,8 @@ class BuildSessionLoggerTest {
         logger.finishBuildSession("", null)
         assertEquals(1, statFilesCount())
 
-        val statsFolder = rootFolder.listFiles().single()
-        val singleStatFile = statsFolder.listFiles().single()
+        val statsFolder = rootFolder.listFiles()?.single() ?: fail("${rootFolder.absolutePath} was not created")
+        val singleStatFile = statsFolder.listFiles()?.single() ?: fail("stat file was not created")
 
         for (i in 1..200) {
             File(statsFolder, "$i").createNewFile()
@@ -110,24 +110,24 @@ class BuildSessionLoggerTest {
         logger.finishBuildSession("", null)
 
         assertTrue(
-            statsFolder.listFiles().filter { it.name == singleStatFile.name }.count() == 1,
+            statsFolder.listFiles()?.count { it.name == singleStatFile.name } == 1,
             "Could not find expected file ${singleStatFile.name}"
         )
 
         // files not matching the pattern should not be affected
         assertEquals(
             200,
-            statsFolder.listFiles().filter { !it.name.matches(BuildSessionLogger.STATISTICS_FILE_NAME_PATTERN.toRegex()) }.count(),
+            statsFolder.listFiles()?.count { !it.name.matches(BuildSessionLogger.STATISTICS_FILE_NAME_PATTERN.toRegex()) },
             "Some files which should not be affected, were removed"
         )
 
         assertEquals(
             maxFiles,
-            statsFolder.listFiles().filter { it.name.matches(BuildSessionLogger.STATISTICS_FILE_NAME_PATTERN.toRegex()) }.count(),
+            statsFolder.listFiles()?.count { it.name.matches(BuildSessionLogger.STATISTICS_FILE_NAME_PATTERN.toRegex()) },
             "Some files which should not be affected, were removed"
         )
         assertEquals(
-            statsFolder.listFiles().filter { it.name.matches(BuildSessionLogger.STATISTICS_FILE_NAME_PATTERN.toRegex()) }.sorted(),
+            statsFolder.listFiles()?.filter { it.name.matches(BuildSessionLogger.STATISTICS_FILE_NAME_PATTERN.toRegex()) }?.sorted(),
             BuildSessionLogger.listProfileFiles(statsFolder)
         )
     }
@@ -142,7 +142,7 @@ class BuildSessionLoggerTest {
         logger.finishBuildSession("Build", null)
         assertEquals(1, statFilesCount())
 
-        val statFile = rootFolder.listFiles().single().listFiles().single()
+        val statFile = rootFolder.listFiles()?.single()?.listFiles()?.single() ?: fail("Could not find stat file")
         statFile.appendBytes("break format of the file".toByteArray())
 
         logger.startBuildSession(1, startTime)
@@ -196,7 +196,7 @@ class BuildSessionLoggerTest {
         }
         logger.finishBuildSession("Build", null)
 
-        MetricsContainer.readFromFile(rootFolder.listFiles().single().listFiles().single()) {
+        MetricsContainer.readFromFile(rootFolder.listFiles()?.single()?.listFiles()?.single() ?: fail("Could not find stat file")) {
             for (metric in StringMetrics.values()) {
                 assertNotNull(it.getMetric(metric), "Could not find metric ${metric.name}")
             }

libraries/tools/kotlin-gradle-statistics/src/org/jetbrains/kotlin/statistics/BuildSessionLogger.kt

@@ -24,7 +24,7 @@ class BuildSessionLogger(
 
     companion object {
         const val STATISTICS_FOLDER_NAME = "kotlin-profile"
-        const val STATISTICS_FILE_NAME_PATTERN = "\\d{4}-\\d{2}-\\d{2}-\\d{2}-\\d{2}-\\d{2}-\\d{3}.profile"
+        const val STATISTICS_FILE_NAME_PATTERN = "\\d{4}-\\d{2}-\\d{2}-\\d{2}-\\d{2}-\\d{2}-\\d{3}(.\\d+)?.profile"
 
         private const val DEFAULT_MAX_PROFILE_FILES = 1_000
         private const val DEFAULT_MAX_PROFILE_FILE_SIZE = 100_000L
@@ -35,7 +35,9 @@ class BuildSessionLogger(
         }
     }
 
-    private val profileFileNameFormatter = DateTimeFormatter.ofPattern("YYYY-MM-dd-HH-mm-ss-SSS'.profile'")
+    private val profileFileNameFormatter = DateTimeFormatter.ofPattern("YYYY-MM-dd-HH-mm-ss-SSS")
+    private val profileFileNameSuffix = ".profile"
+
     private val statisticsFolder: File = File(
         rootPath,
         STATISTICS_FOLDER_NAME
@@ -80,7 +82,7 @@ class BuildSessionLogger(
         closeTrackingFile()
 
         // Get list of existing files. Try to create folder if possible, return from function if failed to create folder
-        val fileCandidates = listProfileFiles(statisticsFolder) ?: if (statisticsFolder.mkdirs()) emptyList<File>() else return
+        val fileCandidates = listProfileFiles(statisticsFolder) ?: if (statisticsFolder.mkdirs()) emptyList() else return
 
         for ((index, file) in fileCandidates.withIndex()) {
             val toDelete = if (index < fileCandidates.size - maxProfileFiles)
@@ -95,12 +97,21 @@ class BuildSessionLogger(
         }
 
         // emergency check. What if a lot of files are locked due to some reason
-        if (listProfileFiles(statisticsFolder)?.size ?: 0 > maxProfileFiles * 2) {
+        if ((listProfileFiles(statisticsFolder)?.size ?: 0) > maxProfileFiles * 2) {
             trackingFile = NullRecordLogger()
             return
         }
 
-        fun newFile(): File = File(statisticsFolder, profileFileNameFormatter.format(LocalDateTime.now()))
+        fun newFile(): File {
+            val timestamp = profileFileNameFormatter.format(LocalDateTime.now())
+            var result = File(statisticsFolder, timestamp + profileFileNameSuffix)
+            var suffixIndex = 0
+            while (result.exists()) {
+                result = File(statisticsFolder, "${timestamp}.${suffixIndex++}$profileFileNameSuffix")
+            }
+            return result
+        }
+
         val lastFile = fileCandidates.lastOrNull() ?: newFile()
 
         trackingFile = try {