[Kapt] Support dumping processors stats to a file

Using the option -Kapt-dump-processor-timings

plugins/kapt3/kapt3-base/src/org/jetbrains/kotlin/kapt3/base/KaptOptions.kt

@@ -42,7 +42,8 @@ class KaptOptions(
     //if defined use it to run processors instead of creating new one
     val processingClassLoader: ClassLoader?,
     //construct new classloader for these processors instead of using one defined in processingClassLoader
-    val separateClassloaderForProcessors: Set<String>
+    val separateClassloaderForProcessors: Set<String>,
+    val processorsPerfReportFile: File?
 ) : KaptFlags {
     override fun get(flag: KaptFlag) = flags[flag]
 
@@ -72,6 +73,7 @@ class KaptOptions(
 
         var mode: AptMode = AptMode.WITH_COMPILATION
         var detectMemoryLeaks: DetectMemoryLeaksMode = DetectMemoryLeaksMode.DEFAULT
+        var processorsPerfReportFile: File? = null
 
         fun build(): KaptOptions {
             val sourcesOutputDir = this.sourcesOutputDir ?: error("'sourcesOutputDir' must be set")
@@ -85,7 +87,8 @@ class KaptOptions(
                 processingClasspath, processors, processingOptions, javacOptions, KaptFlags.fromSet(flags),
                 mode, detectMemoryLeaks,
                 processingClassLoader = null,
-                separateClassloaderForProcessors = emptySet()
+                separateClassloaderForProcessors = emptySet(),
+                processorsPerfReportFile = processorsPerfReportFile
             )
         }
     }

plugins/kapt3/kapt3-base/src/org/jetbrains/kotlin/kapt3/base/annotationProcessing.kt

@@ -122,6 +122,8 @@ fun KaptContext.doAnnotationProcessing(
             showProcessorTimings(wrappedProcessors, loggerFun)
         }
 
+        options.processorsPerfReportFile?.let { dumpProcessorTiming(wrappedProcessors, options.processorsPerfReportFile, logger::info) }
+
         if (logger.isVerbose) {
             filer.displayState()
         }
@@ -142,6 +144,17 @@ private fun showProcessorTimings(wrappedProcessors: List<ProcessorWrapper>, logg
     }
 }
 
+private fun dumpProcessorTiming(wrappedProcessors: List<ProcessorWrapper>, apReportFile: File, logger: (String) -> Unit) {
+    logger("Dumping Kapt Annotation Processing performance report to ${apReportFile.absolutePath}")
+
+    apReportFile.writeText(buildString {
+        appendLine("Kapt Annotation Processing performance report:")
+        wrappedProcessors.forEach { processor ->
+            appendLine(processor.renderSpentTime())
+        }
+    })
+}
+
 private fun reportIfRunningNonIncrementally(
     listener: MentionedTypesTaskListener?,
     cacheManager: JavaClassCacheManager?,