Handle all failures in Future

Author: bell-db

bridge/src/main/scala/protocbridge/frontend/PluginFrontend.scala

@@ -47,13 +47,15 @@ object PluginFrontend {
       gen: ProtocCodeGenerator,
       request: Array[Byte]
   ): Array[Byte] = {
-    Try {
+    // Use try-catch to handle all Throwable including OutOfMemoryError, StackOverflowError, etc.
+    try {
       gen.run(request)
-    }.recover { case throwable =>
-      createCodeGeneratorResponseWithError(
-        throwable.toString + "\n" + getStackTrace(throwable)
-      )
-    }.get
+    } catch {
+      case throwable: Throwable =>
+        createCodeGeneratorResponseWithError(
+          throwable.toString + "\n" + getStackTrace(throwable)
+        )
+    }
   }
 
   def createCodeGeneratorResponseWithError(error: String): Array[Byte] = {

bridge/src/main/scala/protocbridge/frontend/PosixPluginFrontend.scala

@@ -36,13 +36,35 @@ object PosixPluginFrontend extends PluginFrontend {
 
     Future {
       blocking {
-        val fsin = Files.newInputStream(inputPipe)
-        val response = PluginFrontend.runWithInputStream(plugin, fsin, env)
-        fsin.close()
+        try {
+          val fsin = Files.newInputStream(inputPipe)
+          val response = PluginFrontend.runWithInputStream(plugin, fsin, env)
+          fsin.close()
 
-        val fsout = Files.newOutputStream(outputPipe)
-        fsout.write(response)
-        fsout.close()
+          val fsout = Files.newOutputStream(outputPipe)
+          fsout.write(response)
+          fsout.close()
+        } catch {
+          case e: Throwable =>
+            // Handles rare exceptions not already gracefully handled in `runWithBytes`.
+            // Such exceptions aren't converted to `CodeGeneratorResponse`
+            // because `fsin` might not be fully consumed,
+            // therefore the plugin shell script might hang on `inputPipe`,
+            // and never consume `CodeGeneratorResponse`.
+            System.err.println("Exception occurred in PluginFrontend outside runWithBytes")
+            e.printStackTrace(System.err)
+            // Force an exit of the program.
+            // This is because the plugin shell script might hang on `inputPipe`,
+            // due to `fsin` not fully consumed.
+            // Or it might hang on `outputPipe`, due to `fsout` not closed.
+            // Therefore, the program might be stuck waiting for protoc,
+            // which in turn is waiting for the plugin shell script.
+            //
+            // We can't simply close `fsout` here either,
+            // because `Files.newOutputStream(outputPipe)` will hang
+            // if `outputPipe` is not yet opened by the plugin shell script for reading.
+            sys.exit(1)
+        }
       }
     }
     (sh, InternalState(inputPipe, outputPipe, tempDirPath, sh))