Detect when the app is readin input

Fixes quarkusio#23217

core/deployment/src/main/java/io/quarkus/deployment/console/AeshConsole.java

@@ -86,6 +86,7 @@ public void run() {
             }
         }, "Console Shutdown Hook"));
         prompt = registerStatusLine(0);
+
     }
 
     private void updatePromptOnChange(StringBuilder buffer, int newLines) {
@@ -222,6 +223,26 @@ public void run() {
             });
             // Keyboard handling
             conn.setStdinHandler(keys -> {
+
+                QuarkusConsole.StateChangeInputStream redirectIn = QuarkusConsole.REDIRECT_IN;
+                //see if the users application wants to read the keystrokes:
+                int pos = 0;
+                while (pos < keys.length) {
+                    if (!redirectIn.acceptInput(keys[pos])) {
+                        break;
+                    }
+                    ++pos;
+                }
+                if (pos > 0) {
+                    if (pos == keys.length) {
+                        return;
+                    }
+                    //the app only consumed some keys
+                    //stick the rest in a new array
+                    int[] newKeys = new int[keys.length - pos];
+                    System.arraycopy(keys, pos, newKeys, 0, newKeys.length);
+                    keys = newKeys;
+                }
                 try {
                     if (delegateConnection != null) {
                         //console mode

core/deployment/src/main/java/io/quarkus/deployment/console/ConsoleHelper.java

@@ -47,8 +47,11 @@ public void accept(Connection connection) {
                         connection.setStdinHandler(new Consumer<int[]>() {
                             @Override
                             public void accept(int[] ints) {
+                                QuarkusConsole.StateChangeInputStream redirectIn = QuarkusConsole.REDIRECT_IN;
                                 for (int i : ints) {
-                                    queue.add(i);
+                                    if (redirectIn != null && !redirectIn.acceptInput(i)) {
+                                        queue.add(i);
+                                    }
                                 }
                             }
                         });

core/devmode-spi/src/main/java/io/quarkus/dev/console/QuarkusConsole.java

@@ -1,9 +1,13 @@
 package io.quarkus.dev.console;
 
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InterruptedIOException;
 import java.io.PrintStream;
 import java.util.List;
 import java.util.Locale;
 import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.concurrent.LinkedBlockingDeque;
 import java.util.function.BiPredicate;
 import java.util.function.Consumer;
 
@@ -52,9 +56,12 @@ public abstract class QuarkusConsole {
 
     public final static PrintStream ORIGINAL_OUT = System.out;
     public final static PrintStream ORIGINAL_ERR = System.err;
+    public final static InputStream ORIGINAL_IN = System.in;
 
     public static PrintStream REDIRECT_OUT = null;
     public static PrintStream REDIRECT_ERR = null;
+    public static StateChangeInputStream REDIRECT_IN;
+    protected volatile boolean userReadInProgress;
 
     public synchronized static void installRedirects() {
         if (redirectsInstalled) {
@@ -67,8 +74,10 @@ public synchronized static void installRedirects() {
         QuarkusConsole.INSTANCE.isInputSupported();
         REDIRECT_OUT = new RedirectPrintStream(false);
         REDIRECT_ERR = new RedirectPrintStream(true);
+        REDIRECT_IN = new StateChangeInputStream();
         System.setOut(REDIRECT_OUT);
         System.setErr(REDIRECT_ERR);
+        System.setIn(REDIRECT_IN);
     }
 
     public synchronized static void uninstallRedirects() {
@@ -86,8 +95,10 @@ public synchronized static void uninstallRedirects() {
             REDIRECT_ERR.close();
             REDIRECT_ERR = null;
         }
+        REDIRECT_IN = null;
         System.setOut(ORIGINAL_OUT);
         System.setErr(ORIGINAL_ERR);
+        System.setIn(ORIGINAL_IN);
 
         redirectsInstalled = false;
     }
@@ -176,4 +187,69 @@ public boolean isAnsiSupported() {
         return false;
     }
 
+    protected void userReadStart() {
+
+    }
+
+    protected void userReadStop() {
+
+    }
+
+    public static class StateChangeInputStream extends InputStream {
+
+        private final LinkedBlockingDeque<Integer> queue = new LinkedBlockingDeque<>();
+
+        private volatile boolean reading;
+
+        public synchronized boolean acceptInput(int input) {
+            if (reading) {
+                queue.add(input);
+                notifyAll();
+                return true;
+            }
+            return false;
+        }
+
+        @Override
+        public synchronized int read() throws IOException {
+            reading = true;
+            try {
+                while (queue.isEmpty()) {
+                    try {
+                        wait();
+                    } catch (InterruptedException e) {
+                        throw new InterruptedIOException();
+                    }
+                }
+                return queue.pollFirst();
+            } finally {
+                reading = false;
+            }
+        }
+
+        @Override
+        public synchronized int read(byte[] b, int off, int len) throws IOException {
+            reading = true;
+            int read = 0;
+            try {
+                while (read < len) {
+                    while (queue.isEmpty()) {
+                        try {
+                            wait();
+                        } catch (InterruptedException e) {
+                            throw new InterruptedIOException();
+                        }
+                    }
+                    byte byteValue = queue.poll().byteValue();
+                    b[read++] = byteValue;
+                    if (byteValue == '\n' || byteValue == '\r') {
+                        return read;
+                    }
+                }
+                return read;
+            } finally {
+                reading = false;
+            }
+        }
+    }
 }