Improved error handing for failing runs

codemonstur · codemonstur · commit 546d305ae884 · 2024-03-25T20:55:53.000+01:00
diff --git a/src/main/java/redis/embedded/RedisInstance.java b/src/main/java/redis/embedded/RedisInstance.java
@@ -2,6 +2,7 @@
 
 import java.io.File;
 import java.io.IOException;
+import java.io.InputStream;
 import java.util.Collections;
 import java.util.List;
 import java.util.function.Consumer;
@@ -40,9 +41,10 @@ public synchronized void start() throws IOException {
                 .directory(new File(args.get(0)).getParentFile())
                 .start();
             addShutdownHook("RedisInstanceCleaner", checkedToRuntime(this::stop));
+            awaitServerReady(process, readyPattern, soutListener, serrListener);
+
             if (serrListener != null)
                 newDaemonThread(() -> logStream(process.getErrorStream(), serrListener)).start();
-            awaitServerReady(process, readyPattern, soutListener);
             if (soutListener != null)
                 newDaemonThread(() -> logStream(process.getInputStream(), soutListener)).start();
 
@@ -52,11 +54,22 @@ public synchronized void start() throws IOException {
         }
     }
 
-    private static void awaitServerReady(final Process process, final Pattern readyPattern,
-                                           final Consumer<String> soutListener) throws IOException {
+    private static void awaitServerReady(final Process process, final Pattern readyPattern
+            , final Consumer<String> soutListener, final Consumer<String> serrListener) throws IOException {
         final StringBuilder log = new StringBuilder();
-        if (!findMatchInStream(process.getInputStream(), readyPattern, soutListener, log))
-            throw new IOException("Ready pattern not found in log. Startup log: " + log);
+        if (!findMatchInStream(process.getInputStream(), readyPattern, soutListener, log)) {
+            final String stdOut = log.toString();
+            final String stdErr = readFully(process.getErrorStream(), serrListener);
+
+            throw new IOException("Redis-server process appears not to have started. "
+                + (isNullOrEmpty(stdOut) ? "No output was found in standard-out." : "stdandard-out contains this: " + stdOut)
+                + " "
+                + (isNullOrEmpty(stdErr) ? "No output was found in standard-err." : "stdandard-err contains this: " + stdErr)
+            );
+        }
+    }
+    private static boolean isNullOrEmpty(final String value) {
+        return value == null || value.isEmpty();
     }
 
     public synchronized void stop() throws IOException {
diff --git a/src/main/java/redis/embedded/util/IO.java b/src/main/java/redis/embedded/util/IO.java
@@ -74,6 +74,17 @@ public static boolean findMatchInStream(final InputStream in, final Pattern patt
         return false;
     }
 
+    public static String readFully(final InputStream in, final Consumer<String> listener) {
+        final StringBuilder ret = new StringBuilder();
+        try (final BufferedReader reader = new BufferedReader(new InputStreamReader(in))) {
+            String line; while ((line = reader.readLine()) != null) {
+                if (listener != null) listener.accept(line);
+                ret.append(line);
+            }
+        } catch (final IOException ignored) {}
+        return ret.toString();
+    }
+
     public static Stream<String> processToLines(final String command) throws IOException {
         final Process proc = Runtime.getRuntime().exec(command);
         return new BufferedReader(new InputStreamReader(proc.getInputStream())).lines();
