Merge pull request #6 from skodjob/wait-for

Add `Wait.until()` to the test-frame

Author: kornys

test-frame-common/src/main/java/io/skodjob/wait/Wait.java

@@ -0,0 +1,98 @@
+package io.skodjob.wait;
+
+import java.io.PrintWriter;
+import java.io.StringWriter;
+import java.time.Duration;
+import java.util.function.BooleanSupplier;
+
+public class Wait {
+
+    /**
+     * For every poll (happening once each {@code pollIntervalMs}) checks if supplier {@code ready} is true.
+     * If yes, the wait is closed. Otherwise, waits another {@code pollIntervalMs} and tries again.
+     * Once the wait timeout (specified by {@code timeoutMs} is reached and supplier wasn't true until that time,
+     * throws {@link WaitException}.
+     *
+     * @param description information about on what we are waiting
+     * @param pollIntervalMs poll interval in milliseconds
+     * @param timeoutMs timeout specified in milliseconds
+     * @param ready {@link BooleanSupplier} containing code, which should be executed each poll, verifying readiness
+     *                                     of the particular thing
+     */
+    public static void until(String description, long pollIntervalMs, long timeoutMs, BooleanSupplier ready) {
+        until(description, pollIntervalMs, timeoutMs, ready, () -> {});
+    }
+
+    /**
+     * For every poll (happening once each {@code pollIntervalMs}) checks if supplier {@code ready} is true.
+     * If yes, the wait is closed. Otherwise, waits another {@code pollIntervalMs} and tries again.
+     * Once the wait timeout (specified by {@code timeoutMs} is reached and supplier wasn't true until that time,
+     * runs the {@code onTimeout} (f.e. print of logs, showing the actual value that was checked inside {@code ready}),
+     * and finally throws {@link WaitException}.
+     *
+     * @param description information about on what we are waiting
+     * @param pollIntervalMs poll interval in milliseconds
+     * @param timeoutMs timeout specified in milliseconds
+     * @param ready {@link BooleanSupplier} containing code, which should be executed each poll, verifying readiness
+     *                                     of the particular thing
+     * @param onTimeout {@link Runnable} executed once timeout is reached and before the {@link WaitException} is thrown.
+     */
+    public static void until(String description, long pollIntervalMs, long timeoutMs, BooleanSupplier ready, Runnable onTimeout) {
+        System.out.println("Waiting for " + description);
+        long deadline = System.currentTimeMillis() + timeoutMs;
+
+        String exceptionMessage = null;
+        String previousExceptionMessage = null;
+
+        // in case we are polling every 1s, we want to print exception after x tries, not on the first try
+        // for minutes poll interval will 2 be enough
+        int exceptionAppearanceCount = Duration.ofMillis(pollIntervalMs).toMinutes() > 0 ? 2 : Math.max((int) (timeoutMs / pollIntervalMs) / 4, 2);
+        int exceptionCount = 0;
+        int newExceptionAppearance = 0;
+
+        StringWriter stackTraceError = new StringWriter();
+
+        while (true) {
+            boolean result;
+            try {
+                result = ready.getAsBoolean();
+            } catch (Exception e) {
+                exceptionMessage = e.getMessage();
+
+                if (++exceptionCount == exceptionAppearanceCount && exceptionMessage != null && exceptionMessage.equals(previousExceptionMessage)) {
+                    System.out.println("While waiting for " + description + " exception occurred: " + exceptionMessage);
+                    // log the stacktrace
+                    e.printStackTrace(new PrintWriter(stackTraceError));
+                } else if (exceptionMessage != null && !exceptionMessage.equals(previousExceptionMessage) && ++newExceptionAppearance == 2) {
+                    previousExceptionMessage = exceptionMessage;
+                }
+
+                result = false;
+            }
+            long timeLeft = deadline - System.currentTimeMillis();
+            if (result) {
+                return;
+            }
+            if (timeLeft <= 0) {
+                if (exceptionCount > 1) {
+                    System.out.println("Exception waiting for " + description + ", " + exceptionMessage);
+
+                    if (!stackTraceError.toString().isEmpty()) {
+                        // printing handled stacktrace
+                        System.out.println(stackTraceError);
+                    }
+                }
+                onTimeout.run();
+                WaitException waitException = new WaitException("Timeout after " + timeoutMs + " ms waiting for " + description);
+                waitException.printStackTrace();
+                throw waitException;
+            }
+            long sleepTime = Math.min(pollIntervalMs, timeLeft);
+            try {
+                Thread.sleep(sleepTime);
+            } catch (InterruptedException e) {
+                return;
+            }
+        }
+    }
+}

test-frame-common/src/main/java/io/skodjob/wait/WaitException.java

@@ -0,0 +1,7 @@
+package io.skodjob.wait;
+
+public class WaitException extends RuntimeException {
+    public WaitException(String message) {
+        super(message);
+    }
+}