gharris1727 commented on code in PR #13971:
URL: https://github.com/apache/kafka/pull/13971#discussion_r1264131073
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connect/runtime/src/test/java/org/apache/kafka/connect/runtime/isolation/PluginScannerTest.java:
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@@ -20,79 +20,114 @@
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.TemporaryFolder;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
import java.nio.file.Files;
import java.nio.file.Path;
+import java.util.ArrayList;
+import java.util.Collection;
import java.util.Collections;
+import java.util.HashSet;
import java.util.List;
import java.util.Set;
-import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertThrows;
+import static org.junit.Assert.assertTrue;
+@RunWith(Parameterized.class)
public class PluginScannerTest {
+ private enum ScannerType { Reflection, ServiceLoader };
+
@Rule
public TemporaryFolder pluginDir = new TemporaryFolder();
+ public PluginScanner scanner;
+
+ @Parameterized.Parameters
+ public static Collection<Object[]> parameters() {
+ List<Object[]> values = new ArrayList<>();
+ for (ScannerType type : ScannerType.values()) {
+ values.add(new Object[]{type});
+ }
+ return values;
+ }
+
+ public PluginScannerTest(ScannerType scannerType) {
+ switch (scannerType) {
+ case Reflection:
+ this.scanner = new ReflectionScanner();
+ break;
+ case ServiceLoader:
+ this.scanner = new ServiceLoaderScanner();
+ break;
+ default:
+ throw new IllegalArgumentException("Unknown type " +
scannerType);
+ }
+ }
+
@Test
- public void testLoadingUnloadedPluginClass() {
- DelegatingClassLoader classLoader = initClassLoader(
+ public void testScanningEmptyPluginPath() {
+ PluginScanResult result = scan(
Collections.emptyList()
);
- for (String pluginClassName : TestPlugins.pluginClasses()) {
- assertThrows(ClassNotFoundException.class, () ->
classLoader.loadClass(pluginClassName));
- }
+ assertTrue(result.isEmpty());
}
@Test
- public void testLoadingPluginClass() throws ClassNotFoundException {
- DelegatingClassLoader classLoader = initClassLoader(
+ public void testScanningPluginClasses() {
+ PluginScanResult result = scan(
TestPlugins.pluginPath()
);
+ Set<String> classes = new HashSet<>();
+ result.forEach(pluginDesc -> classes.add(pluginDesc.className()));
for (String pluginClassName : TestPlugins.pluginClasses()) {
- assertNotNull(classLoader.loadClass(pluginClassName));
- assertNotNull(classLoader.pluginClassLoader(pluginClassName));
+ assertTrue("Expected " + pluginClassName + "to be discovered but
it was not",
+ classes.contains(pluginClassName));
Review Comment:
Oh and just to motivate the tweaks I made to your implementation:
If the ServiceLoader implementation can skip over some LinkageErrors, I
think it's possible to have two different plugins throw the same exception and
accidentally trigger the equals condition.
For example, if two plugins implemented NonExistentInterface and appeared
consecutively in the ServiceLoader manifest, I think the logic should show at
least one of the errors, but not fail the worker or shadow other plugins. I
think this would typically happen if a plugin packages both a Source and Sink
that both have the same missing dependency, but the ServiceLoader
implementation could continue to make progress.
There's a heuristic for 100 consecutive failures: if you package 100
consecutive faulty plugins (or have them all on the classpath) then it falls
back to failing the worker. I don't think i've seen more than ~5-10 connectors,
and ~20-30 Transforms packaged together. If the errors are non-consecutive then
the counter resets as well, so the actual number of tolerated hasNext calls
could be quite large, covering most use-cases.
The heuristic is just there to prevent infinite loops if the exception
message happens to contain a memory address, or the exception alternates
between two different messages in the ServiceLoader-not-making-progress case.
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