perf(core): [Init Reflection 2] Cache class lookups and collapse double probes

CHANGELOG.md

@@ -2,9 +2,10 @@
 
 ## Unreleased
 
-### Internal
+### Performance
 
 - Probe class availability without initializing the class during SDK init ([#5635](https://github.com/getsentry/sentry-java/pull/5635))
+- Cache reflective class lookups and avoid double-probing during SDK init ([#5636](https://github.com/getsentry/sentry-java/pull/5636))
 
 ## 8.45.0
 

sentry/src/main/java/io/sentry/ScopesStorageFactory.java

@@ -23,24 +23,23 @@ public final class ScopesStorageFactory {
   private static @NotNull IScopesStorage createInternal(
       final @NotNull LoadClass loadClass, final @NotNull ILogger logger) {
     if (Platform.isJvm()) {
-      if (loadClass.isClassAvailable(OTEL_SCOPES_STORAGE, logger)) {
-        Class<?> otelScopesStorageClazz = loadClass.loadClass(OTEL_SCOPES_STORAGE, logger);
-        if (otelScopesStorageClazz != null) {
-          try {
-            final @Nullable Object otelScopesStorage =
-                otelScopesStorageClazz.getDeclaredConstructor().newInstance();
-            if (otelScopesStorage instanceof IScopesStorage) {
-              return (IScopesStorage) otelScopesStorage;
-            }
-          } catch (InstantiationException e) {
-            // TODO log
-          } catch (IllegalAccessException e) {
-            // TODO log
-          } catch (InvocationTargetException e) {
-            // TODO log
-          } catch (NoSuchMethodException e) {
-            // TODO log
+      final @Nullable Class<?> otelScopesStorageClazz =
+          loadClass.loadClass(OTEL_SCOPES_STORAGE, logger);
+      if (otelScopesStorageClazz != null) {
+        try {
+          final @Nullable Object otelScopesStorage =
+              otelScopesStorageClazz.getDeclaredConstructor().newInstance();
+          if (otelScopesStorage instanceof IScopesStorage) {
+            return (IScopesStorage) otelScopesStorage;
           }
+        } catch (InstantiationException e) {
+          // TODO log
+        } catch (IllegalAccessException e) {
+          // TODO log
+        } catch (InvocationTargetException e) {
+          // TODO log
+        } catch (NoSuchMethodException e) {
+          // TODO log
         }
       }
     }

sentry/src/main/java/io/sentry/SpanFactoryFactory.java

@@ -15,24 +15,23 @@ public final class SpanFactoryFactory {
   public static @NotNull ISpanFactory create(
       final @NotNull LoadClass loadClass, final @NotNull ILogger logger) {
     if (Platform.isJvm()) {
-      if (loadClass.isClassAvailable(OTEL_SPAN_FACTORY, logger)) {
-        Class<?> otelSpanFactoryClazz = loadClass.loadClass(OTEL_SPAN_FACTORY, logger);
-        if (otelSpanFactoryClazz != null) {
-          try {
-            final @Nullable Object otelSpanFactory =
-                otelSpanFactoryClazz.getDeclaredConstructor().newInstance();
-            if (otelSpanFactory instanceof ISpanFactory) {
-              return (ISpanFactory) otelSpanFactory;
-            }
-          } catch (InstantiationException e) {
-            // TODO log
-          } catch (IllegalAccessException e) {
-            // TODO log
-          } catch (InvocationTargetException e) {
-            // TODO log
-          } catch (NoSuchMethodException e) {
-            // TODO log
+      final @Nullable Class<?> otelSpanFactoryClazz =
+          loadClass.loadClass(OTEL_SPAN_FACTORY, logger);
+      if (otelSpanFactoryClazz != null) {
+        try {
+          final @Nullable Object otelSpanFactory =
+              otelSpanFactoryClazz.getDeclaredConstructor().newInstance();
+          if (otelSpanFactory instanceof ISpanFactory) {
+            return (ISpanFactory) otelSpanFactory;
           }
+        } catch (InstantiationException e) {
+          // TODO log
+        } catch (IllegalAccessException e) {
+          // TODO log
+        } catch (InvocationTargetException e) {
+          // TODO log
+        } catch (NoSuchMethodException e) {
+          // TODO log
         }
       }
     }

sentry/src/main/java/io/sentry/util/LoadClass.java

@@ -4,13 +4,25 @@
 import io.sentry.ILogger;
 import io.sentry.SentryLevel;
 import io.sentry.SentryOptions;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 /** An Adapter for making Class.forName testable */
 @Open
 public class LoadClass {
 
+  /** Sentinel cached for class names that are known to be unavailable. */
+  private static final Object NOT_AVAILABLE = new Object();
+
+  /**
+   * Whether a class is on the classpath does not change during the lifetime of the process, so
+   * results are cached to avoid repeated {@link Class#forName} lookups (and the exceptions they
+   * throw for absent classes) when the same class is probed more than once.
+   */
+  private static final Map<String, Object> CLASSES = new ConcurrentHashMap<>();
+
   /**
    * Try to load a class via reflection
    *
@@ -19,11 +31,18 @@ public class LoadClass {
    * @return a Class&lt;?&gt; if it's available, or null
    */
   public @Nullable Class<?> loadClass(final @NotNull String clazz, final @Nullable ILogger logger) {
+    final @Nullable Object cached = CLASSES.get(clazz);
+    if (cached != null) {
+      return cached == NOT_AVAILABLE ? null : (Class<?>) cached;
+    }
     try {
       // Don't initialize the class just to probe for availability; it gets initialized lazily on
       // first use. This avoids running unrelated static initializers during SDK init.
-      return Class.forName(clazz, false, LoadClass.class.getClassLoader());
+      final Class<?> loadedClass = Class.forName(clazz, false, LoadClass.class.getClassLoader());
+      CLASSES.put(clazz, loadedClass);
+      return loadedClass;
     } catch (ClassNotFoundException e) {
+      CLASSES.put(clazz, NOT_AVAILABLE);
       if (logger != null) {
         logger.log(SentryLevel.INFO, "Class not available: " + clazz);
       }