Ensure Hints do not cause memory leaks (#2387)

Co-authored-by: Alexander Dinauer <adinauer@users.noreply.github.com>
Co-authored-by: Roman Zavarnitsyn <rom4ek93@gmail.com>

CHANGELOG.md

@@ -11,6 +11,7 @@
 - Use `canonicalName` in Fragment Integration for better de-obfuscation ([#2379](https://github.com/getsentry/sentry-java/pull/2379))
 - Fix Timber and Fragment integrations auto-installation for obfuscated builds ([#2379](https://github.com/getsentry/sentry-java/pull/2379))
 - Don't attach screenshots to events from Hybrid SDKs ([#2360](https://github.com/getsentry/sentry-java/pull/2360))
+- Ensure Hints do not cause memory leaks ([#2387](https://github.com/getsentry/sentry-java/pull/2387))
 
 ### Dependencies
 

sentry/api/sentry.api

@@ -249,6 +249,7 @@ public final class io/sentry/Hint {
 	public fun <init> ()V
 	public fun addAttachment (Lio/sentry/Attachment;)V
 	public fun addAttachments (Ljava/util/List;)V
+	public fun clear ()V
 	public fun clearAttachments ()V
 	public fun get (Ljava/lang/String;)Ljava/lang/Object;
 	public fun getAs (Ljava/lang/String;Ljava/lang/Class;)Ljava/lang/Object;

sentry/src/main/java/io/sentry/Hint.java

@@ -2,8 +2,10 @@
 
 import java.util.ArrayList;
 import java.util.HashMap;
+import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
+import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
@@ -39,16 +41,17 @@ public final class Hint {
     return hint;
   }
 
-  public void set(@NotNull String name, @Nullable Object hint) {
+  public synchronized void set(@NotNull String name, @Nullable Object hint) {
     internalStorage.put(name, hint);
   }
 
-  public @Nullable Object get(@NotNull String name) {
+  public synchronized @Nullable Object get(@NotNull String name) {
     return internalStorage.get(name);
   }
 
   @SuppressWarnings("unchecked")
-  public <T extends Object> @Nullable T getAs(@NotNull String name, @NotNull Class<T> clazz) {
+  public synchronized <T extends Object> @Nullable T getAs(
+      @NotNull String name, @NotNull Class<T> clazz) {
     Object hintValue = internalStorage.get(name);
 
     if (clazz.isInstance(hintValue)) {
@@ -60,7 +63,7 @@ public void set(@NotNull String name, @Nullable Object hint) {
     }
   }
 
-  public void remove(@NotNull String name) {
+  public synchronized void remove(@NotNull String name) {
     internalStorage.remove(name);
   }
 
@@ -89,6 +92,23 @@ public void clearAttachments() {
     attachments.clear();
   }
 
+  /**
+   * Clears all attributes added via {@link #set(String, Object)} Note: SDK internal attributes are
+   * being kept. This is useful to avoid leaking any objects (e.g. Android activities) being
+   * referenced.
+   */
+  @ApiStatus.Internal
+  public synchronized void clear() {
+    final Iterator<Map.Entry<String, Object>> iterator = internalStorage.entrySet().iterator();
+
+    while (iterator.hasNext()) {
+      final Map.Entry<String, Object> entry = iterator.next();
+      if (entry.getKey() == null || !entry.getKey().startsWith("sentry:")) {
+        iterator.remove();
+      }
+    }
+  }
+
   public void setScreenshot(@Nullable Attachment screenshot) {
     this.screenshot = screenshot;
   }

sentry/src/main/java/io/sentry/SentryClient.java

@@ -178,6 +178,7 @@ private boolean shouldApplyScopeData(
       final SentryEnvelope envelope =
           buildEnvelope(event, attachments, session, traceContext, null);
 
+      hint.clear();
       if (envelope != null) {
         transport.send(envelope, hint);
       }
@@ -483,6 +484,7 @@ public void captureSession(final @NotNull Session session, final @Nullable Hint
     }
 
     try {
+      hint.clear();
       transport.send(envelope, hint);
     } catch (IOException e) {
       options.getLogger().log(SentryLevel.ERROR, "Failed to capture envelope.", e);
@@ -588,6 +590,7 @@ public void captureSession(final @NotNull Session session, final @Nullable Hint
           buildEnvelope(
               transaction, filterForTransaction(getAttachments(hint)), null, traceContext, null);
 
+      hint.clear();
       if (envelope != null) {
         transport.send(envelope, hint);
       } else {

sentry/src/test/java/io/sentry/hints/HintTest.kt

@@ -1,7 +1,9 @@
 package io.sentry.hints
 
 import io.sentry.Attachment
+import io.sentry.CachedEvent
 import io.sentry.Hint
+import io.sentry.TypeCheckHint.SENTRY_TYPE_CHECK_HINT
 import kotlin.test.Test
 import kotlin.test.assertEquals
 import kotlin.test.assertNotNull
@@ -197,6 +199,24 @@ class HintTest {
         assertEquals(listOf(attachment3, attachment4), hint.attachments)
     }
 
+    @Test
+    fun `calling clear does not remove internal sentry attrs, attachments or screenshots`() {
+        val userAttribute = "app_label"
+
+        val hint = Hint()
+        hint.set(SENTRY_TYPE_CHECK_HINT, CachedEvent())
+        hint.set(userAttribute, "test label")
+        hint.addAttachment(newAttachment("test attachment"))
+        hint.screenshot = newAttachment("2")
+
+        hint.clear()
+
+        assertNotNull(hint.get(SENTRY_TYPE_CHECK_HINT))
+        assertNull(hint.get(userAttribute))
+        assertEquals(1, hint.attachments.size)
+        assertNotNull(hint.screenshot)
+    }
+
     companion object {
         fun newAttachment(content: String) = Attachment(content.toByteArray(), "$content.txt")
     }