Add an experiment enrollment manager.

service/src/main/java/org/whispersystems/textsecuregcm/configuration/dynamic/DynamicConfiguration.java

@@ -1,5 +1,19 @@
 package org.whispersystems.textsecuregcm.configuration.dynamic;
 
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+import javax.validation.Valid;
+import java.util.Collections;
+import java.util.Map;
+import java.util.Optional;
+
 public class DynamicConfiguration {
 
+  @JsonProperty
+  @Valid
+  private Map<String, DynamicExperimentEnrollmentConfiguration> experiments = Collections.emptyMap();
+
+  public Optional<DynamicExperimentEnrollmentConfiguration> getExperimentEnrollmentConfiguration(final String experimentName) {
+    return Optional.ofNullable(experiments.get(experimentName));
+  }
 }

service/src/main/java/org/whispersystems/textsecuregcm/configuration/dynamic/DynamicExperimentEnrollmentConfiguration.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2021 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.whispersystems.textsecuregcm.configuration.dynamic;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+import javax.validation.Valid;
+import javax.validation.constraints.Max;
+import javax.validation.constraints.Min;
+import java.util.Collections;
+import java.util.Map;
+import java.util.Set;
+import java.util.UUID;
+
+public class DynamicExperimentEnrollmentConfiguration {
+
+    @JsonProperty
+    @Valid
+    private Set<UUID> enrolledUuids = Collections.emptySet();
+
+    @JsonProperty
+    @Valid
+    @Min(0)
+    @Max(100)
+    private int enrollmentPercentage = 0;
+
+    public Set<UUID> getEnrolledUuids() {
+        return enrolledUuids;
+    }
+
+    public int getEnrollmentPercentage() {
+        return enrollmentPercentage;
+    }
+}

service/src/main/java/org/whispersystems/textsecuregcm/experiment/ExperimentEnrollmentManager.java

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2021 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.whispersystems.textsecuregcm.experiment;
+
+import org.whispersystems.textsecuregcm.configuration.dynamic.DynamicExperimentEnrollmentConfiguration;
+import org.whispersystems.textsecuregcm.storage.Account;
+import org.whispersystems.textsecuregcm.storage.DynamicConfigurationManager;
+
+import java.util.Collections;
+import java.util.Optional;
+import java.util.Set;
+import java.util.UUID;
+
+public class ExperimentEnrollmentManager {
+
+    private final DynamicConfigurationManager dynamicConfigurationManager;
+
+    public ExperimentEnrollmentManager(final DynamicConfigurationManager dynamicConfigurationManager) {
+        this.dynamicConfigurationManager = dynamicConfigurationManager;
+    }
+
+    public boolean isEnrolled(final Account account, final String experimentName) {
+        final Optional<DynamicExperimentEnrollmentConfiguration> maybeConfiguration = dynamicConfigurationManager.getConfiguration().getExperimentEnrollmentConfiguration(experimentName);
+
+        final Set<UUID> enrolledUuids = maybeConfiguration.map(DynamicExperimentEnrollmentConfiguration::getEnrolledUuids)
+                                                          .orElse(Collections.emptySet());
+
+        final boolean enrolled;
+
+        if (enrolledUuids.contains(account.getUuid())) {
+            enrolled = true;
+        } else {
+            final int threshold = maybeConfiguration.map(DynamicExperimentEnrollmentConfiguration::getEnrollmentPercentage).orElse(0);
+            final int enrollmentHash = ((account.getUuid().hashCode() ^ experimentName.hashCode()) & Integer.MAX_VALUE) % 100;
+
+            enrolled = enrollmentHash < threshold;
+        }
+
+        return enrolled;
+    }
+}

service/src/main/java/org/whispersystems/textsecuregcm/storage/DynamicConfigurationManager.java

@@ -31,7 +31,6 @@ public class DynamicConfigurationManager implements Managed {
   private final String          clientId;
   private final AmazonAppConfig appConfigClient;
 
-  private final ObjectMapper                            mapper           = new ObjectMapper(new YAMLFactory()).configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
   private final AtomicReference<DynamicConfiguration>   configuration    = new AtomicReference<>();
   private final AtomicBoolean                           running          = new AtomicBoolean(true);
   private final Logger                                  logger           = LoggerFactory.getLogger(DynamicConfigurationManager.class);
@@ -40,6 +39,8 @@ public class DynamicConfigurationManager implements Managed {
 
   private boolean initialized = false;
 
+  public static final ObjectMapper OBJECT_MAPPER = new ObjectMapper(new YAMLFactory()).configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
+
   public DynamicConfigurationManager(String application, String environment, String configurationName) {
     this(AmazonAppConfigClient.builder()
                               .withClientConfiguration(new ClientConfiguration().withClientExecutionTimeout(10000).withRequestTimeout(10000))
@@ -104,7 +105,7 @@ public class DynamicConfigurationManager implements Managed {
 
     if (!StringUtils.equals(lastConfigResult.getConfigurationVersion(), previousVersion)) {
       logger.info("Received new config version: {}", lastConfigResult.getConfigurationVersion());
-      maybeDynamicConfiguration = Optional.of(mapper.readValue(StandardCharsets.UTF_8.decode(lastConfigResult.getContent().asReadOnlyBuffer()).toString(), DynamicConfiguration.class));
+      maybeDynamicConfiguration = Optional.of(OBJECT_MAPPER.readValue(StandardCharsets.UTF_8.decode(lastConfigResult.getContent().asReadOnlyBuffer()).toString(), DynamicConfiguration.class));
     } else {
       // No change since last version
       maybeDynamicConfiguration = Optional.empty();

service/src/test/java/org/whispersystems/textsecuregcm/configuration/dynamic/DynamicConfigurationTest.java

@@ -0,0 +1,62 @@
+/*
+ * Copyright 2021 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.whispersystems.textsecuregcm.configuration.dynamic;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import org.junit.Test;
+import org.whispersystems.textsecuregcm.storage.DynamicConfigurationManager;
+
+import java.util.Collections;
+import java.util.Set;
+import java.util.UUID;
+
+import static org.junit.Assert.*;
+
+public class DynamicConfigurationTest {
+
+    @Test
+    public void testParseExperimentConfig() throws JsonProcessingException {
+        {
+            final String emptyConfigYaml = "test: true";
+            final DynamicConfiguration emptyConfig = DynamicConfigurationManager.OBJECT_MAPPER.readValue(emptyConfigYaml, DynamicConfiguration.class);
+
+            assertFalse(emptyConfig.getExperimentEnrollmentConfiguration("test").isPresent());
+        }
+
+        {
+            final String experimentConfigYaml =
+                    "experiments:\n" +
+                    "  percentageOnly:\n" +
+                    "    enrollmentPercentage: 12\n" +
+                    "  uuidsAndPercentage:\n" +
+                    "    enrolledUuids:\n" +
+                    "      - 717b1c09-ed0b-4120-bb0e-f4697534b8e1\n" +
+                    "      - 279f264c-56d7-4bbf-b9da-de718ff90903\n" +
+                    "    enrollmentPercentage: 77\n" +
+                    "  uuidsOnly:\n" +
+                    "    enrolledUuids:\n" +
+                    "      - 71618739-114c-4b1f-bb0d-6478a44eb600";
+
+            final DynamicConfiguration config = DynamicConfigurationManager.OBJECT_MAPPER.readValue(experimentConfigYaml, DynamicConfiguration.class);
+
+            assertFalse(config.getExperimentEnrollmentConfiguration("unconfigured").isPresent());
+
+            assertTrue(config.getExperimentEnrollmentConfiguration("percentageOnly").isPresent());
+            assertEquals(12, config.getExperimentEnrollmentConfiguration("percentageOnly").get().getEnrollmentPercentage());
+            assertEquals(Collections.emptySet(), config.getExperimentEnrollmentConfiguration("percentageOnly").get().getEnrolledUuids());
+
+            assertTrue(config.getExperimentEnrollmentConfiguration("uuidsAndPercentage").isPresent());
+            assertEquals(77, config.getExperimentEnrollmentConfiguration("uuidsAndPercentage").get().getEnrollmentPercentage());
+            assertEquals(Set.of(UUID.fromString("717b1c09-ed0b-4120-bb0e-f4697534b8e1"), UUID.fromString("279f264c-56d7-4bbf-b9da-de718ff90903")),
+                         config.getExperimentEnrollmentConfiguration("uuidsAndPercentage").get().getEnrolledUuids());
+
+            assertTrue(config.getExperimentEnrollmentConfiguration("uuidsOnly").isPresent());
+            assertEquals(0, config.getExperimentEnrollmentConfiguration("uuidsOnly").get().getEnrollmentPercentage());
+            assertEquals(Set.of(UUID.fromString("71618739-114c-4b1f-bb0d-6478a44eb600")),
+                         config.getExperimentEnrollmentConfiguration("uuidsOnly").get().getEnrolledUuids());
+        }
+    }
+}

service/src/test/java/org/whispersystems/textsecuregcm/experiment/ExperimentEnrollmentManagerTest.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright 2021 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.whispersystems.textsecuregcm.experiment;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.whispersystems.textsecuregcm.configuration.dynamic.DynamicConfiguration;
+import org.whispersystems.textsecuregcm.configuration.dynamic.DynamicExperimentEnrollmentConfiguration;
+import org.whispersystems.textsecuregcm.storage.Account;
+import org.whispersystems.textsecuregcm.storage.DynamicConfigurationManager;
+
+import java.util.Collections;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.UUID;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+public class ExperimentEnrollmentManagerTest {
+
+    private DynamicExperimentEnrollmentConfiguration experimentEnrollmentConfiguration;
+
+    private ExperimentEnrollmentManager experimentEnrollmentManager;
+
+    private Account account;
+
+    private static final UUID ACCOUNT_UUID = UUID.randomUUID();
+    private static final String EXPERIMENT_NAME = "test";
+
+    @Before
+    public void setUp() {
+        final DynamicConfigurationManager dynamicConfigurationManager = mock(DynamicConfigurationManager.class);
+        final DynamicConfiguration dynamicConfiguration = mock(DynamicConfiguration.class);
+
+        experimentEnrollmentConfiguration = mock(DynamicExperimentEnrollmentConfiguration.class);
+        experimentEnrollmentManager = new ExperimentEnrollmentManager(dynamicConfigurationManager);
+        account = mock(Account.class);
+
+        when(dynamicConfigurationManager.getConfiguration()).thenReturn(dynamicConfiguration);
+        when(dynamicConfiguration.getExperimentEnrollmentConfiguration(EXPERIMENT_NAME)).thenReturn(Optional.of(experimentEnrollmentConfiguration));
+        when(account.getUuid()).thenReturn(ACCOUNT_UUID);
+    }
+
+    @Test
+    public void testIsEnrolled() {
+        assertFalse(experimentEnrollmentManager.isEnrolled(account, EXPERIMENT_NAME));
+        assertFalse(experimentEnrollmentManager.isEnrolled(account, EXPERIMENT_NAME + "-unrelated-experiment"));
+
+        when(experimentEnrollmentConfiguration.getEnrolledUuids()).thenReturn(Set.of(ACCOUNT_UUID));
+        assertTrue(experimentEnrollmentManager.isEnrolled(account, EXPERIMENT_NAME));
+
+        when(experimentEnrollmentConfiguration.getEnrolledUuids()).thenReturn(Collections.emptySet());
+        when(experimentEnrollmentConfiguration.getEnrollmentPercentage()).thenReturn(0);
+
+        assertFalse(experimentEnrollmentManager.isEnrolled(account, EXPERIMENT_NAME));
+
+        when(experimentEnrollmentConfiguration.getEnrollmentPercentage()).thenReturn(100);
+        assertTrue(experimentEnrollmentManager.isEnrolled(account, EXPERIMENT_NAME));
+    }
+}