Merge pull request #15409 from vespa-engine/mortent/pow-two-lb

Use 'power of two choices' lb algorithm

2 files changed, 22 insertions, 0 deletions

diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/model/LbServicesProducer.java b/configserver/src/main/java/com/yahoo/vespa/config/server/model/LbServicesProducer.java
index ae258445e88..d816c3215a7 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/model/LbServicesProducer.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/model/LbServicesProducer.java
@@ -9,7 +9,10 @@ import com.yahoo.config.model.api.ServiceInfo;
 import com.yahoo.config.provision.ApplicationId;
 import com.yahoo.config.provision.TenantName;
 import com.yahoo.config.provision.Zone;
+import com.yahoo.vespa.flags.BooleanFlag;
+import com.yahoo.vespa.flags.FetchVector;
 import com.yahoo.vespa.flags.FlagSource;
+import com.yahoo.vespa.flags.Flags;
 
 import java.util.Collections;
 import java.util.Comparator;
@@ -32,10 +35,12 @@ public class LbServicesProducer implements LbServicesConfig.Producer {
 
     private final Map<TenantName, Set<ApplicationInfo>> models;
     private final Zone zone;
+    private final BooleanFlag usePowerOfTwoChoicesLb;
 
     public LbServicesProducer(Map<TenantName, Set<ApplicationInfo>> models, Zone zone, FlagSource flagSource) {
         this.models = models;
         this.zone = zone;
+        usePowerOfTwoChoicesLb = Flags.USE_POWER_OF_TWO_CHOICES_LOAD_BALANCING.bindTo(flagSource);
     }
 
     @Override
@@ -67,6 +72,7 @@ public class LbServicesProducer implements LbServicesConfig.Producer {
     private LbServicesConfig.Tenants.Applications.Builder getAppConfig(ApplicationInfo app) {
         LbServicesConfig.Tenants.Applications.Builder ab = new LbServicesConfig.Tenants.Applications.Builder();
         ab.activeRotation(getActiveRotation(app));
+        ab.usePowerOfTwoChoicesLb(usePowerOfTwoChoicesLb(app));
         app.getModel().getHosts().stream()
                 .sorted((a, b) -> a.getHostname().compareTo(b.getHostname()))
                 .forEach(hostInfo -> ab.hosts(hostInfo.getHostname(), getHostsConfig(hostInfo)));
@@ -87,6 +93,10 @@ public class LbServicesProducer implements LbServicesConfig.Producer {
         return activeRotation;
     }
 
+    private boolean usePowerOfTwoChoicesLb(ApplicationInfo app) {
+        return usePowerOfTwoChoicesLb.with(FetchVector.Dimension.APPLICATION_ID, app.getApplicationId().serializedForm()).value();
+    }
+
     private LbServicesConfig.Tenants.Applications.Hosts.Builder getHostsConfig(HostInfo hostInfo) {
         LbServicesConfig.Tenants.Applications.Hosts.Builder hb = new LbServicesConfig.Tenants.Applications.Hosts.Builder();
         hb.hostname(hostInfo.getHostname());
diff --git a/configserver/src/test/java/com/yahoo/vespa/config/server/model/LbServicesProducerTest.java b/configserver/src/test/java/com/yahoo/vespa/config/server/model/LbServicesProducerTest.java
index 325db1feba6..6729be20305 100644
--- a/configserver/src/test/java/com/yahoo/vespa/config/server/model/LbServicesProducerTest.java
+++ b/configserver/src/test/java/com/yahoo/vespa/config/server/model/LbServicesProducerTest.java
@@ -16,6 +16,7 @@ import com.yahoo.config.provision.RegionName;
 import com.yahoo.config.provision.TenantName;
 import com.yahoo.config.provision.Zone;
 import com.yahoo.vespa.config.ConfigPayload;
+import com.yahoo.vespa.flags.Flags;
 import com.yahoo.vespa.flags.InMemoryFlagSource;
 import com.yahoo.vespa.model.VespaModel;
 import org.junit.Test;
@@ -108,6 +109,17 @@ public class LbServicesProducerTest {
         }
     }
 
+    @Test
+    public void use_power_of_two_lb_is_configured_from_feature_flag() throws IOException, SAXException {
+            RegionName regionName = RegionName.from("us-east-1");
+
+            LbServicesConfig conf = createModelAndGetLbServicesConfig(regionName);
+            assertFalse(conf.tenants("foo").applications("foo:prod:" + regionName.value() + ":default").usePowerOfTwoChoicesLb());
+
+            flagSource.withBooleanFlag(Flags.USE_POWER_OF_TWO_CHOICES_LOAD_BALANCING.id(), true);
+            conf = createModelAndGetLbServicesConfig(regionName);
+            assertTrue(conf.tenants("foo").applications("foo:prod:" + regionName.value() + ":default").usePowerOfTwoChoicesLb());
+    }
     private LbServicesConfig createModelAndGetLbServicesConfig(RegionName regionName) throws IOException, SAXException {
         Zone zone = new Zone(Environment.prod, regionName);
         Map<TenantName, Set<ApplicationInfo>> testModel = createTestModel(new DeployState.Builder()