Add request property requiredGeneration to http get config requests

Response should be 412 Precondition Failed if config found
does not have same generations as property.

7 files changed, 73 insertions, 16 deletions

diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/http/HttpConfigRequest.java b/configserver/src/main/java/com/yahoo/vespa/config/server/http/HttpConfigRequest.java
index 3baa57b2b01..e043afdbf43 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/http/HttpConfigRequest.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/http/HttpConfigRequest.java
@@ -30,15 +30,18 @@ import java.util.Set;
  */
 public class HttpConfigRequest implements GetConfigRequest, TenantRequest {
 
-    private static final String HTTP_PROPERTY_NOCACHE = "noCache";
+    private static final String NOCACHE = "noCache";
+    private static final String REQUIRED_GENERATION = "requiredGeneration";
     private final ConfigKey<?> key;
     private final ApplicationId appId;
     private final boolean noCache;
+    private final Optional<Long> requiredGeneration;
 
-    private HttpConfigRequest(ConfigKey<?> key, ApplicationId appId, boolean noCache) {
+    private HttpConfigRequest(ConfigKey<?> key, ApplicationId appId, boolean noCache, Optional<Long> requiredGeneration) {
         this.key = key;
         this.appId = appId;
         this.noCache = noCache;
+        this.requiredGeneration = requiredGeneration;
     }
 
     private static ConfigKey<?> fromRequestV1(HttpRequest req) {
@@ -59,7 +62,10 @@ public class HttpConfigRequest implements GetConfigRequest, TenantRequest {
     }
 
     public static HttpConfigRequest createFromRequestV1(HttpRequest req) {
-        return new HttpConfigRequest(fromRequestV1(req), ApplicationId.defaultId(), req.getBooleanProperty(HTTP_PROPERTY_NOCACHE));
+        return new HttpConfigRequest(fromRequestV1(req),
+                                     ApplicationId.defaultId(),
+                                     req.getBooleanProperty(NOCACHE),
+                                     requiredGeneration(req));
     }
 
     public static HttpConfigRequest createFromRequestV2(HttpRequest req) {
@@ -89,7 +95,8 @@ public class HttpConfigRequest implements GetConfigRequest, TenantRequest {
         cNamespace = nns.second;
         return new HttpConfigRequest(new ConfigKey<>(cName, cId, cNamespace),
                                      new ApplicationId.Builder().applicationName(application).tenant(tenant).build(),
-                                     req.getBooleanProperty(HTTP_PROPERTY_NOCACHE));
+                                     req.getBooleanProperty(NOCACHE),
+                                     requiredGeneration(req));
     }
 
     // The URL pattern with full app id given
@@ -117,7 +124,10 @@ public class HttpConfigRequest implements GetConfigRequest, TenantRequest {
                               .applicationName(application)
                               .instanceName(instance)
                               .build();
-        return new HttpConfigRequest(new ConfigKey<>(cName, cId, cNamespace), appId, req.getBooleanProperty(HTTP_PROPERTY_NOCACHE));
+        return new HttpConfigRequest(new ConfigKey<>(cName, cId, cNamespace),
+                                     appId,
+                                     req.getBooleanProperty(NOCACHE),
+                                     requiredGeneration(req));
     }
 
     /**
@@ -144,7 +154,11 @@ public class HttpConfigRequest implements GetConfigRequest, TenantRequest {
     public static void throwModelNotReady() {
         throw new NotFoundException("Config not available, verify that an application package has been deployed and activated.");
     }
-    
+
+    public static void throwPreconditionFailed(long requiredGeneration) {
+        throw new PreconditionFailedException("Config for required generation " + requiredGeneration + " could not be found.");
+    }
+
     /**
      * If the given config is produced by the model at all
      *
@@ -199,4 +213,11 @@ public class HttpConfigRequest implements GetConfigRequest, TenantRequest {
     @Override
     public PayloadChecksums configPayloadChecksums() { return PayloadChecksums.empty(); }
 
+    public Optional<Long> requiredGeneration() { return requiredGeneration; }
+
+    static Optional<Long> requiredGeneration(HttpRequest req) {
+        Optional<String> requiredGeneration = Optional.ofNullable(req.getProperty(REQUIRED_GENERATION));
+        return requiredGeneration.map(Long::parseLong);
+    }
+
 }
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/http/HttpErrorResponse.java b/configserver/src/main/java/com/yahoo/vespa/config/server/http/HttpErrorResponse.java
index 40ce16145e7..3b5269cdf11 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/http/HttpErrorResponse.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/http/HttpErrorResponse.java
@@ -16,6 +16,7 @@ import static com.yahoo.jdisc.Response.Status.CONFLICT;
 import static com.yahoo.jdisc.Response.Status.INTERNAL_SERVER_ERROR;
 import static com.yahoo.jdisc.Response.Status.METHOD_NOT_ALLOWED;
 import static com.yahoo.jdisc.Response.Status.NOT_FOUND;
+import static com.yahoo.jdisc.Response.Status.PRECONDITION_FAILED;
 import static com.yahoo.jdisc.Response.Status.REQUEST_TIMEOUT;
 
 /**
@@ -51,7 +52,8 @@ public class HttpErrorResponse extends HttpResponse {
         CERTIFICATE_NOT_READY,
         LOAD_BALANCER_NOT_READY,
         CONFIG_NOT_CONVERGED,
-        REINDEXING_STATUS_UNAVAILABLE
+        REINDEXING_STATUS_UNAVAILABLE,
+        PRECONDITION_FAILED
     }
 
     public static HttpErrorResponse notFoundError(String msg) {
@@ -114,6 +116,10 @@ public class HttpErrorResponse extends HttpResponse {
         return new HttpErrorResponse(CONFLICT, ErrorCode.REINDEXING_STATUS_UNAVAILABLE.name(), msg);
     }
 
+    public static HttpResponse preconditionFailed(String msg) {
+        return new HttpErrorResponse(PRECONDITION_FAILED, ErrorCode.PRECONDITION_FAILED.name(), msg);
+    }
+
     @Override
     public void render(OutputStream stream) throws IOException {
         new JsonFormat(true).encode(stream, slime);
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/http/HttpHandler.java b/configserver/src/main/java/com/yahoo/vespa/config/server/http/HttpHandler.java
index dc3a05e65f9..a0e814f32d8 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/http/HttpHandler.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/http/HttpHandler.java
@@ -71,6 +71,8 @@ public class HttpHandler extends ThreadedHttpRequestHandler {
             return HttpErrorResponse.loadBalancerNotReady(getMessage(e, request));
         } catch (ReindexingStatusException e) {
             return HttpErrorResponse.reindexingStatusUnavailable(getMessage(e, request));
+        } catch (PreconditionFailedException e) {
+            return HttpErrorResponse.preconditionFailed(getMessage(e, request));
         } catch (Exception e) {
             log.log(Level.WARNING, "Unexpected exception handling a config server request", e);
             return HttpErrorResponse.internalServerError(getMessage(e, request));
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/http/NotFoundException.java b/configserver/src/main/java/com/yahoo/vespa/config/server/http/NotFoundException.java
index eb008de6ee5..688890c75b2 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/http/NotFoundException.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/http/NotFoundException.java
@@ -5,7 +5,6 @@ package com.yahoo.vespa.config.server.http;
  * Exception that will create a http response with NOT_FOUND response code (404)
  *
  * @author hmusum
- * @since 5.1.17
  */
 public class NotFoundException extends RuntimeException {
 
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/http/PreconditionFailedException.java b/configserver/src/main/java/com/yahoo/vespa/config/server/http/PreconditionFailedException.java
new file mode 100644
index 00000000000..ef3924425c2
--- /dev/null
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/http/PreconditionFailedException.java
@@ -0,0 +1,16 @@
+// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.vespa.config.server.http;
+
+/**
+ * Exception that will create a http response with NOT_FOUND response code (404)
+ *
+ * @author hmusum
+ */
+public class PreconditionFailedException extends RuntimeException {
+
+    public PreconditionFailedException(String message) {
+        super(message);
+    }
+
+}
+
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/http/v2/HttpGetConfigHandler.java b/configserver/src/main/java/com/yahoo/vespa/config/server/http/v2/HttpGetConfigHandler.java
index 3ab3df99a10..0389b2a6c98 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/http/v2/HttpGetConfigHandler.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/http/v2/HttpGetConfigHandler.java
@@ -4,31 +4,27 @@ package com.yahoo.vespa.config.server.http.v2;
 import com.yahoo.component.annotation.Inject;
 import com.yahoo.container.jdisc.HttpRequest;
 import com.yahoo.container.jdisc.HttpResponse;
-import java.util.logging.Level;
 import com.yahoo.vespa.config.protocol.ConfigResponse;
 import com.yahoo.vespa.config.server.RequestHandler;
-import com.yahoo.vespa.config.server.http.v2.request.HttpConfigRequests;
-import com.yahoo.vespa.config.server.tenant.TenantRepository;
 import com.yahoo.vespa.config.server.http.HttpConfigRequest;
 import com.yahoo.vespa.config.server.http.HttpConfigResponse;
 import com.yahoo.vespa.config.server.http.HttpHandler;
-
+import com.yahoo.vespa.config.server.http.v2.request.HttpConfigRequests;
+import com.yahoo.vespa.config.server.tenant.TenantRepository;
 import java.util.Optional;
+import java.util.logging.Level;
 
 /**
  * HTTP handler for a getConfig operation
  *
  * @author Ulf Lilleengen
- * @since 5.1
  */
 public class HttpGetConfigHandler extends HttpHandler {
 
     private final TenantRepository tenantRepository;
 
     @Inject
-    public HttpGetConfigHandler(HttpHandler.Context ctx,
-                                TenantRepository tenantRepository)
-    {
+    public HttpGetConfigHandler(HttpHandler.Context ctx, TenantRepository tenantRepository) {
         super(ctx);
         this.tenantRepository = tenantRepository;
     }
@@ -45,6 +41,8 @@ public class HttpGetConfigHandler extends HttpHandler {
         log.log(Level.FINE, () -> "nocache=" + request.noCache());
         ConfigResponse config = requestHandler.resolveConfig(request.getApplicationId(), request, Optional.empty());
         if (config == null) HttpConfigRequest.throwModelNotReady();
+        if (request.requiredGeneration().isPresent() && request.requiredGeneration().get() != config.getGeneration())
+            HttpConfigRequest.throwPreconditionFailed(request.requiredGeneration().get());
         return config;
     }
 }
diff --git a/configserver/src/test/java/com/yahoo/vespa/config/server/http/v2/HttpGetConfigHandlerTest.java b/configserver/src/test/java/com/yahoo/vespa/config/server/http/v2/HttpGetConfigHandlerTest.java
index a0b5b879e45..401bd1ae55b 100644
--- a/configserver/src/test/java/com/yahoo/vespa/config/server/http/v2/HttpGetConfigHandlerTest.java
+++ b/configserver/src/test/java/com/yahoo/vespa/config/server/http/v2/HttpGetConfigHandlerTest.java
@@ -25,6 +25,7 @@ import org.junit.rules.TemporaryFolder;
 import java.io.File;
 import java.io.IOException;
 import java.util.Collections;
+import java.util.Map;
 
 import static com.yahoo.jdisc.Response.Status.BAD_REQUEST;
 import static com.yahoo.jdisc.Response.Status.NOT_FOUND;
@@ -131,6 +132,20 @@ public class HttpGetConfigHandlerTest {
         assertTrue(renderedString, renderedString.startsWith(expected));
     }
 
+    @Test
+    public void require_that_required_generation_property_works() throws IOException {
+        HttpRequest request = HttpRequest.createTestRequest(configUri, GET, null, Map.of("requiredGeneration", "2"));
+        HttpResponse response = handler.handle(request);
+        String renderedString = SessionHandlerTest.getRenderedString(response);
+        assertTrue(renderedString, renderedString.startsWith(expected));
+
+        request = HttpRequest.createTestRequest(configUri, GET, null, Map.of("requiredGeneration", "3"));
+        response = handler.handle(request);
+        assertEquals(412, response.getStatus());
+        renderedString = SessionHandlerTest.getRenderedString(response);
+        assertEquals("{\"error-code\":\"PRECONDITION_FAILED\",\"message\":\"Config for required generation 3 could not be found.\"}", renderedString);
+    }
+
     private PrepareParams prepareParams() {
         return new PrepareParams.Builder().applicationId(applicationId).build();
     }