Refactor RoutingManager

gateway-ha/pom.xml

@@ -62,11 +62,6 @@
             <artifactId>jackson-dataformat-yaml</artifactId>
         </dependency>
 
-        <dependency>
-            <groupId>com.google.errorprone</groupId>
-            <artifactId>error_prone_annotations</artifactId>
-        </dependency>
-
         <dependency>
             <groupId>com.google.guava</groupId>
             <artifactId>guava</artifactId>

gateway-ha/src/main/java/io/trino/gateway/ha/clustermonitor/HealthCheckObserver.java

@@ -28,6 +28,6 @@ public HealthCheckObserver(RoutingManager routingManager)
     @Override
     public void observe(java.util.List<ClusterStats> clustersStats)
     {
-        routingManager.updateBackEndStats(clustersStats);
+        routingManager.updateClusterStats(clustersStats);
     }
 }

gateway-ha/src/main/java/io/trino/gateway/ha/router/BaseRoutingManager.java

@@ -0,0 +1,279 @@
+/*
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.trino.gateway.ha.router;
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Function;
+import com.google.common.base.Strings;
+import com.google.common.cache.CacheBuilder;
+import com.google.common.cache.CacheLoader;
+import com.google.common.cache.LoadingCache;
+import io.airlift.log.Logger;
+import io.trino.gateway.ha.clustermonitor.ClusterStats;
+import io.trino.gateway.ha.clustermonitor.TrinoStatus;
+import io.trino.gateway.ha.config.ProxyBackendConfiguration;
+import io.trino.gateway.ha.config.RoutingConfiguration;
+import jakarta.annotation.Nullable;
+import jakarta.ws.rs.HttpMethod;
+
+import java.net.HttpURLConnection;
+import java.net.URL;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * This class performs health check, stats counts for each backend and provides a backend given
+ * request object. Default implementation comes here.
+ */
+public abstract class BaseRoutingManager
+        implements RoutingManager
+{
+    private static final Logger log = Logger.get(BaseRoutingManager.class);
+    private final ExecutorService executorService = Executors.newFixedThreadPool(5);
+    private final GatewayBackendManager gatewayBackendManager;
+    private final ConcurrentHashMap<String, TrinoStatus> backendToStatus;
+    private final String defaultRoutingGroup;
+    private final QueryHistoryManager queryHistoryManager;
+    private final LoadingCache<String, String> queryIdBackendCache;
+    private final LoadingCache<String, String> queryIdRoutingGroupCache;
+    private final LoadingCache<String, String> queryIdExternalUrlCache;
+
+    public BaseRoutingManager(GatewayBackendManager gatewayBackendManager, QueryHistoryManager queryHistoryManager, RoutingConfiguration routingConfiguration)
+    {
+        this.gatewayBackendManager = gatewayBackendManager;
+        this.defaultRoutingGroup = routingConfiguration.getDefaultRoutingGroup();
+        this.queryHistoryManager = queryHistoryManager;
+        this.queryIdBackendCache = buildCache(this::findBackendForUnknownQueryId);
+        this.queryIdRoutingGroupCache = buildCache(this::findRoutingGroupForUnknownQueryId);
+        this.queryIdExternalUrlCache = buildCache(this::findExternalUrlForUnknownQueryId);
+        this.backendToStatus = new ConcurrentHashMap<>();
+    }
+
+    /**
+     * Provide a strategy to select a backend out of all available backends
+     */
+    protected abstract Optional<ProxyBackendConfiguration> selectBackend(List<ProxyBackendConfiguration> backends, String user);
+
+    @Override
+    public void setBackendForQueryId(String queryId, String backend)
+    {
+        queryIdBackendCache.put(queryId, backend);
+    }
+
+    @Override
+    public void setRoutingGroupForQueryId(String queryId, String routingGroup)
+    {
+        queryIdRoutingGroupCache.put(queryId, routingGroup);
+    }
+
+    /**
+     * Performs routing to a default backend.
+     */
+    public ProxyBackendConfiguration provideDefaultBackendConfiguration(String user)
+    {
+        List<ProxyBackendConfiguration> backends = gatewayBackendManager.getActiveDefaultBackends().stream()
+                .filter(backEnd -> isBackendHealthy(backEnd.getName()))
+                .toList();
+        return selectBackend(backends, user).orElseThrow(() -> new IllegalStateException("Number of active backends found zero"));
+    }
+
+    /**
+     * Performs routing to a given cluster group. This falls back to a default backend, if no scheduled
+     * backend is found.
+     */
+    @Override
+    public ProxyBackendConfiguration provideBackendConfiguration(String routingGroup, String user)
+    {
+        List<ProxyBackendConfiguration> backends = gatewayBackendManager.getActiveBackends(routingGroup).stream()
+                .filter(backEnd -> isBackendHealthy(backEnd.getName()))
+                .toList();
+        return selectBackend(backends, user).orElseGet(() -> provideDefaultBackendConfiguration(user));
+    }
+
+    /**
+     * Performs cache look up, if a backend not found, it checks with all backends and tries to find
+     * out which backend has info about given query id.
+     */
+    @Nullable
+    @Override
+    public String findBackendForQueryId(String queryId)
+    {
+        String backendAddress = null;
+        try {
+            backendAddress = queryIdBackendCache.get(queryId);
+        }
+        catch (ExecutionException e) {
+            log.warn("Exception while loading queryId from cache %s", e.getLocalizedMessage());
+        }
+        return backendAddress;
+    }
+
+    @Nullable
+    @Override
+    public String findExternalUrlForQueryId(String queryId)
+    {
+        String externalUrl = null;
+        try {
+            externalUrl = queryIdExternalUrlCache.get(queryId);
+        }
+        catch (ExecutionException e) {
+            log.warn("Exception while loading queryId from cache %s", e.getLocalizedMessage());
+        }
+        return externalUrl;
+    }
+
+    /**
+     * Looks up the routing group associated with the queryId in the cache.
+     * If it's not in the cache, look up in query history
+     */
+    @Nullable
+    @Override
+    public String findRoutingGroupForQueryId(String queryId)
+    {
+        String routingGroup = null;
+        try {
+            routingGroup = queryIdRoutingGroupCache.get(queryId);
+        }
+        catch (ExecutionException e) {
+            log.warn("Exception while loading queryId from routing group cache %s", e.getLocalizedMessage());
+        }
+        return routingGroup;
+    }
+
+    @Override
+    public void updateBackEndHealth(String backendId, TrinoStatus value)
+    {
+        log.info("backend %s isHealthy %s", backendId, value);
+        backendToStatus.put(backendId, value);
+    }
+
+    @Override
+    public void updateClusterStats(List<ClusterStats> stats)
+    {
+        for (ClusterStats clusterStats : stats) {
+            updateBackEndHealth(clusterStats.clusterId(), clusterStats.trinoStatus());
+        }
+    }
+
+    @VisibleForTesting
+    void setExternalUrlForQueryId(String queryId, String externalUrl)
+    {
+        queryIdExternalUrlCache.put(queryId, externalUrl);
+    }
+
+    @VisibleForTesting
+    String findBackendForUnknownQueryId(String queryId)
+    {
+        String backend;
+        backend = queryHistoryManager.getBackendForQueryId(queryId);
+        if (Strings.isNullOrEmpty(backend)) {
+            log.debug("Unable to find backend mapping for [%s]. Searching for suitable backend", queryId);
+            backend = searchAllBackendForQuery(queryId);
+        }
+        return backend;
+    }
+
+    /**
+     * This tries to find out which backend may have info about given query id. If not found returns
+     * the first healthy backend.
+     */
+    private String searchAllBackendForQuery(String queryId)
+    {
+        List<ProxyBackendConfiguration> backends = gatewayBackendManager.getAllBackends();
+
+        Map<String, Future<Integer>> responseCodes = new HashMap<>();
+        try {
+            for (ProxyBackendConfiguration backend : backends) {
+                String target = backend.getProxyTo() + "/v1/query/" + queryId;
+
+                Future<Integer> call =
+                        executorService.submit(
+                                () -> {
+                                    URL url = new URL(target);
+                                    HttpURLConnection conn = (HttpURLConnection) url.openConnection();
+                                    conn.setConnectTimeout((int) TimeUnit.SECONDS.toMillis(5));
+                                    conn.setReadTimeout((int) TimeUnit.SECONDS.toMillis(5));
+                                    conn.setRequestMethod(HttpMethod.HEAD);
+                                    return conn.getResponseCode();
+                                });
+                responseCodes.put(backend.getProxyTo(), call);
+            }
+            for (Map.Entry<String, Future<Integer>> entry : responseCodes.entrySet()) {
+                if (entry.getValue().isDone()) {
+                    int responseCode = entry.getValue().get();
+                    if (responseCode == 200) {
+                        log.info("Found query [%s] on backend [%s]", queryId, entry.getKey());
+                        setBackendForQueryId(queryId, entry.getKey());
+                        return entry.getKey();
+                    }
+                }
+            }
+        }
+        catch (Exception e) {
+            log.warn("Query id [%s] not found", queryId);
+        }
+        // Fallback on first active backend if queryId mapping not found.
+        return gatewayBackendManager.getActiveBackends(defaultRoutingGroup).get(0).getProxyTo();
+    }
+
+    /**
+     * Attempts to look up the routing group associated with the query id from query history table
+     */
+    private String findRoutingGroupForUnknownQueryId(String queryId)
+    {
+        String routingGroup = queryHistoryManager.getRoutingGroupForQueryId(queryId);
+        setRoutingGroupForQueryId(queryId, routingGroup);
+        return routingGroup;
+    }
+
+    /**
+     * Attempts to look up the external url associated with the query id from query history table
+     */
+    private String findExternalUrlForUnknownQueryId(String queryId)
+    {
+        String externalUrl = queryHistoryManager.getExternalUrlForQueryId(queryId);
+        setExternalUrlForQueryId(queryId, externalUrl);
+        return externalUrl;
+    }
+
+    private static LoadingCache<String, String> buildCache(Function<String, String> loader)
+    {
+        return CacheBuilder.newBuilder()
+                .maximumSize(10000)
+                .expireAfterAccess(30, TimeUnit.MINUTES)
+                .build(
+                        new CacheLoader<>()
+                        {
+                            @Override
+                            public String load(String queryId)
+                            {
+                                return loader.apply(queryId);
+                            }
+                        });
+    }
+
+    private boolean isBackendHealthy(String backendId)
+    {
+        TrinoStatus status = backendToStatus.getOrDefault(backendId, TrinoStatus.UNKNOWN);
+        return status == TrinoStatus.HEALTHY;
+    }
+}