Implement database cache

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

@@ -14,7 +14,6 @@
 package io.trino.gateway.ha.router;
 
 import com.google.common.collect.ImmutableList;
-import io.airlift.log.Logger;
 import io.trino.gateway.ha.config.ProxyBackendConfiguration;
 import io.trino.gateway.ha.persistence.dao.GatewayBackend;
 import io.trino.gateway.ha.persistence.dao.GatewayBackendDao;
@@ -23,78 +22,84 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
+import java.util.concurrent.atomic.AtomicReference;
 
+import static com.google.common.collect.ImmutableList.toImmutableList;
 import static java.util.Objects.requireNonNull;
 
 public class HaGatewayManager
  implements GatewayBackendManager
 {
- private static final Logger log = Logger.get(HaGatewayManager.class);
-
  private final GatewayBackendDao dao;
+ private final AtomicReference<List<GatewayBackend>> cache = new AtomicReference<>();
 
  public HaGatewayManager(Jdbi jdbi)
  {
  dao = requireNonNull(jdbi, "jdbi is null").onDemand(GatewayBackendDao.class);
+ cache.set(ImmutableList.of());
+ fetchAllBackendsToCache();
  }
 
  @Override
  public List<ProxyBackendConfiguration> getAllBackends()
  {
- List<GatewayBackend> proxyBackendList = dao.findAll();
+ List<GatewayBackend> proxyBackendList = cache.get();
  return upcast(proxyBackendList);
  }
 
  @Override
  public List<ProxyBackendConfiguration> getAllActiveBackends()
  {
- List<GatewayBackend> proxyBackendList = dao.findActiveBackend();
+ List<GatewayBackend> proxyBackendList = cache.get().stream()
+ .filter(GatewayBackend::active)
+ .collect(toImmutableList());
  return upcast(proxyBackendList);
  }
 
  @Override
  public List<ProxyBackendConfiguration> getActiveAdhocBackends()
  {
- try {
- List<GatewayBackend> proxyBackendList = dao.findActiveAdhocBackend();
- return upcast(proxyBackendList);
- }
- catch (Exception e) {
- log.info("Error fetching all backends: %s", e.getLocalizedMessage());
- }
- return ImmutableList.of();
+ return getActiveBackends("adhoc");
  }
 
  @Override
  public List<ProxyBackendConfiguration> getActiveBackends(String routingGroup)
  {
- List<GatewayBackend> proxyBackendList = dao.findActiveBackendByRoutingGroup(routingGroup);
+ List<GatewayBackend> proxyBackendList = cache.get().stream()
+ .filter(GatewayBackend::active)
+ .filter(backend -> backend.routingGroup().equals(routingGroup))
+ .collect(toImmutableList());
  return upcast(proxyBackendList);
  }
 
  @Override
  public Optional<ProxyBackendConfiguration> getBackendByName(String name)
  {
- List<GatewayBackend> proxyBackendList = dao.findByName(name);
+ List<GatewayBackend> proxyBackendList = cache.get().stream()
+ .filter(backend -> backend.name().equals(name))
+ .collect(toImmutableList());
  return upcast(proxyBackendList).stream().findAny();
  }
 
  @Override
  public void deactivateBackend(String backendName)
  {
  dao.deactivate(backendName);
+ fetchAllBackendsToCache();
  }
 
  @Override
  public void activateBackend(String backendName)
  {
  dao.activate(backendName);
+ fetchAllBackendsToCache();
  }
 
  @Override
  public ProxyBackendConfiguration addBackend(ProxyBackendConfiguration backend)
  {
  dao.create(backend.getName(), backend.getRoutingGroup(), backend.getProxyTo(), backend.getExternalUrl(), backend.isActive());
+ fetchAllBackendsToCache();
  return backend;
  }
 
@@ -108,12 +113,14 @@ public ProxyBackendConfiguration updateBackend(ProxyBackendConfiguration backend
  else {
  dao.update(backend.getName(), backend.getRoutingGroup(), backend.getProxyTo(), backend.getExternalUrl(), backend.isActive());
  }
+ fetchAllBackendsToCache();
  return backend;
  }
 
  public void deleteBackend(String name)
  {
  dao.deleteByName(name);
+ fetchAllBackendsToCache();
  }
 
  private static List<ProxyBackendConfiguration> upcast(List<GatewayBackend> gatewayBackendList)
@@ -130,4 +137,9 @@ private static List<ProxyBackendConfiguration> upcast(List<GatewayBackend> gatew
  }
  return proxyBackendConfigurations;
  }
+
+ private void fetchAllBackendsToCache()
+ {
+ cache.set(dao.findAll());
+ }
 }