added cookies test. fixed handling Bad Gateway status from server

Author: chernser

client-v2/src/main/java/com/clickhouse/client/api/Client.java

@@ -1153,7 +1153,7 @@ public CompletableFuture<CommandResponse> execute(String sql) {
                     } catch (Exception e) {
                         throw new ClientException("Failed to get command response", e);
                     }
-                });
+                }, sharedOperationExecutor);
     }
 
     private String startOperation() {

client-v2/src/main/java/com/clickhouse/client/api/internal/HttpAPIClientHelper.java

@@ -145,7 +145,10 @@ public ClassicHttpResponse executeRequest(ClickHouseNode server, Map<String, Obj
                 } finally {
                     httpResponse.close();
                 }
-            } else if (httpResponse.getCode() >= 500) {
+            } else if (httpResponse.getCode() == HttpStatus.SC_BAD_GATEWAY) {
+                httpResponse.close();
+                throw new ClientException("Server returned '502 Bad gateway'. Check network and proxy settings.");
+            } else if (httpResponse.getCode() >= HttpStatus.SC_INTERNAL_SERVER_ERROR) {
                 httpResponse.close();
                 return httpResponse;
             }

client-v2/src/test/java/com/clickhouse/client/ProxyTests.java

@@ -12,6 +12,8 @@
 import com.github.tomakehurst.wiremock.client.WireMock;
 import com.github.tomakehurst.wiremock.common.Slf4jNotifier;
 import com.github.tomakehurst.wiremock.core.WireMockConfiguration;
+import com.github.tomakehurst.wiremock.http.Fault;
+import com.github.tomakehurst.wiremock.stubbing.Scenario;
 import org.apache.hc.core5.http.HttpHeaders;
 import org.apache.hc.core5.http.HttpStatus;
 import org.testng.Assert;
@@ -105,6 +107,31 @@ public void testPrivateProxyWithCredentials() {
         }
     }
 
+    @Test(groups = { "integration" })
+    public void testProxyWithCookies() {
+        client.set(clientBuilder(initProxy(), true).build());
+        final int targetPort = getServer(ClickHouseProtocol.HTTP).getPort();
+
+        proxy.get().addStubMapping(post(urlMatching("/.*"))
+                        .inScenario("routeCookies")
+                        .whenScenarioStateIs(Scenario.STARTED)
+                .willReturn(aResponse().withHeader(HttpHeaders.SET_COOKIE, "routeName=routeA")
+                        .proxiedFrom("http://localhost:" + targetPort)).willSetStateTo("cookies").build());
+
+        proxy.get().addStubMapping(post(urlMatching("/.*"))
+                        .inScenario("routeCookies")
+                        .whenScenarioStateIs("cookies")
+                        .withHeader(HttpHeaders.COOKIE, equalTo("routeName=routeA"))
+                .willReturn(aResponse().proxiedFrom("http://localhost:" + targetPort)).build());
+
+        try {
+            client.get().execute("select 1").get();
+            client.get().execute("select 1").get();
+        } catch (Exception e) {
+            fail("Should not have thrown exception.", e);
+        }
+    }
+
     private Client.Builder clientBuilder(int proxyPort, boolean onlyNewImplementation) {
         return new Client.Builder()
                 .addEndpoint(Protocol.HTTP, "clickhouse", 8123, false)