Server context code + test

Author: Paultagoras

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

@@ -154,6 +154,10 @@ public class Client implements AutoCloseable {
 
     private final ColumnToMethodMatchingStrategy columnToMethodMatchingStrategy;
 
+    // Server context
+    private String serverUser;
+    private String serverVersion;
+
     private Client(Set<String> endpoints, Map<String,String> configuration, boolean useNewImplementation,
                    ExecutorService sharedOperationExecutor, ColumnToMethodMatchingStrategy columnToMethodMatchingStrategy) {
         this.endpoints = endpoints;
@@ -179,8 +183,25 @@ private Client(Set<String> endpoints, Map<String,String> configuration, boolean
             LOG.info("Using old http client implementation");
         }
         this.columnToMethodMatchingStrategy = columnToMethodMatchingStrategy;
+
+        updateServerContext();
     }
 
+    private void updateServerContext() {
+        try (QueryResponse response = this.query("SELECT currentUser() AS user, timezone() AS timezone, version() AS version LIMIT 1").get()) {
+            try (ClickHouseBinaryFormatReader reader = this.newBinaryFormatReader(response)) {
+                if (reader.next() != null) {
+                    serverUser = reader.getString("user");
+                    this.configuration.put(ClientConfigProperties.SERVER_TIMEZONE.getKey(), reader.getString("timezone"));
+                    serverVersion = reader.getString("version");
+                }
+            }
+        } catch (Exception e) {
+            LOG.error("Failed to get server info", e);
+        }
+    }
+
+
     /**
      * Returns default database name that will be used by operations if not specified.
      *
@@ -216,6 +237,7 @@ public void close() {
         }
     }
 
+
     public static class Builder {
         private Set<String> endpoints;
 
@@ -1015,6 +1037,7 @@ public Client build() {
             return new Client(this.endpoints, this.configuration, this.useNewImplementation, this.sharedOperationExecutor, this.columnToMethodMatchingStrategy);
         }
 
+
         private static final int DEFAULT_NETWORK_BUFFER_SIZE = 300_000;
 
         private void setDefaults() {

client-v2/src/test/java/com/clickhouse/client/query/QueryTests.java

@@ -1957,4 +1957,20 @@ public void testReadingSimpleAggregateFunction() throws Exception {
             Assert.assertFalse(reader.hasNext());
         }
     }
+
+
+    @Test(groups = {"integration"})
+    public void testServerTimezone() throws Exception {
+        final String sql = "SELECT now() as t, toDateTime(now(), 'UTC') as utc_time, toDateTime(now(), 'America/New_York') as est_time";
+        try (QueryResponse response = client.query(sql).get(1, TimeUnit.SECONDS)) {
+            ClickHouseBinaryFormatReader reader = client.newBinaryFormatReader(response);
+            Assert.assertNotNull(reader.next());
+            ZonedDateTime serverTime = reader.getZonedDateTime(1);
+            ZonedDateTime serverUtcTime = reader.getZonedDateTime(2);
+            ZonedDateTime serverEstTime = reader.getZonedDateTime(3);
+            Assert.assertEquals(serverTime.withZoneSameInstant(ZoneId.of("UTC")), serverUtcTime);
+            Assert.assertEquals(serverTime, serverUtcTime);
+            Assert.assertEquals(serverUtcTime.withZoneSameInstant(ZoneId.of("America/New_York")), serverEstTime);
+        }
+    }
 }