merge 930 new feature

pgjdbc/src/main/java/org/postgresql/GlobalConnectionTracker.java

@@ -0,0 +1,96 @@
+package org.postgresql;
+
+import org.postgresql.core.QueryExecutor;
+import org.postgresql.jdbc.PgConnection;
+import org.postgresql.log.Log;
+import org.postgresql.log.Logger;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Properties;
+
+/**
+ * Keeps track of connection reference and host spec in a global map.
+ */
+public class GlobalConnectionTracker {
+
+    private static final Map<String, HashMap<Integer, QueryExecutor>> connectionManager = new HashMap<>();
+    private static Log LOGGER = Logger.getLogger(GlobalConnectionTracker.class.getName());
+
+    /**
+     *
+     * @param props the parsed/defaulted connection properties
+     * @return
+     */
+    private static boolean isForceTargetServerSlave(Properties props){
+        return PGProperty.FORCE_TARGET_SERVER_SLAVE.getBoolean(props) &&
+                ("slave".equals(PGProperty.TARGET_SERVER_TYPE.get(props)) || "secondary".equals(PGProperty.TARGET_SERVER_TYPE.get(props)));
+    }
+    /**
+     * Store the actual query executor and connection host spec.
+     *
+     * @param props the parsed/defaulted connection properties
+     * @param queryExecutor
+     */
+    public static void possessConnectionReference(QueryExecutor queryExecutor, Properties props) {
+        if(!isForceTargetServerSlave(props)) return;
+        int identityQueryExecute = System.identityHashCode(queryExecutor);
+        String hostSpec = queryExecutor.getHostSpec().toString();
+        synchronized (connectionManager) {
+            HashMap<Integer, QueryExecutor> hostConnection = connectionManager.getOrDefault(hostSpec, null);
+            if (hostConnection == null) {
+                hostConnection = new HashMap<>();
+            }
+            hostConnection.put(identityQueryExecute, queryExecutor);
+            connectionManager.put(hostSpec, hostConnection);
+        }
+    }
+
+    /**
+     * Clear the reference when the connection is closed.
+     *
+     * @param props the parsed/defaulted connection properties
+     * @param queryExecutor
+     */
+    public static void releaseConnectionReference(QueryExecutor queryExecutor, Properties props) {
+        if(!isForceTargetServerSlave(props)) return;
+        String hostSpec = queryExecutor.getHostSpec().toString();
+        int identityQueryExecute = System.identityHashCode(queryExecutor);
+        synchronized (connectionManager) {
+            HashMap<Integer, QueryExecutor> hostConnection = connectionManager.getOrDefault(hostSpec, null);
+            if (hostConnection != null) {
+                if (hostConnection.get(identityQueryExecute) != null) {
+                    hostConnection.put(identityQueryExecute, null);
+                } else {
+                    LOGGER.info("[SWITCHOVER] The identity of the queryExecutor has changed!");
+                }
+            } else {
+                LOGGER.info("[SWITCHOVER] No connection found under this host!");
+            }
+        }
+    }
+
+    /**
+     * Close all existing connections under the specified host.
+     *
+     * @param props the parsed/defaulted connection properties
+     * @param hostSpec ip and port.
+     */
+    public static void closeOldConnection(String hostSpec, Properties props) {
+        if(!isForceTargetServerSlave(props)) return;
+        synchronized (connectionManager) {
+            HashMap<Integer, QueryExecutor> hostConnection = connectionManager.getOrDefault(hostSpec, null);
+            if (hostConnection != null) {
+                LOGGER.info("[SWITCHOVER] The hostSpec: " + hostSpec + " status from slave to master, start to close the original connection.");
+                for (QueryExecutor queryExecutor : hostConnection.values()) {
+                    if (queryExecutor != null && !queryExecutor.isClosed()) {
+                        queryExecutor.setAvailability(false);
+                    }
+                }
+                hostConnection.clear();
+                LOGGER.info("[SWITCHOVER] The hostSpec: " + hostSpec + " status from slave to master, end to close the original connection.");
+            }
+        }
+    }
+
+}