/** * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you 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. */ #ifndef __ZK_ADAPTER_H__ #define __ZK_ADAPTER_H__ #include #include extern "C" { #include "zookeeper.h" } namespace zktreeutil { using std::string; using std::vector; /** * \brief A cluster related exception. */ class ZooKeeperException : public std::exception { public: /** * \brief Constructor. * * @param msg the detailed message associated with this exception */ ZooKeeperException(const string& msg) : m_message(msg), m_zkErrorCode(0) {} /** * \brief Constructor. * * @param msg the detailed message associated with this exception * @param errorCode the ZK error code associated with this exception */ ZooKeeperException(const string &msg, int errorCode) : m_zkErrorCode(errorCode) { char tmp[100]; sprintf( tmp, " (ZK error code: %d)", errorCode ); m_message = msg + tmp; } /** * \brief Destructor. */ ~ZooKeeperException() throw() {} /** * \brief Returns detailed description of the exception. */ const char *what() const throw() { return m_message.c_str(); } /** * \brief Returns the ZK error code. */ int getZKErrorCode() const { return m_zkErrorCode; } private: /** * The detailed message associated with this exception. */ string m_message; /** * The optional error code received from ZK. */ int m_zkErrorCode; }; /** * \brief This class encapsulates configuration of a ZK client. */ class ZooKeeperConfig { public: /** * \brief Constructor. * * @param hosts the comma separated list of host and port pairs of ZK nodes * @param leaseTimeout the lease timeout (heartbeat) * @param autoReconnect whether to allow for auto-reconnect * @param connectTimeout the connect timeout, in milliseconds; */ ZooKeeperConfig(const string &hosts, int leaseTimeout, bool autoReconnect = true, long long int connectTimeout = 15000) : m_hosts(hosts), m_leaseTimeout(leaseTimeout), m_autoReconnect(autoReconnect), m_connectTimeout(connectTimeout) {} /** * \brief Returns the list of ZK hosts to connect to. */ string getHosts() const { return m_hosts; } /** * \brief Returns the lease timeout. */ int getLeaseTimeout() const { return m_leaseTimeout; } /** * \brief Returns whether {@link ZooKeeperAdapter} should attempt * \brief to automatically reconnect in case of a connection failure. */ bool getAutoReconnect() const { return m_autoReconnect; } /** * \brief Gets the connect timeout. * * @return the connect timeout */ long long int getConnectTimeout() const { return m_connectTimeout; } private: /** * The host addresses of ZK nodes. */ const string m_hosts; /** * The ZK lease timeout. */ const int m_leaseTimeout; /** * True if this adapater should attempt to autoreconnect in case * the current session has been dropped. */ const bool m_autoReconnect; /** * How long to wait, in milliseconds, before a connection * is established to ZK. */ const long long int m_connectTimeout; }; /** * \brief This is a wrapper around ZK C synchrounous API. */ class ZooKeeperAdapter { public: /** * \brief Constructor. * Attempts to create a ZK adapter, optionally connecting * to the ZK. Note, that if the connection is to be established * and the given listener is NULL, some events may be lost, * as they may arrive asynchronously before this method finishes. * * @param config the ZK configuration * @throw ZooKeeperException if cannot establish connection to the given ZK */ ZooKeeperAdapter(ZooKeeperConfig config) throw(ZooKeeperException); /** * \brief Destructor. */ ~ZooKeeperAdapter(); /** * \brief Returns the current config. */ const ZooKeeperConfig &getZooKeeperConfig() const { return m_zkConfig; } /** * \brief Restablishes connection to the ZK. * If this adapter is already connected, the current connection * will be dropped and a new connection will be established. * * @throw ZooKeeperException if cannot establish connection to the ZK */ void reconnect() throw(ZooKeeperException); /** * \brief Disconnects from the ZK and unregisters {@link #mp_zkHandle}. */ void disconnect(); /** * \brief Creates a new node identified by the given path. * This method will optionally attempt to create all missing ancestors. * * @param path the absolute path name of the node to be created * @param value the initial value to be associated with the node * @param flags the ZK flags of the node to be created * @param createAncestors if true and there are some missing ancestor nodes, * this method will attempt to create them * * @return true if the node has been successfully created; false otherwise * @throw ZooKeeperException if the operation has failed */ bool createNode(const string &path, const string &value = "", int flags = 0, bool createAncestors = true) throw(ZooKeeperException); /** * \brief Deletes a node identified by the given path. * * @param path the absolute path name of the node to be deleted * @param recursive if true this method will attempt to remove * all children of the given node if any exist * @param version the expected version of the node. The function will * fail if the actual version of the node does not match * the expected version * * @return true if the node has been deleted; false otherwise * @throw ZooKeeperException if the operation has failed */ bool deleteNode(const string &path, bool recursive = false, int version = -1) throw(ZooKeeperException); /** * \brief Retrieves list of all children of the given node. * * @param path the absolute path name of the node for which to get children * @return the list of absolute paths of child nodes, possibly empty * @throw ZooKeeperException if the operation has failed */ vector getNodeChildren( const string &path) throw(ZooKeeperException); /** * \brief Check the existence of path to a znode. * * @param path the absolute path name of the znode * @return TRUE if the znode exists; FALSE otherwise * @throw ZooKeeperException if the operation has failed */ bool nodeExists(const string &path) throw(ZooKeeperException); /** * \brief Gets the given node's data. * * @param path the absolute path name of the node to get data from * * @return the node's data * @throw ZooKeeperException if the operation has failed */ string getNodeData(const string &path) throw(ZooKeeperException); /** * \brief Sets the given node's data. * * @param path the absolute path name of the node to get data from * @param value the node's data to be set * @param version the expected version of the node. The function will * fail if the actual version of the node does not match * the expected version * * @throw ZooKeeperException if the operation has failed */ void setNodeData(const string &path, const string &value, int version = -1) throw(ZooKeeperException); /** * \brief Validates the given path to a node in ZK. * * @param the path to be validated * * @throw ZooKeeperException if the given path is not valid * (for instance it doesn't start with "/") */ static void validatePath(const string &path) throw(ZooKeeperException); private: /** * Verifies whether the connection is established, * optionally auto reconnecting. * * @throw ZooKeeperConnection if this client is disconnected * and auto-reconnect failed or was not allowed */ void verifyConnection() throw(ZooKeeperException); private: /** * The current ZK configuration. */ const ZooKeeperConfig m_zkConfig; /** * The current ZK session. */ zhandle_t *mp_zkHandle; }; } /* end of 'namespace zktreeutil' */ #endif /* __ZK_ADAPTER_H__ */