Public Member Functions
	ZKWrapper (const std::string &host, int &error_code, const std::string &root)

std::string	prepend_zk_root (const std::string &path) const

std::string	removeZKRoot (const std::string &path) const

std::string	removeZKRootAndDir (const std::string &prefix, const std::string &path) const

bool	create (const std::string &path, const std::vector< std::uint8_t > &data, int &error_code, bool ephemeral, bool sync=true) const

bool	create_ephemeral (const std::string &path, const std::vector< std::uint8_t > &data, int &error_code, bool sync=true) const

bool	create_sequential (const std::string &path, const std::vector< std::uint8_t > &data, std::string &new_path, bool ephemeral, int &error_code, bool sync=true) const

bool	recursive_create (const std::string &path, const std::vector< std::uint8_t > &data, int &error_code, bool sync=true) const

bool	exists (const std::string &path, bool &exist, int &error_code) const

bool	wexists (const std::string &path, bool &exist, watcher_fn watch, void *watcherCtx, int &error_code) const

bool	delete_node (const std::string &path, int &error_code, bool sync=true) const

bool	recursive_delete (const std::string &path, int &error_code) const

bool	get_children (const std::string &path, std::vector< std::string > &children, int &error_code) const

bool	wget_children (const std::string &path, std::vector< std::string > &children, watcher_fn watch, void *watcherCtx, int &error_code) const

bool	get (const std::string &path, std::vector< std::uint8_t > &data, int &error_code, bool resize) const

bool	get_info (const std::string &path, struct Stat &stat, int &error_code) const

bool	wget (const std::string &path, std::vector< std::uint8_t > &data, watcher_fn watch, void *watcherCtx, int &error_code, bool resize) const

bool	set (const std::string &path, const std::vector< std::uint8_t > &data, int &error_code, bool sync=true, int version=-1) const

std::shared_ptr< ZooOp >	build_create_op (const std::string &path, const std::vector< std::uint8_t > &data, const int flags=0) const

std::shared_ptr< ZooOp >	build_delete_op (const std::string &path, int version=-1) const

std::shared_ptr< ZooOp >	build_set_op (const std::string &path, const std::vector< std::uint8_t > &data, int version=-1) const

bool	execute_multi (const std::vector< std::shared_ptr< ZooOp >> operations, std::vector< zoo_op_result > &results, int &error_code, bool sync=true) const

bool	flush (const std::string &full_path, bool synchronous=false) const

void	close ()

Static Public Member Functions
static std::string	translate_error (int error_code)

static std::string	translate_watch_event_type (int type)

static std::string	translate_watch_state (int state)

static void	watcher_znode_data (zhandle_t zzh, int type, int state, const char path, void *watcherCtx)

static std::vector< uint8_t >	get_byte_vector (const std::string &string)

static void	print_error (int error)

Static Public Attributes
static const std::vector < std::uint8_t >	EMPTY_VECTOR = std::vector<std::uint8_t>(0)

Friends
void	watcher (zhandle_t zzh, int type, int state, const char path, void *watcherCtx)

Constructor & Destructor Documentation

ZKWrapper::ZKWrapper	(	const std::string &	host,
		int &	error_code,
		const std::string &	root
	)

Initializes zookeeper. If error_code is ZOK after return, a connection to ZooKeeper would have been established, and the root would have been created.

Parameters

host	The location of where Zookeeper is running. For local development this will usually be 'localhost:2181'
error_code	Integer reference, set to a value in ZK_ERRORS Otherwise, an error code is returned. The meaning of an error code can be retrieved from translate_error()
root

Member Function Documentation

std::shared_ptr< ZooOp > ZKWrapper::build_create_op	(	const std::string &	path,
		const std::vector< std::uint8_t > &	data,
		const int	flags = `0`
	)		const

Parameters

path	path of znode
data	data to initialize the node with. Set to the empty string to create an empty znode
flags	node flags: ZOO_EPHEMERAL, ZOO_SEQUENCE, ZOO_EPHEMERAL \|\| ZOO_SEQUENCE

Returns: a ZooOp to be used in execute_multi

std::shared_ptr< ZooOp > ZKWrapper::build_delete_op	(	const std::string &	path,
		int	version = `-1`
	)		const

Parameters

path	of znode
version	Checks the version of the znode before deleting. Defaults to -1, which does not perform the check.

Returns: a ZooOp to be used in execute_multi

std::shared_ptr< ZooOp > ZKWrapper::build_set_op	(	const std::string &	path,
		const std::vector< std::uint8_t > &	data,
		int	version = `-1`
	)		const

Parameters

path
data
version

Returns

bool ZKWrapper::create	(	const std::string &	path,
		const std::vector< std::uint8_t > &	data,
		int &	error_code,
		bool	ephemeral,
		bool	sync = `true`
	)		const

Create a znode in zookeeper

Parameters

path	The location of the new znode within the zookeeper structure
data	The data contained in this znode
error_code	Int reference, set to a value in ZK_ERRORS

Returns: True if the operation completed successfully, False otherwise (caller should check 'error_code' value)

bool ZKWrapper::create_sequential	(	const std::string &	path,
		const std::vector< std::uint8_t > &	data,
		std::string &	new_path,
		bool	ephemeral,
		int &	error_code,
		bool	sync = `true`
	)		const

Creates a sequential znode

Parameters

path	The path to the new sequential znode. The last component must end in "-" like: '/foo/bar-'. When the node is created, a 10 digit sequential ID unique to the parent node will be appended to the name.
data	The data contained in this znode
new_path	Will contain the value of the newly created path
ephemeral	If true, the created node will ephemeral
error_code	Int reference, set to a value in ZK_ERRORS

Returns: True if the operation completed successfully, False otherwise (caller should check 'error_code' value)

bool ZKWrapper::delete_node	(	const std::string &	path,
		int &	error_code,
		bool	sync = `true`
	)		const

Deletes a znode from zookeeper

Parameters

path	The path to the znode that should be deleted
error_code	Int reference, set to a value in ZK_ERRORS

Returns: True if the operation completed successfully, False otherwise (caller should check 'error_code' value)

bool ZKWrapper::execute_multi	(	const std::vector< std::shared_ptr< ZooOp >>	operations,
		std::vector< zoo_op_result > &	results,
		int &	error_code,
		bool	sync = `true`
	)		const

Runs all of the zookeeper operations within the operations vector atomically (without ordering). Atomic execution mean that either all of the operations will succeed, else they will all be rolled back.

Parameters

operations	a vector of operations to be executed
results	a vector that maps to the results of each of the executed operations
error_code	Int reference, set to a value in ZK_ERRORS

Returns: True if the operation worked successfully; false otherwise.

bool ZKWrapper::exists	(	const std::string &	path,
		bool &	exist,
		int &	error_code
	)		const

Checks if a znode exists or not.

Parameters

path	The path to the node
exist	Set to true if a znode exists at the given path, false otherwise
error_code	Int reference, set to a value in ZK_ERRORS

Returns: True if the operation completed successfully, False otherwise (caller should check 'error_code' value)

bool ZKWrapper::flush	(	const std::string &	full_path,
		bool	synchronous = `false`
	)		const

Flush changes inside of ZooKeeper

Parameters

full_path	the full path of the znode directory to be flushed. Must be qualified with the ZooKeeper root
synchronous	Whether this operation is blocking

Returns: true on success

bool ZKWrapper::get	(	const std::string &	path,
		std::vector< std::uint8_t > &	data,
		int &	error_code,
		bool	resize
	)		const

Gets the data associated with a node.

Parameters

path	The path to the node
data	Reference to a vector which will be filled with the znode data. The 2016 folks claimed that this field "Should be of size MAX_PAYLOAD when passed in, will be resized in this method." We (2017) are not sure why there is a MAX_PAYLOAD limit in the first place, and the 2016 folks never honored their own requirement.
error_code	Int reference, set to a value in ZK_ERRORS
resize	Should automatic resizing of the data vector be performed? If this argument is false, then the data buffer is expected to be large enough to hold everything in the node, otherwise the operation will fail.

Returns: True if the operation completed successfully and all of the node data fits within the data buffer; False otherwise (caller should check 'error_code' value)

bool ZKWrapper::get_children	(	const std::string &	path,
		std::vector< std::string > &	children,
		int &	error_code
	)		const

This function gets a list of children of the znode specified by the path

Parameters

path	The path of parent node
children	Reference to a vector which will be populated with the names of the children znodes of the given path TODO: How large should this vector be when passed in?
error_code	Int reference, set to a value in ZK_ERRORS

Returns: True if the operation completed successfully, False otherwise (caller should check 'error_code' value)

bool ZKWrapper::get_info	(	const std::string &	path,
		struct Stat &	stat,
		int &	error_code
	)		const

Gets the info associated with a znode

Parameters

path	The path to the node
stat	Reference to a stat struct to be filled with znode info
error_code	Int reference, set to a value in ZK_ERRORS

Returns: True if the operation completed successfully, False otherwise (caller should check 'error_code' value)

std::string ZKWrapper::prepend_zk_root ( const std::string & path ) const

Prepends the ZooKeeper root to all paths passed in

Parameters

path	the original path

Returns: the updated path

bool ZKWrapper::recursive_create	(	const std::string &	path,
		const std::vector< std::uint8_t > &	data,
		int &	error_code,
		bool	sync = `true`
	)		const

Recursively creates a new znode, non-existent znodes in the specified path will be created

Parameters

path	The path to create
data	The data to store in the new znode
error_code	Int reference, set to a value in ZK_ERRORS

Returns: True if the operation completed successfully, False otherwise (caller should check 'error_code' value)

bool ZKWrapper::recursive_delete	(	const std::string &	path,
		int &	error_code
	)		const

Recursively deletes the znode specified in the path and any children of that path

Parameters

path	The path the znode (and its children) which will be deleted
error_code	Int reference, set to a value in ZK_ERRORS

Returns: True if the operation completed successfully, False otherwise (caller should check 'error_code' value)

bool ZKWrapper::set	(	const std::string &	path,
		const std::vector< std::uint8_t > &	data,
		int &	error_code,
		bool	sync = `true`,
		int	version = `-1`
	)		const

Sets the data in a given znode

Parameters

path	The path to the znode
data	The data that this znode should contain
version	A version number indicating changes to the data at this node
error_code	Int reference, set to a value in ZK_ERRORS

Returns: True if the operation completed successfully, False otherwise (caller should check 'error_code' value)

std::string ZKWrapper::translate_error ( int error_code )

static

Translate numerical error code to zookeeper error string

Parameters

error_code Int reference, set to a value in ZK_ERRORS

Returns: A string translation of the error code

bool ZKWrapper::wexists	(	const std::string &	path,
		bool &	exist,
		watcher_fn	watch,
		void *	watcherCtx,
		int &	error_code
	)		const

This function is similar to 'exists' except it allows the caller to specify a watcher object rather than a boolean watch flag.

Parameters

path	The path to the znode that needs to be checked
exist	Set to true if a znode exists at the given path, false otherwise
watch	A watcher function
watcherCtx	User specific data, will be passed to the watcher callback.
error_code	Int reference, set to a value in ZK_ERRORS

Returns: True if the operation completed successfully, False otherwise (caller should check 'error_code' value)

bool ZKWrapper::wget	(	const std::string &	path,
		std::vector< std::uint8_t > &	data,
		watcher_fn	watch,
		void *	watcherCtx,
		int &	error_code,
		bool	resize
	)		const

This function is similar to 'get' except it allows one to specify a watcher object.

Parameters

path	The path to the node
data	Reference to a vector which will be filled with the znode data Should be of size MAX_PAYLOAD when passed in, will be resized in this method
watch	A watcher function
watcherCtx	User specific data, will be passed to the watcher callback.
error_code	Int reference, set to a value in ZK_ERRORS
resize	Should automatic resizing of the data vector be performed? If this argument is false, then the data buffer is expected to be large enough to hold everything in the node, otherwise the operation will fail.

Returns: True if the operation completed successfully, False otherwise (caller should check 'error_code' value)

bool ZKWrapper::wget_children	(	const std::string &	path,
		std::vector< std::string > &	children,
		watcher_fn	watch,
		void *	watcherCtx,
		int &	error_code
	)		const

Similar to 'get_children', except it allows one to specify a watcher object rather than a boolean watch flag.

Parameters

path	The path to get children of and the node to place the watch on
children	Reference to a vector which will be populated with the names of the children znodes of the given path TODO: How large should this vector be when passed in?
watch	A watcher function
watcherCtx	User specific data, will be passed to the watcher callback.
error_code	Int reference, set to a value in ZK_ERRORS

Returns: True if the operation completed successfully, False otherwise (caller should check 'error_code' value)

Friends And Related Function Documentation

void watcher	(	zhandle_t *	zzh,
		int	type,
		int	state,
		const char *	path,
		void *	watcherCtx
	)

friend

Currently watches the zookeeper handle and closes zookeeper on failed auths or expired sessions.

Parameters

zzh	zookeeper handle
type	type of event
state	state of the event
path	path to the watcher node
watcherCtx	the state of the watcher

The documentation for this class was generated from the following files:

zkwrapper/include/zkwrapper.h
zkwrapper/source/zkwrapper.cc

Public Member Functions

Static Public Member Functions

Static Public Attributes

Friends

Constructor & Destructor Documentation

Member Function Documentation

Friends And Related Function Documentation