#include <tdb.h>
#include <ctdb_protocol.h>
-/* The type of the first arg should match the arg given to ctdb_connect() */
+/**
+ * ctdb - a library for accessing tdbs controlled by ctdbd
+ *
+ * ctdbd (clustered tdb daemon) is a daemon designed to syncronize TDB
+ * databases across a cluster. Using this library, you can communicate with
+ * the daemon to access the databases, pass messages across the cluster, and
+ * control the daemon itself.
+ *
+ * The general API is event-driven and asynchronous: you call the
+ * *_send functions, supplying callbacks, then when the ctdbd file
+ * descriptor is usable, call ctdb_service() to perform read from it
+ * and call your callbacks, which use the *_recv functions to unpack
+ * the replies from ctdbd.
+ *
+ * There is also a synchronous wrapper for each function for trivial
+ * programs; these can be found in the section marked "Synchronous API".
+ */
+
typedef void (*ctdb_log_fn_t)(void *log_priv,
int severity, const char *format, va_list ap);
+/**
+ * ctdb_connect - connect to ctdb using the specified domain socket.
+ * @addr: the socket address, or NULL for default
+ * @log: the logging function
+ * @log_priv: the private argument to the logging function.
+ *
+ * Returns a ctdb context if successful or NULL. Use ctdb_free() to
+ * release the returned ctdb_connection when finished.
+ *
+ * The log() function can be typesafe: the log_priv arg and signature
+ * of log() should match. The priority passed to log() os as per
+ * syslog(3).
+ *
+ * See Also:
+ * ctdb_log_file()
+ */
+struct ctdb_connection *ctdb_connect(const char *addr,
+ ctdb_log_fn_t log_fn, void *log_priv);
-/* All *_send() functions are guaranteed to be non-blocking and fully
- * asynchronous. The non-_send variants are synchronous.
+/**
+ * ctdb_log_file - example logging function
+ *
+ * Logs everything at priority LOG_WARNING or above to the file given (via
+ * the log_priv argument, usually stderr).
*/
+void ctdb_log_file(FILE *, int, const char *, va_list);
-/*
- * Connect to ctdb using the specified domain socket.
- * Returns a ctdb context if successful or NULL.
+/**
+ * ctdb_log_level - level at which to call logging function
*
+ * This variable globally controls filtering on the logging function.
+ * It is initialized to LOG_WARNING, meaning that strange but nonfatal
+ * events, as well as errors and API misuses are reported.
+ *
+ * Set it to LOG_DEBUG to receive all messages.
*/
-struct ctdb_connection *ctdb_connect(const char *addr,
- ctdb_log_fn_t log_fn, void *log_priv);
+extern int ctdb_log_level;
+
+/***
+ *
+ * Asynchronous API
+ *
+ ***/
+/**
+ * ctdb_get_fd - get the filedescriptor to select/poll on
+ * @ctdb: the ctdb_connection from ctdb_connect.
+ *
+ * By using poll or select on this file descriptor, you will know when to call
+ * ctdb_service().
+ *
+ * See Also:
+ * ctdb_which_events(), ctdb_service()
+ */
int ctdb_get_fd(struct ctdb_connection *ctdb);
+/**
+ * ctdb_which_events - determine which events ctdb_service wants to see
+ * @ctdb: the ctdb_connection from ctdb_connect.
+ *
+ * This returns POLLIN, possibly or'd with POLLOUT if there are writes
+ * pending. You can set this straight into poll.events.
+ *
+ * See Also:
+ * ctdb_service()
+ */
int ctdb_which_events(struct ctdb_connection *ctdb);
+/**
+ * ctdb_service - service any I/O and callbacks from ctdbd communication
+ * @ctdb: the ctdb_connection from ctdb_connect.
+ * @revents: which events are available.
+ *
+ * This is the core of the library: it read and writes to the ctdbd
+ * socket. It may call callbacks registered with the various _send
+ * functions.
+ *
+ * revents is a bitset: POLLIN and/or POLLOUT may be set to indicate
+ * it is worth attempting to read/write the (nonblocking)
+ * filedescriptor respectively.
+ *
+ * Note that the synchronous functions call this internally.
+ * Returns false on catastrophic failure.
+ */
bool ctdb_service(struct ctdb_connection *ctdb, int revents);
+/**
+ * struct ctdb_request - handle for an outstanding request
+ *
+ * This opaque structure returned from various *_send functions gives
+ * you a handle by which you can cancel a request. You can't do
+ * anything else with it until the request is completed and it is
+ * handed to your callback function.
+ */
struct ctdb_request;
+/**
+ * ctdb_request_free - free a completed request
+ *
+ * This frees a request: you should only call it once it has been
+ * handed to your callback. For incomplete requests, see ctdb_cancel().
+ */
void ctdb_request_free(struct ctdb_connection *ctdb, struct ctdb_request *req);
-/*
- * Callback for completed requests: it would normally unpack the request
- * using ctdb_*_recv().
- * You must free the request using ctdb_request_free().
+/**
+ * ctdb_callback_t - callback for completed requests.
*
- * Note that due to macro magic, your callback doesn't have to take void *,
- * it can take a type which matches the actual private parameter.
+ * This would normally unpack the request using ctdb_*_recv(). You
+ * must free the request using ctdb_request_free().
+ *
+ * Note that due to macro magic, actual your callback can be typesafe:
+ * instead of taking a void *, it can take a type which matches the
+ * actual private parameter.
*/
typedef void (*ctdb_callback_t)(struct ctdb_connection *ctdb,
struct ctdb_request *req, void *private);
-
-/*
- * functions to attach to a database
- * if the database does not exist it will be created.
+/**
+ * struct ctdb_db - connection to a particular open TDB
+ *
+ * This represents a particular open database: you receive it from
+ * ctdb_attachdb or ctdb_attachdb_recv to manipulate a database.
*
* You have to free the handle with ctdb_detach_db() when finished with it.
*/
struct ctdb_db;
+/**
+ * ctdb_attachdb_send - open a clustered TDB
+ * @ctdb: the ctdb_connection from ctdb_connect.
+ * @name: the filename of the database (no /).
+ * @persistent: whether the database is persistent across ctdbd's life
+ * @tdb_flags: the flags to pass to tdb_open.
+ * @callback: the callback when we're attached or failed (typesafe)
+ * @cbdata: the argument to callback()
+ *
+ * This function connects to a TDB controlled by ctdbd. It can create
+ * a new TDB if it does not exist, depending on tdb_flags. Returns
+ * the pending request, or NULL on error.
+ */
struct ctdb_request *
ctdb_attachdb_send(struct ctdb_connection *ctdb,
const char *name, int persistent, uint32_t tdb_flags,
- ctdb_callback_t callback, void *private_data);
+ ctdb_callback_t callback, void *cbdata);
+/**
+ * ctdb_attachdb_recv - read an ctdb_attach reply from ctdbd
+ * @ctdb: the ctdb_connection from ctdb_connect.
+ * @req: the completed request.
+ *
+ * This returns NULL if something went wrong, or otherwise the open database.
+ */
struct ctdb_db *ctdb_attachdb_recv(struct ctdb_connection *ctdb,
struct ctdb_request *req);
-struct ctdb_db *ctdb_attachdb(struct ctdb_connection *ctdb,
- const char *name, int persistent,
- uint32_t tdb_flags);
+/**
+ * struct ctdb_lock - a record lock on a clustered TDB database
+ *
+ * This locks a subset of the database across the entire cluster; it
+ * is the fundamental sychronization element for ctdb. You cannot have
+ * more than one lock at once.
+ *
+ * You MUST NOT block during holding this lock and MUST release it
+ * quickly by performing ctdb_release_lock(lock).
+ */
struct ctdb_lock;
-/*
- * functions to read a record from the database
- * when the callback is invoked, the client will hold an exclusive lock
- * on the record, the client MUST NOT block during holding this lock and MUST
- * release it quickly by performing ctdb_release_lock(lock).
+/**
+ * ctdb_rrl_callback_t - callback for ctdb_readrecordlock_async
*
- * When the lock is released, data is freed too, so make sure to copy the data
- * before that.
+ * This is not the standard ctdb_callback_t, because there is often no
+ * request required to access a database record (ie. if it is local already).
+ * So the callback is handed the lock directly: it might be NULL if there
+ * was an error obtaining the lock.
*
- * This returns true on success: the callback may have already been called,
- * or it might be awaiting a response from ctdbd.
+ * See Also:
+ * ctdb_readrecordlock_async(), ctdb_readrecordlock()
*/
typedef void (*ctdb_rrl_callback_t)(struct ctdb_db *ctdb_db,
struct ctdb_lock *lock,
TDB_DATA data,
void *private);
-bool
-ctdb_readrecordlock_async(struct ctdb_db *ctdb_db, TDB_DATA key,
- ctdb_rrl_callback_t callback, void *private_data);
-/* Returns null on failure. */
-struct ctdb_lock *ctdb_readrecordlock(struct ctdb_db *ctdb_db, TDB_DATA key,
- TDB_DATA *data);
+/**
+ * ctdb_readrecordlock_async - read and lock a record
+ * @ctdb_db: the database handle from ctdb_attachdb/ctdb_attachdb_recv.
+ * @key: the key of the record to lock.
+ * @callback: the callback once the record is locked (typesafe).
+ * @cbdata: the argument to callback()
+ *
+ * This returns true on success. Commonly, we can obtain the record
+ * immediately and so the callback will be invoked. Otherwise a request
+ * will be queued to ctdbd for the record.
+ *
+ * If failure is immediate, false is returned. Otherwise, the callback
+ * may receive a NULL lock arg to indicate asynchronous failure.
+ */
+bool ctdb_readrecordlock_async(struct ctdb_db *ctdb_db, TDB_DATA key,
+ ctdb_rrl_callback_t callback, void *cbdata);
-/*
- * Function to write data to a record
- * This function may ONLY be called while holding a lock to the record
- * created by ctdb_readrecordlock*, and before calling
- * ctdb_release_lock() to release the lock.
+/**
+ * ctdb_writerecord - write a locked record in a TDB
+ * @lock: the lock from ctdb_readrecordlock/ctdb_readrecordlock_recv
+ * @data: the new data to place in the record.
*/
int ctdb_writerecord(struct ctdb_lock *lock, TDB_DATA data);
-
+/**
+ * ctdb_release_lock - release a record lock on a TDB
+ * @lock: the lock from ctdb_readrecordlock/ctdb_readrecordlock_async
+ */
void ctdb_release_lock(struct ctdb_lock *lock);
-/*
- * messaging functions
- * these functions provide a messaging layer for applications to communicate
- * with eachother across
+/**
+ * ctdb_message_fn_t - messaging callback for ctdb messages
+ *
+ * ctdbd provides a simple messaging API; you can register for a particular
+ * 64-bit id on which you want to send messages, and send to other ids.
+ *
+ * See Also:
+ * ctdb_set_message_handler_send()
+ */
+typedef void (*ctdb_message_fn_t)(struct ctdb_connection *,
+ uint64_t srvid, TDB_DATA data, void *);
+
+/**
+ * ctdb_set_message_handler_send - register for messages to a srvid
+ * @ctdb: the ctdb_connection from ctdb_connect.
+ * @srvid: the 64 bit identifier for our messages.
+ * @handler: the callback when we receive such a message (typesafe)
+ * @callback: the callback when ctdb replies to our message (typesafe)
+ * @cbdata: the argument to callback() and handler()
+ *
+ * Note: our callback will always be called before handler.
+ *
+ * See Also:
+ * ctdb_set_message_handler_recv(), ctdb_remove_message_handler_send()
*/
-typedef void (*ctdb_message_fn_t)(struct ctdb_connection *, uint64_t srvid, TDB_DATA data, void *);
-
struct ctdb_request *
ctdb_set_message_handler_send(struct ctdb_connection *ctdb, uint64_t srvid,
ctdb_message_fn_t handler,
ctdb_callback_t callback,
- void *private_data);
+ void *cbdata);
+/**
+ * ctdb_set_message_handler_recv - read a set_message_handler result
+ * @ctdb: the ctdb_connection from ctdb_connect.
+ * @req: the completed request
+ *
+ * If this returns true, the registered handler may be called from the next
+ * ctdb_service(). If this returns false, the registration failed.
+ */
bool ctdb_set_message_handler_recv(struct ctdb_connection *ctdb,
struct ctdb_request *handle);
-bool ctdb_set_message_handler(struct ctdb_connection *ctdb, uint64_t srvid,
- ctdb_message_fn_t handler, void *private_data);
-
-
-
-/*
- * unregister a message handler and stop listening on teh specified port
+/**
+ * ctdb_remove_message_handler_send - unregister for messages to a srvid
+ * @ctdb: the ctdb_connection from ctdb_connect.
+ * @srvid: the 64 bit identifier for our messages.
+ * @callback: the callback when ctdb replies to our message (typesafe)
+ * @cbdata: the argument to callback()
+ *
+ * This undoes a successful ctdb_set_message_handler or
+ * ctdb_set_message_handler_recv.
*/
struct ctdb_request *
ctdb_remove_message_handler_send(struct ctdb_connection *ctdb, uint64_t srvid,
- ctdb_callback_t callback,
- void *private_data);
+ ctdb_callback_t callback, void *cbdata);
+/**
+ * ctdb_remove_message_handler_recv - read a remove_message_handler result
+ * @ctdb: the ctdb_connection from ctdb_connect.
+ * @req: the completed request
+ *
+ * After this returns true, the registered handler will no longer be called.
+ * If this returns false, the de-registration failed.
+ */
bool ctdb_remove_message_handler_recv(struct ctdb_request *handle);
-bool ctdb_remove_message_handler(struct ctdb_connection *ctdb, uint64_t srvid);
-
-
-/*
- * send a message to a specific node/port
- * this function is non-blocking
+/**
+ * ctdb_send_message - send a message via ctdbd
+ * @ctdb: the ctdb_connection from ctdb_connect.
+ * @pnn: the physical node number to send to
+ * @srvid: the 64 bit identifier for this message type.
+ * @data: the data to send
+ *
+ * This allows arbitrary messages to be sent across the cluster to those
+ * listening (via ctdb_set_message_handler et al).
+ *
+ * This queues a message to be sent: you will need to call
+ * ctdb_service() to actually send the message. There is no callback
+ * because there is no acknowledgement.
+ *
+ * See Also:
+ * ctdb_getpnn_send(), ctdb_getpnn()
*/
bool ctdb_send_message(struct ctdb_connection *ctdb, uint32_t pnn, uint64_t srvid, TDB_DATA data);
-
-
-/*
- * functions to read the pnn number of the local node
+/**
+ * ctdb_getpnn_send - read the pnn number of a node.
+ * @ctdb: the ctdb_connection from ctdb_connect.
+ * @destnode: the destination node (see below)
+ * @callback: the callback when ctdb replies to our message (typesafe)
+ * @cbdata: the argument to callback()
+ *
+ * There are several special values for destnode, detailed in
+ * ctdb_protocol.h, particularly CTDB_CURRENT_NODE which means the
+ * local ctdbd.
*/
struct ctdb_request *
ctdb_getpnn_send(struct ctdb_connection *ctdb,
uint32_t destnode,
ctdb_callback_t callback,
- void *private_data);
+ void *cbdata);
+/**
+ * ctdb_getpnn_recv - read an ctdb_getpnn reply from ctdbd
+ * @ctdb: the ctdb_connection from ctdb_connect.
+ * @req: the completed request.
+ * @pnn: a pointer to the pnn to fill in
+ *
+ * This returns false if something went wrong, or otherwise fills in pnn.
+ */
bool ctdb_getpnn_recv(struct ctdb_connection *ctdb,
struct ctdb_request *req, uint32_t *pnn);
-bool ctdb_getpnn(struct ctdb_connection *ctdb,
- uint32_t destnode,
- uint32_t *pnn);
-
-
-
-/*
- * functions to read the recovery master of a node
+/**
+ * ctdb_getrecmaster_send - read the recovery master of a node
+ * @ctdb: the ctdb_connection from ctdb_connect.
+ * @destnode: the destination node (see below)
+ * @callback: the callback when ctdb replies to our message (typesafe)
+ * @cbdata: the argument to callback()
+ *
+ * There are several special values for destnode, detailed in
+ * ctdb_protocol.h, particularly CTDB_CURRENT_NODE which means the
+ * local ctdbd.
*/
struct ctdb_request *
ctdb_getrecmaster_send(struct ctdb_connection *ctdb,
uint32_t destnode,
- ctdb_callback_t callback,
- void *private_data);
+ ctdb_callback_t callback, void *cbdata);
+
+/**
+ * ctdb_getrecmaster_recv - read an ctdb_getrecmaster reply from ctdbd
+ * @ctdb: the ctdb_connection from ctdb_connect.
+ * @req: the completed request.
+ * @recmaster: a pointer to the recmaster to fill in
+ *
+ * This returns false if something went wrong, or otherwise fills in
+ * recmaster.
+ */
bool ctdb_getrecmaster_recv(struct ctdb_connection *ctdb,
struct ctdb_request *handle,
uint32_t *recmaster);
-bool ctdb_getrecmaster(struct ctdb_connection *ctdb,
- uint32_t destnode,
- uint32_t *recmaster);
+/**
+ * ctdb_cancel - cancel an uncompleted request
+ * @ctdb: the ctdb_connection from ctdb_connect.
+ * @req: the uncompleted request.
+ *
+ * This cancels a request, returning true. You may not cancel a
+ * request which has already been completed (ie. once its callback has
+ * been called); you should simply use ctdb_request_free() in that case.
+ */
+void ctdb_cancel(struct ctdb_connection *ctdb, struct ctdb_request *req);
+
+/***
+ *
+ * Synchronous API
+ *
+ ***/
+
+/**
+ * ctdb_attachdb - open a clustered TDB (synchronous)
+ * @ctdb: the ctdb_connection from ctdb_connect.
+ * @name: the filename of the database (no /).
+ * @persistent: whether the database is persistent across ctdbd's life
+ * @tdb_flags: the flags to pass to tdb_open.
+ *
+ * Do a ctdb_attachdb_send and wait for it to complete.
+ * Returns NULL on failure.
+ */
+struct ctdb_db *ctdb_attachdb(struct ctdb_connection *ctdb,
+ const char *name, int persistent,
+ uint32_t tdb_flags);
+/**
+ * ctdb_readrecordlock - read and lock a record (synchronous)
+ * @ctdb_db: the database handle from ctdb_attachdb/ctdb_attachdb_recv.
+ * @key: the key of the record to lock.
+ * @req: a pointer to the request, if one is needed.
+ *
+ * Do a ctdb_readrecordlock_send and wait for it to complete.
+ * Returns NULL on failure.
+ */
+struct ctdb_lock *ctdb_readrecordlock(struct ctdb_db *ctdb_db, TDB_DATA key,
+ TDB_DATA *data);
-/*
- * cancel a request
+/**
+ * ctdb_set_message_handler - register for messages to a srvid (synchronous)
+ * @ctdb: the ctdb_connection from ctdb_connect.
+ * @srvid: the 64 bit identifier for our messages.
+ * @handler: the callback when we receive such a message (typesafe)
+ * @cbdata: the argument to handler()
+ *
+ * If this returns true, the message handler can be called from any
+ * ctdb_service() (which is also called indirectly by other
+ * synchronous functions). If this returns false, the registration
+ * failed.
*/
-void ctdb_cancel(struct ctdb_connection *ctdb, struct ctdb_request *req);
+bool ctdb_set_message_handler(struct ctdb_connection *ctdb, uint64_t srvid,
+ ctdb_message_fn_t handler, void *cbdata);
-/*
- * functions for logging errors
+/**
+ * ctdb_remove_message_handler - deregister for messages (synchronous)
+ * @ctdb: the ctdb_connection from ctdb_connect.
+ * @srvid: the 64 bit identifier for our messages.
+ *
+ * If this returns true, the message handler will no longer be called.
+ * If this returns false, the deregistration failed.
*/
-extern int ctdb_log_level; /* LOG_WARNING and above by default. */
-void ctdb_log_file(FILE *, int severity, const char *format, va_list ap);
+bool ctdb_remove_message_handler(struct ctdb_connection *ctdb, uint64_t srvid);
+/**
+ * ctdb_getpnn - read the pnn number of a node (synchronous)
+ * @ctdb: the ctdb_connection from ctdb_connect.
+ * @destnode: the destination node (see below)
+ * @pnn: a pointer to the pnn to fill in
+ *
+ * There are several special values for destnode, detailed in
+ * ctdb_protocol.h, particularly CTDB_CURRENT_NODE which means the
+ * local ctdbd.
+ *
+ * Returns true and fills in *pnn on success.
+ */
+bool ctdb_getpnn(struct ctdb_connection *ctdb,
+ uint32_t destnode,
+ uint32_t *pnn);
+
+/**
+ * ctdb_getrecmaster - read the recovery master of a node (synchronous)
+ * @ctdb: the ctdb_connection from ctdb_connect.
+ * @destnode: the destination node (see below)
+ * @recmaster: a pointer to the recmaster to fill in
+ *
+ * There are several special values for destnode, detailed in
+ * ctdb_protocol.h, particularly CTDB_CURRENT_NODE which means the
+ * local ctdbd.
+ *
+ * Returns true and fills in *recmaster on success.
+ */
+bool ctdb_getrecmaster(struct ctdb_connection *ctdb,
+ uint32_t destnode,
+ uint32_t *recmaster);
/* These ugly macro wrappers make the callbacks typesafe. */
#include <ctdb_typesafe_cb.h>
git.samba.org / rusty / ctdb.git / commitdiff