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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-04 18:04:16 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-04 18:04:16 +0000
commita68fb2d8219f6bccc573009600e9f23e89226a5e (patch)
treed742d35d14ae816e99293d2b01face30e9f3a46b /wsrep-lib/wsrep-API/v26/wsrep_api.h
parentInitial commit. (diff)
downloadmariadb-10.6-upstream.tar.xz
mariadb-10.6-upstream.zip
Adding upstream version 1:10.6.11.upstream/1%10.6.11upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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+/* Copyright (C) 2009-2013 Codership Oy <info@codership.com>
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; version 2 of the License.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License along
+ with this program; if not, write to the Free Software Foundation, Inc.,
+ 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/*!
+ @file wsrep API declaration.
+
+ HOW TO READ THIS FILE.
+
+ Due to C language rules this header layout doesn't lend itself to intuitive
+ reading. So here's the scoop: in the end this header declares two main types:
+
+ * struct wsrep_init_args
+
+ and
+
+ * struct wsrep
+
+ wsrep_init_args contains initialization parameters for wsrep provider like
+ names, addresses, etc. and pointers to callbacks. The callbacks will be called
+ by provider when it needs to do something application-specific, like log a
+ message or apply a writeset. It should be passed to init() call from
+ wsrep API. It is an application part of wsrep API contract.
+
+ struct wsrep is the interface to wsrep provider. It contains all wsrep API
+ calls. It is a provider part of wsrep API contract.
+
+ Finally, wsrep_load() method loads (dlopens) wsrep provider library. It is
+ defined in wsrep_loader.c unit and is part of libwsrep.a (which is not a
+ wsrep provider, but a convenience library).
+
+ wsrep_unload() does the reverse.
+
+*/
+#ifndef WSREP_H
+#define WSREP_H
+
+#include <stdint.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <time.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**************************************************************************
+ * *
+ * wsrep replication API *
+ * *
+ **************************************************************************/
+
+#define WSREP_INTERFACE_VERSION "26"
+
+/*! Empty backend spec */
+#define WSREP_NONE "none"
+
+
+/*!
+ * @brief log severity levels, passed as first argument to log handler
+ */
+typedef enum wsrep_log_level
+{
+ WSREP_LOG_FATAL, //!< Unrecoverable error, application must quit.
+ WSREP_LOG_ERROR, //!< Operation failed, must be repeated.
+ WSREP_LOG_WARN, //!< Unexpected condition, but no operational failure.
+ WSREP_LOG_INFO, //!< Informational message.
+ WSREP_LOG_DEBUG //!< Debug message. Shows only of compiled with debug.
+} wsrep_log_level_t;
+
+/*!
+ * @brief error log handler
+ *
+ * All messages from wsrep provider are directed to this
+ * handler, if present.
+ *
+ * @param level log level
+ * @param message log message
+ */
+typedef void (*wsrep_log_cb_t)(wsrep_log_level_t, const char *);
+
+
+/*!
+ * Certain provider capabilities application may want to know about
+ */
+#define WSREP_CAP_MULTI_MASTER ( 1ULL << 0 )
+#define WSREP_CAP_CERTIFICATION ( 1ULL << 1 )
+#define WSREP_CAP_PARALLEL_APPLYING ( 1ULL << 2 )
+#define WSREP_CAP_TRX_REPLAY ( 1ULL << 3 )
+#define WSREP_CAP_ISOLATION ( 1ULL << 4 )
+#define WSREP_CAP_PAUSE ( 1ULL << 5 )
+#define WSREP_CAP_CAUSAL_READS ( 1ULL << 6 )
+#define WSREP_CAP_CAUSAL_TRX ( 1ULL << 7 )
+#define WSREP_CAP_INCREMENTAL_WRITESET ( 1ULL << 8 )
+#define WSREP_CAP_SESSION_LOCKS ( 1ULL << 9 )
+#define WSREP_CAP_DISTRIBUTED_LOCKS ( 1ULL << 10 )
+#define WSREP_CAP_CONSISTENCY_CHECK ( 1ULL << 11 )
+#define WSREP_CAP_UNORDERED ( 1ULL << 12 )
+#define WSREP_CAP_ANNOTATION ( 1ULL << 13 )
+#define WSREP_CAP_PREORDERED ( 1ULL << 14 )
+#define WSREP_CAP_STREAMING ( 1ULL << 15 )
+#define WSREP_CAP_SNAPSHOT ( 1ULL << 16 )
+#define WSREP_CAP_NBO ( 1ULL << 17 )
+
+typedef uint32_t wsrep_cap_t; //!< capabilities bitmask
+
+/*!
+ * Writeset flags
+ *
+ * TRX_END the writeset and all preceding writesets must be committed
+ * ROLLBACK all preceding writesets in a transaction must be rolled back
+ * ISOLATION the writeset must be applied AND committed in isolation
+ * PA_UNSAFE the writeset cannot be applied in parallel
+ * COMMUTATIVE the order in which the writeset is applied does not matter
+ * NATIVE the writeset contains another writeset in this provider format
+ *
+ * TRX_START shall be set on the first trx fragment by provider
+ * TRX_PREPARE shall be set on the fragment which prepares the transaction
+ *
+ * Note that some of the flags are mutually exclusive (e.g. TRX_END and
+ * ROLLBACK).
+ */
+#define WSREP_FLAG_TRX_END ( 1ULL << 0 )
+#define WSREP_FLAG_ROLLBACK ( 1ULL << 1 )
+#define WSREP_FLAG_ISOLATION ( 1ULL << 2 )
+#define WSREP_FLAG_PA_UNSAFE ( 1ULL << 3 )
+#define WSREP_FLAG_COMMUTATIVE ( 1ULL << 4 )
+#define WSREP_FLAG_NATIVE ( 1ULL << 5 )
+#define WSREP_FLAG_TRX_START ( 1ULL << 6 )
+#define WSREP_FLAG_TRX_PREPARE ( 1ULL << 7 )
+#define WSREP_FLAG_SNAPSHOT ( 1ULL << 8 )
+#define WSREP_FLAG_IMPLICIT_DEPS ( 1ULL << 9 )
+
+#define WSREP_FLAGS_LAST WSREP_FLAG_IMPLICIT_DEPS
+#define WSREP_FLAGS_MASK ((WSREP_FLAGS_LAST << 1) - 1)
+
+
+typedef uint64_t wsrep_trx_id_t; //!< application transaction ID
+typedef uint64_t wsrep_conn_id_t; //!< application connection ID
+typedef int64_t wsrep_seqno_t; //!< sequence number of a writeset, etc.
+#ifdef __cplusplus
+typedef bool wsrep_bool_t;
+#else
+typedef _Bool wsrep_bool_t; //!< should be the same as standard (C99) bool
+#endif /* __cplusplus */
+
+/*! undefined seqno */
+#define WSREP_SEQNO_UNDEFINED (-1)
+
+
+/*! wsrep provider status codes */
+typedef enum wsrep_status
+{
+ WSREP_OK = 0, //!< success
+ WSREP_WARNING, //!< minor warning, error logged
+ WSREP_TRX_MISSING, //!< transaction is not known by wsrep
+ WSREP_TRX_FAIL, //!< transaction aborted, server can continue
+ WSREP_BF_ABORT, //!< trx was victim of brute force abort
+ WSREP_SIZE_EXCEEDED, //!< data exceeded maximum supported size
+ WSREP_CONN_FAIL, //!< error in client connection, must abort
+ WSREP_NODE_FAIL, //!< error in node state, wsrep must reinit
+ WSREP_FATAL, //!< fatal error, server must abort
+ WSREP_NOT_IMPLEMENTED, //!< feature not implemented
+ WSREP_NOT_ALLOWED //!< operation not allowed
+} wsrep_status_t;
+
+
+/*! wsrep callbacks status codes */
+typedef enum wsrep_cb_status
+{
+ WSREP_CB_SUCCESS = 0, //!< success (as in "not critical failure")
+ WSREP_CB_FAILURE //!< critical failure (consistency violation)
+ /* Technically, wsrep provider has no use for specific failure codes since
+ * there is nothing it can do about it but abort execution. Therefore any
+ * positive number shall indicate a critical failure. Optionally that value
+ * may be used by provider to come to a consensus about state consistency
+ * in a group of nodes. */
+} wsrep_cb_status_t;
+
+
+/*!
+ * UUID type - for all unique IDs
+ */
+typedef union wsrep_uuid {
+ uint8_t data[16];
+ size_t alignment;
+} wsrep_uuid_t;
+
+/*! Undefined UUID */
+static const wsrep_uuid_t WSREP_UUID_UNDEFINED = {{0,}};
+
+/*! UUID string representation length, terminating '\0' not included */
+#define WSREP_UUID_STR_LEN 36
+
+/*!
+ * Scan UUID from string
+ * @return length of UUID string representation or negative error code
+ */
+extern int
+wsrep_uuid_scan (const char* str, size_t str_len, wsrep_uuid_t* uuid);
+
+/*!
+ * Print UUID to string
+ * @return length of UUID string representation or negative error code
+ */
+extern int
+wsrep_uuid_print (const wsrep_uuid_t* uuid, char* str, size_t str_len);
+
+/*!
+ * @brief Compare two UUIDs
+ *
+ * Performs a byte by byte comparison of lhs and rhs.
+ * Returns 0 if lhs and rhs match, otherwise -1 or 1 according to the
+ * difference of the first byte that differs in lsh and rhs.
+ *
+ * @return -1, 0, 1 if lhs is respectively smaller, equal, or greater than rhs
+ */
+extern int
+wsrep_uuid_compare (const wsrep_uuid_t* lhs, const wsrep_uuid_t* rhs);
+
+#define WSREP_MEMBER_NAME_LEN 32 //!< maximum logical member name length
+#define WSREP_INCOMING_LEN 256 //!< max Domain Name length + 0x00
+
+
+/*!
+ * Global transaction identifier
+ */
+typedef struct wsrep_gtid
+{
+ wsrep_uuid_t uuid; /*!< History UUID */
+ wsrep_seqno_t seqno; /*!< Sequence number */
+} wsrep_gtid_t;
+
+/*! Undefined GTID */
+static const wsrep_gtid_t WSREP_GTID_UNDEFINED = {{{0, }}, -1};
+
+/*! Minimum number of bytes guaranteed to store GTID string representation,
+ * terminating '\0' not included (36 + 1 + 20) */
+#define WSREP_GTID_STR_LEN 57
+
+
+/*!
+ * Scan GTID from string
+ * @return length of GTID string representation or negative error code
+ */
+extern int
+wsrep_gtid_scan(const char* str, size_t str_len, wsrep_gtid_t* gtid);
+
+/*!
+ * Print GTID to string
+ * @return length of GTID string representation or negative error code
+ */
+extern int
+wsrep_gtid_print(const wsrep_gtid_t* gtid, char* str, size_t str_len);
+
+/*!
+ * Source/server transaction ID (trx ID assigned at originating node)
+ */
+typedef struct wsrep_stid {
+ wsrep_uuid_t node; //!< source node ID
+ wsrep_trx_id_t trx; //!< local trx ID at source
+ wsrep_conn_id_t conn; //!< local connection ID at source
+} wsrep_stid_t;
+
+/*!
+ * Transaction meta data
+ */
+typedef struct wsrep_trx_meta
+{
+ wsrep_gtid_t gtid; /*!< Global transaction identifier */
+ wsrep_stid_t stid; /*!< Source transaction identifier */
+ wsrep_seqno_t depends_on; /*!< Sequence number of the last transaction
+ this transaction may depend on */
+} wsrep_trx_meta_t;
+
+/*! Abstract data buffer structure */
+typedef struct wsrep_buf
+{
+ const void* ptr; /*!< Pointer to data buffer */
+ size_t len; /*!< Length of buffer */
+} wsrep_buf_t;
+
+/*! Transaction handle struct passed for wsrep transaction handling calls */
+typedef struct wsrep_ws_handle
+{
+ wsrep_trx_id_t trx_id; //!< transaction ID
+ void* opaque; //!< opaque provider transaction context data
+} wsrep_ws_handle_t;
+
+/*!
+ * member status
+ */
+typedef enum wsrep_member_status {
+ WSREP_MEMBER_UNDEFINED, //!< undefined state
+ WSREP_MEMBER_JOINER, //!< incomplete state, requested state transfer
+ WSREP_MEMBER_DONOR, //!< complete state, donates state transfer
+ WSREP_MEMBER_JOINED, //!< complete state
+ WSREP_MEMBER_SYNCED, //!< complete state, synchronized with group
+ WSREP_MEMBER_ERROR, //!< this and above is provider-specific error code
+ WSREP_MEMBER_MAX
+} wsrep_member_status_t;
+
+/*!
+ * static information about a group member (some fields are tentative yet)
+ */
+typedef struct wsrep_member_info {
+ wsrep_uuid_t id; //!< group-wide unique member ID
+ char name[WSREP_MEMBER_NAME_LEN]; //!< human-readable name
+ char incoming[WSREP_INCOMING_LEN]; //!< address for client requests
+} wsrep_member_info_t;
+
+/*!
+ * group status
+ */
+typedef enum wsrep_view_status {
+ WSREP_VIEW_PRIMARY, //!< primary group configuration (quorum present)
+ WSREP_VIEW_NON_PRIMARY, //!< non-primary group configuration (quorum lost)
+ WSREP_VIEW_DISCONNECTED, //!< not connected to group, retrying.
+ WSREP_VIEW_MAX
+} wsrep_view_status_t;
+
+/*!
+ * view of the group
+ */
+typedef struct wsrep_view_info {
+ wsrep_gtid_t state_id; //!< global state ID
+ wsrep_seqno_t view; //!< global view number
+ wsrep_view_status_t status; //!< view status
+ wsrep_cap_t capabilities;//!< capabilities available in the view
+ int my_idx; //!< index of this member in the view
+ int memb_num; //!< number of members in the view
+ int proto_ver; //!< application protocol agreed on the view
+ wsrep_member_info_t members[1];//!< array of member information
+} wsrep_view_info_t;
+
+
+/*!
+ * @brief connected to group
+ *
+ * This handler is called once the first primary view is seen.
+ * The purpose of this call is to provide basic information only,
+ * like node UUID and group UUID.
+ */
+typedef enum wsrep_cb_status (*wsrep_connected_cb_t) (
+ void* app_ctx,
+ const wsrep_view_info_t* view
+);
+
+
+/*!
+ * @brief group view handler
+ *
+ * This handler is called in *total order* corresponding to the group
+ * configuration change. It is to provide a vital information about
+ * new group view.
+ *
+ * @param app_ctx application context
+ * @param recv_ctx receiver context
+ * @param view new view on the group
+ * @param state current state
+ * @param state_len length of current state
+ */
+typedef enum wsrep_cb_status (*wsrep_view_cb_t) (
+ void* app_ctx,
+ void* recv_ctx,
+ const wsrep_view_info_t* view,
+ const char* state,
+ size_t state_len
+);
+
+
+/*!
+ * Magic string to tell provider to engage into trivial (empty) state transfer.
+ * No data will be passed, but the node shall be considered JOINED.
+ * Should be passed in sst_req parameter of wsrep_sst_cb_t.
+ */
+#define WSREP_STATE_TRANSFER_TRIVIAL "trivial"
+
+/*!
+ * Magic string to tell provider not to engage in state transfer at all.
+ * The member will stay in WSREP_MEMBER_UNDEFINED state but will keep on
+ * receiving all writesets.
+ * Should be passed in sst_req parameter of wsrep_sst_cb_t.
+ */
+#define WSREP_STATE_TRANSFER_NONE "none"
+
+
+/*!
+ * @brief Creates and returns State Snapshot Transfer request for provider.
+ *
+ * This handler is called whenever the node is found to miss some of events
+ * from the cluster history (e.g. fresh node joining the cluster).
+ * SST will be used if it is impossible (or impractically long) to replay
+ * missing events, which may be not known in advance, so the node must always
+ * be ready to accept full SST or abort in case event replay is impossible.
+ *
+ * Normally SST request is an opaque buffer that is passed to the
+ * chosen SST donor node and must contain information sufficient for
+ * donor to deliver SST (typically SST method and delivery address).
+ * See above macros WSREP_STATE_TRANSFER_TRIVIAL and WSREP_STATE_TRANSFER_NONE
+ * to modify the standard provider behavior.
+ *
+ * @note Currently it is assumed that sst_req is allocated using
+ * malloc()/calloc()/realloc() and it will be freed by
+ * wsrep provider.
+ *
+ * @param app_ctx application context
+ * @param sst_req location to store SST request
+ * @param sst_req_len location to store SST request length or error code,
+ * value of 0 means no SST.
+ */
+typedef enum wsrep_cb_status (*wsrep_sst_request_cb_t) (
+ void* app_ctx,
+ void** sst_req,
+ size_t* sst_req_len
+);
+
+
+/*!
+ * @brief apply callback
+ *
+ * This handler is called from wsrep library to apply replicated writeset
+ * Must support brute force applying for multi-master operation
+ *
+ * @param recv_ctx receiver context pointer provided by the application
+ * @param ws_handle internal provider writeset handle
+ * @param flags WSREP_FLAG_... flags
+ * @param data data buffer containing the writeset
+ * @param meta transaction meta data of the writeset to be applied
+ * @param exit_loop set to true to exit receive loop
+ *
+ * @return error code:
+ * @retval 0 - success
+ * @retval non-0 - application-specific error code
+ */
+typedef enum wsrep_cb_status (*wsrep_apply_cb_t) (
+ void* recv_ctx,
+ const wsrep_ws_handle_t* ws_handle,
+ uint32_t flags,
+ const wsrep_buf_t* data,
+ const wsrep_trx_meta_t* meta,
+ wsrep_bool_t* exit_loop
+);
+
+
+/*!
+ * @brief unordered callback
+ *
+ * This handler is called to execute unordered actions (actions that need not
+ * to be executed in any particular order) attached to writeset.
+ *
+ * @param recv_ctx receiver context pointer provided by the application
+ * @param data data buffer containing the writeset
+ */
+typedef enum wsrep_cb_status (*wsrep_unordered_cb_t) (
+ void* recv_ctx,
+ const wsrep_buf_t* data
+);
+
+
+/*!
+ * @brief a callback to donate state snapshot
+ *
+ * This handler is called from wsrep library when it needs this node
+ * to deliver state to a new cluster member.
+ * No state changes will be committed for the duration of this call.
+ * Wsrep implementation may provide internal state to be transmitted
+ * to new cluster member for initial state.
+ *
+ * @param app_ctx application context
+ * @param recv_ctx receiver context
+ * @param str_msg state transfer request message
+ * @param gtid current state ID on this node
+ * @param state current wsrep internal state buffer
+ * @param bypass bypass snapshot transfer, only transfer uuid:seqno pair
+ */
+typedef enum wsrep_cb_status (*wsrep_sst_donate_cb_t) (
+ void* app_ctx,
+ void* recv_ctx,
+ const wsrep_buf_t* str_msg,
+ const wsrep_gtid_t* state_id,
+ const wsrep_buf_t* state,
+ wsrep_bool_t bypass
+);
+
+
+/*!
+ * @brief a callback to signal application that wsrep state is synced
+ * with cluster
+ *
+ * This callback is called after wsrep library has got in sync with
+ * rest of the cluster.
+ *
+ * @param app_ctx application context
+ *
+ * @return wsrep_cb_status enum
+ */
+typedef enum wsrep_cb_status (*wsrep_synced_cb_t) (void* app_ctx);
+
+
+/*
+ * An opaque encryption key of arbitrary size - provided by the application
+ * May contain not only the key, but also algorithm specification and the like.
+ */
+typedef wsrep_buf_t wsrep_enc_key_t;
+
+/*
+ * Initialization vector/nonce. Given that most symmetric ciphers use 16 byte
+ * blocks this can be made 32 bytes without much loss of generality.
+ * Must be set by provider to start an encryption/decrytpion operation.
+ */
+typedef char wsrep_enc_iv_t[32];
+
+/*
+ * Encryption context that should be sufficient to deterministically encrypt/
+ * decrypt a data buffer either standalone or as part of a stream. May be used
+ * passed in apply_cb() along with the encrypted replication events to
+ * application as well.
+ *
+ * @param key [in] can be a pointer to const since provider will have to keep
+ * the keys until the last writeset that uses the key is in the
+ * cache
+ * @param iv [in] initialization vector for the beginning of the new
+ * operation.
+ * @param ctx [in/out] ongoing operation context
+ * To initialize a new context the encrypt_cb() caller sets it to
+ * NULL, which signals the encryption of a new continuous buffer.
+ * In that case the callback allocates the new context (using
+ * supplied key and iv) and stores the pointer to it for
+ * processing subsequent data.
+ * The end of the operation is signaled by passing TRUE in the
+ * parameter `last` to the encryption callback, the callback then
+ * finishes any pending encryption and deallocates the context.
+ */
+typedef struct
+{
+ const wsrep_enc_key_t* key;
+ const wsrep_enc_iv_t* iv;
+ void* ctx;
+}
+wsrep_enc_ctx_t;
+
+/*
+ * Encryption direction
+ */
+typedef enum
+{
+ WSREP_ENC = 0, /* encryption */
+ WSREP_DEC = 1 /* decryption */
+}
+wsrep_enc_direction_t;
+
+/*
+ * Encryption/decryption callback. Must be used by both provider and the
+ * application to obtain identical results. Can be NULL for no encryption.
+ *
+ * @param app_ctx application context
+ * @param enc_ctx current operation context
+ * @param input input data buffer
+ * @param output an output buffer, must be at least the size of the input
+ * data plus unwritten bytes from the previous call(s). E.g. in
+ * block mode, encryption/decryption operation will write data
+ * to output in multiples of the algoritm block size. So a call
+ * to encrypt a single byte won't normally write anything to
+ * output waiting for the next input chunk. So on the next call
+ * it may write one byte more than was given in the input.
+ * @param direction of the operation (encryption/decryption)
+ * @param last true if this is the last buffer to encrypt in the stream.
+ * In that case the callback shall write the remaining bytes of
+ * the stream to output (if any) and deallocate ctx->ctx if
+ * allocated previously
+ *
+ * @return a number of bytes written to output or a negative error code.
+ */
+typedef int (*wsrep_encrypt_cb_t)
+(
+ void* app_ctx,
+ wsrep_enc_ctx_t* enc_ctx,
+ const wsrep_buf_t* input,
+ void* output,
+ wsrep_enc_direction_t direction,
+ bool last
+);
+
+
+/*!
+ * Initialization parameters for wsrep provider.
+ */
+struct wsrep_init_args
+{
+ void* app_ctx; //!< Application context for callbacks
+
+ /* Configuration parameters */
+ const char* node_name; //!< Symbolic name of this node (e.g. hostname)
+ const char* node_address; //!< Address to be used by wsrep provider
+ const char* node_incoming; //!< Address for incoming client connections
+ const char* data_dir; //!< Directory where wsrep files are kept if any
+ const char* options; //!< Provider-specific configuration string
+ int proto_ver; //!< Max supported application protocol version
+
+ /* Application initial state information. */
+ const wsrep_gtid_t* state_id; //!< Application state GTID
+ const wsrep_buf_t* state; //!< Initial state for wsrep provider
+
+ /* Application callbacks */
+ wsrep_log_cb_t logger_cb; //!< logging handler
+ wsrep_connected_cb_t connected_cb; //!< connected to group
+ wsrep_view_cb_t view_cb; //!< group view change handler
+ wsrep_sst_request_cb_t sst_request_cb; //!< SST request creator
+ wsrep_encrypt_cb_t encrypt_cb; //!< Encryption callback
+
+ /* Applier callbacks */
+ wsrep_apply_cb_t apply_cb; //!< apply callback
+ wsrep_unordered_cb_t unordered_cb; //!< callback for unordered actions
+
+ /* State Snapshot Transfer callbacks */
+ wsrep_sst_donate_cb_t sst_donate_cb; //!< donate SST
+ wsrep_synced_cb_t synced_cb; //!< synced with group
+};
+
+
+/*! Type of the stats variable value in struct wsrep_status_var */
+typedef enum wsrep_var_type
+{
+ WSREP_VAR_STRING, //!< pointer to null-terminated string
+ WSREP_VAR_INT64, //!< int64_t
+ WSREP_VAR_DOUBLE //!< double
+}
+wsrep_var_type_t;
+
+/*! Generalized stats variable representation */
+struct wsrep_stats_var
+{
+ const char* name; //!< variable name
+ wsrep_var_type_t type; //!< variable value type
+ union {
+ int64_t _int64;
+ double _double;
+ const char* _string;
+ } value; //!< variable value
+};
+
+
+/*! Key struct used to pass certification keys for transaction handling calls.
+ * A key consists of zero or more key parts. */
+typedef struct wsrep_key
+{
+ const wsrep_buf_t* key_parts; /*!< Array of key parts */
+ size_t key_parts_num; /*!< Number of key parts */
+} wsrep_key_t;
+
+/*! Key type:
+ * SHARED - higher level resource shared between clients, e.g. SQL table
+ * REFERENCE - resource referenced but not modified, e.g. parent row
+ * UPDATE - resource is modified
+ * EXCLUSIVE - resource is either created or deleted */
+typedef enum wsrep_key_type
+{
+ WSREP_KEY_SHARED = 0,
+ WSREP_KEY_REFERENCE,
+ WSREP_KEY_UPDATE,
+ WSREP_KEY_EXCLUSIVE
+} wsrep_key_type_t;
+
+/*! Data type:
+ * ORDERED state modification event that should be applied and committed
+ * in order.
+ * UNORDERED some action that does not modify state and execution of which is
+ * optional and does not need to happen in order.
+ * ANNOTATION (human readable) writeset annotation. */
+typedef enum wsrep_data_type
+{
+ WSREP_DATA_ORDERED = 0,
+ WSREP_DATA_UNORDERED,
+ WSREP_DATA_ANNOTATION
+} wsrep_data_type_t;
+
+
+/*!
+ * @brief Helper method to reset trx writeset handle state when trx id changes
+ *
+ * Instead of passing wsrep_ws_handle_t directly to wsrep calls,
+ * wrapping handle with this call offloads bookkeeping from
+ * application.
+ */
+static inline wsrep_ws_handle_t* wsrep_ws_handle_for_trx(
+ wsrep_ws_handle_t* ws_handle,
+ wsrep_trx_id_t trx_id)
+{
+ if (ws_handle->trx_id != trx_id)
+ {
+ ws_handle->trx_id = trx_id;
+ ws_handle->opaque = NULL;
+ }
+ return ws_handle;
+}
+
+
+/*!
+ * A handle for processing preordered actions.
+ * Must be initialized to WSREP_PO_INITIALIZER before use.
+ */
+typedef struct wsrep_po_handle { void* opaque; } wsrep_po_handle_t;
+
+static const wsrep_po_handle_t WSREP_PO_INITIALIZER = { NULL };
+
+
+typedef struct wsrep_st wsrep_t;
+/*!
+ * wsrep interface for dynamically loadable libraries
+ */
+struct wsrep_st {
+
+ const char *version; //!< interface version string
+
+ /*!
+ * @brief Initializes wsrep provider
+ *
+ * @param wsrep provider handle
+ * @param args wsrep initialization parameters
+ */
+ wsrep_status_t (*init) (wsrep_t* wsrep,
+ const struct wsrep_init_args* args);
+
+ /*!
+ * @brief Returns provider capabilities bitmap
+ *
+ * Note that these are potential provider capabilities. Provider will
+ * offer only capabilities supported by all members in the view
+ * (see wsrep_view_info).
+ *
+ * @param wsrep provider handle
+ */
+ wsrep_cap_t (*capabilities) (wsrep_t* wsrep);
+
+ /*!
+ * @brief Passes provider-specific configuration string to provider.
+ *
+ * @param wsrep provider handle
+ * @param conf configuration string
+ *
+ * @retval WSREP_OK configuration string was parsed successfully
+ * @retval WSREP_WARNING could not parse configuration string, no action taken
+ */
+ wsrep_status_t (*options_set) (wsrep_t* wsrep, const char* conf);
+
+ /*!
+ * @brief Returns provider-specific string with current configuration values.
+ *
+ * @param wsrep provider handle
+ *
+ * @return a dynamically allocated string with current configuration
+ * parameter values
+ */
+ char* (*options_get) (wsrep_t* wsrep);
+
+ /*!
+ * @brief A call to set/rotate the key in provider.
+ *
+ * This may happen asynchronously and so is a best effort operation.
+ * Some buffers may still be encrypted with a previous key.
+ *
+ * @param a key object for the encryption callback
+ *
+ * return success or an error code
+ */
+ wsrep_status_t (*enc_set_key)(wsrep_t* wsrep, const wsrep_enc_key_t* key);
+
+ /*!
+ * @brief Opens connection to cluster
+ *
+ * Returns when either node is ready to operate as a part of the cluster
+ * or fails to reach operating status.
+ *
+ * @param wsrep provider handle
+ * @param cluster_name unique symbolic cluster name
+ * @param cluster_url URL-like cluster address (backend://address)
+ * @param state_donor name of the node to be asked for state transfer.
+ * @param bootstrap a flag to request initialization of a new wsrep
+ * service rather then a connection to the existing one.
+ * cluster_url may still carry important initialization
+ * parameters, like backend spec and/or listen address.
+ */
+ wsrep_status_t (*connect) (wsrep_t* wsrep,
+ const char* cluster_name,
+ const char* cluster_url,
+ const char* state_donor,
+ wsrep_bool_t bootstrap);
+
+ /*!
+ * @brief Closes connection to cluster.
+ *
+ * @param wsrep this wsrep handler
+ */
+ wsrep_status_t (*disconnect)(wsrep_t* wsrep);
+
+ /*!
+ * @brief start receiving replication events
+ *
+ * This function does not return until provider is closed or \p exit_loop
+ * parameter to wsrep_apply_cb_t() is set to true.
+ *
+ * @param wsrep provider handle
+ * @param recv_ctx receiver context
+ */
+ wsrep_status_t (*recv)(wsrep_t* wsrep, void* recv_ctx);
+
+ /*!
+ * @brief Tells provider that a given writeset has a read view associated
+ * with it.
+ *
+ * @param wsrep provider handle
+ * @param handle writeset handle
+ * @param rv read view GTID established by the caller or if NULL,
+ * provider will infer it internally.
+ */
+ wsrep_status_t (*assign_read_view)(wsrep_t* wsrep,
+ wsrep_ws_handle_t* handle,
+ const wsrep_gtid_t* rv);
+
+ /*!
+ * @brief Certifies transaction with provider.
+ *
+ * Must be called before transaction commit. Returns success code, which
+ * caller must check.
+ *
+ * In case of WSREP_OK, transaction can proceed to commit.
+ * Otherwise transaction must rollback.
+ *
+ * In case of a failure there are two conceptually different situations:
+ * - the writeset was not ordered. In that case meta struct shall contain
+ * undefined GTID: WSREP_UUID_UNDEFINED:WSREP_SEQNO_UNDEFINED.
+ * - the writeset was successfully ordered, but failed certification.
+ * In this case meta struct shall contain a valid GTID.
+ *
+ * Regardless of the return code, if meta struct contains a valid GTID
+ * the commit order critical section must be entered with that GTID.
+ *
+ * @param wsrep provider handle
+ * @param conn_id connection ID
+ * @param ws_handle writeset of committing transaction
+ * @param flags fine tuning the replication WSREP_FLAG_*
+ * @param meta transaction meta data
+ *
+ * @retval WSREP_OK writeset successfully certified, can commit
+ * @retval WSREP_TRX_FAIL must rollback transaction
+ * @retval WSREP_CONN_FAIL must close client connection
+ * @retval WSREP_NODE_FAIL must close all connections and reinit
+ */
+ wsrep_status_t (*certify)(wsrep_t* wsrep,
+ wsrep_conn_id_t conn_id,
+ wsrep_ws_handle_t* ws_handle,
+ uint32_t flags,
+ wsrep_trx_meta_t* meta);
+
+ /*!
+ * @brief Enters commit order critical section.
+ *
+ * Anything executed between this call and commit_order_leave() will be
+ * executed in provider enforced order.
+ *
+ * @param wsrep provider handle
+ * @param ws_handle internal provider writeset handle
+ * @param meta transaction meta data
+ *
+ * @retval WSREP_OK commit order entered successfully
+ * @retval WSREP_NODE_FAIL must close all connections and reinit
+ */
+ wsrep_status_t (*commit_order_enter)(wsrep_t* wsrep,
+ const wsrep_ws_handle_t* ws_handle,
+ const wsrep_trx_meta_t* meta);
+
+ /*!
+ * @brief Leaves commit order critical section
+ *
+ * Anything executed between commit_order_enter() and this call will be
+ * executed in provider enforced order.
+ *
+ * @param wsrep provider handle
+ * @param ws_handle internal provider writeset handle
+ * @param meta transaction meta data
+ * @param error buffer containing error info (null/empty for no error)
+ *
+ * @retval WSREP_OK commit order left successfully
+ * @retval WSREP_NODE_FAIL must close all connections and reinit
+ */
+ wsrep_status_t (*commit_order_leave)(wsrep_t* wsrep,
+ const wsrep_ws_handle_t* ws_handle,
+ const wsrep_trx_meta_t* meta,
+ const wsrep_buf_t* error);
+
+ /*!
+ * @brief Releases resources after transaction commit/rollback.
+ *
+ * Ends total order critical section.
+ *
+ * @param wsrep provider handle
+ * @param ws_handle writeset of committing transaction
+ * @retval WSREP_OK release succeeded
+ */
+ wsrep_status_t (*release) (wsrep_t* wsrep,
+ wsrep_ws_handle_t* ws_handle);
+
+ /*!
+ * @brief Replay trx as a slave writeset
+ *
+ * If local trx has been aborted by brute force, and it has already
+ * replicated before this abort, we must try if we can apply it as
+ * slave trx. Note that slave nodes see only trx writesets and certification
+ * test based on write set content can be different to DBMS lock conflicts.
+ *
+ * @param wsrep provider handle
+ * @param ws_handle writeset of committing transaction
+ * @param trx_ctx transaction context
+ *
+ * @retval WSREP_OK cluster commit succeeded
+ * @retval WSREP_TRX_FAIL must rollback transaction
+ * @retval WSREP_BF_ABORT brute force abort happened after trx replicated
+ * must rollback transaction and try to replay
+ * @retval WSREP_CONN_FAIL must close client connection
+ * @retval WSREP_NODE_FAIL must close all connections and reinit
+ */
+ wsrep_status_t (*replay_trx)(wsrep_t* wsrep,
+ const wsrep_ws_handle_t* ws_handle,
+ void* trx_ctx);
+
+ /*!
+ * @brief Abort certify() call of another thread.
+ *
+ * It is possible, that some high-priority transaction needs to abort
+ * another transaction which is in certify() call waiting for resources.
+ *
+ * The kill routine checks that abort is not attempted against a transaction
+ * which is front of the caller (in total order).
+ *
+ * If the abort was successful, the victim sequence number is stored
+ * into location pointed by the victim_seqno.
+ *
+ * @param wsrep provider handle
+ * @param bf_seqno seqno of brute force trx, running this cancel
+ * @param victim_trx transaction to be aborted, and which is committing
+ * @param victim_seqno seqno of the victim transaction if assigned
+ *
+ * @retval WSREP_OK abort succeeded
+ * @retval WSREP_NOT_ALLOWED the provider declined the abort request
+ * @retval WSREP_TRX_MISSING the victim_trx was missing
+ * @retval WSREP_WARNING abort failed
+ */
+ wsrep_status_t (*abort_certification)(wsrep_t* wsrep,
+ wsrep_seqno_t bf_seqno,
+ wsrep_trx_id_t victim_trx,
+ wsrep_seqno_t* victim_seqno);
+
+ /*!
+ * @brief Send a rollback fragment on behalf of trx
+ *
+ * @param wsrep provider handle
+ * @param trx transaction to be rolled back
+ * @param data data to append to the fragment
+ *
+ * @retval WSREP_OK rollback fragment sent successfully
+ */
+ wsrep_status_t (*rollback)(wsrep_t* wsrep,
+ wsrep_trx_id_t trx,
+ const wsrep_buf_t* data);
+
+ /*!
+ * @brief Appends a row reference to transaction writeset
+ *
+ * Both copy flag and key_type can be ignored by provider (key type
+ * interpreted as WSREP_KEY_EXCLUSIVE).
+ *
+ * @param wsrep provider handle
+ * @param ws_handle writeset handle
+ * @param keys array of keys
+ * @param count length of the array of keys
+ * @param type type of the key
+ * @param copy can be set to FALSE if keys persist through commit.
+ */
+ wsrep_status_t (*append_key)(wsrep_t* wsrep,
+ wsrep_ws_handle_t* ws_handle,
+ const wsrep_key_t* keys,
+ size_t count,
+ enum wsrep_key_type type,
+ wsrep_bool_t copy);
+
+ /*!
+ * @brief Appends data to transaction writeset
+ *
+ * This method can be called any time before certify() call and it appends
+ * a data buffer to the transaction writeset.
+ * Repeated calls of the method will result in direct buffer concatenation
+ * and all data will be passed as a single buffer to the apply callback.
+ *
+ * Both copy and unordered flags can be ignored by provider.
+ *
+ * @param wsrep provider handle
+ * @param ws_handle writeset handle
+ * @param data array of data buffers
+ * @param count buffer count
+ * @param type type of data
+ * @param copy can be set to FALSE if data persists through commit.
+ */
+ wsrep_status_t (*append_data)(wsrep_t* wsrep,
+ wsrep_ws_handle_t* ws_handle,
+ const wsrep_buf_t* data,
+ size_t count,
+ enum wsrep_data_type type,
+ wsrep_bool_t copy);
+
+ /*!
+ * @brief Blocks until the given GTID is committed
+ *
+ * This call will block the caller until the given GTID
+ * is guaranteed to be committed, or until a timeout occurs.
+ * The timeout value is given in parameter tout, if tout is -1,
+ * then the global causal read timeout applies.
+ *
+ * If no pointer upto is provided the call will block until
+ * causal ordering with all possible preceding writes in the
+ * cluster is guaranteed.
+ *
+ * If pointer to gtid is non-null, the call stores the global
+ * transaction ID of the last transaction which is guaranteed
+ * to be committed when the call returns.
+ *
+ * @param wsrep provider handle
+ * @param upto gtid to wait upto
+ * @param tout timeout in seconds
+ * -1 wait for global causal read timeout
+ * @param gtid location to store GTID
+ */
+ wsrep_status_t (*sync_wait)(wsrep_t* wsrep,
+ wsrep_gtid_t* upto,
+ int tout,
+ wsrep_gtid_t* gtid);
+
+ /*!
+ * @brief Returns the last committed gtid
+ *
+ * @param gtid location to store GTID
+ */
+ wsrep_status_t (*last_committed_id)(wsrep_t* wsrep,
+ wsrep_gtid_t* gtid);
+
+ /*!
+ * @brief Clears allocated connection context.
+ *
+ * Whenever a new connection ID is passed to wsrep provider through
+ * any of the API calls, a connection context is allocated for this
+ * connection. This call is to explicitly notify provider of connection
+ * closing.
+ *
+ * @param wsrep provider handle
+ * @param conn_id connection ID
+ * @param query the 'set database' query
+ * @param query_len length of query (does not end with 0)
+ */
+ wsrep_status_t (*free_connection)(wsrep_t* wsrep,
+ wsrep_conn_id_t conn_id);
+
+ /*!
+ * @brief Replicates a query and starts "total order isolation" section.
+ *
+ * Regular mode:
+ *
+ * Replicates the action spec and returns success code, which caller must
+ * check. Total order isolation continues until to_execute_end() is called.
+ * Regular "total order isolation" is achieved by calling to_execute_start()
+ * with WSREP_FLAG_TRX_START and WSREP_FLAG_TRX_END set.
+ *
+ * Two-phase mode:
+ *
+ * In this mode a query execution is split in two phases. The first phase is
+ * acquiring total order isolation to access critical section and the
+ * second phase is to release acquired resources in total order.
+ *
+ * To start the first phase the call is made with WSREP_FLAG_TRX_START set.
+ * The action is replicated and success code is returned. The total order
+ * isolation continues until to_execute_end() is called. However, the provider
+ * will keep the reference to the operation for conflict resolution purposes.
+ *
+ * The second phase is started with WSREP_FLAG_TRX_END set. Provider
+ * returns once it has achieved total ordering isolation for second phase.
+ * Total order isolation continues until to_execute_end() is called.
+ * All references to the operation are cleared by provider before
+ * call to to_execute_end() returns.
+ *
+ * @param wsrep provider handle
+ * @param conn_id connection ID
+ * @param keys array of keys
+ * @param keys_num length of the array of keys
+ * @param action action buffer array to be executed
+ * @param count action buffer count
+ * @param flags flags
+ * @param meta transaction meta data
+ *
+ * @retval WSREP_OK cluster commit succeeded
+ * @retval WSREP_CONN_FAIL must close client connection
+ * @retval WSREP_NODE_FAIL must close all connections and reinit
+ */
+ wsrep_status_t (*to_execute_start)(wsrep_t* wsrep,
+ wsrep_conn_id_t conn_id,
+ const wsrep_key_t* keys,
+ size_t keys_num,
+ const wsrep_buf_t* action,
+ size_t count,
+ uint32_t flags,
+ wsrep_trx_meta_t* meta);
+
+ /*!
+ * @brief Ends the total order isolation section.
+ *
+ * Marks the end of total order isolation. TO locks are freed
+ * and other transactions are free to commit from this point on.
+ *
+ * @param wsrep provider handle
+ * @param conn_id connection ID
+ * @param error error information about TOI operation (empty for no error)
+ *
+ * @retval WSREP_OK cluster commit succeeded
+ * @retval WSREP_CONN_FAIL must close client connection
+ * @retval WSREP_NODE_FAIL must close all connections and reinit
+ */
+ wsrep_status_t (*to_execute_end)(wsrep_t* wsrep,
+ wsrep_conn_id_t conn_id,
+ const wsrep_buf_t* error);
+
+
+ /*!
+ * @brief Collects preordered replication events into a writeset.
+ *
+ * @param wsrep wsrep provider handle
+ * @param handle a handle associated with a given writeset
+ * @param data an array of data buffers.
+ * @param count length of data buffer array.
+ * @param copy whether provider needs to make a copy of events.
+ *
+ * @retval WSREP_OK cluster-wide commit succeeded
+ * @retval WSREP_TRX_FAIL operation failed (e.g. trx size exceeded limit)
+ * @retval WSREP_NODE_FAIL must close all connections and reinit
+ */
+ wsrep_status_t (*preordered_collect) (wsrep_t* wsrep,
+ wsrep_po_handle_t* handle,
+ const wsrep_buf_t* data,
+ size_t count,
+ wsrep_bool_t copy);
+
+ /*!
+ * @brief "Commits" preordered writeset to cluster.
+ *
+ * The contract is that the writeset will be committed in the same (partial)
+ * order this method was called. Frees resources associated with the writeset
+ * handle and reinitializes the handle.
+ *
+ * @param wsrep wsrep provider handle
+ * @param po_handle a handle associated with a given writeset
+ * @param source_id ID of the event producer, also serves as the partial order
+ * or stream ID - events with different source_ids won't be
+ * ordered with respect to each other.
+ * @param flags WSREP_FLAG_... flags
+ * @param pa_range the number of preceding events this event can be processed
+ * in parallel with. A value of 0 means strict serial
+ * processing. Note: commits always happen in wsrep order.
+ * @param commit 'true' to commit writeset to cluster (replicate) or
+ * 'false' to rollback (cancel) the writeset.
+ *
+ * @retval WSREP_OK cluster-wide commit succeeded
+ * @retval WSREP_TRX_FAIL operation failed (e.g. NON-PRIMARY component)
+ * @retval WSREP_NODE_FAIL must close all connections and reinit
+ */
+ wsrep_status_t (*preordered_commit) (wsrep_t* wsrep,
+ wsrep_po_handle_t* handle,
+ const wsrep_uuid_t* source_id,
+ uint32_t flags,
+ int pa_range,
+ wsrep_bool_t commit);
+
+ /*!
+ * @brief Signals to wsrep provider that state snapshot has been sent to
+ * joiner.
+ *
+ * @param wsrep provider handle
+ * @param state_id state ID
+ * @param rcode 0 or negative error code of the operation.
+ */
+ wsrep_status_t (*sst_sent)(wsrep_t* wsrep,
+ const wsrep_gtid_t* state_id,
+ int rcode);
+
+ /*!
+ * @brief Signals to wsrep provider that new state snapshot has been received.
+ * May deadlock if called from sst_prepare_cb.
+ *
+ * @param wsrep provider handle
+ * @param state_id state ID
+ * @param state initial state provided by SST donor
+ * @param rcode 0 or negative error code of the operation.
+ */
+ wsrep_status_t (*sst_received)(wsrep_t* wsrep,
+ const wsrep_gtid_t* state_id,
+ const wsrep_buf_t* state,
+ int rcode);
+
+
+ /*!
+ * @brief Generate request for consistent snapshot.
+ *
+ * If successful, this call will generate internally SST request
+ * which in turn triggers calling SST donate callback on the nodes
+ * specified in donor_spec. If donor_spec is null, callback is
+ * called only locally. This call will block until sst_sent is called
+ * from callback.
+ *
+ * @param wsrep provider handle
+ * @param msg context message for SST donate callback
+ * @param msg_len length of context message
+ * @param donor_spec list of snapshot donors
+ */
+ wsrep_status_t (*snapshot)(wsrep_t* wsrep,
+ const wsrep_buf_t* msg,
+ const char* donor_spec);
+
+ /*!
+ * @brief Returns an array of status variables.
+ * Array is terminated by Null variable name.
+ *
+ * @param wsrep provider handle
+ * @return array of struct wsrep_status_var.
+ */
+ struct wsrep_stats_var* (*stats_get) (wsrep_t* wsrep);
+
+ /*!
+ * @brief Release resources that might be associated with the array.
+ *
+ * @param wsrep provider handle.
+ * @param var_array array returned by stats_get().
+ */
+ void (*stats_free) (wsrep_t* wsrep, struct wsrep_stats_var* var_array);
+
+ /*!
+ * @brief Reset some stats variables to initial value, provider-dependent.
+ *
+ * @param wsrep provider handle.
+ */
+ void (*stats_reset) (wsrep_t* wsrep);
+
+ /*!
+ * @brief Pauses writeset applying/committing.
+ *
+ * @return global sequence number of the paused state or negative error code.
+ */
+ wsrep_seqno_t (*pause) (wsrep_t* wsrep);
+
+ /*!
+ * @brief Resumes writeset applying/committing.
+ */
+ wsrep_status_t (*resume) (wsrep_t* wsrep);
+
+ /*!
+ * @brief Desynchronize from cluster
+ *
+ * Effectively turns off flow control for this node, allowing it
+ * to fall behind the cluster.
+ */
+ wsrep_status_t (*desync) (wsrep_t* wsrep);
+
+ /*!
+ * @brief Request to resynchronize with cluster.
+ *
+ * Effectively turns on flow control. Asynchronous - actual synchronization
+ * event to be delivered via sync_cb.
+ */
+ wsrep_status_t (*resync) (wsrep_t* wsrep);
+
+ /*!
+ * @brief Acquire global named lock
+ *
+ * @param wsrep wsrep provider handle
+ * @param name lock name
+ * @param shared shared or exclusive lock
+ * @param owner 64-bit owner ID
+ * @param tout timeout in nanoseconds.
+ * 0 - return immediately, -1 wait forever.
+ * @return wsrep status or negative error code
+ * @retval -EDEADLK lock was already acquired by this thread
+ * @retval -EBUSY lock was busy
+ */
+ wsrep_status_t (*lock) (wsrep_t* wsrep,
+ const char* name, wsrep_bool_t shared,
+ uint64_t owner, int64_t tout);
+
+ /*!
+ * @brief Release global named lock
+ *
+ * @param wsrep wsrep provider handle
+ * @param name lock name
+ * @param owner 64-bit owner ID
+ * @return wsrep status or negative error code
+ * @retval -EPERM lock does not belong to this owner
+ */
+ wsrep_status_t (*unlock) (wsrep_t* wsrep, const char* name, uint64_t owner);
+
+ /*!
+ * @brief Check if global named lock is locked
+ *
+ * @param wsrep wsrep provider handle
+ * @param name lock name
+ * @param owner if not NULL will contain 64-bit owner ID
+ * @param node if not NULL will contain owner's node UUID
+ * @return true if lock is locked
+ */
+ wsrep_bool_t (*is_locked) (wsrep_t* wsrep, const char* name, uint64_t* conn,
+ wsrep_uuid_t* node);
+
+ /*!
+ * wsrep provider name
+ */
+ const char* provider_name;
+
+ /*!
+ * wsrep provider version
+ */
+ const char* provider_version;
+
+ /*!
+ * wsrep provider vendor name
+ */
+ const char* provider_vendor;
+
+ /*!
+ * @brief Frees allocated resources before unloading the library.
+ * @param wsrep provider handle
+ */
+ void (*free)(wsrep_t* wsrep);
+
+ void *dlh; //!< reserved for future use
+ void *ctx; //!< reserved for implementation private context
+};
+
+
+/*!
+ *
+ * @brief Loads wsrep library
+ *
+ * @param spec path to wsrep library. If NULL or WSREP_NONE initializes dummy
+ * pass-through implementation.
+ * @param hptr wsrep handle
+ * @param log_cb callback to handle loader messages. Otherwise writes to stderr.
+ *
+ * @return zero on success, errno on failure
+ */
+int wsrep_load(const char* spec, wsrep_t** hptr, wsrep_log_cb_t log_cb);
+
+/*!
+ * @brief Unloads the wsrep library. The application must call
+ * wsrep->free() before unload to release library side resources.
+ *
+ * @param hptr wsrep handler pointer
+ */
+void wsrep_unload(wsrep_t* hptr);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* WSREP_H */