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raft.h
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/
raft.h
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#ifndef RAFT_H_
#define RAFT_H_
/**
* Copyright (c) 2013, Willem-Hendrik Thiart
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*
* @file
* @author Willem Thiart himself@willemthiart.com
* @version 0.1
*/
typedef struct
{
/** The ID that this node used to have.
* So that we can tell which nodes were removed/added when the
* configuration changes */
int old_id;
/** User data pointer for addressing.
* Examples of what this could be:
* - void* pointing to implementor's networking data
* - a (IP,Port) tuple */
void* udata_address;
} raft_node_configuration_t;
typedef struct
{
/* candidate's term */
int term;
/* candidate requesting vote */
int candidate_id;
/* idx of candidate's last log entry */
int last_log_idx;
/* term of candidate's last log entry */
int last_log_term;
} msg_requestvote_t;
typedef struct
{
/* the entry's unique ID */
unsigned int id;
/* entry data */
unsigned char* data;
/* length of entry data */
unsigned int len;
} msg_entry_t;
typedef struct
{
/* the entry's unique ID */
unsigned int id;
/* whether or not the entry was committed */
int was_committed;
} msg_entry_response_t;
typedef struct
{
/* currentTerm, for candidate to update itself */
int term;
/* true means candidate received vote */
int vote_granted;
} msg_requestvote_response_t;
typedef struct
{
int term;
int leader_id;
int prev_log_idx;
int prev_log_term;
int n_entries;
msg_entry_t* entries;
int leader_commit;
} msg_appendentries_t;
typedef struct
{
/* currentTerm, for leader to update itself */
int term;
/* success true if follower contained entry matching
* prevLogidx and prevLogTerm */
int success;
/* Non-Raft fields follow: */
/* Having the following fields allows us to do less book keeping in
* regards to full fledged RPC */
/* This is the highest log IDX we've received and appended to our log */
int current_idx;
/* The first idx that we received within the appendentries message */
int first_idx;
} msg_appendentries_response_t;
typedef void* raft_server_t;
typedef void* raft_node_t;
typedef enum
{
RAFT_MSG_REQUESTVOTE,
RAFT_MSG_REQUESTVOTE_RESPONSE,
RAFT_MSG_APPENDENTRIES,
RAFT_MSG_APPENDENTRIES_RESPONSE,
RAFT_MSG_ENTRY,
RAFT_MSG_ENTRY_RESPONSE,
} raft_message_type_e;
/**
* @param raft The Raft server making this callback
* @param udata User data that is passed from Raft server
* @param node The peer's ID that we are sending this message to
* @return 0 on error */
typedef int (
*func_send_requestvote_f
) (
raft_server_t* raft,
void *udata,
int node,
msg_requestvote_t* msg
);
/**
* @param raft The Raft server making this callback
* @param udata User data that is passed from Raft server
* @param node The peer's ID that we are sending this message to
* @return 0 on error */
typedef int (
*func_send_requestvote_response_f
) (
raft_server_t* raft,
void *udata,
int node,
msg_requestvote_response_t* msg
);
/**
* @param raft The Raft server making this callback
* @param udata User data that is passed from Raft server
* @param node The peer's ID that we are sending this message to
* @return 0 on error */
typedef int (
*func_send_appendentries_f
) (
raft_server_t* raft,
void *udata,
int node,
msg_appendentries_t* msg
);
/**
* @param raft The Raft server making this callback
* @param udata User data that is passed from Raft server
* @param node The peer's ID that we are sending this message to
* @return 0 on error */
typedef int (
*func_send_appendentries_response_f
) (
raft_server_t* raft,
void *udata,
int node,
msg_appendentries_response_t* msg
);
/**
* @param raft The Raft server making this callback
* @param udata User data that is passed from Raft server
* @param node The peer's ID that we are sending this message to
* @return 0 on error */
typedef int (
*func_send_entries_f
) (
raft_server_t* raft,
void *udata,
int node,
msg_entry_t* msg
);
/**
* @param raft The Raft server making this callback
* @param udata User data that is passed from Raft server
* @param node The peer's ID that we are sending this message to
* @return 0 on error */
typedef int (
*func_send_entries_response_f
) (
raft_server_t* raft,
void *udata,
int node,
msg_entry_response_t* msg
);
#ifndef HAVE_FUNC_LOG
#define HAVE_FUNC_LOG
typedef void (
*func_log_f
) (
raft_server_t* raft,
void *udata,
const char *buf,
...
);
#endif
/**
* Apply this log to the state machine
* @param raft The Raft server making this callback
* @param udata User data that is passed from Raft server
* @param data Data to be applied to the log
* @param len Length in bytes of data to be applied
* @return 0 on error */
typedef int (
*func_applylog_f
) (
raft_server_t* raft,
void *udata,
const unsigned char *data,
const int len
);
typedef struct
{
func_send_requestvote_f send_requestvote;
func_send_requestvote_response_f send_requestvote_response;
func_send_appendentries_f send_appendentries;
func_send_appendentries_response_f send_appendentries_response;
func_send_entries_f send_entries;
func_send_entries_response_f send_entries_response;
func_log_f log;
func_applylog_f applylog;
} raft_cbs_t;
typedef struct
{
/* entry's term */
unsigned int term;
/* the entry's unique ID */
unsigned int id;
/* entry data */
unsigned char* data;
/* length of entry data */
unsigned int len;
/* number of nodes that have this entry */
unsigned int num_nodes;
} raft_entry_t;
/**
* Initialise a new Raft server
*
* Request timeout defaults to 200 milliseconds
* Election timeout defaults to 1000 milliseconds
*
* @return newly initialised Raft server */
raft_server_t* raft_new();
/**
* De-Initialise Raft server
* Free all memory */
void raft_free(raft_server_t* me_);
/**
* Set callbacks.
* Callbacks need to be set by the user for CRaft to work.
*
* @param funcs Callbacks
* @param udata "User data" - user's context that's included in a callback */
void raft_set_callbacks(raft_server_t* me, raft_cbs_t* funcs, void* udata);
/**
* Set configuration
* @param nodes Array of nodes. End of array is marked by NULL entry
* @param my_idx Index of the node that refers to this Raft server */
void raft_set_configuration(raft_server_t* me_,
raft_node_configuration_t* nodes, int my_idx);
/**
* Set election timeout
* The amount of time that needs to elapse before we assume the leader is down
* @param msec Election timeout in milliseconds */
void raft_set_election_timeout(raft_server_t* me, int msec);
/**
* Set request timeout in milliseconds
* The amount of time before we resend an appendentries message
* @param msec Request timeout in milliseconds */
void raft_set_request_timeout(raft_server_t* me_, int msec);
/**
* Process events that are dependent on time passing
* @param msec_elapsed Time in milliseconds since the last call
* @return 0 on error */
int raft_periodic(raft_server_t* me, int msec_elapsed);
/**
* Receive an appendentries message
* @param node Index of the node who sent us this message
* @param ae The appendentries message
* @return 0 on error */
int raft_recv_appendentries(raft_server_t* me, int node,
msg_appendentries_t* ae);
/**
* Receive a response from an appendentries message we sent
* @param node Index of the node who sent us this message
* @param r The appendentries response message
* @return 0 on error */
int raft_recv_appendentries_response(raft_server_t* me_,
int node, msg_appendentries_response_t* r);
/**
* Receive a requestvote message
* @param node Index of the node who sent us this message
* @param vr The requestvote message
* @return 0 on error */
int raft_recv_requestvote(raft_server_t* me, int node,
msg_requestvote_t* vr);
/**
* Receive a response from a requestvote message we sent
* @param node Index of the node who sent us this message
* @param r The requestvote response message
* @param node The node this response was sent by */
int raft_recv_requestvote_response(raft_server_t* me, int node,
msg_requestvote_response_t* r);
/**
* Receive an entry message from client.
* Append the entry to the log
* Send appendentries to followers
* @param node Index of the node who sent us this message
* @param e The entry message */
int raft_recv_entry(raft_server_t* me, int node, msg_entry_t* e);
/**
* @return the server's node ID */
int raft_get_nodeid(raft_server_t* me_);
/**
* @return currently configured election timeout in milliseconds */
int raft_get_election_timeout(raft_server_t* me);
/**
* @return number of nodes that this server has */
int raft_get_num_nodes(raft_server_t* me);
/**
* @return number of items within log */
int raft_get_log_count(raft_server_t* me);
/**
* @return current term */
int raft_get_current_term(raft_server_t* me);
/**
* @return current log index */
int raft_get_current_idx(raft_server_t* me);
/**
* @return 1 if follower; 0 otherwise */
int raft_is_follower(raft_server_t* me);
/**
* @return 1 if leader; 0 otherwise */
int raft_is_leader(raft_server_t* me);
/**
* @return 1 if candidate; 0 otherwise */
int raft_is_candidate(raft_server_t* me);
/**
* @return currently elapsed timeout in milliseconds */
int raft_get_timeout_elapsed(raft_server_t* me);
/**
* @return request timeout in milliseconds */
int raft_get_request_timeout(raft_server_t* me_);
/**
* @return index of last applied entry */
int raft_get_last_applied_idx(raft_server_t* me);
/**
* @return 1 if node is leader; 0 otherwise */
int raft_node_is_leader(raft_node_t* node);
/**
* @return the node's next index */
int raft_node_get_next_idx(raft_node_t* node);
/**
* @param idx The entry's index
* @return entry from index */
raft_entry_t* raft_get_entry_from_idx(raft_server_t* me_, int idx);
/**
* @param node The node's index
* @return node pointed to by node index */
raft_node_t* raft_get_node(raft_server_t *me_, int node);
/**
* @return number of votes this server has received this election */
int raft_get_nvotes_for_me(raft_server_t* me_);
/**
* @return node ID of who I voted for */
int raft_get_voted_for(raft_server_t* me);
#endif /* RAFT_H_ */