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evrpc(3) | Library Functions Manual | evrpc(3) |
NAME
evrpc -This header files provides basic support for an RPC server and client.
SYNOPSIS
#include <event2/rpc.h>Macros
#define EVRPC_GENERATE(rpcname, reqstruct, rplystruct)
Enumerations
enum EVRPC_HOOK_RESULT { EVRPC_TERMINATE = -1, EVRPC_CONTINUE = 0, EVRPC_PAUSE = 1 }
Functions
void * evrpc_add_hook (void *vbase, enum EVRPC_HOOK_TYPE hook_type, int(*cb)(void *, struct evhttp_request *, struct evbuffer *, void *), void *cb_arg)
Detailed Description
This header files provides basic support for an RPC server and client.EVRPC_HEADER(SendCommand, Request, Reply);
SendCommand is the name of the RPC command. Request is the name of a structure generated by event_rpcgen.py. It contains all parameters relating to the SendCommand RPC. The server needs to fill in the Reply structure. Reply is the name of a structure generated by event_rpcgen.py. It contains the answer to the RPC.
To register an RPC with an HTTP server, you need to first create an RPC base with:
struct evrpc_base *base = evrpc_init(http);
A specific RPC can then be registered with
EVRPC_REGISTER(base, SendCommand, Request, Reply, FunctionCB, arg);
when the server receives an appropriately formatted RPC, the user callback is invoked. The callback needs to fill in the reply structure.
void FunctionCB(EVRPC_STRUCT(SendCommand)* rpc, void *arg);
To send the reply, call EVRPC_REQUEST_DONE(rpc);
See the regression test for an example.
Macro Definition Documentation
#define EVRPC_GENERATE(rpcname, reqstruct, rplystruct)
Value:
int evrpc_send_request_##rpcname(struct evrpc_pool *pool, struct reqstruct *request, struct rplystruct *reply, void (*cb)(struct evrpc_status *, struct reqstruct *, struct rplystruct *, void *cbarg), void *cbarg) { return evrpc_send_request_generic(pool, request, reply, (void (*)(struct evrpc_status *, void *, void *, void *))cb, cbarg, #rpcname, (void (*)(struct evbuffer *, void *))reqstruct##_marshal, (void (*)(void *))rplystruct##_clear, (int (*)(void *, struct evbuffer *))rplystruct##_unmarshal); }
Generates the code for receiving and sending an RPC message. EVRPC_GENERATE is used to create the code corresponding to sending and receiving a particular RPC message
Parameters:
See Also:
#define EVRPC_HEADER(rpcname, reqstruct, rplystruct)
Value:
EVRPC_STRUCT(rpcname) { struct evrpc_hook_meta *hook_meta; struct reqstruct* request; struct rplystruct* reply; struct evrpc* rpc; struct evhttp_request* http_req; struct evbuffer* rpc_data; }; int evrpc_send_request_##rpcname(struct evrpc_pool *, struct reqstruct *, struct rplystruct *, void (*)(struct evrpc_status *, struct reqstruct *, struct rplystruct *, void *cbarg), void *);
Creates the definitions and prototypes for an RPC. You need to use EVRPC_HEADER to create structures and function prototypes needed by the server and client implementation. The structures have to be defined in an .rpc file and converted to source code via event_rpcgen.py
Parameters:
See Also:
#define EVRPC_MAKE_CTX(rpcname, reqstruct, rplystruct, pool, request, reply, cb, cbarg)
Value:
evrpc_make_request_ctx(pool, request, reply, #rpcname, (void (*)(struct evbuffer *, void *))reqstruct##_marshal, (void (*)(void *))rplystruct##_clear, (int (*)(void *, struct evbuffer *))rplystruct##_unmarshal, (void (*)(struct evrpc_status *, void *, void *, void *))cb, cbarg)
Creates a context structure that contains rpc specific information. EVRPC_MAKE_CTX is used to populate a RPC specific context that contains information about marshaling the RPC data types.
Parameters:
#define EVRPC_MAKE_REQUEST(name, pool, request, reply, cb, cbarg) evrpc_send_request_##name((pool), (request), (reply), (cb), (cbarg))
launches an RPC and sends it to the server EVRPC_MAKE_REQUEST() is used by the client to send an RPC to the server.Parameters:
Returns:
#define EVRPC_REGISTER(base, name, request, reply, callback, cbarg)
Value:
evrpc_register_generic(base, #name, (void (*)(struct evrpc_req_generic *, void *))callback, cbarg, (void *(*)(void *))request##_new, NULL, (void (*)(void *))request##_free, (int (*)(void *, struct evbuffer *))request##_unmarshal, (void *(*)(void *))reply##_new, NULL, (void (*)(void *))reply##_free, (int (*)(void *))reply##_complete, (void (*)(struct evbuffer *, void *))reply##_marshal)
register RPCs with the HTTP Server registers a new RPC with the HTTP server, each RPC needs to have a unique name under which it can be identified.
Parameters:
#define EVRPC_REQUEST_DONE(rpc_req)
Value:
do { struct evrpc_req_generic *_req = (struct evrpc_req_generic *)(rpc_req); evrpc_request_done(_req); } while (/*CONSTCOND*/0)
Creates the reply to an RPC request. EVRPC_REQUEST_DONE is used to answer a request; the reply is expected to have been filled in. The request and reply pointers become invalid after this call has finished.
Parameters:
#define EVRPC_REQUEST_HTTP(rpc_req) (rpc_req)->http_req
Provides access to the HTTP request object underlying an RPC. Access to the underlying http object; can be used to look at headers or for getting the remote ip addressParameters:
Returns:
#define EVRPC_STRUCT(rpcname) struct evrpc_req__##rpcname
The type of a specific RPC Message. Parameters:
#define EVRPC_UNREGISTER(base, name) evrpc_unregister_rpc((base), #name)
Unregisters an already registered RPC. Parameters:Returns:
See Also:
#define EVTAG_ASSIGN(msg, member, value) (*(msg)->base->member##_assign)((msg), (value))
Assigns a value to the member in the message. Parameters:
#define EVTAG_ASSIGN_WITH_LEN(msg, member, value, len) (*(msg)->base->member##_assign)((msg), (value), (len))
Assigns a value to the member in the message. Parameters:
#define EVTAG_GET(msg, member, pvalue) (*(msg)->base->member##_get)((msg), (pvalue))
Returns the value for a member. Parameters:Returns:
#define EVTAG_GET_WITH_LEN(msg, member, pvalue, plen) (*(msg)->base->member##_get)((msg), (pvalue), (plen))
Returns the value for a member. Parameters:Returns:
#define EVTAG_HAS(msg, member) ((msg)->member##_set == 1)
Determines if the member has been set in the message. Parameters:Returns:
#define INPUT EVRPC_INPUT
Deprecated alias for EVRPC_INPUT. Not available on windows, where it conflicts with platform headers.#define OUTPUT EVRPC_OUTPUT
Deprecated alias for EVRPC_OUTPUT. Not available on windows, where it conflicts with platform headers.Enumeration Type Documentation
enum EVRPC_HOOK_RESULT
Return value from hook processing functions.
Enumerator
- EVRPC_TERMINATE
- indicates the rpc should be terminated
- EVRPC_CONTINUE
- continue processing the rpc
- EVRPC_PAUSE
- pause processing request until resumed
enum EVRPC_HOOK_TYPE
Hooks for changing the input and output of RPCs; this can be used to implement compression, authentication, encryption, ...
Enumerator
- EVRPC_INPUT
- apply the function to an input hook
- EVRPC_OUTPUT
- apply the function to an output hook
Function Documentation
void* evrpc_add_hook (void *vbase, enum EVRPC_HOOK_TYPEhook_type, int(*)(void *, struct evhttp_request *, struct evbuffer *, void *)cb, void *cb_arg)
adds a processing hook to either an rpc base or rpc pool If a hook returns TERMINATE, the processing is aborted. On CONTINUE, the request is immediately processed after the hook returns. If the hook returns PAUSE, request processing stops until evrpc_resume_request() has been called.The add functions return handles that can be used for removing hooks.
Parameters:
Returns:
See Also:
void evrpc_free (struct evrpc_base *base)
Frees the evrpc base. For now, you are responsible for making sure that no rpcs are ongoing.Parameters:
See Also:
void evrpc_hook_add_meta (void *ctx, const char *key, const void *data, size_tdata_size)
adds meta data to request evrpc_hook_add_meta() allows hooks to add meta data to a request. for a client request, the meta data can be inserted by an outgoing request hook and retrieved by the incoming request hook.Parameters:
int evrpc_hook_find_meta (void *ctx, const char *key, void **data, size_t *data_size)
retrieves meta data previously associated evrpc_hook_find_meta() can be used to retrieve meta data associated to a request by a previous hook.Parameters:
Returns:
struct evhttp_connection* evrpc_hook_get_connection (void *ctx) [read]
returns the connection object associated with the request Parameters:Returns:
struct evrpc_base* evrpc_init (struct evhttp *server) [read]
Creates a new rpc base from which RPC requests can be received. Parameters:Returns:
See Also:
int evrpc_make_request (struct evrpc_request_wrapper *ctx)
Makes an RPC request based on the provided context. This is a low-level function and should not be used directly unless a custom context object is provided. Use EVRPC_MAKE_REQUEST() instead.Parameters:
Returns:
See Also:
void evrpc_pool_add_connection (struct evrpc_pool *pool, struct evhttp_connection *evcon)
Adds a connection over which rpc can be dispatched to the pool. The connection object must have been newly created.Parameters:
void evrpc_pool_free (struct evrpc_pool *pool)
frees an rpc connection pool Parameters:See Also:
struct evrpc_pool* evrpc_pool_new (struct event_base *base) [read]
creates an rpc connection pool a pool has a number of connections associated with it. rpc requests are always made via a pool.Parameters:
Returns:
See Also:
void evrpc_pool_remove_connection (struct evrpc_pool *pool, struct evhttp_connection *evcon)
Removes a connection from the pool. The connection object must have been newly created.Parameters:
void evrpc_pool_set_timeout (struct evrpc_pool *pool, inttimeout_in_secs)
Sets the timeout in secs after which a request has to complete. The RPC is completely aborted if it does not complete by then. Setting the timeout to 0 means that it never timeouts and can be used to implement callback type RPCs.Any connection already in the pool will be updated with the new timeout. Connections added to the pool after set_timeout has be called receive the pool timeout only if no timeout has been set for the connection itself.
Parameters:
int evrpc_register_generic (struct evrpc_base *base, const char *name, void(*)(struct evrpc_req_generic *, void *)callback, void *cbarg, void *(*)(void *)req_new, void *req_new_arg, void(*)(void *)req_free, int(*)(void *, struct evbuffer *)req_unmarshal, void *(*)(void *)rpl_new, void *rpl_new_arg, void(*)(void *)rpl_free, int(*)(void *)rpl_complete, void(*)(struct evbuffer *, void *)rpl_marshal)
Function for registering a generic RPC with the RPC base. Do not call this function directly, use EVRPC_REGISTER() instead.See Also:
int evrpc_register_rpc (struct evrpc_base *, struct evrpc *, void(*)(struct evrpc_req_generic *, void *), void *)
Low level function for registering an RPC with a server. Use EVRPC_REGISTER() instead.See Also:
int evrpc_remove_hook (void *vbase, enum EVRPC_HOOK_TYPEhook_type, void *handle)
removes a previously added hook Parameters:Returns:
See Also:
int evrpc_resume_request (void *vbase, void *ctx, enum EVRPC_HOOK_RESULTres)
resume a paused request Parameters:
int evrpc_send_request_generic (struct evrpc_pool *pool, void *request, void *reply, void(*)(struct evrpc_status *, void *, void *, void *)cb, void *cb_arg, const char *rpcname, void(*)(struct evbuffer *, void *)req_marshal, void(*)(void *)rpl_clear, int(*)(void *, struct evbuffer *)rpl_unmarshal)
Function for sending a generic RPC request. Do not call this function directly, use EVRPC_MAKE_REQUEST() instead.See Also:
Author
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