libevent
2.2.1
Event notification library
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This header files provides basic support for an RPC server and client. More...
Go to the source code of this file.
Macros | |
#define | EVRPC_GENERATE(rpcname, reqstruct, rplystruct) |
Generates the code for receiving and sending an RPC message. More... | |
#define | EVRPC_HEADER(rpcname, reqstruct, rplystruct) |
Creates the definitions and prototypes for an RPC. More... | |
#define | EVRPC_MAKE_CTX(rpcname, reqstruct, rplystruct, pool, request, reply, cb, cbarg) |
Creates a context structure that contains rpc specific information. More... | |
#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 More... | |
#define | EVRPC_REGISTER(base, name, request, reply, callback, cbarg) |
register RPCs with the HTTP Server More... | |
#define | EVRPC_REQUEST_DONE(rpc_req) |
Creates the reply to an RPC request. More... | |
#define | EVRPC_REQUEST_HTTP(rpc_req) (rpc_req)->http_req |
Provides access to the HTTP request object underlying an RPC. More... | |
#define | EVRPC_STRUCT(rpcname) struct evrpc_req__##rpcname |
The type of a specific RPC Message. More... | |
#define | EVRPC_UNREGISTER(base, name) evrpc_unregister_rpc((base), #name) |
Unregisters an already registered RPC. More... | |
#define | EVTAG_ARRAY_ADD(msg, member) (*(msg)->base->member##_add)(msg) |
Allocates a new entry in the array and returns it. | |
#define | EVTAG_ARRAY_ADD_VALUE(msg, member, value) (*(msg)->base->member##_add)((msg), (value)) |
Adds a value to an array. | |
#define | EVTAG_ARRAY_GET(msg, member, offset, pvalue) (*(msg)->base->member##_get)((msg), (offset), (pvalue)) |
Gets a variable at the specified offset from the array. | |
#define | EVTAG_ARRAY_LEN(msg, member) ((msg)->member##_length) |
Returns the number of entries in the array. | |
#define | EVTAG_ASSIGN(msg, member, value) (*(msg)->base->member##_assign)((msg), (value)) |
Assigns a value to the member in the message. More... | |
#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. More... | |
#define | EVTAG_GET(msg, member, pvalue) (*(msg)->base->member##_get)((msg), (pvalue)) |
Returns the value for a member. More... | |
#define | EVTAG_GET_WITH_LEN(msg, member, pvalue, plen) (*(msg)->base->member##_get)((msg), (pvalue), (plen)) |
Returns the value for a member. More... | |
#define | EVTAG_HAS(msg, member) ((msg)->member##_set == 1) |
Determines if the member has been set in the message. More... | |
#define | INPUT EVRPC_INPUT |
Deprecated alias for EVRPC_INPUT. More... | |
#define | OUTPUT EVRPC_OUTPUT |
Deprecated alias for EVRPC_OUTPUT. More... | |
Enumerations | |
enum | EVRPC_HOOK_RESULT { EVRPC_TERMINATE = -1, EVRPC_CONTINUE = 0, EVRPC_PAUSE = 1 } |
Return value from hook processing functions. More... | |
enum | EVRPC_HOOK_TYPE { EVRPC_INPUT, EVRPC_OUTPUT } |
Hooks for changing the input and output of RPCs; this can be used to implement compression, authentication, encryption, ... More... | |
Functions | |
EVENT2_EXPORT_SYMBOL void * | evrpc_add_hook (void *vbase, enum EVRPC_HOOK_TYPE hook_type, int(*cb)(void *, struct evhttp_request *, struct evbuffer *, void *), void *cb_arg) |
adds a processing hook to either an rpc base or rpc pool More... | |
EVENT2_EXPORT_SYMBOL void | evrpc_free (struct evrpc_base *base) |
Frees the evrpc base. More... | |
EVENT2_EXPORT_SYMBOL void * | evrpc_get_reply (struct evrpc_req_generic *req) |
EVENT2_EXPORT_SYMBOL void * | evrpc_get_request (struct evrpc_req_generic *req) |
accessors for request and reply | |
EVENT2_EXPORT_SYMBOL int | evrpc_hook_add_meta (void *ctx, const char *key, const void *data, size_t data_size) |
adds meta data to request More... | |
EVENT2_EXPORT_SYMBOL int | evrpc_hook_find_meta (void *ctx, const char *key, void **data, size_t *data_size) |
retrieves meta data previously associated More... | |
EVENT2_EXPORT_SYMBOL struct evhttp_connection * | evrpc_hook_get_connection (void *ctx) |
returns the connection object associated with the request More... | |
EVENT2_EXPORT_SYMBOL struct evrpc_base * | evrpc_init (struct evhttp *server) |
Creates a new rpc base from which RPC requests can be received. More... | |
EVENT2_EXPORT_SYMBOL int | evrpc_make_request (struct evrpc_request_wrapper *ctx) |
Makes an RPC request based on the provided context. More... | |
EVENT2_EXPORT_SYMBOL struct evrpc_request_wrapper * | evrpc_make_request_ctx (struct evrpc_pool *pool, void *request, void *reply, const char *rpcname, void(*req_marshal)(struct evbuffer *, void *), void(*rpl_clear)(void *), int(*rpl_unmarshal)(void *, struct evbuffer *), void(*cb)(struct evrpc_status *, void *, void *, void *), void *cbarg) |
use EVRPC_GENERATE instead | |
EVENT2_EXPORT_SYMBOL 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. More... | |
EVENT2_EXPORT_SYMBOL void | evrpc_pool_free (struct evrpc_pool *pool) |
frees an rpc connection pool More... | |
EVENT2_EXPORT_SYMBOL struct evrpc_pool * | evrpc_pool_new (struct event_base *base) |
creates an rpc connection pool More... | |
EVENT2_EXPORT_SYMBOL void | evrpc_pool_remove_connection (struct evrpc_pool *pool, struct evhttp_connection *evcon) |
Removes a connection from the pool. More... | |
EVENT2_EXPORT_SYMBOL void | evrpc_pool_set_timeout (struct evrpc_pool *pool, int timeout_in_secs) |
Sets the timeout in secs after which a request has to complete. More... | |
EVENT2_EXPORT_SYMBOL int | evrpc_register_generic (struct evrpc_base *base, const char *name, void(*callback)(struct evrpc_req_generic *, void *), void *cbarg, void *(*req_new)(void *), void *req_new_arg, void(*req_free)(void *), int(*req_unmarshal)(void *, struct evbuffer *), void *(*rpl_new)(void *), void *rpl_new_arg, void(*rpl_free)(void *), int(*rpl_complete)(void *), void(*rpl_marshal)(struct evbuffer *, void *)) |
Function for registering a generic RPC with the RPC base. More... | |
EVENT2_EXPORT_SYMBOL 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. More... | |
EVENT2_EXPORT_SYMBOL int | evrpc_remove_hook (void *vbase, enum EVRPC_HOOK_TYPE hook_type, void *handle) |
removes a previously added hook More... | |
EVENT2_EXPORT_SYMBOL void | evrpc_request_done (struct evrpc_req_generic *req) |
completes the server response to an rpc request | |
EVENT2_EXPORT_SYMBOL struct evrpc_pool * | evrpc_request_get_pool (struct evrpc_request_wrapper *ctx) |
accessors for obscure and undocumented functionality | |
EVENT2_EXPORT_SYMBOL void | evrpc_request_set_cb (struct evrpc_request_wrapper *ctx, void(*cb)(struct evrpc_status *, void *request, void *reply, void *arg), void *cb_arg) |
EVENT2_EXPORT_SYMBOL void | evrpc_request_set_pool (struct evrpc_request_wrapper *ctx, struct evrpc_pool *pool) |
EVENT2_EXPORT_SYMBOL int | evrpc_resume_request (void *vbase, void *ctx, enum EVRPC_HOOK_RESULT res) |
resume a paused request More... | |
EVENT2_EXPORT_SYMBOL int | evrpc_send_request_generic (struct evrpc_pool *pool, void *request, void *reply, void(*cb)(struct evrpc_status *, void *, void *, void *), void *cb_arg, const char *rpcname, void(*req_marshal)(struct evbuffer *, void *), void(*rpl_clear)(void *), int(*rpl_unmarshal)(void *, struct evbuffer *)) |
Function for sending a generic RPC request. More... | |
EVENT2_EXPORT_SYMBOL int | evrpc_unregister_rpc (struct evrpc_base *base, const char *name) |
This header files provides basic support for an RPC server and client.
To support RPCs in a server, every supported RPC command needs to be defined and registered.
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.
#define EVRPC_GENERATE | ( | rpcname, | |
reqstruct, | |||
rplystruct | |||
) |
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
rpcname | the name of the RPC |
reqstruct | the name of the RPC request structure |
rplystruct | the name of the RPC reply structure |
#define EVRPC_HEADER | ( | rpcname, | |
reqstruct, | |||
rplystruct | |||
) |
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
rpcname | the name of the RPC |
reqstruct | the name of the RPC request structure |
rplystruct | the name of the RPC reply structure |
#define EVRPC_MAKE_CTX | ( | rpcname, | |
reqstruct, | |||
rplystruct, | |||
pool, | |||
request, | |||
reply, | |||
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.
rpcname | the name of the RPC |
reqstruct | the name of the RPC request structure |
rplystruct | the name of the RPC reply structure |
pool | the evrpc_pool over which to make the request |
request | a pointer to the RPC request structure object |
reply | a pointer to the RPC reply structure object |
cb | the callback function to call when the RPC has completed |
cbarg | the argument to supply to the callback |
#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.
name | the name of the RPC |
pool | the evrpc_pool that contains the connection objects over which the request should be sent. |
request | a pointer to the RPC request structure - it contains the data to be sent to the server. |
reply | a pointer to the RPC reply structure. It is going to be filled if the request was answered successfully |
cb | the callback to invoke when the RPC request has been answered |
cbarg | an additional argument to be passed to the client |
#define EVRPC_REGISTER | ( | base, | |
name, | |||
request, | |||
reply, | |||
callback, | |||
cbarg | |||
) |
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.
base | the evrpc_base structure in which the RPC should be registered. |
name | the name of the RPC |
request | the name of the RPC request structure |
reply | the name of the RPC reply structure |
callback | the callback that should be invoked when the RPC is received. The callback has the following prototype void (callback)(EVRPC_STRUCT(Message) rpc, void *arg) |
cbarg | an additional parameter that can be passed to the callback. The parameter can be used to carry around state. |
#define EVRPC_REQUEST_DONE | ( | rpc_req | ) |
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.
rpc_req | the rpc request structure provided to the server callback |
#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 address
rpc_req | the rpc request structure provided to the server callback |
#define EVRPC_STRUCT | ( | rpcname | ) | struct evrpc_req__##rpcname |
The type of a specific RPC Message.
rpcname | the name of the RPC message |
#define EVRPC_UNREGISTER | ( | base, | |
name | |||
) | evrpc_unregister_rpc((base), #name) |
Unregisters an already registered RPC.
base | the evrpc_base object from which to unregister an RPC |
name | the name of the rpc to unregister |
#define EVTAG_ASSIGN | ( | msg, | |
member, | |||
value | |||
) | (*(msg)->base->member##_assign)((msg), (value)) |
Assigns a value to the member in the message.
msg | the message to which to assign a value |
member | the name of the member variable |
value | the value to assign |
#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.
msg | the message to which to assign a value |
member | the name of the member variable |
value | the value to assign |
len | the length of the value |
#define EVTAG_GET | ( | msg, | |
member, | |||
pvalue | |||
) | (*(msg)->base->member##_get)((msg), (pvalue)) |
Returns the value for a member.
msg | the message from which to get the value |
member | the name of the member variable |
pvalue | a pointer to the variable to hold the value |
#define EVTAG_GET_WITH_LEN | ( | msg, | |
member, | |||
pvalue, | |||
plen | |||
) | (*(msg)->base->member##_get)((msg), (pvalue), (plen)) |
Returns the value for a member.
msg | the message from which to get the value |
member | the name of the member variable |
pvalue | a pointer to the variable to hold the value |
plen | a pointer to the length of the value |
#define EVTAG_HAS | ( | msg, | |
member | |||
) | ((msg)->member##_set == 1) |
Determines if the member has been set in the message.
msg | the message to inspect |
member | the member variable to test for presences |
#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.
enum EVRPC_HOOK_RESULT |
enum EVRPC_HOOK_TYPE |
EVENT2_EXPORT_SYMBOL void* evrpc_add_hook | ( | void * | vbase, |
enum EVRPC_HOOK_TYPE | hook_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.
vbase | a pointer to either struct evrpc_base or struct evrpc_pool |
hook_type | either INPUT or OUTPUT |
cb | the callback to call when the hook is activated |
cb_arg | an additional argument for the callback |
EVENT2_EXPORT_SYMBOL void evrpc_free | ( | struct evrpc_base * | base | ) |
Frees the evrpc base.
For now, you are responsible for making sure that no rpcs are ongoing.
base | the evrpc_base object to be freed |
EVENT2_EXPORT_SYMBOL int evrpc_hook_add_meta | ( | void * | ctx, |
const char * | key, | ||
const void * | data, | ||
size_t | data_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.
ctx | the context provided to the hook call |
key | a NUL-terminated c-string |
data | the data to be associated with the key |
data_size | the size of the data |
EVENT2_EXPORT_SYMBOL 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.
ctx | the context provided to the hook call |
key | a NUL-terminated c-string |
data | pointer to a data pointer that will contain the retrieved data |
data_size | pointer to the size of the data |
EVENT2_EXPORT_SYMBOL struct evhttp_connection* evrpc_hook_get_connection | ( | void * | ctx | ) |
returns the connection object associated with the request
ctx | the context provided to the hook call |
EVENT2_EXPORT_SYMBOL struct evrpc_base* evrpc_init | ( | struct evhttp * | server | ) |
Creates a new rpc base from which RPC requests can be received.
server | a pointer to an existing HTTP server |
EVENT2_EXPORT_SYMBOL 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.
ctx | a context from EVRPC_MAKE_CTX() |
EVENT2_EXPORT_SYMBOL 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.
pool | the pool to which to add the connection |
evcon | the connection to add to the pool. |
EVENT2_EXPORT_SYMBOL void evrpc_pool_free | ( | struct evrpc_pool * | pool | ) |
frees an rpc connection pool
pool | a pointer to an evrpc_pool allocated via evrpc_pool_new() |
EVENT2_EXPORT_SYMBOL struct evrpc_pool* evrpc_pool_new | ( | struct event_base * | base | ) |
creates an rpc connection pool
a pool has a number of connections associated with it. rpc requests are always made via a pool.
base | a pointer to an struct event_based object; can be left NULL in singled-threaded applications |
EVENT2_EXPORT_SYMBOL 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.
pool | the pool from which to remove the connection |
evcon | the connection to remove from the pool. |
EVENT2_EXPORT_SYMBOL void evrpc_pool_set_timeout | ( | struct evrpc_pool * | pool, |
int | timeout_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.
pool | a pointer to a struct evrpc_pool object |
timeout_in_secs | the number of seconds after which a request should timeout and a failure be returned to the callback. |
EVENT2_EXPORT_SYMBOL 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.
EVENT2_EXPORT_SYMBOL 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.
EVENT2_EXPORT_SYMBOL int evrpc_remove_hook | ( | void * | vbase, |
enum EVRPC_HOOK_TYPE | hook_type, | ||
void * | handle | ||
) |
removes a previously added hook
vbase | a pointer to either struct evrpc_base or struct evrpc_pool |
hook_type | either INPUT or OUTPUT |
handle | a handle returned by evrpc_add_hook() |
EVENT2_EXPORT_SYMBOL int evrpc_resume_request | ( | void * | vbase, |
void * | ctx, | ||
enum EVRPC_HOOK_RESULT | res | ||
) |
resume a paused request
vbase | a pointer to either struct evrpc_base or struct evrpc_pool |
ctx | the context pointer provided to the original hook call |
EVENT2_EXPORT_SYMBOL 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.