R2 Study Record

Setting up the Libevent library
1. Rewrite log behavior

#include <event2/Event.h>#include<stdio.h>Static voidDISCARD_CB (intSeverityConst Char*msg) {    /*This is callback does nothing.*/}StaticFILE *logfile =NULL;Static voidWRITE_TO_FILE_CB (intSeverityConst Char*msg) {    Const Char*s; if(!logfile)return; Switch(severity) { Case_event_log_debug:s="Debug";  Case_event_log_msg:s="msg";  Case_event_log_warn:s="warn";  Case_event_log_err:s="Error"; default:/*never reached*/s="?"; } fprintf (LogFile,"[%s]%s\n", S, msg);}/*Turn off all logging from Libevent.*/voidSuppress_logging (void) {event_set_log_callback (DISCARD_CB);}/*Redirect all Libevent logs messages to the C stdio file ' F '.*/voidSet_logfile (FILE *f) {logfile=F; Event_set_log_callback (WRITE_TO_FILE_CB);}

2. Override the exception exit action:

void (*EVENT_FATAL_CB) (int  err); void event_set_fatal_callback (EVENT_FATAL_CB CB);

3. Override the memory management method:

void event_set_mem_functions (void * (*malloc_fn) (size_t sz),void * (*REALLOC_FN) (void *ptr, size_t sz), void (*FREE_FN) (void *ptr));

4. Locks and Threads
Libevent default support for Win and Unix-like line libraries, if you want to implement the line libraries you need to implement:
Locks
Locking
Unlocking
Lock allocation
Lock destruction
Conditions
Condition variable Creation
Condition variable Destruction
Waiting on a condition variable
Signaling/broadcasting to a condition variable
Threads
Thread ID Detection

#defineEvthread_write 0x04#defineEvthread_read 0x08#defineEvthread_try 0x10#defineEvthread_locktype_recursive 1#defineEvthread_locktype_readwrite 2#defineEvthread_lock_api_version 1structEvthread_lock_callbacks {intlock_api_version;        unsigned supported_locktypes; void*(*alloc)        (unsigned locktype); void(* Free)(void*Lock, unsigned locktype); int(*Lock) (unsigned mode,void*Lock); int(*unlock) (unsigned mode,void*Lock);};intEvthread_set_lock_callbacks (Const structEvthread_lock_callbacks *);voidEvthread_set_id_callback (unsignedLong(*ID_FN) (void));structEvthread_condition_callbacks {intcondition_api_version; void*(*alloc_condition)        (unsigned condtype); void(*free_condition) (void*cond); int(*signal_condition) (void*cond,intbroadcast); int(*wait_condition) (void*cond,void*Lock,                        Const structTimeval *timeout);};intEvthread_set_condition_callbacks (Const structEvthread_condition_callbacks *);

R2 Study Record