Code:
Structure RW_LOCK is to realize the read/write lock, and the rest of the code is test data

 
# include & lt; Pthread. H> 
# include & lt; stdio.h> 
# include & lt; Unistd. H> 
//pthread_rwlock_t 
//pthread_mutex_t 
//pthread_cond_t 
The class RW_LOCK {
Public: 
RW_LOCK () {
Pthread_mutex_init (& amp; Mutex, NULL); 
Ref_t=0; 
} 
Void writelock () 
{
While (true) 
{
Pthread_mutex_lock (& amp; Mutex); 
If (ref_t==0) {
return ; 
} 
The else {
Pthread_mutex_unlock (& amp; Mutex); 
} 
} 
} 
Void writeunlock () 
{
Pthread_mutex_unlock (& amp; Mutex); 
} 
Void readlock () 
{
Pthread_mutex_lock (& amp; Mutex); 
Ref_t + +; 
Pthread_mutex_unlock (& amp; Mutex); 
} 
Void readunlock () 
{
Pthread_mutex_lock (& amp; Mutex); 
Ref_t -; 
Pthread_mutex_unlock (& amp; Mutex); 
} 
~ RW_LOCK () 
{
Pthread_mutex_destroy (& amp; Mutex); 
} 
Private: 
pthread_mutex_t mutex; 
Int ref_t; 
} rwmutex; 
Void * the fill nothing (void *) 
{
for(int i=1; i<=100; + + I) 
{
Rwmutex. Writelock (); 
Printf (" the begin write. \ n "); 
Printf (" end write. \ n "); 
Sleep (1); 
Rwmutex. Writeunlock (); 
Sleep (1); 
} 
Return NULL; 
} 
Void * know1 nothing (void *) 
{
for(int i=1; i<=100; + + I) 
{
Rwmutex. Readlock (); 
Printf (" the begin read1. \ n "); 
Sleep (1); 
Printf (" end read1. \ n "); 
Rwmutex. Readunlock (); 
Sleep (1); 
} 
Return NULL; 
} 
Void * know2 nothing (void *) 
{
for(int i=1; i<=100; + + I) 
{
Rwmutex. Readlock (); 
Printf (" the begin read2. \ n "); 
Sleep (1); 
Printf (" end read2. \ n "); 
Rwmutex. Readunlock (); 
Sleep (1); 
} 
Return NULL; 
} 
Int main () 
{
Pthread_t t1, t2, t3, t4; 
Pthread_create (& amp; T1, NULL, the fill, NULL); 
Pthread_create (& amp; T2, NULL, know1, NULL); 
Pthread_create (& amp; T3, NULL, know1, NULL); 
Pthread_create (& amp; T4, NULL, know2, NULL); 
Pthread_join (t1, NULL); 
Pthread_join (t2, NULL); 
Pthread_join (t3, NULL); 
Pthread_join (t4, NULL); 
return 0; 
} 

Tested had not found the problem, but also ah please (one thousand the interviewer asked him, he wrote a wrong just embarrassing)

CodePudding user response:

There is nothing wrong with code is pretty simple, logical, is writing a spin lock, lock is relatively expensive,

CodePudding user response:

Priority would be better if you can consider

CodePudding user response:

reference 1st floor SDGHCHJ response:

code is pretty simple, there is nothing wrong with logic, is to write a spin lock, lock is relatively expensive,

uh-huh, I'll think of some way to improve it,

CodePudding user response:

Don't ask the interviewer, the interviewer usually ask dick have one question,
Such as a warm up first, what is a deadlock, what circumstances can a deadlock?
Then, how to detect deadlock ~ ~ ~ ~?

CodePudding user response:

reference 4 floor yukint response:

don't ask the interviewer, the interviewer usually ask dick have one question,
Such as a warm up first, what is a deadlock, what circumstances can a deadlock?
Then, how to detect deadlock ~ ~ ~ ~?

ha ha ha, in the oral say ok, if make a detection algorithm of deadlock that GG