Optimization of queue under multi-thread

0. Preface

The previous time in looking at the lock-free queue related things to find an article on the Lock queue algorithm optimization, so look at its principle and use C to implement the queue. The queue is linkedblockingqueue in Java and implements this functionality.

Related article: Simple, Fast, and practical non-blocking and Blocking Concurrent Queue algorithms

Algorithm optimization of multi-thread queue

1. Fundamentals

For multi-threading, multiple producers and multi-consumer environments, can be optimized by separating the lock at the head of the team and the end of the team. Initially, using an empty node, when inserting an element into an empty queue or ejecting the last element node, you do not need to acquire both sides of the lock (because the tail and head pointers need to be modified at the same time, but an empty node can prevent this from happening).

2. C Simple Implementation

#include <pthread.h>#include<stdlib.h>#include<assert.h>typedefstructqnode{void*PValue; structQnode *Pnext;} Qnode;typedefstructqueue{Qnode*Phead; Qnode*Ptail;    pthread_mutex_t headlock; pthread_mutex_t Taillock;} Tqueue; Tqueue*Inittqueue () {Tqueue* Pqueue =malloc(sizeof(*pqueue));    ASSERT (Pqueue); Qnode*pemptynode =malloc(sizeof(*Pemptynode));    ASSERT (Pemptynode); Pemptynode->pnext =NULL; Pqueue->phead = Pqueue->ptail =Pemptynode; Pthread_mutex_init (&pQueue->headlock, NULL); Pthread_mutex_init (&pQueue->Taillock, NULL); returnPqueue;}voidEnQueue (Tqueue *pqueue,void*pValue)    {assert (Pqueue); Qnode*pnewnode =malloc(sizeof(*Pnewnode)); Pnewnode->pvalue =PValue; Pnewnode->pnext =NULL; Pthread_mutex_lock (&pQueue->Taillock); Pqueue->ptail->pnext =Pnewnode; Pqueue->ptail =Pnewnode; Pthread_mutex_unlock (&pQueue->taillock);}void* DeQueue (Tqueue *pqueue) {    void*pvalue =NULL; Pthread_mutex_lock (&pQueue->headlock); Qnode*ppopnode = pqueue->Phead; if(NULL = = ppopnode->Pnext) {Pthread_mutex_unlock (&pQueue->headlock); returnNULL; } pValue= ppopnode->pnext->PValue; Pqueue->phead = ppopnode->Pnext; Pthread_mutex_unlock (&pQueue->headlock);  Free(Ppopnode); returnPValue;}void* Producer (void*parg) {Tqueue* Pqueue = (tqueue*) parg; Const intNmsgnums =Ten;  for(inti =1; I <= nmsgnums; ++i) {EnQueue (Pqueue, (void*) (i); } EnQueue (Pqueue,0);}void* Consumer (void*parg) {Tqueue* Pqueue = (tqueue*) parg;  while(1)    {        intNmsg = (int) DeQueue (pqueue); if(Nmsg = =0)        {             Break; } printf ("%u msg[%d]\n", Pthread_self (), nmsg); }}#defineMax_pthreads 3intMainintargcChar Const*argv[]) {Tqueue* Pqueue =Inittqueue ();    ASSERT (Pqueue);    pthread_t Producerid[max_pthreads];    pthread_t Consumerid[max_pthreads];  for(inti =0; i < max_pthreads; ++i) {pthread_create (&producerid[i], NULL, Producer, (void*) pqueue); Pthread_create (&consumerid[i], NULL, Consumer, (void*) pqueue); }     for(inti =0; i < max_pthreads; ++i) {pthread_join (producerid[i], NULL);    Pthread_join (Consumerid[i], NULL); }    return 0;}

Optimization of queue under multi-thread