Question

我正在做一个库来实现一个双缓冲区，基本的想法是我将需要缓冲区，一个将被写入而另一个读取，并且每次写入缓冲区变满时它们都会交换。当我交换缓冲区并从valgrind获取时，我一直有内存泄漏：

#include<stdlib.h>
#include<stdio.h>
#include<string.h>
#include<pthread.h>
#include"data_structures.h"

#define BUFFER_SIZE 4000    

typedef enum {firstBuf, secondBuf} currentBuf;

typedef struct {
    char *buffer1;
    char *buffer2;
    currentBuf current;
    int index;
} double_buffer;


pthread_cond_t buffer_cheio = PTHREAD_COND_INITIALIZER;
pthread_cond_t buffer_vazio = PTHREAD_COND_INITIALIZER;
pthread_mutex_t mutex;
double_buffer *build_double_buffer(){
    double_buffer *db = (double_buffer *)malloc(sizeof(double_buffer));
    db->buffer1 = (char *)calloc(BUFFER_SIZE, sizeof(char));
    db->buffer2 = (char *)calloc(BUFFER_SIZE, sizeof(char));
    db->buffer1[0] = '\0';
    db->buffer2[0] = '\0';
    db->index = 0;
    pthread_mutex_init(&mutex, NULL);
    db->current = firstBuf;
    return db;
}

void setDoubleBuffer(double_buffer *db, char *info){
    pthread_mutex_lock(&mutex);
    int len = strlen(info)+1;
    if(db->index + len > BUFFER_SIZE){
        switch(db->current){
            case firstBuf:
                while(db->buffer2[0] != '\0'){
                    pthread_cond_wait(&buffer_vazio, &mutex);
                }
                break;
            case secondBuf:
                while(db->buffer1[0] != '\0'){
                    pthread_cond_wait(&buffer_vazio, &mutex);
                }
        }
        swapBuffer(db);
    }
    if(db->current == firstBuf){
        if(!(db->index + len > BUFFER_SIZE)){
            strcat(db->buffer1, info);
        }else{
            printf("erro");
        }
    }else{
        if(!(db->index + len > BUFFER_SIZE)){
            strcat(db->buffer2, info);
        }else{
            printf("erro");
        }
    }
        db->index += len;
        pthread_cond_signal(&buffer_cheio);
    pthread_mutex_unlock(&mutex);
}

void swapBuffer(double_buffer *db){
    int i;
    char *buf1;
    char *buf2;
    if(db->current == firstBuf) {
        buf1 = db->buffer1;
        buf2 = db->buffer2;
    } else {
        buf2 = db->buffer1;
        buf1 = db->buffer2;
    }
    for(i = 0; i < BUFFER_SIZE -1 || buf1[i] == '\0'; i++){ //line 85
        buf2[i] = buf1[i]; //line 86
    }
    buf1[0] ='\0';
    db->index = 0;
    if(db->current == firstBuf){
        db->current = secondBuf;
    }else{
        db->current = firstBuf;
    }
}

void get_buffer(char *receiveBuffer, double_buffer *db){
    pthread_mutex_lock(&mutex);
    int i;
    while(db->buffer1[0] == '\0' || db->buffer2[0] == '\0'){
        pthread_cond_wait(&buffer_cheio, &mutex);
    }
    if(db->current == firstBuf){
        for(i = 0; i < BUFFER_SIZE || db->buffer2[i] == '\0'; i++){
            receiveBuffer[i] = db->buffer2[i];
        }
        db->buffer2[0] = '\0';
    }else{
        for(i = 0; i < BUFFER_SIZE || db->buffer1[i] == '\0'; i++){
            receiveBuffer[i] = db->buffer1[i];
        }
        db->buffer1[0] = '\0';
    }
    pthread_cond_signal(&buffer_vazio);
    pthread_mutex_unlock(&mutex);
}

我一直在尝试让它工作，但我无法看到我在做内存泄漏的地方而不是如何解决它。代码如下：

//main thread before creating the threads
log_buffer = build_double_buffer();
//temparature thread
while(1){
    char *log_string = NULL;
    log_string = (char *)malloc(sizeof(char)*MAX_BUFFER_SIZE);

    //code that calculates T

    sprintf(log_string, "Temperura: %f\n", T);
    setDoubleBuffer(log_buffer, log_string);
}

调用它的代码是：

{{1}}

双缓冲区呈现内存泄漏[ANSI C]

0 个答案: