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你的错了吧,你和大家说的相反呢。 如果对端发送比较快,但是本端接收不及时会导致数据被覆盖,建议使用环形缓冲区做缓存,如果是本端处理不及时导致的,那么环形缓冲区是比较好的解决方法;根据发送的速率和本端处理的速度来确定环形缓冲区使用多大的。
接收方不及时recv,会导致发送方send超时。
如果对端发送比较快,但是本端接收不及时会导致数据被覆盖,建议使用环形缓冲区做缓存,如果是本端处理不及时导致的,那么环形缓冲区是比较好的解决方法;根据发送的速率和本端处理的速度来确定环形缓冲区使用多大的。
//循环向a函数每次发送200个字节长度(这个是固定的)的buffer,
//a函数中需要将循环传进来的buffer,组成240字节(也是固定的)的新buffer进行处理,
//在处理的时候每次从新buffer中取两个字节打印
#ifdef _MSC_VER
#pragma warning(disable:4996)
#endif
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#ifdef _MSC_VER
#include <windows.h>
#include <process.h>
#include <io.h>
#define MYVOID void
#define vsnprintf _vsnprintf
#else
#include <unistd.h>
#include <sys/time.h>
#include <pthread.h>
#define CRITICAL_SECTION pthread_mutex_t
#define MYVOID void *
#endif
//Log{
#define MAXLOGSIZE 20000000
#define MAXLINSIZE 16000
#include <time.h>
#include <sys/timeb.h>
#include <stdarg.h>
char logfilename1[]="MyLog1.log";
char logfilename2[]="MyLog2.log";
static char logstr[MAXLINSIZE+1];
char datestr[16];
char timestr[16];
char mss[4];
CRITICAL_SECTION cs_log;
FILE *flog;
#ifdef _MSC_VER
void Lock(CRITICAL_SECTION *l) {
EnterCriticalSection(l);
}
void Unlock(CRITICAL_SECTION *l) {
LeaveCriticalSection(l);
}
void sleep_ms(int ms) {
Sleep(ms);
}
#else
void Lock(CRITICAL_SECTION *l) {
pthread_mutex_lock(l);
}
void Unlock(CRITICAL_SECTION *l) {
pthread_mutex_unlock(l);
}
void sleep_ms(int ms) {
usleep(ms*1000);
}
#endif
void LogV(const char *pszFmt,va_list argp) {
struct tm *now;
struct timeb tb;
if (NULL==pszFmt||0==pszFmt[0]) return;
vsnprintf(logstr,MAXLINSIZE,pszFmt,argp);
ftime(&tb);
now=localtime(&tb.time);
sprintf(datestr,"%04d-%02d-%02d",now->tm_year+1900,now->tm_mon+1,now->tm_mday);
sprintf(timestr,"%02d:%02d:%02d",now->tm_hour ,now->tm_min ,now->tm_sec );
sprintf(mss,"%03d",tb.millitm);
printf("%s %s.%s %s",datestr,timestr,mss,logstr);
flog=fopen(logfilename1,"a");
if (NULL!=flog) {
fprintf(flog,"%s %s.%s %s",datestr,timestr,mss,logstr);
if (ftell(flog)>MAXLOGSIZE) {
fclose(flog);
if (rename(logfilename1,logfilename2)) {
remove(logfilename2);
rename(logfilename1,logfilename2);
}
} else {
fclose(flog);
}
}
}
void Log(const char *pszFmt,...) {
va_list argp;
Lock(&cs_log);
va_start(argp,pszFmt);
LogV(pszFmt,argp);
va_end(argp);
Unlock(&cs_log);
}
//Log}
#define ASIZE 200
#define BSIZE 240
#define CSIZE 2
char Abuf[ASIZE];
char Cbuf[CSIZE];
CRITICAL_SECTION cs_HEX;
CRITICAL_SECTION cs_BBB;
struct FIFO_BUFFER {
int head;
int tail;
int size;
char data[BSIZE];
} BBB;
int No_Loop=0;
void HexDump(int cn,char *buf,int len) {
int i,j,k;
char binstr[80];
Lock(&cs_HEX);
for (i=0;i<len;i++) {
if (0==(i%16)) {
sprintf(binstr,"%03d %04x -",cn,i);
sprintf(binstr,"%s %02x",binstr,(unsigned char)buf[i]);
} else if (15==(i%16)) {
sprintf(binstr,"%s %02x",binstr,(unsigned char)buf[i]);
sprintf(binstr,"%s ",binstr);
for (j=i-15;j<=i;j++) {
sprintf(binstr,"%s%c",binstr,('!'<buf[j]&&buf[j]<='~')?buf[j]:'.');
}
Log("%s\n",binstr);
} else {
sprintf(binstr,"%s %02x",binstr,(unsigned char)buf[i]);
}
}
if (0!=(i%16)) {
k=16-(i%16);
for (j=0;j<k;j++) {
sprintf(binstr,"%s ",binstr);
}
sprintf(binstr,"%s ",binstr);
k=16-k;
for (j=i-k;j<i;j++) {
sprintf(binstr,"%s%c",binstr,('!'<buf[j]&&buf[j]<='~')?buf[j]:'.');
}
Log("%s\n",binstr);
}
Unlock(&cs_HEX);
}
int GetFromRBuf(int cn,CRITICAL_SECTION *cs,struct FIFO_BUFFER *fbuf,char *buf,int len) {
int lent,len1,len2;
lent=0;
Lock(cs);
if (fbuf->size>=len) {
lent=len;
if (fbuf->head+lent>BSIZE) {
len1=BSIZE-fbuf->head;
memcpy(buf ,fbuf->data+fbuf->head,len1);
len2=lent-len1;
memcpy(buf+len1,fbuf->data ,len2);
fbuf->head=len2;
} else {
memcpy(buf ,fbuf->data+fbuf->head,lent);
fbuf->head+=lent;
}
fbuf->size-=lent;
}
Unlock(cs);
return lent;
}
MYVOID thdB(void *pcn) {
char *recv_buf;
int recv_nbytes;
int cn;
int wc;
int pb;
cn=(int)pcn;
Log("%03d thdB thread begin...\n",cn);
while (1) {
sleep_ms(10);
recv_buf=(char *)Cbuf;
recv_nbytes=CSIZE;
wc=0;
while (1) {
pb=GetFromRBuf(cn,&cs_BBB,&BBB,recv_buf,recv_nbytes);
if (pb) {
Log("%03d recv %d bytes\n",cn,pb);
HexDump(cn,recv_buf,pb);
sleep_ms(1);
} else {
sleep_ms(1000);
}
if (No_Loop) break;//
wc++;
if (wc>3600) Log("%03d %d==wc>3600!\n",cn,wc);
}
if (No_Loop) break;//
}
#ifndef _MSC_VER
pthread_exit(NULL);
#endif
}
int PutToRBuf(int cn,CRITICAL_SECTION *cs,struct FIFO_BUFFER *fbuf,char *buf,int len) {
int lent,len1,len2;
Lock(cs);
lent=len;
if (fbuf->size+lent>BSIZE) {
lent=BSIZE-fbuf->size;
}
if (fbuf->tail+lent>BSIZE) {
len1=BSIZE-fbuf->tail;
memcpy(fbuf->data+fbuf->tail,buf ,len1);
len2=lent-len1;
memcpy(fbuf->data ,buf+len1,len2);
fbuf->tail=len2;
} else {
memcpy(fbuf->data+fbuf->tail,buf ,lent);
fbuf->tail+=lent;
}
fbuf->size+=lent;
Unlock(cs);
return lent;
}
MYVOID thdA(void *pcn) {
char *send_buf;
int send_nbytes;
int cn;
int wc;
int a;
int pa;
cn=(int)pcn;
Log("%03d thdA thread begin...\n",cn);
a=0;
while (1) {
sleep_ms(100);
memset(Abuf,a,ASIZE);
a=(a+1)%256;
if (16==a) {No_Loop=1;break;}//去掉这句可以让程序一直循环直到按Ctrl+C或Ctrl+Break或当前目录下存在文件No_Loop
send_buf=(char *)Abuf;
send_nbytes=ASIZE;
Log("%03d sending %d bytes\n",cn,send_nbytes);
HexDump(cn,send_buf,send_nbytes);
wc=0;
while (1) {
pa=PutToRBuf(cn,&cs_BBB,&BBB,send_buf,send_nbytes);
Log("%03d sent %d bytes\n",cn,pa);
HexDump(cn,send_buf,pa);
send_buf+=pa;
send_nbytes-=pa;
if (send_nbytes<=0) break;//
sleep_ms(1000);
if (No_Loop) break;//
wc++;
if (wc>3600) Log("%03d %d==wc>3600!\n",cn,wc);
}
if (No_Loop) break;//
}
#ifndef _MSC_VER
pthread_exit(NULL);
#endif
}
int main() {
#ifdef _MSC_VER
InitializeCriticalSection(&cs_log);
InitializeCriticalSection(&cs_HEX);
InitializeCriticalSection(&cs_BBB);
#else
pthread_t threads[2];
int threadsN;
int rc;
pthread_mutex_init(&cs_log,NULL);
pthread_mutex_init(&cs_HEX,NULL);
pthread_mutex_init(&cs_BBB,NULL);
#endif
Log("Start===========================================================\n");
BBB.head=0;
BBB.tail=0;
BBB.size=0;
#ifdef _MSC_VER
_beginthread((void(__cdecl *)(void *))thdA,0,(void *)1);
_beginthread((void(__cdecl *)(void *))thdB,0,(void *)2);
#else
threadsN=0;
rc=pthread_create(&(threads[threadsN++]),NULL,thdA,(void *)1);if (rc) Log("%d=pthread_create %d error!\n",rc,threadsN-1);
rc=pthread_create(&(threads[threadsN++]),NULL,thdB,(void *)2);if (rc) Log("%d=pthread_create %d error!\n",rc,threadsN-1);
#endif
if (!access("No_Loop",0)) {
remove("No_Loop");
if (!access("No_Loop",0)) {
No_Loop=1;
}
}
while (1) {
sleep_ms(1000);
if (No_Loop) break;//
if (!access("No_Loop",0)) {
No_Loop=1;
}
}
sleep_ms(3000);
Log("End=============================================================\n");
#ifdef _MSC_VER
DeleteCriticalSection(&cs_BBB);
DeleteCriticalSection(&cs_HEX);
DeleteCriticalSection(&cs_log);
#else
pthread_mutex_destroy(&cs_BBB);
pthread_mutex_destroy(&cs_HEX);
pthread_mutex_destroy(&cs_log);
#endif
return 0;
}
任何收发两端速度不一致的通讯,都需要在它们之间使用一个足够大的FIFO缓冲区。
对任何FIFO缓冲区的使用,都需要仔细考虑接收端接收时超时无数据和发送端发送时FIFO缓冲区已满这两种情况下该如何做。
这些概念都在这段经典代码中有所体现。
这段经典代码还包括以下必须考虑的因素:
◆跨Windows和Linux平台
◆多线程锁
◆多线程日志
◆日志文件占用的磁盘空间可控
◆日志中的时间包括毫秒
◆传输的数据对应的每个字节到底是几
◆如何退出多线程程序
◆……
任何收发两端速度不一致的通讯,都需要在它们之间使用一个足够大的FIFO缓冲区。 对任何FIFO缓冲区的使用,都需要仔细考虑接收端接收时超时无数据和发送端发送时FIFO缓冲区已满这两种情况下该如何做。 这些概念都在这段经典代码中有所体现。 这段经典代码还包括以下必须考虑的因素: ◆跨Windows和Linux平台 ◆多线程锁 ◆多线程日志 ◆日志文件占用的磁盘空间可控 ◆日志中的时间包括毫秒 ◆传输的数据对应的每个字节到底是几 ◆如何退出多线程程序 ◆……//循环向a函数每次发送200个字节长度(这个是固定的)的buffer, //a函数中需要将循环传进来的buffer,组成240字节(也是固定的)的新buffer进行处理, //在处理的时候每次从新buffer中取两个字节打印 #ifdef _MSC_VER #pragma warning(disable:4996) #endif #include <stdio.h> #include <stdlib.h> #include <string.h> #ifdef _MSC_VER #include <windows.h> #include <process.h> #include <io.h> #define MYVOID void #define vsnprintf _vsnprintf #else #include <unistd.h> #include <sys/time.h> #include <pthread.h> #define CRITICAL_SECTION pthread_mutex_t #define MYVOID void * #endif //Log{ #define MAXLOGSIZE 20000000 #define MAXLINSIZE 16000 #include <time.h> #include <sys/timeb.h> #include <stdarg.h> char logfilename1[]="MyLog1.log"; char logfilename2[]="MyLog2.log"; static char logstr[MAXLINSIZE+1]; char datestr[16]; char timestr[16]; char mss[4]; CRITICAL_SECTION cs_log; FILE *flog; #ifdef _MSC_VER void Lock(CRITICAL_SECTION *l) { EnterCriticalSection(l); } void Unlock(CRITICAL_SECTION *l) { LeaveCriticalSection(l); } void sleep_ms(int ms) { Sleep(ms); } #else void Lock(CRITICAL_SECTION *l) { pthread_mutex_lock(l); } void Unlock(CRITICAL_SECTION *l) { pthread_mutex_unlock(l); } void sleep_ms(int ms) { usleep(ms*1000); } #endif void LogV(const char *pszFmt,va_list argp) { struct tm *now; struct timeb tb; if (NULL==pszFmt||0==pszFmt[0]) return; vsnprintf(logstr,MAXLINSIZE,pszFmt,argp); ftime(&tb); now=localtime(&tb.time); sprintf(datestr,"%04d-%02d-%02d",now->tm_year+1900,now->tm_mon+1,now->tm_mday); sprintf(timestr,"%02d:%02d:%02d",now->tm_hour ,now->tm_min ,now->tm_sec ); sprintf(mss,"%03d",tb.millitm); printf("%s %s.%s %s",datestr,timestr,mss,logstr); flog=fopen(logfilename1,"a"); if (NULL!=flog) { fprintf(flog,"%s %s.%s %s",datestr,timestr,mss,logstr); if (ftell(flog)>MAXLOGSIZE) { fclose(flog); if (rename(logfilename1,logfilename2)) { remove(logfilename2); rename(logfilename1,logfilename2); } } else { fclose(flog); } } } void Log(const char *pszFmt,...) { va_list argp; Lock(&cs_log); va_start(argp,pszFmt); LogV(pszFmt,argp); va_end(argp); Unlock(&cs_log); } //Log} #define ASIZE 200 #define BSIZE 240 #define CSIZE 2 char Abuf[ASIZE]; char Cbuf[CSIZE]; CRITICAL_SECTION cs_HEX; CRITICAL_SECTION cs_BBB; struct FIFO_BUFFER { int head; int tail; int size; char data[BSIZE]; } BBB; int No_Loop=0; void HexDump(int cn,char *buf,int len) { int i,j,k; char binstr[80]; Lock(&cs_HEX); for (i=0;i<len;i++) { if (0==(i%16)) { sprintf(binstr,"%03d %04x -",cn,i); sprintf(binstr,"%s %02x",binstr,(unsigned char)buf[i]); } else if (15==(i%16)) { sprintf(binstr,"%s %02x",binstr,(unsigned char)buf[i]); sprintf(binstr,"%s ",binstr); for (j=i-15;j<=i;j++) { sprintf(binstr,"%s%c",binstr,('!'<buf[j]&&buf[j]<='~')?buf[j]:'.'); } Log("%s\n",binstr); } else { sprintf(binstr,"%s %02x",binstr,(unsigned char)buf[i]); } } if (0!=(i%16)) { k=16-(i%16); for (j=0;j<k;j++) { sprintf(binstr,"%s ",binstr); } sprintf(binstr,"%s ",binstr); k=16-k; for (j=i-k;j<i;j++) { sprintf(binstr,"%s%c",binstr,('!'<buf[j]&&buf[j]<='~')?buf[j]:'.'); } Log("%s\n",binstr); } Unlock(&cs_HEX); } int GetFromRBuf(int cn,CRITICAL_SECTION *cs,struct FIFO_BUFFER *fbuf,char *buf,int len) { int lent,len1,len2; lent=0; Lock(cs); if (fbuf->size>=len) { lent=len; if (fbuf->head+lent>BSIZE) { len1=BSIZE-fbuf->head; memcpy(buf ,fbuf->data+fbuf->head,len1); len2=lent-len1; memcpy(buf+len1,fbuf->data ,len2); fbuf->head=len2; } else { memcpy(buf ,fbuf->data+fbuf->head,lent); fbuf->head+=lent; } fbuf->size-=lent; } Unlock(cs); return lent; } MYVOID thdB(void *pcn) { char *recv_buf; int recv_nbytes; int cn; int wc; int pb; cn=(int)pcn; Log("%03d thdB thread begin...\n",cn); while (1) { sleep_ms(10); recv_buf=(char *)Cbuf; recv_nbytes=CSIZE; wc=0; while (1) { pb=GetFromRBuf(cn,&cs_BBB,&BBB,recv_buf,recv_nbytes); if (pb) { Log("%03d recv %d bytes\n",cn,pb); HexDump(cn,recv_buf,pb); sleep_ms(1); } else { sleep_ms(1000); } if (No_Loop) break;// wc++; if (wc>3600) Log("%03d %d==wc>3600!\n",cn,wc); } if (No_Loop) break;// } #ifndef _MSC_VER pthread_exit(NULL); #endif } int PutToRBuf(int cn,CRITICAL_SECTION *cs,struct FIFO_BUFFER *fbuf,char *buf,int len) { int lent,len1,len2; Lock(cs); lent=len; if (fbuf->size+lent>BSIZE) { lent=BSIZE-fbuf->size; } if (fbuf->tail+lent>BSIZE) { len1=BSIZE-fbuf->tail; memcpy(fbuf->data+fbuf->tail,buf ,len1); len2=lent-len1; memcpy(fbuf->data ,buf+len1,len2); fbuf->tail=len2; } else { memcpy(fbuf->data+fbuf->tail,buf ,lent); fbuf->tail+=lent; } fbuf->size+=lent; Unlock(cs); return lent; } MYVOID thdA(void *pcn) { char *send_buf; int send_nbytes; int cn; int wc; int a; int pa; cn=(int)pcn; Log("%03d thdA thread begin...\n",cn); a=0; while (1) { sleep_ms(100); memset(Abuf,a,ASIZE); a=(a+1)%256; if (16==a) {No_Loop=1;break;}//去掉这句可以让程序一直循环直到按Ctrl+C或Ctrl+Break或当前目录下存在文件No_Loop send_buf=(char *)Abuf; send_nbytes=ASIZE; Log("%03d sending %d bytes\n",cn,send_nbytes); HexDump(cn,send_buf,send_nbytes); wc=0; while (1) { pa=PutToRBuf(cn,&cs_BBB,&BBB,send_buf,send_nbytes); Log("%03d sent %d bytes\n",cn,pa); HexDump(cn,send_buf,pa); send_buf+=pa; send_nbytes-=pa; if (send_nbytes<=0) break;// sleep_ms(1000); if (No_Loop) break;// wc++; if (wc>3600) Log("%03d %d==wc>3600!\n",cn,wc); } if (No_Loop) break;// } #ifndef _MSC_VER pthread_exit(NULL); #endif } int main() { #ifdef _MSC_VER InitializeCriticalSection(&cs_log); InitializeCriticalSection(&cs_HEX); InitializeCriticalSection(&cs_BBB); #else pthread_t threads[2]; int threadsN; int rc; pthread_mutex_init(&cs_log,NULL); pthread_mutex_init(&cs_HEX,NULL); pthread_mutex_init(&cs_BBB,NULL); #endif Log("Start===========================================================\n"); BBB.head=0; BBB.tail=0; BBB.size=0; #ifdef _MSC_VER _beginthread((void(__cdecl *)(void *))thdA,0,(void *)1); _beginthread((void(__cdecl *)(void *))thdB,0,(void *)2); #else threadsN=0; rc=pthread_create(&(threads[threadsN++]),NULL,thdA,(void *)1);if (rc) Log("%d=pthread_create %d error!\n",rc,threadsN-1); rc=pthread_create(&(threads[threadsN++]),NULL,thdB,(void *)2);if (rc) Log("%d=pthread_create %d error!\n",rc,threadsN-1); #endif if (!access("No_Loop",0)) { remove("No_Loop"); if (!access("No_Loop",0)) { No_Loop=1; } } while (1) { sleep_ms(1000); if (No_Loop) break;// if (!access("No_Loop",0)) { No_Loop=1; } } sleep_ms(3000); Log("End=============================================================\n"); #ifdef _MSC_VER DeleteCriticalSection(&cs_BBB); DeleteCriticalSection(&cs_HEX); DeleteCriticalSection(&cs_log); #else pthread_mutex_destroy(&cs_BBB); pthread_mutex_destroy(&cs_HEX); pthread_mutex_destroy(&cs_log); #endif return 0; }