paho.mqtt.c打印日志
mqtt中自身就带有日志系统Log.h和Log.c,这些日志文件是在客户端调用MQTTClient_create函数是初始化的,MQTTClient_create源码如下:
int MQTTClient_create(MQTTClient* handle, const char* serverURI, const char* clientId,
int persistence_type, void* persistence_context)
{
int rc = 0;
MQTTClients *m = NULL;
FUNC_ENTRY;
rc = Thread_lock_mutex(mqttclient_mutex);
if (serverURI == NULL || clientId == NULL)
{
rc = MQTTCLIENT_NULL_PARAMETER;
goto exit;
}
if (!UTF8_validateString(clientId))
{
rc = MQTTCLIENT_BAD_UTF8_STRING;
goto exit;
}
if (!initialized)
{
#if defined(HEAP_H)
Heap_initialize();
#endif
Log_initialize((Log_nameValue*)MQTTClient_getVersionInfo());
bstate->clients = ListInitialize();
Socket_outInitialize();
Socket_setWriteCompleteCallback(MQTTClient_writeComplete);
handles = ListInitialize();
#if defined(OPENSSL)
SSLSocket_initialize();
#endif
initialized = 1;
}
m = malloc(sizeof(MQTTClients));
*handle = m;
memset(m, '\0', sizeof(MQTTClients));
if (strncmp(URI_TCP, serverURI, strlen(URI_TCP)) == 0)
serverURI += strlen(URI_TCP);
#if defined(OPENSSL)
else if (strncmp(URI_SSL, serverURI, strlen(URI_SSL)) == 0)
{
serverURI += strlen(URI_SSL);
m->ssl = 1;
}
#endif
m->serverURI = MQTTStrdup(serverURI);
ListAppend(handles, m, sizeof(MQTTClients));
m->c = malloc(sizeof(Clients));
memset(m->c, '\0', sizeof(Clients));
m->c->context = m;
m->c->outboundMsgs = ListInitialize();
m->c->inboundMsgs = ListInitialize();
m->c->messageQueue = ListInitialize();
m->c->clientID = MQTTStrdup(clientId);
m->connect_sem = Thread_create_sem();
m->connack_sem = Thread_create_sem();
m->suback_sem = Thread_create_sem();
m->unsuback_sem = Thread_create_sem();
#if !defined(NO_PERSISTENCE)
rc = MQTTPersistence_create(&(m->c->persistence), persistence_type, persistence_context);
if (rc == 0)
{
rc = MQTTPersistence_initialize(m->c, m->serverURI);
if (rc == 0)
MQTTPersistence_restoreMessageQueue(m->c);
}
#endif
ListAppend(bstate->clients, m->c, sizeof(Clients) + 3*sizeof(List));
exit:
Thread_unlock_mutex(mqttclient_mutex);
FUNC_EXIT_RC(rc);
return rc;
}
可以看到MQTTClient_create中调用了Log_initialize来初始化日志系统,Log_initialize源码为:
int Log_initialize(Log_nameValue* info)
{
int rc = -1;
char* envval = NULL;
if ((trace_queue = malloc(sizeof(traceEntry) * trace_settings.max_trace_entries)) == NULL)
return rc;
trace_queue_size = trace_settings.max_trace_entries;
if ((envval = getenv("MQTT_C_CLIENT_TRACE")) != NULL && strlen(envval) > 0)
{
if (strcmp(envval, "ON") == 0 || (trace_destination = fopen(envval, "w")) == NULL)
trace_destination = stdout;
else
{
trace_destination_name = malloc(strlen(envval) + 1);
strcpy(trace_destination_name, envval);
trace_destination_backup_name = malloc(strlen(envval) + 3);
sprintf(trace_destination_backup_name, "%s.0", trace_destination_name);
}
}
if ((envval = getenv("MQTT_C_CLIENT_TRACE_MAX_LINES")) != NULL && strlen(envval) > 0)
{
max_lines_per_file = atoi(envval);
if (max_lines_per_file <= 0)
max_lines_per_file = 1000;
}
if ((envval = getenv("MQTT_C_CLIENT_TRACE_LEVEL")) != NULL && strlen(envval) > 0)
{
if (strcmp(envval, "MAXIMUM") == 0 || strcmp(envval, "TRACE_MAXIMUM") == 0)
trace_settings.trace_level = TRACE_MAXIMUM;
else if (strcmp(envval, "MEDIUM") == 0 || strcmp(envval, "TRACE_MEDIUM") == 0)
trace_settings.trace_level = TRACE_MEDIUM;
else if (strcmp(envval, "MINIMUM") == 0 || strcmp(envval, "TRACE_MEDIUM") == 0)
trace_settings.trace_level = TRACE_MINIMUM;
else if (strcmp(envval, "PROTOCOL") == 0 || strcmp(envval, "TRACE_PROTOCOL") == 0)
trace_output_level = TRACE_PROTOCOL;
else if (strcmp(envval, "ERROR") == 0 || strcmp(envval, "TRACE_ERROR") == 0)
trace_output_level = LOG_ERROR;
}
Log_output(TRACE_MINIMUM, "=========================================================");
Log_output(TRACE_MINIMUM, " Trace Output");
if (info)
{
while (info->name)
{
snprintf(msg_buf, sizeof(msg_buf), "%s: %s", info->name, info->value);
Log_output(TRACE_MINIMUM, msg_buf);
info++;
}
}
#if !defined(WIN32) && !defined(WIN64)
struct stat buf;
if (stat("/proc/version", &buf) != -1)
{
FILE* vfile;
if ((vfile = fopen("/proc/version", "r")) != NULL)
{
int len;
strcpy(msg_buf, "/proc/version: ");
len = strlen(msg_buf);
if (fgets(&msg_buf[len], sizeof(msg_buf) - len, vfile))
Log_output(TRACE_MINIMUM, msg_buf);
fclose(vfile);
}
}
#endif
Log_output(TRACE_MINIMUM, "=========================================================");
return rc;
}
在Log_initialize中可以看到,日志系统主要通过调用getenv获取环境变量"MQTT_C_CLIENT_TRACE"和"MQTT_C_CLIENT_TRACE_LEVEL"的值来配置日志操作的, 前者表示日志文件路径,后者表示日志文件等级。
这里可以使用c函数_putenv_s(头文件#include <stdlib.h>)来设置当前进程的环境变量,这里举例如下,设置日志文件路径为"D:\\client.log",日志等级为"MAXIMUM",表示打印所有日志。
int result = _putenv_s("MQTT_C_CLIENT_TRACE", "D:\\client.log"); result = _putenv_s("MQTT_C_CLIENT_TRACE_LEVEL","MAXIMUM");
除此之外,还有如下日志等级:
log等级 | 说明 |
---|---|
ERROR | ERROR log输出较少,出现ERROR情况下打印log |
PROTOCOL | 只打印mosquitto协议相关的log |
MINIMUM | 输出全部log |
MEDIUM | 输出全部log |
MAXIMUM | 输出全部log,包括内存分配和释放 |
后三种log输出内容基本一致。
这样一来,就可以在连接mqtt的时候打印日志了,但是切记调用mqtt API函数的工程跟mqtt的工程运行库设置需要一样(同时为MDd/MD或MT/MTd),不然不能打印日志。
打印的日志如下:
参考资料:
http://www.eclipse.org/paho/files/mqttdoc/MQTTClient/html/tracing.html
posted on 2017-09-20 20:25 SpartacusIn21 阅读(2481) 评论(0) 编辑 收藏 举报