我怎么能输出重定向到一个日志提振？ [英] How can I redirect output to a boost log?
问题描述
我有一个使用升压日志中的C ++程序，我打开一个用户提供的动态链接库。我想标准错误重定向到升压日志，让随时随地用户的库所做的：
I have a C++ program that uses boost log, and I load a user-provided dynamic link library. I'd like to redirect stderr to the boost log, so that anytime the user's library does:
std::cerr << "Some stuff";
这产生相同的结果**为：
It produces the same result** as:
BOOST_LOG_SEV(log,info) << "Some stuff";
这是可能的，这样的话我该怎么办呢？
Is this possible, and if so then how do I do it?
（另外，我不知道该怎么办的严重性......因为 CERR＆LT;＆LT; 不privide严重程度的信息，我开在该建议，以及...）
(Also, I'm not sure what to do about the severity... since cerr << doesn't privide severity information. I'm open to suggestions on that as well...)
**通过同样的结果我的意思是，它被记录到相同的日志文件中的日志消息的休息，相同的日志格式应用到这些行。
** By "same result" I mean that it gets logged to the same log file as the rest of the log messages, and the same log formatter is applied to those lines.
推荐答案
下面是我的C ++ 11的实现。这个类可以用于任何（不只是提高）来捕获标准输出/标准错误一行接一行的基础上，调用用户功能（可以是一个lambda）来处理它。
Here's my C++11 implementation. This class can be used for anything (not just boost) to capture stdout/stderr on a line-by-line basis and calling a user function (could be a lambda) to process it.
警告：如果您重定向标准错误和标准输出和使用升压，然后重定向标准错误，然后再标准输出。否则，升压会写回环标准错误信息返回到标准输出，你会得到另一个提振日志条目内提振日志条目。
Warning: if you redirect stderr and stdout and are using Boost, then redirect stderr first, then stdout. Otherwise, Boost will write loopback the stderr message back to stdout, and you'll get a boost log entry inside another boost log entry.
cout << "testing out before 1 2 3 " << endl;
cerr << "testing err before 1 2 3 " << endl;
{
StdErrHandler err([](const char* line){
BOOST_LOG_TRIVIAL(error) << "ERROR:" << strlen(line) << " " << line;
});
StdOutHandler out([](const char* line){
BOOST_LOG_TRIVIAL(info) << "OUT:" << strlen(line) << " " << line;
});
cout << "cout testing 1 2 3 " << endl;
cerr << "cerr testing 1 2 3 " << endl;
}
cout << "testing out after 1 2 3 " << endl;
cerr << "testing err after 1 2 3 " << endl;
示例输出
pa-poca$ ./test
testing out before 1 2 3
testing err before 1 2 3
[2014-08-01 12:24:56.468335] [0x000007f89d8990d4] [error] ERROR:19 cerr testing 1 2 3
[2014-08-01 12:24:56.468360] [0x000007f89d8990d4] [info] OUT:19 cout testing 1 2 3
testing out after 1 2 3
testing err after 1 2 3
code
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <string.h>
#include <signal.h>
#include <sys/wait.h>
class StdioHandler
{
private:
pid_t pid = 0;
int origfd;
int streamid;
int pipefd[2];
public:
enum class Stream
{
stdout = STDOUT_FILENO,
stderr = STDERR_FILENO
};
StdioHandler(Stream stream, std::function<void(const char*)> callback)
:streamid(static_cast<int>(stream))
{
origfd = dup(streamid);
pipe(pipefd); // create pipe
pid = fork(); //spawn a child process to handle output of pipe
if (pid == 0)
{
char line[256];
FILE* output;
close(pipefd[1]);
output = fdopen(pipefd[0], "r");
if (output)
{
while(fgets(line, sizeof(line), output))
{
int n = strlen(line);
if (n > 0)
if (line[n-1] == '\n') line[n-1] = 0;
callback(line);
}
fclose(output);
}
abort();
} else {
// connect input of pipe to
close(pipefd[0]);
dup2(pipefd[1], streamid);
}
}
~StdioHandler()
{
int status;
usleep(10000);
close(pipefd[1]);
kill(pid,SIGINT);
waitpid(pid, &status, 0);
dup2(origfd, streamid);
}
};
class StdOutHandler : public StdioHandler
{
public:
StdOutHandler(std::function<void(const char*)> callback) :
StdioHandler(Stream::stdout, callback)
{
}
};
class StdErrHandler : public StdioHandler
{
public:
StdErrHandler(std::function<void(const char*)> callback) :
StdioHandler(Stream::stderr, callback)
{
}
};
这篇关于我怎么能输出重定向到一个日志提振？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
