Hi,

Just wondering which logger library is thread safe?

https://code.dlang.org/

Need to find a mature one to be used in a multi-threaded env.

Thanks.

On Wednesday, 12 July 2023 at 01:24:41 UTC, mw wrote:

Oh, forget to mention: need output to logger file.

On Wednesday, 12 July 2023 at 01:26:25 UTC, mw wrote:

tried:

https://run.dlang.io/is/ufy4yF

import std.experimental.logger;

void main() {
    std.experimental.logger.sharedLog.trace("msg");
}

but:

onlineapp.d(4): Error: none of the overloads of template std.logger.core.Logger.memLogFunctions!LogLevel.trace.logImpl are callable using argument types !()(string) shared
/dlang/dmd/linux/bin64/../../src/phobos/std/logger/core.d(734): Candidates are: logImpl(int line = __LINE__, string file = __FILE__, string funcName = __FUNCTION__, string prettyFuncName = __PRETTY_FUNCTION__, string moduleName = __MODULE__, A...)(lazy A args)
/dlang/dmd/linux/bin64/../../src/phobos/std/logger/core.d(780): logImpl(int line = __LINE__, string file = __FILE__, string funcName = __FUNCTION__, string prettyFuncName = __PRETTY_FUNCTION__, string moduleName = __MODULE__, A...)(lazy bool condition, lazy A args)

so, how to fix this compiler error?

On Wednesday, 12 July 2023 at 01:55:00 UTC, mw wrote:

import std.experimental.logger;

void main() {
    std.experimental.logger.sharedLog.trace("msg");
}

See examples at https://dlang.org/phobos/std_logger.html
and https://dlang.org/phobos/std_logger_filelogger.html

import std.stdio;
import std.logger;

void main() {
    //auto file = File("logFile.log", "w");
    auto file = stderr; // stdout

    auto logger = new FileLogger(file);
    //auto logger = new FileLogger(file, LogLevel.fatal);

    logger.log("log message");
    logger.info("info message");
    logger.warning(5 < 6, "Logging with LogLevel.warning if 5 is less than 6");
    logger.warningf(5 < 6, "Logging with LogLevel.warning if %s is %s than 6", 5, "less");
    logger.critical("Logging with critical LogLevel");
    logger.log(LogLevel.trace, 5 < 6, "Logging"," with its default LogLevel if 5 is less than 6");
    //logger.fatal("fatal message");
}

On Wednesday, 12 July 2023 at 04:48:23 UTC, Danilo wrote:

import std.experimental.logger;

void main() {
    std.experimental.logger.sharedLog.trace("msg");
}

But what's wrong with my code? the strange compiler error?

On Wednesday, 12 July 2023 at 05:27:27 UTC, mw wrote:

Might be a bug/issue in the logger module.

sharedLog uses the shared attribute,
but the base class for everything ("abstract class Logger")
does not use the shared attribute anywhere.

• https://github.com/dlang/phobos/blob/master/std/logger/core.d#L516C22-L516C22

It works when you cast away the shared attribute from sharedLog,
so I think that's the problem.

import std.stdio;
import std.logger;

void main() {

    stdThreadLocalLog = new FileLogger(stderr);
    stdThreadLocalLog.trace("local msg");

    //-----------------------------------------------

    sharedLog = cast(shared)new FileLogger(stderr);

    //sharedLog.trace("shared msg");                                          // ERROR
    (cast()sharedLog).trace("shared msg");                                    // WORKS, cast away 'shared'

    //sharedLog.memLogFunctions!(LogLevel.trace).logImpl("shared msg");       // ERROR
    (cast()sharedLog).memLogFunctions!(LogLevel.trace).logImpl("shared msg"); // WORKS, cast away 'shared'
}

WebFreak said you can just use trace(), info() etc. inside threads. It is thread-safe by default.

module app;

import std.stdio;
import std.logger;

void main() {

    //auto file = File("logFile.log", "w");
    auto file = stderr; // stdout

    sharedLog = cast(shared)new FileLogger(file);

    import core.thread : Thread, msecs;

    Thread[100] threads;

    for(int i=0; i<threads.length; i++) {
        threads[i] = new Thread(
            function void() {
                info("thread info");
                trace("thread trace");
            }
        );
        threads[i].start();
    }

    for(int i=0; i<threads.length; i++) {
        threads[i].join();
    }
}

On Wednesday, 12 July 2023 at 09:47:26 UTC, Danilo wrote:

cast away? the variable itself is called sharedLog, the cast completely defeat the purpose.

Sigh, D is so broken on such basic stuff.