logger: use {fmt} for header generation

Change-Id: I3ee8a5051e8aace1737d40364bd5defae044636c

src/logger.cpp

@@ -27,6 +27,11 @@
 
 #include "client/ring_signal.h"
 
+#include <fmt/core.h>
+#include <fmt/format.h>
+#include <fmt/std.h>
+#include <fmt/compile.h>
+
 #ifdef _MSC_VER
 #include <sys_time.h>
 #else
@@ -38,8 +43,6 @@
 #include <functional>
 #include <fstream>
 #include <string>
-#include <sstream>
-#include <iomanip>
 #include <ios>
 #include <mutex>
 #include <thread>
@@ -137,44 +140,14 @@ stripDirName(const char* path)
 static std::string
 contextHeader(const char* const file, int line)
 {
-    static char* timestamp_fmt = getenv("JAMI_TIMESTAMP_FMT");
-
 #ifdef __linux__
     auto tid = syscall(__NR_gettid) & 0xffff;
 #else
     auto tid = std::this_thread::get_id();
 #endif // __linux__
 
-    std::ostringstream out;
-
-    out << '[';
-
-    // Timestamp
-    if (timestamp_fmt) {
-        time_t t;
-        struct tm tm;
-        char buf[128];
-
-        time(&t);
-
-#ifdef _WIN32
-        /* NOTE!  localtime(3) is MT-Safe on win32 */
-        tm = *localtime(&t);
-#else
-        localtime_r(&t, &tm);
-#endif
-
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wformat-nonliteral"
-        strftime(buf, sizeof(buf), timestamp_fmt, &tm);
-#pragma GCC diagnostic pop
-
-        out << buf;
-
-    } else {
     unsigned int secs, milli;
     struct timeval tv;
-
     if (!gettimeofday(&tv, NULL)) {
         secs = tv.tv_sec;
         milli = tv.tv_usec / 1000; // suppose that milli < 1000
@@ -183,27 +156,11 @@ contextHeader(const char* const file, int line)
         milli = 0;
     }
 
-        const auto prev_fill = out.fill();
-
-        out << secs << '.' << std::right << std::setw(3) << std::setfill('0') << milli << std::left;
-        out.fill(prev_fill);
-    }
-
-    out << '|' << std::right << std::setw(5) << std::setfill(' ') << tid << std::left;
-
-    // Context
     if (file) {
-#ifdef RING_UWP
-        constexpr auto width = 26;
-#else
-        constexpr auto width = 18;
-#endif
-        out << "|" << std::setw(width) << stripDirName(file) << ":" << std::setw(5)
-            << std::setfill(' ') << line;
+        return fmt::format(FMT_COMPILE("[{: >3d}.{:0<3d}|{: >4}|{: <18s}:{: <4d}]"), secs, milli, tid, stripDirName(file), line);
+    } else {
+        return fmt::format(FMT_COMPILE("[{: >3d}.{:0<3d}|{: >4}]"), secs, milli, tid);
     }
-
-    out << "] ";
-    return out.str();
 }
 
 struct BufDeleter