[libcamera-devel] [PATCH 2/3] libcamera: Add initial logger

[Laurent Pinchart]

The logger is based on the ostream API, allowing code to log messages in
a native way. It automatically logs the time stamp, severity level, file
name and line number.

Many important features are missing, such as logging to file, logging
classes, and log filtering based on the severity level, file name and
class.

Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
---
 src/libcamera/include/.keep_empty |  0
 src/libcamera/include/log.h       | 38 +++++++++++++++
 src/libcamera/include/utils.h     | 12 +++++
 src/libcamera/log.cpp             | 81 +++++++++++++++++++++++++++++++
 src/libcamera/meson.build         |  5 +-
 5 files changed, 135 insertions(+), 1 deletion(-)
 delete mode 100644 src/libcamera/include/.keep_empty
 create mode 100644 src/libcamera/include/log.h
 create mode 100644 src/libcamera/include/utils.h
 create mode 100644 src/libcamera/log.cpp

diff --git a/src/libcamera/include/.keep_empty b/src/libcamera/include/.keep_empty
deleted file mode 100644
index e69de29bb2d1..000000000000
diff --git a/src/libcamera/include/log.h b/src/libcamera/include/log.h
new file mode 100644
index 000000000000..76acd1520868
--- /dev/null
+++ b/src/libcamera/include/log.h
@@ -0,0 +1,38 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2018, Google Inc.
+ *
+ * log.h - Logging infrastructure
+ */
+#ifndef __LIBCAMERA_LOG_H__
+#define __LIBCAMERA_LOG_H__
+
+#include <sstream>
+
+namespace libcamera {
+
+enum LogSeverity {
+	LogInfo,
+	LogWarning,
+	LogError,
+};
+
+class LogMessage
+{
+public:
+	LogMessage(const char *fileName, unsigned int line,
+		  LogSeverity severity);
+	LogMessage(const LogMessage&) = delete;
+	~LogMessage();
+
+	std::ostream& stream() { return msgStream; }
+
+private:
+	std::ostringstream msgStream;
+};
+
+#define LOG(severity) LogMessage(__FILE__, __LINE__, Log##severity).stream()
+
+};
+
+#endif /* __LIBCAMERA_LOG_H__ */
diff --git a/src/libcamera/include/utils.h b/src/libcamera/include/utils.h
new file mode 100644
index 000000000000..3ffa6f4ea591
--- /dev/null
+++ b/src/libcamera/include/utils.h
@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2018, Google Inc.
+ *
+ * utils.h - Miscellaneous utility functions
+ */
+#ifndef __LIBCAMERA_UTILS_H__
+#define __LIBCAMERA_UTILS_H__
+
+#define ARRAY_SIZE(a)	(sizeof(a) / sizeof(a[0]))
+
+#endif /* __LIBCAMERA_UTILS_H__ */
diff --git a/src/libcamera/log.cpp b/src/libcamera/log.cpp
new file mode 100644
index 000000000000..18ccfa32d8b4
--- /dev/null
+++ b/src/libcamera/log.cpp
@@ -0,0 +1,81 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2018, Google Inc.
+ *
+ * log.h - Logging infrastructure
+ */
+
+#include <cstdio>
+#include <ctime>
+#include <iomanip>
+#include <string.h>
+
+#include "log.h"
+#include "utils.h"
+
+/**
+ * \file log.h
+ * \brief Logging infrastructure
+ */
+
+namespace libcamera {
+
+/**
+ * \enum LogSeverity
+ * Log message severity
+ * \var Info
+ * Informational message
+ * \var Warning
+ * Warning message, signals a potential issue
+ * \var Error
+ * Error message, signals an unrecoverable issue
+ */
+
+/**
+ * \def LOG(severity)
+ * \brief Log a message
+ *
+ * Return an std::ostream reference to which a message can be logged using the
+ * iostream API. The \a severity controls whether the message is printed or
+ * dropped, depending on the global log level.
+ */
+
+static const char *log_severity_name(LogSeverity severity)
+{
+	static const char * const names[] = {
+		"INFO",
+		"WARN",
+		" ERR",
+	};
+
+	if ((unsigned int)severity < ARRAY_SIZE(names))
+		return names[severity];
+	else
+		return "UNKN";
+}
+
+LogMessage::LogMessage(const char *fileName, unsigned int line,
+		       LogSeverity severity)
+{
+	/* Log the timestamp, severity and file information. */
+	struct timespec timestamp;
+	clock_gettime(CLOCK_MONOTONIC, &timestamp);
+	msgStream << "[" << timestamp.tv_sec / (60 * 60) << ":"
+		  << std::setw(2) << (timestamp.tv_sec / 60) % 60 << ":"
+		  << std::setw(2) << timestamp.tv_sec % 60 << "."
+		  << std::setw(9) << timestamp.tv_nsec << "]";
+
+	msgStream << " " << log_severity_name(severity);
+	msgStream << " " << basename(fileName) << ":" << line << " ";
+}
+
+LogMessage::~LogMessage()
+{
+	msgStream << std::endl;
+
+	std::string msg(msgStream.str());
+	fwrite(msg.data(), msg.size(), 1, stderr);
+	fflush(stderr);
+}
+
+};
diff --git a/src/libcamera/meson.build b/src/libcamera/meson.build
index 07d9cd448342..fe38f8b2b5b4 100644
--- a/src/libcamera/meson.build
+++ b/src/libcamera/meson.build
@@ -1,4 +1,7 @@
-sources = ['main.cpp']
+sources = files([
+    'log.cpp',
+    'main.cpp',
+])
 
 includes = [
     libcamera_includes,
-- 
Regards,

Laurent Pinchart