Logging: add `src/plugins/comp-logging.h` (BT_COMP_LOG*())

This new header is intended to be included by the different component
class files so that their logging statements can automatically include
the component's name. The BT_COMP_LOG*() macros prepend a prefix similar
to this to the logging message:

    [mein-sink]

where `mein-sink` is a component's name.

Having the component name within each logging message of a given
component class adds valuable context and can help resolve issues
faster.

I did not include the plugin name and the component class's type and
name within the prefix because we already have them thanks to the
logging tag, for example `PLUGIN/SRC.CTF.FS`. This would be redundant,
make the logging message longer, and make `comp-logging.h` more complex.

The BT_COMP_LOG*() macros rely on the `BT_COMP_LOG_SELF_COMP`
definition. This is an expression which is, in the logging statement
context, the `bt_self_component *` address. Because we have the self
component there, we are free to prepend more contextual information to
the logging message in the future, should we need it.

Typically, when a component class source file defines
`BT_LOG_OUTPUT_LEVEL` to `(my_comp->log_level)`, where `my_comp` points
to the component's private structure, it will also define
`BT_COMP_LOG_SELF_COMP` to `(my_comp->self_comp)`.

If `BT_COMP_LOG_SELF_COMP` evaluates to `NULL`, the macros use the
prefix

    [N/A]

This could be the case when instrumenting code that is shared for both
graph and non-graph contexts, for example the metadata and stream
decoders of the `ctf` plugin which can also be used within a query
operation.

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
Change-Id: I62c63ed78d234922f556631726fb7bb852924f0a
Reviewed-on: https://review.lttng.org/c/babeltrace/+/1468
Tested-by: jenkins <jenkins@lttng.org>
Reviewed-by: Francis Deslauriers <francis.deslauriers@efficios.com>

diff --git a/src/plugins/Makefile.am b/src/plugins/Makefile.am
index 0c53f76492667303b6b82022719c9ba8c3bdf757..aa0c6dba15b82512635946e2dd816bb9016f810e 100644 (file)
--- a/src/plugins/Makefile.am
+++ b/src/plugins/Makefile.am
@@ -3,3 +3,5 @@ SUBDIRS = utils text ctf
 if ENABLE_DEBUG_INFO
 SUBDIRS += lttng-utils
 endif
+
+EXTRA_DIST = comp-logging.h

diff --git a/src/plugins/comp-logging.h b/src/plugins/comp-logging.h
new file mode 100644 (file)
index 0000000..d1399f7
--- /dev/null
+++ b/src/plugins/comp-logging.h
@@ -0,0 +1,142 @@
+#ifndef BABELTRACE_PLUGINS_COMP_LOGGING_H
+#define BABELTRACE_PLUGINS_COMP_LOGGING_H
+
+/*
+ * Copyright 2019 Philippe Proulx <pproulx@efficios.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef BT_LOG_TAG
+# error Please define a tag with BT_LOG_TAG before including this file.
+#endif
+
+#ifndef BT_LOG_OUTPUT_LEVEL
+# error Please define a log level expression with BT_LOG_OUTPUT_LEVEL before including this file.
+#endif
+
+#ifndef BT_COMP_LOG_SELF_COMP
+# error Please define a self component address expression with BT_COMP_LOG_SELF_COMP before including this file.
+#endif
+
+#include <stdlib.h>
+#include <babeltrace2/graph/self-component.h>
+#include <babeltrace2/graph/component-const.h>
+#include <babeltrace2/graph/component-class-const.h>
+#include "logging/log.h"
+
+#define _BT_COMP_LOG_COMP_PREFIX       "[%s] "
+#define _BT_COMP_LOG_COMP_NA_STR       "N/A"
+
+/* Logs with level `_lvl` for self component `_self_comp` */
+#define BT_COMP_LOG(_lvl, _self_comp, _fmt, ...)                       \
+       BT_LOG_WRITE((_lvl), BT_LOG_TAG, _BT_COMP_LOG_COMP_PREFIX _fmt, \
+               (_self_comp) ?                                          \
+                       bt_component_get_name(                          \
+                               bt_self_component_as_component(_self_comp)) : \
+                       _BT_COMP_LOG_COMP_NA_STR,                       \
+               ##__VA_ARGS__)
+
+#define BT_COMP_LOG_CUR_LVL(_lvl, _cur_lvl, _self_comp, _fmt, ...)     \
+       BT_LOG_WRITE_CUR_LVL((_lvl), (_cur_lvl), BT_LOG_TAG,            \
+               _BT_COMP_LOG_COMP_PREFIX _fmt,                          \
+               (_self_comp) ?                                          \
+                       bt_component_get_name(                          \
+                               bt_self_component_as_component(_self_comp)) : \
+                       _BT_COMP_LOG_COMP_NA_STR,                       \
+               ##__VA_ARGS__)
+
+#define BT_COMP_LOG_ERRNO(_lvl, _self_comp, _msg, _fmt, ...)           \
+       BT_LOG_WRITE_ERRNO((_lvl), BT_LOG_TAG, _msg,                    \
+               _BT_COMP_LOG_COMP_PREFIX _fmt,                          \
+               (_self_comp) ?                                          \
+                       bt_component_get_name(                          \
+                               bt_self_component_as_component(_self_comp)) : \
+                       _BT_COMP_LOG_COMP_NA_STR,                       \
+               ##__VA_ARGS__)
+
+#define BT_COMP_LOG_ERRNO_CUR_LVL(_lvl, _cur_lvl, _self_comp, _msg, _fmt, ...) \
+       BT_LOG_WRITE_ERRNO_CUR_LVL((_lvl), (_cur_lvl), BT_LOG_TAG, _msg, \
+               _BT_COMP_LOG_COMP_PREFIX _fmt,                          \
+               (_self_comp) ?                                          \
+                       bt_component_get_name(                          \
+                               bt_self_component_as_component(_self_comp)) : \
+                       _BT_COMP_LOG_COMP_NA_STR,                       \
+               ##__VA_ARGS__)
+
+#define BT_COMP_LOG_MEM(_lvl, _self_comp, _data_ptr, _data_sz, _fmt, ...) \
+       BT_LOG_WRITE_MEM((_lvl), BT_LOG_TAG, (_data_ptr), (_data_sz),   \
+               _BT_COMP_LOG_COMP_PREFIX _fmt,                          \
+               (_self_comp) ?                                          \
+                       bt_component_get_name(                          \
+                               bt_self_component_as_component(_self_comp)) : \
+                       _BT_COMP_LOG_COMP_NA_STR,                       \
+               ##__VA_ARGS__)
+
+/* Specific per-level logging macros; they use `BT_COMP_LOG_SELF_COMP` */
+#define BT_COMP_LOGF(_fmt, ...) \
+       BT_COMP_LOG(BT_LOG_FATAL, (BT_COMP_LOG_SELF_COMP), _fmt, ##__VA_ARGS__)
+#define BT_COMP_LOGE(_fmt, ...) \
+       BT_COMP_LOG(BT_LOG_ERROR, (BT_COMP_LOG_SELF_COMP), _fmt, ##__VA_ARGS__)
+#define BT_COMP_LOGW(_fmt, ...) \
+       BT_COMP_LOG(BT_LOG_WARN, (BT_COMP_LOG_SELF_COMP), _fmt, ##__VA_ARGS__)
+#define BT_COMP_LOGI(_fmt, ...) \
+       BT_COMP_LOG(BT_LOG_INFO, (BT_COMP_LOG_SELF_COMP), _fmt, ##__VA_ARGS__)
+#define BT_COMP_LOGD(_fmt, ...) \
+       BT_COMP_LOG(BT_LOG_DEBUG, (BT_COMP_LOG_SELF_COMP), _fmt, ##__VA_ARGS__)
+#define BT_COMP_LOGV(_fmt, ...) \
+       BT_COMP_LOG(BT_LOG_VERBOSE, (BT_COMP_LOG_SELF_COMP), _fmt, ##__VA_ARGS__)
+#define BT_COMP_LOGF_STR(_str) \
+       BT_COMP_LOG(BT_LOG_FATAL, (BT_COMP_LOG_SELF_COMP), "%s", (_str))
+#define BT_COMP_LOGE_STR(_str) \
+       BT_COMP_LOG(BT_LOG_ERROR, (BT_COMP_LOG_SELF_COMP), "%s", (_str))
+#define BT_COMP_LOGW_STR(_str) \
+       BT_COMP_LOG(BT_LOG_WARN, (BT_COMP_LOG_SELF_COMP), "%s", (_str))
+#define BT_COMP_LOGI_STR(_str) \
+       BT_COMP_LOG(BT_LOG_INFO, (BT_COMP_LOG_SELF_COMP), "%s", (_str))
+#define BT_COMP_LOGD_STR(_str) \
+       BT_COMP_LOG(BT_LOG_DEBUG, (BT_COMP_LOG_SELF_COMP), "%s", (_str))
+#define BT_COMP_LOGV_STR(_str) \
+       BT_COMP_LOG(BT_LOG_VERBOSE, (BT_COMP_LOG_SELF_COMP), "%s", (_str))
+#define BT_COMP_LOGF_ERRNO(_msg, _fmt, ...) \
+       BT_COMP_LOG_ERRNO(BT_LOG_FATAL, (BT_COMP_LOG_SELF_COMP), _msg, _fmt, ##__VA_ARGS__)
+#define BT_COMP_LOGE_ERRNO(_msg, _fmt, ...) \
+       BT_COMP_LOG_ERRNO(BT_LOG_ERROR, (BT_COMP_LOG_SELF_COMP), _msg, _fmt, ##__VA_ARGS__)
+#define BT_COMP_LOGW_ERRNO(_msg, _fmt, ...) \
+       BT_COMP_LOG_ERRNO(BT_LOG_WARN, (BT_COMP_LOG_SELF_COMP), _msg, _fmt, ##__VA_ARGS__)
+#define BT_COMP_LOGI_ERRNO(_msg, _fmt, ...) \
+       BT_COMP_LOG_ERRNO(BT_LOG_INFO, (BT_COMP_LOG_SELF_COMP), _msg, _fmt, ##__VA_ARGS__)
+#define BT_COMP_LOGD_ERRNO(_msg, _fmt, ...) \
+       BT_COMP_LOG_ERRNO(BT_LOG_DEBUG, (BT_COMP_LOG_SELF_COMP), _msg, _fmt, ##__VA_ARGS__)
+#define BT_COMP_LOGV_ERRNO(_msg, _fmt, ...) \
+       BT_COMP_LOG_ERRNO(BT_LOG_VERBOSE, (BT_COMP_LOG_SELF_COMP), _msg, _fmt, ##__VA_ARGS__)
+#define BT_COMP_LOGF_MEM(_data_ptr, _data_sz, _fmt, ...) \
+       BT_COMP_LOG_MEM(BT_LOG_FATAL, (BT_COMP_LOG_SELF_COMP), (_data_ptr), (_data_sz), _fmt, ##__VA_ARGS__)
+#define BT_COMP_LOGE_MEM(_data_ptr, _data_sz, _fmt, ...) \
+       BT_COMP_LOG_MEM(BT_LOG_ERROR, (BT_COMP_LOG_SELF_COMP), (_data_ptr), (_data_sz), _fmt, ##__VA_ARGS__)
+#define BT_COMP_LOGW_MEM(_data_ptr, _data_sz, _fmt, ...) \
+       BT_COMP_LOG_MEM(BT_LOG_WARN, (BT_COMP_LOG_SELF_COMP), (_data_ptr), (_data_sz), _fmt, ##__VA_ARGS__)
+#define BT_COMP_LOGI_MEM(_data_ptr, _data_sz, _fmt, ...) \
+       BT_COMP_LOG_MEM(BT_LOG_INFO, (BT_COMP_LOG_SELF_COMP), (_data_ptr), (_data_sz), _fmt, ##__VA_ARGS__)
+#define BT_COMP_LOGD_MEM(_data_ptr, _data_sz, _fmt, ...) \
+       BT_COMP_LOG_MEM(BT_LOG_DEBUG, (BT_COMP_LOG_SELF_COMP), (_data_ptr), (_data_sz), _fmt, ##__VA_ARGS__)
+#define BT_COMP_LOGV_MEM(_data_ptr, _data_sz, _fmt, ...) \
+       BT_COMP_LOG_MEM(BT_LOG_VERBOSE, (BT_COMP_LOG_SELF_COMP), (_data_ptr), (_data_sz), _fmt, ##__VA_ARGS__)
+
+#endif /* BABELTRACE_PLUGINS_COMP_LOGGING_H */