Merge bitcoin/bitcoin#24464: logging: Add severity level to logs

e11cdc930375eaec8d737e116138b2f2018c099f  logging: Add log severity level to net.cpp (klementtan)
a8290649a6578df120a71c9493acdf071e010d96 logging: Add severity level to logs. (klementtan)

Pull request description:

  **Overview**: This PR introduces a new macro, `LogPrintLevel`, that allows developers to add logs with the severity level. Additionally, it will also print the log category if it is specified.

  Sample log:
  ```
  2022-03-04T16:41:15Z [opencon] [net:debug] trying connection XX.XX.XXX.XXX:YYYYY lastseen=2.7hrs
  ```

  **Motivation**: This feature was suggested in #20576 and I believe that it will bring the following benefits:
  * Allow for easier filtering of logs in `debug.log`
  * Can be extended to allow users to select the minimum level of logs they would like to view (not in the scope of this PR)

  **Details**:
  * New log format. `... [category:level]...`. ie:
    * Do not print category if `category == NONE`
    * Do not print level if `level == NONE`
    * If `category == NONE` and `level == NONE`, do not print any fields (current behaviour)
  * Previous logging functions:
    * `LogPrintf`:  no changes in log as it calls `LogPrintf_` with `category = NONE` and `level = NONE`
    * `LogPrint`: prints additional `[category]` field as it calls `LogPrintf_` with `category = category` and `level = NONE`
  * `net.cpp`: As a proof of concept, updated logs with obvious severity (ie prefixed with `Warning/Error:..`) to use the new logging with severity.

  **Testing**:
  * Compiling and running `bitcoind` with this PR should instantly display logs with the category name (ie `net/tor/...`)
  * Grepping for `net:debug` in `debug.log` should display the updated logs with severity level:
    <details>
    <summary>Code</summary>

    ```
    $ grep "net:debug" debug.log

    2022-03-04T16:41:15Z [opencon] [net:debug] trying connection XXX:YYY lastseen=2.7hrs
    2022-03-04T16:41:16Z [opencon] [net:debug] trying connection XXX:YYY lastseen=16.9hrs
    2022-03-04T16:41:17Z [opencon] [net:debug] trying connection XXX:YYY lastseen=93.2hrs
    2022-03-04T16:41:18Z [opencon] [net:debug] trying connection XXX:YYY lastseen=2.7hrs
    ```
    </details>

ACKs for top commit:
  laanwj:
    Code review and lightly tested ACK e11cdc930375eaec8d737e116138b2f2018c099f

Tree-SHA512: 89a8c86667ccc0688e5acfdbd399aac1f5bec9f978a160e40b0210b0d9b8fdc338479583fc5bd2e2bc785821363f174f578d52136d228e8f638a20abbf0a568f

1 files changed, 26 insertions, 9 deletions

diff --git a/src/logging.h b/src/logging.h
index ae8cad906c..421c3395c2 100644
--- a/src/logging.h
+++ b/src/logging.h
@@ -67,6 +67,13 @@ namespace BCLog {
         BLOCKSTORE  = (1 << 26),
         ALL         = ~(uint32_t)0,
     };
+    enum class Level {
+        Debug = 0,
+        None = 1,
+        Info = 2,
+        Warning = 3,
+        Error = 4,
+    };
 
     class Logger
     {
@@ -105,7 +112,7 @@ namespace BCLog {
         std::atomic<bool> m_reopen_file{false};
 
         /** Send a string to the log output */
-        void LogPrintStr(const std::string& str, const std::string& logging_function, const std::string& source_file, const int source_line);
+        void LogPrintStr(const std::string& str, const std::string& logging_function, const std::string& source_file, const int source_line, const BCLog::LogFlags category, const BCLog::Level level);
 
         /** Returns whether logs will be written to any output */
         bool Enabled() const
@@ -173,7 +180,7 @@ bool GetLogCategory(BCLog::LogFlags& flag, const std::string& str);
 // peer can fill up a user's disk with debug.log entries.
 
 template <typename... Args>
-static inline void LogPrintf_(const std::string& logging_function, const std::string& source_file, const int source_line, const char* fmt, const Args&... args)
+static inline void LogPrintf_(const std::string& logging_function, const std::string& source_file, const int source_line, const BCLog::LogFlags flag, const BCLog::Level level, const char* fmt, const Args&... args)
 {
     if (LogInstance().Enabled()) {
         std::string log_msg;
@@ -183,19 +190,29 @@ static inline void LogPrintf_(const std::string& logging_function, const std::st
             /* Original format string will have newline so don't add one here */
             log_msg = "Error \"" + std::string(fmterr.what()) + "\" while formatting log message: " + fmt;
         }
-        LogInstance().LogPrintStr(log_msg, logging_function, source_file, source_line);
+        LogInstance().LogPrintStr(log_msg, logging_function, source_file, source_line, flag, level);
     }
 }
 
-#define LogPrintf(...) LogPrintf_(__func__, __FILE__, __LINE__, __VA_ARGS__)
+
+#define LogPrintLevel_(category, level, ...) LogPrintf_(__func__, __FILE__, __LINE__, category, level, __VA_ARGS__)
+
+#define LogPrintf(...) LogPrintLevel_(BCLog::LogFlags::NONE, BCLog::Level::None, __VA_ARGS__)
 
 // Use a macro instead of a function for conditional logging to prevent
 // evaluating arguments when logging for the category is not enabled.
-#define LogPrint(category, ...)              \
-    do {                                     \
-        if (LogAcceptCategory((category))) { \
-            LogPrintf(__VA_ARGS__);          \
-        }                                    \
+#define LogPrint(category, ...)                                        \
+    do {                                                               \
+        if (LogAcceptCategory((category))) {                           \
+            LogPrintLevel_(category, BCLog::Level::None, __VA_ARGS__); \
+        }                                                              \
+    } while (0)
+
+#define LogPrintLevel(level, category, ...)               \
+    do {                                                  \
+        if (LogAcceptCategory((category))) {              \
+            LogPrintLevel_(category, level, __VA_ARGS__); \
+        }                                                 \
     } while (0)
 
 #endif // BITCOIN_LOGGING_H