From bd74991862fdb6b7e6a0fc7b4dece309cdfe1b9d Mon Sep 17 00:00:00 2001
From: Sergei Zobov <sergey@szobov.ru>
Date: Wed, 19 Feb 2020 16:20:20 +0300
Subject: [PATCH] Add preserve_parent_name in async/logger::clone method

... in order to support logical hierarchy of loggers.

Imagine you have something like this architecture:

Application / Controller / First
                         / Second

And you want to have a log messages and understand from witch part it come,
after this changes you can do:

```
first_controller_logger = controller_logger.clone("first", true);
```
and you will get in log output something similar to:

```
[2014-10-31 23:46:59.678] [controller.first] [info] Some message
```

What is quite convenient.

Actually now you can do it by wrapping clone method, but with my changes it
won't require any user's code.

Thanks.
---
 include/spdlog/async_logger-inl.h |  9 +++++++--
 include/spdlog/async_logger.h     |  2 +-
 include/spdlog/logger-inl.h       | 10 +++++++---
 include/spdlog/logger.h           |  2 +-
 tests/test_misc.cpp               |  8 ++++++++
 5 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/include/spdlog/async_logger-inl.h b/include/spdlog/async_logger-inl.h
index 356db0e7..c35dc197 100644
--- a/include/spdlog/async_logger-inl.h
+++ b/include/spdlog/async_logger-inl.h
@@ -84,9 +84,14 @@ SPDLOG_INLINE void spdlog::async_logger::backend_flush_()
     }
 }
 
-SPDLOG_INLINE std::shared_ptr<spdlog::logger> spdlog::async_logger::clone(std::string new_name)
+SPDLOG_INLINE std::shared_ptr<spdlog::logger> spdlog::async_logger::clone(std::string new_name, bool preserve_parent_name)
 {
     auto cloned = std::make_shared<spdlog::async_logger>(*this);
-    cloned->name_ = std::move(new_name);
+    if (preserve_parent_name) {
+        cloned->name_ += ".";
+        cloned->name_ += new_name;
+    } else {
+        cloned->name_ = std::move(new_name);
+    }
     return cloned;
 }
diff --git a/include/spdlog/async_logger.h b/include/spdlog/async_logger.h
index 829c5acc..8896cb36 100644
--- a/include/spdlog/async_logger.h
+++ b/include/spdlog/async_logger.h
@@ -49,7 +49,7 @@ public:
     async_logger(std::string logger_name, sink_ptr single_sink, std::weak_ptr<details::thread_pool> tp,
         async_overflow_policy overflow_policy = async_overflow_policy::block);
 
-    std::shared_ptr<logger> clone(std::string new_name) override;
+    std::shared_ptr<logger> clone(std::string new_name, bool preserve_parent_name = false) override;
 
 protected:
     void sink_it_(const details::log_msg &msg) override;
diff --git a/include/spdlog/logger-inl.h b/include/spdlog/logger-inl.h
index 95a485f1..f43c0bf1 100644
--- a/include/spdlog/logger-inl.h
+++ b/include/spdlog/logger-inl.h
@@ -154,10 +154,14 @@ SPDLOG_INLINE void logger::set_error_handler(err_handler handler)
 }
 
 // create new logger with same sinks and configuration.
-SPDLOG_INLINE std::shared_ptr<logger> logger::clone(std::string logger_name)
-{
+SPDLOG_INLINE std::shared_ptr<logger> logger::clone(std::string logger_name, bool preserve_parent_name) {
     auto cloned = std::make_shared<logger>(*this);
-    cloned->name_ = std::move(logger_name);
+    if (preserve_parent_name) {
+        cloned->name_ += ".";
+        cloned->name_ += logger_name;
+    } else {
+        cloned->name_ = std::move(logger_name);
+    }
     return cloned;
 }
 
diff --git a/include/spdlog/logger.h b/include/spdlog/logger.h
index b78d8544..7b1139cb 100644
--- a/include/spdlog/logger.h
+++ b/include/spdlog/logger.h
@@ -347,7 +347,7 @@ public:
     void set_error_handler(err_handler);
 
     // create new logger with same sinks and configuration.
-    virtual std::shared_ptr<logger> clone(std::string logger_name);
+    virtual std::shared_ptr<logger> clone(std::string logger_name, bool preserve_parent_name = false);
 
 protected:
     std::string name_;
diff --git a/tests/test_misc.cpp b/tests/test_misc.cpp
index 576005a4..c7209bc1 100644
--- a/tests/test_misc.cpp
+++ b/tests/test_misc.cpp
@@ -112,6 +112,10 @@ TEST_CASE("clone-logger", "[clone]")
     REQUIRE(test_sink->lines()[0] == "Some message 1");
     REQUIRE(test_sink->lines()[1] == "Some message 2");
 
+    auto cloned_with_parent_name = cloned->clone("sub_logger", /* preserve_parent_name = */ true);
+
+    REQUIRE(cloned_with_parent_name->name() == "clone.sub_logger");
+
     spdlog::drop_all();
 }
 
@@ -139,6 +143,10 @@ TEST_CASE("clone async", "[clone]")
     REQUIRE(test_sink->lines()[0] == "Some message 1");
     REQUIRE(test_sink->lines()[1] == "Some message 2");
 
+    auto cloned_with_parent_name = cloned->clone("sub_logger", /* preserve_parent_name = */ true);
+
+    REQUIRE(cloned_with_parent_name->name() == "clone.sub_logger");
+
     spdlog::drop_all();
 }