[ 原始碼： spdlog ]
套件：libspdlog-dev（1:1.3.1-1）
Very fast, header only, C++ logging library
Features: Very fast - performance is the primary goal; Headers only; No dependencies - just copy and use; call style using the excellent cppformat library; ostream call style is supported too; Optional extremely fast asynchronous mode - using lockfree queues and other tricks to reach millions of calls/sec; Custom formatting; Multi/Single threaded loggers; Easily extendable with custom log targets (just implement a single function in the sink interface). Severity based filtering - threshold levels can be modified in runtime as well as in compile time.
Various log targets: Rotating log files, Daily log files, Console logging, Linux syslog.