xtr
What is it?
XTR is a C++ logging library aimed at applications with low-latency or real-time requirements. The cost of log statements is minimised by delegating as much work as possible to a background thread.
It is designed so that the cost of a log statement is consistently fast---i.e. every call is fast, not just the average case. No allocations or system calls are made when a log statement is made.
Features
- Fast (please see benchmark results).
- No allocations when logging, even when logging strings.
- Formatting, I/O etc are all delegated to a background thread. Work done at the log statement call-site is minimized---for example a no argument log statement only involves writing a single pointer to a ring buffer.
- Safe: No references taken to arguments unless explicitly requested.
- Comprehensive suite of unit tests which run cleanly under AddressSanitizer, UndefinedBehaviourSanitizer, ThreadSanitizer and LeakSanitizer.
- Log sinks with independent log levels (so that levels for different subsystems may be modified independently).
- Ability to modify log levels via an external command.
- Non-printable characters are sanitized for safety (to prevent terminal escape sequence injection attacks).
- Formatting done via fmtlib.
- Support for custom I/O back-ends (e.g. to log to the network or syslogd).
- Support for logrotate integration.
- Support for systemd journal integration.
Supported platforms
- Linux (x86-64)
- FreeBSD (x86-64)
Documentation
Benchmarks
Below is the output of make benchmark on a stock Ryzen 5950X, with g++ version 10.2.1. No cores are isolated. Benchmarks with isolation, and on other CPUs will be completed soon.
2021-07-31 22:30:11
Running build/g++-release/benchmark/benchmark
Run on (32 X 6614.06 MHz CPU s)
CPU Caches:
L1 Data 32K (x16)
L1 Instruction 32K (x16)
L2 Unified 512K (x16)
L3 Unified 32768K (x2)
Load Average: 1.26, 1.53, 1.42
***WARNING*** CPU scaling is enabled, the benchmark real time measurements may be noisy and will incur extra overhead.
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Benchmark Time CPU Iterations
-----------------------------------------------------------------------------------------
logger_benchmark_discard 3.12 ns 3.11 ns 220642542
logger_benchmark_devnull 3.17 ns 3.16 ns 213233572
logger_benchmark_tsc_discard 9.97 ns 9.95 ns 71544694
logger_benchmark_tsc_devnull 9.81 ns 9.79 ns 72024706
logger_benchmark_clock_realtime_coarse_discard 9.50 ns 9.48 ns 75301078
logger_benchmark_clock_realtime_coarse_devnull 9.02 ns 8.99 ns 77431937
logger_benchmark_int_discard 4.64 ns 4.63 ns 151861070
logger_benchmark_int_devnull 4.62 ns 4.61 ns 151949835
logger_benchmark_long_discard 4.61 ns 4.60 ns 151969132
logger_benchmark_long_devnull 4.61 ns 4.60 ns 152198709
logger_benchmark_double_discard 4.84 ns 4.82 ns 145809754
logger_benchmark_double_devnull 4.81 ns 4.80 ns 145367066
logger_benchmark_c_str_discard 7.63 ns 7.60 ns 93103583
logger_benchmark_c_str_devnull 7.33 ns 7.30 ns 95755773
logger_benchmark_str_view_discard 5.69 ns 5.66 ns 122769764
logger_benchmark_str_view_devnull 5.67 ns 5.64 ns 124657115
logger_benchmark_str_discard 7.36 ns 7.33 ns 96002018
logger_benchmark_str_devnull 7.32 ns 7.29 ns 96072575
logger_benchmark_non_blocking_discard 3.13 ns 3.12 ns 224529741
logger_benchmark_non_blocking_devnull 3.09 ns 3.08 ns 228207878
Installation notes
See INSTALL.md
