ZLToolKit: a C++ networking toolbox that its own users rarely install directly

Three libraries wearing one name: network, thread and utility

The README organises the project into three groups, and the split is the fastest way to understand its scope. The network library covers TCP and UDP clients described as thread safe so callers never touch socket APIs directly, TCP and UDP servers built by implementing a Session class, and wrappers over common socket operations.

The thread library is a timer built on threads, a semaphore, thread groups, and a thread pool that runs tasks either synchronously or asynchronously and accepts both std::function and lambdas.

The utility library is the widest of the three: file operations, an std::cout style logger with colour highlighting, source location and asynchronous printing, INI config file reading and writing, a listener-pattern message broadcaster, a reference-counted pool built on smart pointers, a ring buffer that supports both active reads and read events, a MySQL connection pool that builds SQL with question mark placeholders in synchronous or asynchronous modes, a thread safe SSL wrapper, and a command line argument parser. The repository topics match that inventory: epoll, logger, network, ringbuffer, sql, ssl, threadpool, timer.

For scale, GitHub reports 2,200 stars and 634 forks. The fork count is roughly a third of the star count, which is unusual for a library and consistent with it being consumed as a dependency inside larger projects.

One event loop abstraction over three very different kernels

The network IO adaptation table is the most informative part of the README, because it shows that the portability claim is real and shows where the compromises are. Multiplexing is epoll or select on Linux and Android, wepoll over IOCP or select on Windows, and kqueue or select on macOS and iOS. UDP uses recvmmsg and sendmmsg on Linux, which is the batched path, against plain recvfrom and sendto elsewhere. TCP is the narrowest row, using recvfrom and sendmsg on Linux and macOS against the Windows equivalents.

So the abstraction covers the three kernel models you actually meet in production, and the UDP batching is Linux only. If you are moving a latency sensitive UDP service between Linux and macOS, this table is telling you that you will not get the same syscall pattern on both.

      |      | Linux(Android)    | Windows             | MacOS(iOS/Unix)  |
|:----:|:-----------------:|:-------------------:|:----------------:|
| 多路复用 | epoll/select      | wepoll(iocp)/select | kqueue/select    |

The project also states that it avoids raw pointers, which is a C++11 era design decision that reads differently now than it did when written: the code leans on smart pointers and reference-counted pools, and the ring buffer is one of the pieces where that ownership model pays off.

Building on five platforms, and the scripts the root may not have

The README documents a build path per platform, and each one reduces to a single script invocation after you have the toolchain:

  cd ZLToolKit
  ./build_for_linux.sh
  

The Linux notes give the author's own environment as Ubuntu 16.04 64 bit with gcc 5.4, stating gcc 4.7 as the minimum, and cmake 3.5.1. The macOS path runs `./build_for_mac.sh` under macOS Sierra 10.12.1 with Xcode 8.3.1, Homebrew 1.1.3 and cmake 3.8.0. Android runs `./build_for_android.sh` with `ANDROID_NDK_ROOT` exported and points at android-ndk-r14b. iOS runs `./build_for_ios.sh`, or you generate an Xcode project yourself:

  cmake .. -DCMAKE_TOOLCHAIN_FILE=../cmake/iOS.cmake -DIOS_PLATFORM=SIMULATOR64 -G "Xcode"

Windows is the outlier, because there is no script. The instructions open the project in cmake-gui, generate the Visual Studio solution, then build ZLToolKit_static, ZLToolKit_shared, ALL_BUILD and INSTALL in that order, and finally run the test cases.

Here is the practical wrinkle. Those documented environment versions are from 2016 to 2017, and the repository root listing shows `.clang-format`, `.github/`, `.gitignore`, `.travis.yml`, `AUTHORS`, `CMakeLists.txt`, `LICENSE`, `README.md`, `cmake/`, `src/` and `tests/`. There is no `build_for_linux.sh`, `build_for_mac.sh`, `build_for_ios.sh` or `build_for_android.sh` in that listing. The build entry point that is definitely present is `CMakeLists.txt`, so if a documented script is missing from your checkout, configure and build through CMake directly rather than assuming you cloned the wrong branch. Note also that the badges at the top of the README point at GitHub Actions workflows for Linux, macOS and Windows while a `.travis.yml` file is also present, so both CI configurations have existed at some point.

The QA section answers stability and performance by pointing elsewhere

Three questions get three answers, and two of them redirect you.

On performance, the answer is that the author built a streaming server on top of this library, ZLMediaKit, benchmarked it, and points you at that project's benchmark.md. On stability, the answer is that the library went through valgrind testing and long running load tests, and that the author used it in several production projects, claiming it can run for months without a watchdog. Neither answer gives you a number, which is normal for a project of this type but means you should treat both as claims from the author rather than as measurements you can rely on.

The third answer is the most useful one on the page. Compiling on Windows produces many errors, and the explanation is that the main code was developed on macOS and Linux using UTF-8 files without a byte order mark, which Windows tooling handles badly. The suggested fix is to add a BOM and rebuild. That is the kind of note that saves an afternoon, and it is the clearest signal that the primary development targets are the Unix platforms.

Contact details are a QQ group and an email address, but the README asks that questions about the project go through the issue tracker, since email is not answered.

Licensing is permissive for the original code and conditional for the rest

GitHub reports MIT for the repository and the README agrees for the project's own code, allowing commercial and non commercial use as long as copyright information is retained. The second paragraph is the part that needs reading twice: the project also uses fragments of other open source code, and for commercial use you are told to replace or remove those parts yourself. The disclaimer then places any commercial dispute or infringement liability on the user, not the project or its developers.

That is a common arrangement in Chinese infrastructure libraries and it is more honest than a bare MIT badge, but it does put a burden on you. If you are building a commercial product, budget time to audit what came from where rather than treating the licence as settled. The `AUTHORS` file at the repository root is a reasonable starting point for that audit.

There are no GitHub releases for this repository at all, despite 2,200 stars and 634 forks, so there is no version history to consult and no changelog to diff against. The repository was last pushed on 2026-09-25, and CI runs on three platforms via GitHub Actions, so the code is being worked on even though nothing is being tagged. Plan on tracking the default branch rather than pinning a version.

Editorial conclusion

ZLToolKit is at its strongest as the layer under a larger system rather than as a library you adopt on its own, and the README says so plainly by pointing every performance and stability claim at ZLMediaKit and its benchmark file. If you do want it directly, the per platform build scripts are the shortest route and they run one command, but note that the tree shows no `build_for_linux.sh` at the root, so check what your checkout actually contains before running the documented command. The Windows BOM advice in the QA section is the most practically useful line in the whole README.

Frequently asked questions

Official sources

1. Issues
2. License: MIT
3. README
4. ZLMediaKit/ZLToolKit on GitHub