clcache

What clcache is

clcache is a free, open-source Python script for Microsoft Visual C++ builds on Windows. It intercepts calls to cl.exe and reuses cached object files when a build can use an existing result; invocations it does not support can be relayed to the compiler. The cache key combines preprocessed source, a normalized command line, and the compiler binary’s size and modification time.

The documented cache path handles compile invocations using /c, supports /Z7, and excludes /link and /Zi. Command-line options let users inspect cache statistics, clean or clear cached data, and set the maximum cache size. The default is 1073741824 bytes (1 GiB). Object files can be compressed at levels 1 through 9, though changing compression settings requires clearing the cache. Hard-link mode can improve speed and disk usage when the cache and build directories are on the same drive.

The project documents Visual Studio and MSBuild integration and recommends disabling TrackFileAccess to avoid cache and file-tracking problems. A running clcachesrv.py process can cache file hashes; a memcached backend can save and restore cached data. The source uses the BSD 3-Clause License unless an individual file states otherwise.

Who it suits

clcache suits Windows developers compiling with Microsoft Visual C++ cl.exe through Visual Studio or MSBuild who want to reuse object files. It can also fit workflows that use AppVeyor or a self-hosted setup, provided the documented invocation requirements fit their builds.

Limits

The default maximum cache size is 1073741824 bytes (1 GiB). The documented cache path requires /c, excludes /link and /Zi, and does not support INCLUDE or LIBPATH; changes to those environment variables may not be detected. Changing compression settings requires clearing the cache.

Getting started

1. Open the project website on GitHub.
2. Use a Windows environment with Microsoft Visual C++ cl.exe.
3. Integrate clcache with Visual Studio or MSBuild using the project documentation.
4. Use compile invocations that include /c; /Z7 is supported, while /link and /Zi are excluded.
5. Set the cache size or other cache options from the command line if needed.

Verdict

Choose clcache if you build on Windows with Microsoft Visual C++ cl.exe and want a local cache for supported compile commands. Check the invocation and environment-variable limits against your build, especially if it relies on /Zi, /link, INCLUDE, or LIBPATH changes.