ACE 5.7 Changes You Should Know About, But (Probably) Don’t

ACE 5.7 was released last week (see my newsletter article for info including new platforms supported at ACE 5.7). It was a happy day for ACE users, as ACE 5.7 contains many important fixes, especially in the Service Configurator framework and the ACE_Dev_Poll_Reactor class. Indeed, a recent survey of Riverace’s ACE support customers revealed that nearly 53% are planning to upgrade to ACE 5.7 immediately.

As the rollouts started happening, a few unsuspected changes were noticed that users should know about. Riverace posted these notes in the ACE Knowledge Base last week but I’m also proactively describing them here because I suspect there may be more users out there who may trip over these issues as ACE 5.7 adoption picks up.

The LIB Makefile Variable

Many ACE users reuse the ACE GNU Makefile scheme to take advantage of ACE’s well-tuned system for knowing how to build ACE applications. This is a popular mechanism to reuse because it automatically picks up the ACE configuration settings and compiler options. This is very important to ensure that ACE-built settings match the application’s ACE-related settings for a successful build.

When reusing the ACE make scheme to build libraries the LIB makefile variable specifies the library name to build. This has worked for many years. However, during ACE 5.7 development support was added to the GNU Make scheme to enable its use on Windows with Visual C++. Visual C++ uses the LIB environment variable as a search path for libraries at link time, which clashed with the existing use of the LIB variable. Therefore, the old LIB variable was renamed to LIB_CHECKED. This broke existing builds.

Since the Windows case requires LIB be left available for Visual C++, the name change wasn’t reverted; however, I added a patch that reverts the LIB behavior on non-Windows build systems. The patch will be available in the ACE 5.7.1 bug-fix-only beta as well as in ACE 5.7a for Riverace support customers. If you’re stuck on this problem now, and you’re a support customer, open a case to get the patch immediately.

Note that if you generate your application’s project files with MPC instead of hand-coding to the ACE make scheme, you can avoid the LIB name problem by regenerating your projects after ACE 5.7 is installed.

Symlink Default for Build Libaries Changed from Absolute to Relative

When ACE builds libraries it can “install” them by creating a symbolic link. In ACE 5.6 and earlier, the link used an absolute path to the original file. In ACE 5.7 the default behavior changed to create a link relative to the $ACE_ROOT/ace directory. This helps to enable relocating an entire tree without breaking the links, but in some cases can cause invalid links. For example, if you are building your own libraries that do not get relocated with ACE, or won’t have the same directory hierarchy, the links will not be valid.

To change to the pre-5.7 behavior of creating links with absolute pathnames, build with the make variable symlinks=absolute. You can either specify symlinks=absolute on the make command line or add it to your $ACE_ROOT/include/makeinclude/platform_macros.GNU file prior to including wrapper_macros.GNU.

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