Re: [libvirt] PATCH: 1/4: Add OOM hooks to the memory allocator

This patch adds extra code to src/memory.c which allows us to force an OOM condition on specific allocations. This is not code you *ever* want to use in a production build, so its all conditional on TEST_OOM, which is enabled by passing --enable-test-oom to the configure script. The hooks work as follows... - The test suite first calls virAllocTestInit() to initialize the hooks. This causes it to start counting allocations. ....then run the code you want to check for OOM... - Next call virAllocTestCount() to find out how many allocations were made. - Given a number of allocations 'n', we need to repeat 'n' times... - Call virAllocTestOOM(n, m) to tell it to fail the n'th allocation upto the (n + m -1)'th allocation. eg, virAllocTestOOM(3, 2) will cause allocations 3 and 4 to fail. ... run the code you want to check and verify it reports OOM in the way you expect. It can be quite hard to find out just where allocation failure bugs are hiding. So there is also a virAllocTestHook() function which lets you register a callback to be invoked at the time an allocation is artificially failed. Obvious use for this is to capture a stack trace.

diff -r 9f962ac84b09 configure.in

+if test "${enable_oom}" = yes; then + have_trace=yes + AC_CHECK_HEADER([execinfo.h],[],[have_trace=no]) + AC_CHECK_FUNC([backtrace],[],[have_trace=no]) + if test "$have_trace" = "yes"; then + AC_DEFINE([HAVE_TRACE], 1, [Whether backtrace() is available])