The gflags project updated their CMake config last year with a
`gflags` ALIAS target. This can be used instead of the legacy
`${gflags_LIBRARIES}` and `${gflags_INCLUDE_DIRS}` variables. It also
looks cleaner.
Fixes#198
Don't rely on an internal-linkage extern "C" function having an
unmangled name. This isn't required by the ABI, and in fact is not
valid for a conforming compiler(!). Instead, allow symbolization to
produce either a mangled or an unmangled name here.
The macro NDEBUG could be automatically defined for release build on
some build environments (e.g. MSVC). If we use NDEBUG as a key to
distinguish using DCHECK as CHECK (I call this DCHECK is enabled) or
not, we cannot make DCHECK enabled for release build on such
environments.
Considering people use a program with glog for presubmit testing or
dogfooding, they should need to do release build with DCHECK enabled.
Previously, the implementation of google::GetStackTrace() that uses
libunwind uses a global variable that enforces that only one thread may
invoke libunwind at a time. However, libunwind is thread-safe. The
comment above the variable indicates that it is to protect against
reentrancy issues.
Instead of using a global variable, it would be much better to use a
thread-local variable to protect against these reentrancy issues. That
should provide the needed reentrancy protection while allowing multiple
threads to get stack traces at the same time.
It also allows for the removal of the atomic CAS operations on the
variable.
Resolves#160.
There can be a large kernel overhead involved in POSIX_FADV_DONTNEED.
There is no point in calling this per item logged, so rate limit
to at most once per 2MiB written.
With a simple test program that logs 100K items at WARNING level:
Before:
$ time strace -c -e fadvise64 log.test \
-log_dir=/dev/shm -logtofiles=true -logtostderr=false
% time seconds usecs/call calls errors syscall
------ ----------- ----------- --------- --------- ----------------
100.00 12.522509 125 99957 fadvise64
------ ----------- ----------- --------- --------- ----------------
real 0m52.671s
user 0m2.194s
sys 0m44.022s
After:
$ time strace -c -e fadvise64 log.test \
-log_dir=/dev/shm -logtofiles=true -logtostderr=false
% time seconds usecs/call calls errors syscall
------ ----------- ----------- --------- --------- ----------------
100.00 0.000759 152 5 fadvise64
------ ----------- ----------- --------- --------- ----------------
real 0m4.206s
user 0m1.436s
sys 0m3.153s
Fixes issue #84
Under some circumstances like cross-compilation, the user might not want
to enable support for gflags.
This patch allows support for --without-gflags
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
