Hi, This is a release announcement for the Userspace RCU project.
This is a set of releases, including the new 0.14 branch with the 0.14.0 release, and bug fix releases for the 0.13 and 0.12 branches. The 0.12.5 release is the last of the 0.12 branch, which reaches end of life with the release of 0.14.
Here are the new features introduced in urcu 0.14.0: - C99 and C++11 are now the baseline requirements, as documented in README.md. - Introduce public APIs for C++, An important point to consider: urcu/compiler.h needs to include <type_traits> in C++, which prevents including urcu/compiler.h from extern "C" code. - Introduce new grace period polling APIs in urcu-memb,mb,signal,qsbr,bp flavors: struct urcu_gp_poll_state start_poll_synchronize_rcu(void); bool poll_state_synchronize_rcu(struct urcu_gp_poll_state state); This allow periodically polling to check if a started grace period has completed, and thus check for grace period completion and some other condition as well. - rculfhash: introduce cds_lfht_node_init_deleted Allow initializing lfht node to "removed" state to allow querying whether the node is published in a hash table before it is added to the hash table and after it has been removed from the hash table. - Disable signals in URCU background threads Applications using signalfd depend on signals being blocked in all threads of the process, otherwise threads with unblocked signals can receive them and starve the signalfd. While some threads in URCU do block signals (e.g. workqueue worker for rculfhash), the call_rcu, defer_rcu, and rculfhash partition_resize_helper threads do not. Always block all signals before creating threads, and only unblock SIGRCU when registering a urcu-signal thread. Restore the SIGRCU signal to its pre-registration blocked state on unregistration. For rculfhash, cds_lfht_worker_init can be removed, because its only effect is to block all signals except SIGRCU. Blocking all signals is already done by the workqueue code, and unbloking SIGRCU is now done by the urcu signal flavor thread regisration. - Always use '__thread' for Thread local storage except on MSVC Use the GCC extension '__thread' [1] for Thread local storage on all C and C++ compilers except MSVC. While C11 and C++11 respectively offer '_Thread_local' and 'thread_local' as potentialy faster implementations, they offer no guarantees of compatibility when used in a library interface which might be used by both C and C++ client code. - Various test framework improvements. - Wire up membarrier system call on Alpha. The only missing architecture without membarrier wired up is MIPS. https://bugs.lttng.org/issues/940 Here are the fixes introduced in urcu 0.14.0, 0.13.3 and 0.12.5: - Fix: auto-resize hash table destroy deadlock Fix a deadlock for auto-resize hash tables when cds_lfht_destroy is called with RCU read-side lock held. - Join call_rcu worker thread in call_rcu_data_free (eliminate leaks) - Teardown default call_rcu worker on application exit Teardown the default call_rcu worker thread if there are no queued callbacks on process exit. This prevents leaking memory. Here is how an application can ensure graceful teardown of this worker thread: - An application queuing call_rcu callbacks should invoke rcu_barrier() before it exits. - When chaining call_rcu callbacks, the number of calls to rcu_barrier() on application exit must match at least the maximum number of chained callbacks. - If an application chains callbacks endlessly, it would have to be modified to stop chaining callbacks when it detects an application exit (e.g. with a flag), and wait for quiescence with rcu_barrier() after setting that flag. - The statements above apply to a library which queues call_rcu callbacks, only it needs to invoke rcu_barrier in its library destructor. - Allow building on MSYS2 Update cygwin libtool config in `configure.ac` to match MSYS2 build environments as well. MSYS2 is also a Windows build environment that produces DLLs. Feedback is welcome! Mathieu Project website: https://liburcu.org Git repository: git://git.liburcu.org/urcu.git -- Mathieu Desnoyers EfficiOS Inc. https://www.efficios.com _______________________________________________ lttng-dev mailing list lttng-dev@lists.lttng.org https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
