lokinet/llarp/iwp
Jason Rhinelander b4440094b0 De-abseil, part 2: mutex, locks, (most) time
- util::Mutex is now a std::shared_timed_mutex, which is capable of
  exclusive and shared locks.

- util::Lock is still present as a std::lock_guard<util::Mutex>.

- the locking annotations are preserved, but updated to the latest
  supported by clang rather than using abseil's older/deprecated ones.

- ACQUIRE_LOCK macro is gone since we don't pass mutexes by pointer into
  locks anymore (WTF abseil).

- ReleasableLock is gone.  Instead there are now some llarp::util helper
  methods to obtain unique and/or shared locks:
    - `auto lock = util::unique_lock(mutex);` gets an RAII-but-also
      unlockable object (std::unique_lock<T>, with T inferred from
      `mutex`).
    - `auto lock = util::shared_lock(mutex);` gets an RAII shared (i.e.
      "reader") lock of the mutex.
    - `auto lock = util::unique_locks(mutex1, mutex2, mutex3);` can be
      used to atomically lock multiple mutexes at once (returning a
      tuple of the locks).
  This are templated on the mutex which makes them a bit more flexible
  than using a concrete type: they can be used for any type of lockable
  mutex, not only util::Mutex.  (Some of the code here uses them for
  getting locks around a std::mutex).  Until C++17, using the RAII types
  is painfully verbose:

  ```C++
  // pre-C++17 - needing to figure out the mutex type here is annoying:
  std::unique_lock<util::Mutex> lock(mutex);
  // pre-C++17 and even more verbose (but at least the type isn't needed):
  std::unique_lock<decltype(mutex)> lock(mutex);
  // our compromise:
  auto lock = util::unique_lock(mutex);
  // C++17:
  std::unique_lock lock(mutex);
  ```

  All of these functions will also warn (under gcc or clang) if you
  discard the return value.  You can also do fancy things like
  `auto l = util::unique_lock(mutex, std::adopt_lock)` (which lets a
  lock take over an already-locked mutex).

- metrics code is gone, which also removes a big pile of code that was
  only used by metrics:
  - llarp::util::Scheduler
  - llarp:🧵:TimerQueue
  - llarp::util::Stopwatch
2020-02-21 23:22:47 -04:00
..
iwp.cpp De-abseil, part 2: mutex, locks, (most) time 2020-02-21 23:22:47 -04:00
iwp.hpp Make format 2019-12-06 10:13:09 -07:00
linklayer.cpp De-abseil, part 2: mutex, locks, (most) time 2020-02-21 23:22:47 -04:00
linklayer.hpp Make format 2019-12-06 10:13:09 -07:00
message_buffer.cpp fix typo, reduce delivery timeout 2019-12-14 13:50:36 -05:00
message_buffer.hpp finish multithread cryptography first pass 2019-09-16 12:12:05 -04:00
session.cpp Merge pull request #1092 from majestrate/reduce-iwp-multiack-frequency-2020-02-10 2020-02-11 07:09:28 -05:00
session.hpp Make format 2020-02-10 12:51:54 -07:00