Slightly microptimize SEE

Reduce of one instruction. It seems a tad faster on
the profiler now. Very slightly but anyhow it is a
code semplification.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Introduce struct Mutex and ConditionVariable

To mimics C++11 std::mutex and std::condition_variable,
also rename locks and condition variables to be more
uniform across the classes.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Explicitly use threads.size()

Instead of just size(). Although code is longer,
should be more immediate to understand when reading.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Document PolyGlotRandoms[] offsets

Should be more clear from where the 'magic' numbers
come from.

Also bit of reformat while there.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Use std::deque to store setup states
Correctly handle handover of setup states

Before the search we setup the starting position doing all the
moves (sent by GUI) from start position to the position just
before to start searching.

To do this we use a set of StateInfo records used by each
do_move() call. These records shall be kept valid during all
the search because repetition draw detection uses them to back
track all the earlier positions keys. The problem is that, while
searching, the GUI could send another 'position' command, this
calls set_position() that clears the states! Of course a crash
follows shortly.

Before searching all the relevant parameters are copied in
start_searching() just for this reason: to fully detach data
accessed during the search from the UCI protocol handling.
So the natural solution would be to copy also the setup states.
Unfortunatly this approach does not work because StateInfo
contains a pointer to the previous record, so naively copying and
then freeing the original memory leads to a crash.

That's why we use two std::auto_ptr (one belonging to UCI and another
to Search) to safely transfer ownership of the StateInfo records to
the search, after we have setup the root position.

As a nice side-effect all the possible memory leaks are magically
sorted out for us by std::auto_ptr semantic.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Introduce serialization of accesses to std::cout

When many threds concurrently print you need to serialize
the access to std::cout to avoid output lines are intermixed
with the contents of each thread.

This is not strictly needed at the moment because
only main thread prints out, although some ad-hoc
test could trigger UCI::loop() printing while searching.

Anyhow we want to lift this pretty avoidable constrain
also as a prerequisite for future work.

This patch just introduces the support, next one will enable
the serialization.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Convert to sync_cout and sync_endl

Serialize access to std::cout all over the code.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Terminate threads before to exit main()

It is very difficult and risky to assure
that a running thread doesn't access a global
variable. This is currently true, but could
change in the future and we don't want to rely
on code that works 'by accident'. The threads
are still running when ThreadPool destructor is
called (after main() returns) and this could
lead to crashes if a thread accesses a global
that has been already freed. The solution is to
use an exit() function and call it while we are
still in main(), ensuring global variables are
still alive at threads termination time.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Don't need to memset HashTable

Default c'tor Entry() already initializes
to zero all its POD members.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Retire Time::restart()

Simplify API.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Slightly simplify SEE

Some renaming and small code reshuffle.

No fuctional change.
Unroll least valuable attacker loop in SEE

This allows to reduce the scanning for new X-ray attacks
according to the capturing piece type.

It seems to be just a very small speed increase in MSVC 64
bit and gcc 32 bit, I guess cache issues value more than some
instruction less to execute (as usual).

No functional change.
Greatly speed up SEE

Simply reshuffling the code inverting the condition in next_attacker()
yields a miraculous speed up of more than 3% under gcc!

On my laptop a bench run goes from 320Knps to 330Knps

No functional change.
Rename current_time() to now()

Follow C++11 naming conventions.

No functional change.
Get rid of struct Time

We just need the milliseconds of current system
time for our needs. This allows to simplify the
API.

No functional change.
Simplify Option c'tor

No functional change.
Revert "Simplify Option c'tor"

std::to_string() is C++11 material, not c++03.

So revert the patch.
Enable link time optimization only when optimizing

Because it is quite slow, skip it when 'optimize' flag is 'no'

No functional change.
Rename *last to *end

It is a more correct name because it points past the
last move of the list.

No functional change.