Fix TT: Gains 83.0 +/- 32.5 elo

Chess/nimfish/nimfishpkg/search.nim

@@ -127,6 +127,8 @@ proc log(self: SearchManager, depth: int) =
         elapsedMsec = elapsed.inMilliseconds.uint64
         nps = 1000 * (self.nodeCount div max(elapsedMsec, 1))
     var logMsg = &"info depth {depth} time {elapsedMsec} nodes {self.nodeCount} nps {nps}"
+    if not self.transpositionTable.isNil():
+        logMsg &= &" hashfull {self.transpositionTable.getFillEstimate()}"     
     if self.bestMoveRoot != nullMove():
         logMsg &= &" score cp {self.bestRootScore} pv {self.bestMoveRoot.toAlgebraic()}"
     echo logMsg
@@ -268,8 +270,8 @@ proc search(self: SearchManager, depth, ply: int, alpha, beta: Score): Score {.d
         var score: Score
         var fullDepth = true
         when defined(searchLMR):
-            if extension == 0 and i >= 3 and not move.isCapture():
-                # Late Move Reduction: assume our move orderer did a good job,
+            if extension == 0 and i >= 5 and not move.isCapture():
+                # Late Move Reductions: assume our move orderer did a good job,
                 # so it is not worth it to look at all moves at the same depth equally.
                 # If this move turns out to be better than we expected, we'll re-search
                 # it at full depth

Chess/nimfish/nimfishpkg/transpositions.nim

@@ -44,16 +44,41 @@ type
         bestMove*: Move
 
     TTable* = ref object
+        ## A transposition table
         data: seq[TTEntry]
+        when defined(debug):
+            hits: uint64
+            occupancy: uint64
+            collisions: uint64
         size: uint64
 
 
+func size*(self: TTable): uint64 = self.size
+
+when defined(debug):
+    func hits*(self: TTable): uint64 = self.hits
+    func collisions*(self: TTable): uint64 = self.collisions
+    func occupancy*(self: TTable): uint64 = self.occupancy
+
+
+func getFillEstimate*(self: TTable): uint64 =
+    # For performance reasons, we estimate the occupancy by
+    # looking at the first 1000 entries in the table. Why 1000?
+    # Because the "hashfull" info message is conventionally not a 
+    # percentage, but rather a per...millage? It's in thousandths 
+    # rather than hundredths is the point, don't ask me why
+    for i in 0..999:
+        if self.data[i].hash != ZobristKey(0):
+            inc(result)
+
+
 proc newTranspositionTable*(size: uint64): TTable =
     ## Initializes a new transposition table of
     ## size bytes
     new(result)
     let numEntries = size div sizeof(TTEntry).uint64
     result.data = newSeq[TTEntry](numEntries)
+    result.size = numEntries
 
 
 func getIndex(self: TTable, key: ZobristKey): uint64 = 
@@ -71,7 +96,15 @@ func getIndex(self: TTable, key: ZobristKey): uint64 =
 
 func store*(self: TTable, depth: uint8, score: Score, hash: ZobristKey, bestMove: Move, flag: TTentryFlag) =
     ## Stores an entry in the transposition table
-    self.data[self.getIndex(hash)] = TTEntry(flag: flag, score: int16(score), hash: hash, depth: depth, bestMove: bestMove)
+    when defined(debug):
+        let idx = self.getIndex(hash)
+        if self.data[idx].hash != ZobristKey(0):
+            inc(self.collisions)
+        else:
+            inc(self.occupancy)
+        self.data[idx] = TTEntry(flag: flag, score: int16(score), hash: hash, depth: depth, bestMove: bestMove)
+    else:
+        self.data[self.getIndex(hash)] = TTEntry(flag: flag, score: int16(score), hash: hash, depth: depth, bestMove: bestMove)
 
 
 proc get*(self: TTable, hash: ZobristKey, depth: uint8): tuple[success: bool, entry: TTEntry] =
@@ -83,6 +116,9 @@ proc get*(self: TTable, hash: ZobristKey, depth: uint8): tuple[success: bool, en
     ## it's true
     result.entry = self.data[self.getIndex(hash)]
     result.success = result.entry.hash == hash and result.entry.depth >= depth
+    when defined(debug):
+        if result.success:
+            inc(self.hits)
 
 
 proc get*(self: TTable, hash: ZobristKey): tuple[success: bool, entry: TTEntry] =
@@ -92,4 +128,7 @@ proc get*(self: TTable, hash: ZobristKey): tuple[success: bool, entry: TTEntry]
     ## or other anomaly: the result should be considered 
     ## invalid unless it's true
     result.entry = self.data[self.getIndex(hash)]
-    result.success = result.entry.hash == hash
+    result.success = result.entry.hash == hash
+    when defined(debug):
+        if result.success:
+            inc(self.hits)

Chess/nimfish/nimfishpkg/uci.nim

@@ -354,10 +354,10 @@ proc startUCISession* =
                     session.board = newDefaultChessboard()
                 of Go:
                     when defined(useTT):
-                        if session.transpositionTable.isNil():
+                        if session.transpositionTable.isNil() or session.transpositionTable.size() == 0:
+                            session.transpositionTable = newTranspositionTable(session.hashTableSize * 1024 * 1024)
                             if session.debug:
                                 echo &"info string created {session.hashTableSize} MiB TT"
-                            session.transpositionTable = newTranspositionTable(session.hashTableSize * 1024 * 1024)
                     session.searchThread = new Thread[tuple[session: UCISession, command: UCICommand]]
                     createThread(session.searchThread[], bestMove, (session, cmd))
                     if session.debug: