SearchSharedData Struct Reference

Thread-safe shared state for search coordination and Lazy SMP. More...

#include <ISearch.h>

Collaboration diagram for SearchSharedData:

Classes
struct	SearchConfig
	Runtime tunable parameters for the search algorithm. More...
struct	VizNode
	Represents a single node in the search tree for export and visualization. More...

Public Types
enum class	PruneReason : uint8_t {   NONE = 0 , LMP , FUTILITY , SEE ,   DRAW , RAZOR , REVERSE_FUTILITY , NULL_MOVE ,   INTERNAL , LAZY_EVAL , TB_CUTOFF , TT_CUTOFF ,   BETA_CUTOFF , DEPTH_LIMIT , SINGULAR_SKIP }
	Enumeration of reasons why a node might be pruned (used for tree visualization). More...

Public Attributes
std::atomic< bool >	stop {false}
	Global flag to immediately stop all search threads.
std::atomic< bool >	disableTablebase {false}
	Disables tablebase probing (e.g., when Syzygy coverage is incomplete).
std::atomic< uint64_t >	totalNodes {0}
	Global node count across all threads.
std::atomic< int >	selDepth {0}
	Maximum selective depth reached by any thread.
std::atomic< uint64_t >	tbHits {0}
	Total tablebase hits across all threads.
std::atomic< uint64_t >	ttHits {0}
	Total transposition table hits across all threads.
std::atomic< int >	mainThreadScore {0}
	Main thread's current score (used by helpers for aspiration windows).
std::atomic< int >	mainThreadDepth {0}
	Main thread's completed depth (used by helpers for early termination).
std::atomic< int >	targetDepth {0}
	Target search depth (set by main thread at search start).
int	numThreads {1}
	Total number of active search threads.
std::atomic< int64_t >	startTimeNs {0}
	Search start time in steady_clock nanoseconds (atomic for ponderhit updates).
int64_t	softLimit = 0
	Soft time limit in milliseconds.
int64_t	hardLimit = 0
	Hard time limit in milliseconds.
struct SearchSharedData::SearchConfig	config
int	lazyEvalMaxDepth = 6
	Maximum depth to apply lazy evaluation.
int	lazyEvalBaseMargin = 350
	Base margin for lazy evaluation (approx 1 Sigma of residual error).
int	lazyEvalDepthMargin = 60
	Depth multiplier margin for lazy evaluation.
int	lazyEvalMinMargin = 200
	Absolute minimum margin for lazy evaluation.
bool	enableLazyEval = false
	Flag to enable or disable lazy evaluation.
std::vector< VizNode >	vizTree
	Stores edges for top layers of the search tree.
bool	exportTree = false
	Flag to enable tree export visualization.
int	exportTreeDepth = 4
	Maximum depth to record nodes for tree visualization.

Detailed Description

Thread-safe shared state for search coordination and Lazy SMP.

This struct holds the atomic variables used to coordinate multiple search threads, manage time limits, and collect statistics across the entire engine.

Member Enumeration Documentation

PruneReason

enum class SearchSharedData::PruneReason : uint8_t

strong

Enumeration of reasons why a node might be pruned (used for tree visualization).

Enumerator
NONE	Not pruned - fully searched.
LMP	Late Move Pruning.
FUTILITY	Futility Pruning.
SEE	Static Exchange Evaluation pruning.
DRAW	Draw by repetition or 50-move rule.
RAZOR	Razoring (drop to qsearch).
REVERSE_FUTILITY	Reverse Futility / Static Null Move.
NULL_MOVE	Null Move Pruning cutoff.
INTERNAL	Internal Node Pruning (Eval Margin).
LAZY_EVAL	Lazy Eval skip (fast score sufficient).
TB_CUTOFF	Tablebase cutoff.
TT_CUTOFF	Transposition table cutoff.
BETA_CUTOFF	Normal beta cutoff.
DEPTH_LIMIT	Beyond exportTreeDepth and not PV.
SINGULAR_SKIP	Skipped during singular extension search.

Member Data Documentation

config

struct SearchSharedData::SearchConfig SearchSharedData::config

disableTablebase

std::atomic<bool> SearchSharedData::disableTablebase {false}

Disables tablebase probing (e.g., when Syzygy coverage is incomplete).

enableLazyEval

bool SearchSharedData::enableLazyEval = false

Flag to enable or disable lazy evaluation.

exportTree

bool SearchSharedData::exportTree = false

Flag to enable tree export visualization.

exportTreeDepth

int SearchSharedData::exportTreeDepth = 4

Maximum depth to record nodes for tree visualization.

hardLimit

int64_t SearchSharedData::hardLimit = 0

Hard time limit in milliseconds.

lazyEvalBaseMargin

int SearchSharedData::lazyEvalBaseMargin = 350

Base margin for lazy evaluation (approx 1 Sigma of residual error).

lazyEvalDepthMargin

int SearchSharedData::lazyEvalDepthMargin = 60

Depth multiplier margin for lazy evaluation.

lazyEvalMaxDepth

int SearchSharedData::lazyEvalMaxDepth = 6

Maximum depth to apply lazy evaluation.

lazyEvalMinMargin

int SearchSharedData::lazyEvalMinMargin = 200

Absolute minimum margin for lazy evaluation.

mainThreadDepth

std::atomic<int> SearchSharedData::mainThreadDepth {0}

Main thread's completed depth (used by helpers for early termination).

mainThreadScore

std::atomic<int> SearchSharedData::mainThreadScore {0}

Main thread's current score (used by helpers for aspiration windows).

numThreads

int SearchSharedData::numThreads {1}

Total number of active search threads.

selDepth

std::atomic<int> SearchSharedData::selDepth {0}

Maximum selective depth reached by any thread.

softLimit

int64_t SearchSharedData::softLimit = 0

Soft time limit in milliseconds.

startTimeNs

std::atomic<int64_t> SearchSharedData::startTimeNs {0}

Search start time in steady_clock nanoseconds (atomic for ponderhit updates).

stop

std::atomic<bool> SearchSharedData::stop {false}

Global flag to immediately stop all search threads.

targetDepth

std::atomic<int> SearchSharedData::targetDepth {0}

Target search depth (set by main thread at search start).

tbHits

std::atomic<uint64_t> SearchSharedData::tbHits {0}

Total tablebase hits across all threads.

totalNodes

std::atomic<uint64_t> SearchSharedData::totalNodes {0}

Global node count across all threads.

ttHits

std::atomic<uint64_t> SearchSharedData::ttHits {0}

Total transposition table hits across all threads.

vizTree

std::vector<VizNode> SearchSharedData::vizTree

Stores edges for top layers of the search tree.

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The documentation for this struct was generated from the following file:

• engine/src/search/ISearch.h