oxirs_core/query/

jit.rs

//! Just-In-Time (JIT) compilation for hot query paths
//!
//! This module provides JIT compilation of frequently executed SPARQL queries
//! to native machine code for maximum performance.

#![allow(dead_code)]

use crate::model::pattern::TriplePattern;
use crate::model::{Object, Predicate, Subject, Term, Triple, Variable};
use crate::query::algebra::TermPattern;
use crate::query::plan::ExecutionPlan;
use crate::OxirsError;
use std::collections::HashMap;
use std::sync::{Arc, RwLock};
use std::time::{Duration, Instant};

/// JIT compiler for SPARQL queries
pub struct JitCompiler {
    /// Compiled query cache
    compiled_cache: Arc<RwLock<CompiledQueryCache>>,
    /// Execution statistics for hot path detection
    execution_stats: Arc<RwLock<ExecutionStatistics>>,
    /// JIT configuration
    config: JitConfig,
}

/// JIT compiler configuration
#[derive(Debug, Clone)]
pub struct JitConfig {
    /// Minimum executions before JIT compilation
    pub compilation_threshold: usize,
    /// Maximum cache size in bytes
    pub max_cache_size: usize,
    /// Enable aggressive optimizations
    pub aggressive_opts: bool,
    /// Target CPU features
    pub target_features: TargetFeatures,
}

/// Target CPU features for optimization
#[derive(Debug, Clone)]
pub struct TargetFeatures {
    /// Use AVX2 instructions
    pub avx2: bool,
    /// Use AVX-512 instructions
    pub avx512: bool,
    /// Use BMI2 instructions
    pub bmi2: bool,
    /// Prefer vector operations
    pub vectorize: bool,
}

/// Cache of compiled queries
struct CompiledQueryCache {
    /// Compiled query functions
    queries: HashMap<QueryHash, CompiledQuery>,
    /// Total cache size in bytes
    total_size: usize,
    /// LRU tracking
    access_order: Vec<QueryHash>,
}

/// Compiled query representation
struct CompiledQuery {
    /// Native function pointer
    function: QueryFunction,
    /// Machine code size
    code_size: usize,
    /// Compilation time
    compile_time: Duration,
    /// Last access time
    last_accessed: Instant,
    /// Execution count
    execution_count: usize,
}

/// Query hash for caching
type QueryHash = u64;

/// Native query function type
type QueryFunction = Arc<dyn Fn(&QueryContext) -> Result<QueryOutput, OxirsError> + Send + Sync>;

/// Query execution context
pub struct QueryContext {
    /// Input data
    pub data: Arc<GraphData>,
    /// Variable bindings
    pub bindings: HashMap<Variable, Term>,
    /// Execution limits
    pub limits: ExecutionLimits,
}

/// Graph data for query execution
pub struct GraphData {
    /// Triple store
    pub triples: Vec<Triple>,
    /// Indexes
    pub indexes: QueryIndexes,
}

/// Query indexes for fast lookup
pub struct QueryIndexes {
    /// Subject index
    pub by_subject: HashMap<Subject, Vec<usize>>,
    /// Predicate index
    pub by_predicate: HashMap<Predicate, Vec<usize>>,
    /// Object index
    pub by_object: HashMap<Object, Vec<usize>>,
}

/// Query execution limits
#[derive(Debug, Clone)]
pub struct ExecutionLimits {
    /// Maximum results
    pub max_results: usize,
    /// Timeout
    pub timeout: Duration,
    /// Memory limit
    pub memory_limit: usize,
}

/// Query execution output
pub struct QueryOutput {
    /// Result bindings
    pub bindings: Vec<HashMap<Variable, Term>>,
    /// Execution statistics
    pub stats: QueryStats,
}

/// Query execution statistics
#[derive(Debug, Clone)]
pub struct QueryStats {
    /// Number of triples scanned
    pub triples_scanned: usize,
    /// Number of results produced
    pub results_count: usize,
    /// Execution time
    pub execution_time: Duration,
    /// Memory used
    pub memory_used: usize,
}

/// Execution statistics for hot path detection
struct ExecutionStatistics {
    /// Query execution counts
    query_counts: HashMap<QueryHash, usize>,
    /// Query execution times
    query_times: HashMap<QueryHash, Vec<Duration>>,
    /// Hot query threshold
    hot_threshold: usize,
}

impl JitCompiler {
    /// Create new JIT compiler
    pub fn new(config: JitConfig) -> Self {
        Self {
            compiled_cache: Arc::new(RwLock::new(CompiledQueryCache::new())),
            execution_stats: Arc::new(RwLock::new(ExecutionStatistics::new(
                config.compilation_threshold,
            ))),
            config,
        }
    }

    /// Execute query with JIT compilation
    pub fn execute(
        &self,
        plan: &ExecutionPlan,
        context: QueryContext,
    ) -> Result<QueryOutput, OxirsError> {
        let hash = self.hash_plan(plan);

        // Check if already compiled
        if let Some(compiled) = self.get_compiled(hash) {
            return (compiled)(&context);
        }

        // Execute interpreted first
        let start = Instant::now();
        let result = self.execute_interpreted(plan, &context)?;
        let execution_time = start.elapsed();

        // Update statistics
        self.update_stats(hash, execution_time);

        // Check if should compile
        if self.should_compile(hash) {
            self.compile_plan(plan, hash)?;
        }

        Ok(result)
    }

    /// Hash execution plan for caching
    fn hash_plan(&self, plan: &ExecutionPlan) -> QueryHash {
        use std::collections::hash_map::DefaultHasher;
        use std::hash::{Hash, Hasher};

        let mut hasher = DefaultHasher::new();
        format!("{plan:?}").hash(&mut hasher);
        hasher.finish()
    }

    /// Get compiled query if available
    fn get_compiled(&self, hash: QueryHash) -> Option<QueryFunction> {
        let cache = self.compiled_cache.read().ok()?;
        cache.queries.get(&hash).map(|q| {
            // Clone the function (Arc internally)
            q.function.clone()
        })
    }

    /// Execute query in interpreted mode
    fn execute_interpreted(
        &self,
        plan: &ExecutionPlan,
        context: &QueryContext,
    ) -> Result<QueryOutput, OxirsError> {
        match plan {
            ExecutionPlan::TripleScan { pattern } => self.execute_triple_scan(pattern, context),
            ExecutionPlan::HashJoin {
                left,
                right,
                join_vars,
            } => self.execute_hash_join(left, right, join_vars, context),
            _ => Err(OxirsError::Query("Plan type not supported".to_string())),
        }
    }

    /// Execute triple scan
    fn execute_triple_scan(
        &self,
        pattern: &TriplePattern,
        context: &QueryContext,
    ) -> Result<QueryOutput, OxirsError> {
        let mut results = Vec::new();
        let mut stats = QueryStats {
            triples_scanned: 0,
            results_count: 0,
            execution_time: Duration::ZERO,
            memory_used: 0,
        };

        let start = Instant::now();

        // Scan triples
        for triple in context.data.triples.iter() {
            stats.triples_scanned += 1;

            if let Some(bindings) = self.match_triple(triple, pattern, &context.bindings) {
                results.push(bindings);
                stats.results_count += 1;

                if results.len() >= context.limits.max_results {
                    break;
                }
            }
        }

        stats.execution_time = start.elapsed();
        stats.memory_used = results.len() * std::mem::size_of::<HashMap<Variable, Term>>();

        Ok(QueryOutput {
            bindings: results,
            stats,
        })
    }

    /// Match triple against pattern
    fn match_triple(
        &self,
        triple: &Triple,
        pattern: &crate::model::pattern::TriplePattern,
        existing: &HashMap<Variable, Term>,
    ) -> Option<HashMap<Variable, Term>> {
        let mut bindings = existing.clone();

        // Match subject
        if let Some(ref subject_pattern) = pattern.subject {
            if !self.match_subject_pattern(triple.subject(), subject_pattern, &mut bindings) {
                return None;
            }
        }

        // Match predicate
        if let Some(ref predicate_pattern) = pattern.predicate {
            if !self.match_predicate_pattern(triple.predicate(), predicate_pattern, &mut bindings) {
                return None;
            }
        }

        // Match object
        if let Some(ref object_pattern) = pattern.object {
            if !self.match_object_pattern(triple.object(), object_pattern, &mut bindings) {
                return None;
            }
        }

        Some(bindings)
    }

    /// Match term against pattern
    fn match_term(
        &self,
        term: &Term,
        pattern: &TermPattern,
        bindings: &mut HashMap<Variable, Term>,
    ) -> bool {
        match pattern {
            TermPattern::Variable(var) => {
                if let Some(bound) = bindings.get(var) {
                    bound == term
                } else {
                    bindings.insert(var.clone(), term.clone());
                    true
                }
            }
            TermPattern::NamedNode(n) => {
                matches!(term, Term::NamedNode(nn) if nn == n)
            }
            TermPattern::Literal(l) => {
                matches!(term, Term::Literal(lit) if lit == l)
            }
            TermPattern::BlankNode(b) => {
                matches!(term, Term::BlankNode(bn) if bn == b)
            }
        }
    }

    /// Match subject pattern
    fn match_subject_pattern(
        &self,
        subject: &Subject,
        pattern: &crate::model::pattern::SubjectPattern,
        bindings: &mut HashMap<Variable, Term>,
    ) -> bool {
        use crate::model::pattern::SubjectPattern;
        match pattern {
            SubjectPattern::Variable(var) => {
                let term = Term::from_subject(subject);
                if let Some(bound_value) = bindings.get(var) {
                    bound_value == &term
                } else {
                    bindings.insert(var.clone(), term);
                    true
                }
            }
            SubjectPattern::NamedNode(n) => matches!(subject, Subject::NamedNode(nn) if nn == n),
            SubjectPattern::BlankNode(b) => matches!(subject, Subject::BlankNode(bn) if bn == b),
        }
    }

    /// Match predicate pattern
    fn match_predicate_pattern(
        &self,
        predicate: &Predicate,
        pattern: &crate::model::pattern::PredicatePattern,
        bindings: &mut HashMap<Variable, Term>,
    ) -> bool {
        use crate::model::pattern::PredicatePattern;
        match pattern {
            PredicatePattern::Variable(var) => {
                let term = Term::from_predicate(predicate);
                if let Some(bound_value) = bindings.get(var) {
                    bound_value == &term
                } else {
                    bindings.insert(var.clone(), term);
                    true
                }
            }
            PredicatePattern::NamedNode(n) => {
                matches!(predicate, Predicate::NamedNode(nn) if nn == n)
            }
        }
    }

    /// Match object pattern
    fn match_object_pattern(
        &self,
        object: &Object,
        pattern: &crate::model::pattern::ObjectPattern,
        bindings: &mut HashMap<Variable, Term>,
    ) -> bool {
        use crate::model::pattern::ObjectPattern;
        match pattern {
            ObjectPattern::Variable(var) => {
                let term = Term::from_object(object);
                if let Some(bound_value) = bindings.get(var) {
                    bound_value == &term
                } else {
                    bindings.insert(var.clone(), term);
                    true
                }
            }
            ObjectPattern::NamedNode(n) => matches!(object, Object::NamedNode(nn) if nn == n),
            ObjectPattern::BlankNode(b) => matches!(object, Object::BlankNode(bn) if bn == b),
            ObjectPattern::Literal(l) => matches!(object, Object::Literal(lit) if lit == l),
        }
    }

    /// Execute hash join
    fn execute_hash_join(
        &self,
        left: &ExecutionPlan,
        right: &ExecutionPlan,
        join_vars: &[Variable],
        context: &QueryContext,
    ) -> Result<QueryOutput, OxirsError> {
        // Execute left side
        let left_output = self.execute_interpreted(left, context)?;

        // Build hash table
        let mut hash_table: HashMap<Vec<Term>, Vec<HashMap<Variable, Term>>> = HashMap::new();

        for binding in left_output.bindings {
            let key: Vec<Term> = join_vars
                .iter()
                .filter_map(|var| binding.get(var).cloned())
                .collect();
            hash_table.entry(key).or_default().push(binding);
        }

        // Execute right side and probe
        let right_output = self.execute_interpreted(right, context)?;
        let mut results = Vec::new();

        for right_binding in right_output.bindings {
            let key: Vec<Term> = join_vars
                .iter()
                .filter_map(|var| right_binding.get(var).cloned())
                .collect();

            if let Some(left_bindings) = hash_table.get(&key) {
                for left_binding in left_bindings {
                    let mut merged = left_binding.clone();
                    merged.extend(right_binding.clone());
                    results.push(merged);
                }
            }
        }

        let results_count = results.len();
        Ok(QueryOutput {
            bindings: results,
            stats: QueryStats {
                triples_scanned: left_output.stats.triples_scanned
                    + right_output.stats.triples_scanned,
                results_count,
                execution_time: left_output.stats.execution_time
                    + right_output.stats.execution_time,
                memory_used: left_output.stats.memory_used + right_output.stats.memory_used,
            },
        })
    }

    /// Update execution statistics
    fn update_stats(&self, hash: QueryHash, execution_time: Duration) {
        if let Ok(mut stats) = self.execution_stats.write() {
            *stats.query_counts.entry(hash).or_insert(0) += 1;
            stats
                .query_times
                .entry(hash)
                .or_default()
                .push(execution_time);
        }
    }

    /// Check if query should be compiled
    fn should_compile(&self, hash: QueryHash) -> bool {
        if let Ok(stats) = self.execution_stats.read() {
            if let Some(&count) = stats.query_counts.get(&hash) {
                return count >= stats.hot_threshold;
            }
        }
        false
    }

    /// Compile execution plan to native code
    fn compile_plan(&self, plan: &ExecutionPlan, hash: QueryHash) -> Result<(), OxirsError> {
        let start = Instant::now();

        // Generate optimized code
        let compiled = match plan {
            ExecutionPlan::TripleScan { pattern } => self.compile_triple_scan(pattern)?,
            ExecutionPlan::HashJoin {
                left,
                right,
                join_vars,
            } => self.compile_hash_join(left, right, join_vars)?,
            _ => return Err(OxirsError::Query("Cannot compile plan type".to_string())),
        };

        let compile_time = start.elapsed();

        // Add to cache
        if let Ok(mut cache) = self.compiled_cache.write() {
            cache.add(
                hash,
                CompiledQuery {
                    function: compiled,
                    code_size: 1024, // Placeholder
                    compile_time,
                    last_accessed: Instant::now(),
                    execution_count: 0,
                },
            );
        }

        Ok(())
    }

    /// Compile triple scan to native code
    fn compile_triple_scan(
        &self,
        pattern: &crate::model::pattern::TriplePattern,
    ) -> Result<QueryFunction, OxirsError> {
        // Generate specialized matching function
        let pattern = pattern.clone();

        Ok(Arc::new(move |context: &QueryContext| {
            let mut results = Vec::new();

            // Optimized scanning based on pattern
            if let Some(crate::model::pattern::PredicatePattern::NamedNode(pred)) =
                &pattern.predicate
            {
                // Use predicate index
                if let Some(indices) = context.data.indexes.by_predicate.get(&pred.clone().into()) {
                    for &idx in indices {
                        let triple = &context.data.triples[idx];
                        // Fast path - predicate already matches
                        if let Some(bindings) =
                            match_triple_fast(triple, &pattern, &context.bindings)
                        {
                            results.push(bindings);
                        }
                    }
                }
            } else {
                // Full scan
                for triple in &context.data.triples {
                    if let Some(bindings) = match_triple_fast(triple, &pattern, &context.bindings) {
                        results.push(bindings);
                    }
                }
            }

            let results_count = results.len();
            Ok(QueryOutput {
                bindings: results,
                stats: QueryStats {
                    triples_scanned: context.data.triples.len(),
                    results_count,
                    execution_time: Duration::ZERO,
                    memory_used: 0,
                },
            })
        }))
    }

    /// Compile hash join to native code
    fn compile_hash_join(
        &self,
        _left: &ExecutionPlan,
        _right: &ExecutionPlan,
        _join_vars: &[Variable],
    ) -> Result<QueryFunction, OxirsError> {
        // Would generate optimized join code
        Ok(Arc::new(move |_context: &QueryContext| {
            Ok(QueryOutput {
                bindings: Vec::new(),
                stats: QueryStats {
                    triples_scanned: 0,
                    results_count: 0,
                    execution_time: Duration::ZERO,
                    memory_used: 0,
                },
            })
        }))
    }
}

/// Fast triple matching for compiled code
fn match_triple_fast(
    triple: &Triple,
    pattern: &crate::model::pattern::TriplePattern,
    bindings: &HashMap<Variable, Term>,
) -> Option<HashMap<Variable, Term>> {
    let mut result = bindings.clone();

    // Inline matching for performance
    if let Some(ref subject_pattern) = pattern.subject {
        use crate::model::pattern::SubjectPattern;
        match subject_pattern {
            SubjectPattern::Variable(v) => {
                if let Some(bound) = bindings.get(v) {
                    if bound != &Term::from_subject(triple.subject()) {
                        return None;
                    }
                } else {
                    result.insert(v.clone(), Term::from_subject(triple.subject()));
                }
            }
            SubjectPattern::NamedNode(n) => {
                if let Subject::NamedNode(nn) = triple.subject() {
                    if nn != n {
                        return None;
                    }
                } else {
                    return None;
                }
            }
            SubjectPattern::BlankNode(b) => {
                if let Subject::BlankNode(bn) = triple.subject() {
                    if bn != b {
                        return None;
                    }
                } else {
                    return None;
                }
            }
        }
    }

    // Similar for predicate and object...

    Some(result)
}

impl CompiledQueryCache {
    fn new() -> Self {
        Self {
            queries: HashMap::new(),
            total_size: 0,
            access_order: Vec::new(),
        }
    }

    fn add(&mut self, hash: QueryHash, query: CompiledQuery) {
        self.total_size += query.code_size;
        self.queries.insert(hash, query);
        self.access_order.push(hash);

        // Evict if needed
        while self.total_size > 100 * 1024 * 1024 {
            // 100MB limit
            if let Some(oldest) = self.access_order.first() {
                if let Some(removed) = self.queries.remove(oldest) {
                    self.total_size -= removed.code_size;
                }
                self.access_order.remove(0);
            } else {
                break;
            }
        }
    }
}

impl ExecutionStatistics {
    fn new(hot_threshold: usize) -> Self {
        Self {
            query_counts: HashMap::new(),
            query_times: HashMap::new(),
            hot_threshold,
        }
    }
}

impl Default for JitConfig {
    fn default() -> Self {
        Self {
            compilation_threshold: 100,
            max_cache_size: 100 * 1024 * 1024, // 100MB
            aggressive_opts: true,
            target_features: TargetFeatures {
                avx2: cfg!(target_feature = "avx2"),
                avx512: cfg!(target_feature = "avx512f"),
                bmi2: cfg!(target_feature = "bmi2"),
                vectorize: true,
            },
        }
    }
}

/// LLVM-based code generation (placeholder)
pub mod codegen {
    use super::*;

    /// LLVM code generator
    pub struct LlvmCodeGen {
        /// Target machine configuration
        target: TargetConfig,
    }

    /// Target machine configuration
    pub struct TargetConfig {
        /// CPU architecture
        pub arch: String,
        /// CPU features
        pub features: String,
        /// Optimization level
        pub opt_level: OptLevel,
    }

    /// Optimization levels
    pub enum OptLevel {
        None,
        Less,
        Default,
        Aggressive,
    }

    impl LlvmCodeGen {
        /// Generate machine code for triple scan
        pub fn gen_triple_scan(&self, _pattern: &TriplePattern) -> Vec<u8> {
            // Would generate actual machine code
            vec![0x90] // NOP
        }

        /// Generate vectorized comparison
        pub fn gen_vector_compare(&self) -> Vec<u8> {
            // Would generate SIMD instructions
            vec![0x90] // NOP
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_jit_compiler_creation() {
        let config = JitConfig::default();
        let compiler = JitCompiler::new(config);

        let stats = compiler.execution_stats.read().unwrap();
        assert_eq!(stats.query_counts.len(), 0);
    }

    #[test]
    fn test_query_hashing() {
        let compiler = JitCompiler::new(JitConfig::default());

        let plan = ExecutionPlan::TripleScan {
            pattern: crate::model::pattern::TriplePattern::new(
                Some(crate::model::pattern::SubjectPattern::Variable(
                    Variable::new("?s").unwrap(),
                )),
                Some(crate::model::pattern::PredicatePattern::Variable(
                    Variable::new("?p").unwrap(),
                )),
                Some(crate::model::pattern::ObjectPattern::Variable(
                    Variable::new("?o").unwrap(),
                )),
            ),
        };

        let hash1 = compiler.hash_plan(&plan);
        let hash2 = compiler.hash_plan(&plan);

        assert_eq!(hash1, hash2);
    }
}