quantrs2_core/optimizations/
gate_cache.rs

1//! Quantum Gate Matrix Caching using SciRS2 Beta.3 Features
2//!
3//! This module demonstrates how to leverage scirs2-core beta.3 caching capabilities
4//! to optimize quantum gate matrix computations.
5
6use crate::error::QuantRS2Result;
7use scirs2_core::cache::{CacheConfig, TTLSizedCache};
8use scirs2_core::memory::{global_buffer_pool, BufferPool};
9use scirs2_core::profiling::{Profiler, Timer};
10use scirs2_core::Complex64;
11use std::collections::HashMap;
12use std::hash::{Hash, Hasher};
13use std::sync::{Arc, Mutex, OnceLock};
14
15/// Hash key for gate matrix caching
16#[derive(Debug, Clone, PartialEq, Eq, Hash)]
17pub struct GateKey {
18    pub gate_type: String,
19    pub parameters: Vec<u64>, // Hash of parameters for caching
20    pub num_qubits: usize,
21}
22
23impl GateKey {
24    pub fn new(gate_type: &str, parameters: &[f64], num_qubits: usize) -> Self {
25        // Convert parameters to hashable representation
26        let param_hashes: Vec<u64> = parameters
27            .iter()
28            .map(|&p| {
29                let mut hasher = std::collections::hash_map::DefaultHasher::new();
30                // Use bits representation for consistent hashing
31                p.to_bits().hash(&mut hasher);
32                hasher.finish()
33            })
34            .collect();
35
36        Self {
37            gate_type: gate_type.to_string(),
38            parameters: param_hashes,
39            num_qubits,
40        }
41    }
42}
43
44/// Cached quantum gate matrix
45#[derive(Debug, Clone)]
46pub struct CachedGateMatrix {
47    pub matrix: Vec<Complex64>,
48    pub size: usize,
49    pub computation_time_us: u64,
50}
51
52/// High-performance quantum gate cache using SciRS2 beta.3 features
53pub struct QuantumGateCache {
54    /// Gate matrix cache with TTL
55    matrix_cache: Arc<Mutex<TTLSizedCache<GateKey, CachedGateMatrix>>>,
56    /// Buffer pool for matrix computations
57    buffer_pool: Arc<BufferPool<Complex64>>,
58    /// Performance metrics
59    cache_hits: Arc<Mutex<u64>>,
60    cache_misses: Arc<Mutex<u64>>,
61    total_computation_time: Arc<Mutex<u64>>,
62}
63
64impl Default for QuantumGateCache {
65    fn default() -> Self {
66        Self::new()
67    }
68}
69
70impl QuantumGateCache {
71    /// Create a new optimized quantum gate cache
72    pub fn new() -> Self {
73        let cache_config = CacheConfig {
74            default_size: 2048, // Cache up to 2048 gate matrices
75            default_ttl: 7200,  // 2 hours TTL for gate matrices
76            enable_caching: true,
77        };
78
79        Self {
80            matrix_cache: Arc::new(Mutex::new(TTLSizedCache::new(
81                cache_config.default_size,
82                cache_config.default_ttl,
83            ))),
84            buffer_pool: Arc::new(BufferPool::new()),
85            cache_hits: Arc::new(Mutex::new(0)),
86            cache_misses: Arc::new(Mutex::new(0)),
87            total_computation_time: Arc::new(Mutex::new(0)),
88        }
89    }
90
91    /// Get or compute a gate matrix with caching and profiling
92    pub fn get_or_compute_matrix<F>(
93        &self,
94        key: GateKey,
95        compute_fn: F,
96    ) -> QuantRS2Result<Vec<Complex64>>
97    where
98        F: FnOnce() -> QuantRS2Result<Vec<Complex64>>,
99    {
100        // Check cache first
101        if let Ok(mut cache) = self.matrix_cache.lock() {
102            if let Some(cached) = cache.get(&key) {
103                if let Ok(mut hits) = self.cache_hits.lock() {
104                    *hits += 1;
105                }
106                return Ok(cached.matrix);
107            }
108        }
109
110        // Cache miss - compute with profiling
111        if let Ok(mut misses) = self.cache_misses.lock() {
112            *misses += 1;
113        }
114
115        let computation_result = Timer::time_function(
116            &format!("gate_matrix_computation_{}", key.gate_type),
117            compute_fn,
118        );
119
120        match computation_result {
121            Ok(matrix) => {
122                // Create cached entry with timing info
123                let cached_matrix = CachedGateMatrix {
124                    matrix: matrix.clone(),
125                    size: matrix.len(),
126                    computation_time_us: 0, // Would be filled by Timer in real implementation
127                };
128
129                // Store in cache
130                if let Ok(mut cache) = self.matrix_cache.lock() {
131                    cache.insert(key, cached_matrix);
132                }
133
134                Ok(matrix)
135            }
136            Err(e) => Err(e),
137        }
138    }
139
140    /// Get cache performance statistics
141    pub fn get_performance_stats(&self) -> QuantumGateCacheStats {
142        let hits = self.cache_hits.lock().map(|g| *g).unwrap_or(0);
143        let misses = self.cache_misses.lock().map(|g| *g).unwrap_or(0);
144        let total_time = self.total_computation_time.lock().map(|g| *g).unwrap_or(0);
145
146        QuantumGateCacheStats {
147            cache_hits: hits,
148            cache_misses: misses,
149            hit_ratio: if hits + misses > 0 {
150                hits as f64 / (hits + misses) as f64
151            } else {
152                0.0
153            },
154            total_computation_time_us: total_time,
155            average_computation_time_us: if misses > 0 { total_time / misses } else { 0 },
156        }
157    }
158
159    /// Pre-warm cache with common gate matrices
160    pub fn prewarm_common_gates(&self) -> QuantRS2Result<()> {
161        use std::f64::consts::{FRAC_1_SQRT_2, PI};
162
163        let common_gates = vec![
164            ("pauli_x", vec![], 1),
165            ("pauli_y", vec![], 1),
166            ("pauli_z", vec![], 1),
167            ("hadamard", vec![], 1),
168            ("phase", vec![PI / 2.0], 1),
169            ("rx", vec![PI / 4.0, PI / 2.0, PI], 1),
170            ("ry", vec![PI / 4.0, PI / 2.0, PI], 1),
171            ("rz", vec![PI / 4.0, PI / 2.0, PI], 1),
172            ("cnot", vec![], 2),
173            ("cz", vec![], 2),
174        ];
175
176        for (gate_name, params, qubits) in common_gates {
177            for param_set in if params.is_empty() {
178                vec![vec![]]
179            } else {
180                params.into_iter().map(|p| vec![p]).collect()
181            } {
182                let key = GateKey::new(gate_name, &param_set, qubits);
183
184                // Compute and cache the matrix
185                let _ = self.get_or_compute_matrix(key, || {
186                    // This would call actual gate matrix computation
187                    // For now, return identity matrix
188                    let size = 1 << qubits;
189                    let mut matrix = vec![Complex64::new(0.0, 0.0); size * size];
190                    for i in 0..size {
191                        matrix[i * size + i] = Complex64::new(1.0, 0.0);
192                    }
193                    Ok(matrix)
194                })?;
195            }
196        }
197
198        Ok(())
199    }
200
201    /// Clear cache and reset statistics
202    pub fn clear_cache(&self) {
203        if let Ok(mut cache) = self.matrix_cache.lock() {
204            cache.clear();
205        }
206        if let Ok(mut hits) = self.cache_hits.lock() {
207            *hits = 0;
208        }
209        if let Ok(mut misses) = self.cache_misses.lock() {
210            *misses = 0;
211        }
212        if let Ok(mut time) = self.total_computation_time.lock() {
213            *time = 0;
214        }
215    }
216}
217
218/// Cache performance statistics
219#[derive(Debug, Clone)]
220pub struct QuantumGateCacheStats {
221    pub cache_hits: u64,
222    pub cache_misses: u64,
223    pub hit_ratio: f64,
224    pub total_computation_time_us: u64,
225    pub average_computation_time_us: u64,
226}
227
228/// Global quantum gate cache instance
229static GLOBAL_GATE_CACHE: OnceLock<QuantumGateCache> = OnceLock::new();
230
231/// Get the global quantum gate cache
232pub fn global_gate_cache() -> &'static QuantumGateCache {
233    GLOBAL_GATE_CACHE.get_or_init(QuantumGateCache::new)
234}
235
236/// Convenience macro for caching gate matrix computations
237#[macro_export]
238macro_rules! cached_gate_matrix {
239    ($gate_type:expr, $params:expr, $qubits:expr, $compute:expr) => {{
240        let key = $crate::optimizations::gate_cache::GateKey::new($gate_type, $params, $qubits);
241        $crate::optimizations::gate_cache::global_gate_cache()
242            .get_or_compute_matrix(key, || $compute)
243    }};
244}
245
246#[cfg(test)]
247mod tests {
248    use super::*;
249
250    #[test]
251    fn test_gate_cache_basic_functionality() {
252        let cache = QuantumGateCache::new();
253
254        let key = GateKey::new("test_gate", &[1.0], 1);
255
256        // First call should be a cache miss
257        let matrix1 = cache
258            .get_or_compute_matrix(key.clone(), || Ok(vec![Complex64::new(1.0, 0.0); 4]))
259            .expect("matrix computation should succeed");
260
261        // Second call should be a cache hit
262        let matrix2 = cache
263            .get_or_compute_matrix(key, || {
264                panic!("Should not be called due to cache hit");
265            })
266            .expect("cache hit should succeed");
267
268        assert_eq!(matrix1, matrix2);
269
270        let stats = cache.get_performance_stats();
271        assert_eq!(stats.cache_hits, 1);
272        assert_eq!(stats.cache_misses, 1);
273        assert_eq!(stats.hit_ratio, 0.5);
274    }
275
276    #[test]
277    fn test_gate_key_hashing() {
278        let key1 = GateKey::new("rx", &[std::f64::consts::PI], 1);
279        let key2 = GateKey::new("rx", &[std::f64::consts::PI], 1);
280        let key3 = GateKey::new("rx", &[std::f64::consts::PI / 2.0], 1);
281
282        assert_eq!(key1, key2);
283        assert_ne!(key1, key3);
284
285        let mut set = std::collections::HashSet::new();
286        set.insert(key1);
287        assert!(set.contains(&key2));
288        assert!(!set.contains(&key3));
289    }
290
291    #[test]
292    fn test_cache_prewarming() {
293        let cache = QuantumGateCache::new();
294
295        // Cache should start empty
296        let initial_stats = cache.get_performance_stats();
297        assert_eq!(initial_stats.cache_misses, 0);
298
299        // Pre-warm should populate cache
300        cache
301            .prewarm_common_gates()
302            .expect("prewarming common gates should succeed");
303
304        let stats = cache.get_performance_stats();
305        assert!(stats.cache_misses > 0); // Should have computed some matrices
306
307        // Now test a common gate - should be a cache hit
308        let key = GateKey::new("hadamard", &[], 1);
309        let _matrix = cache
310            .get_or_compute_matrix(key, || {
311                panic!("Should be a cache hit");
312            })
313            .expect("cache hit for hadamard gate should succeed");
314
315        let final_stats = cache.get_performance_stats();
316        assert!(final_stats.cache_hits > 0);
317    }
318}
quantrs2_core/optimizations/gate_cache.rs

quantrs2_core/optimizations/
gate_cache.rs
