context_creator/core/semantic/

cache.rs

//! Modern async cache implementation using moka and parser pools
//! Provides bounded memory usage and timeout protection

use crate::core::semantic::parser_pool::ParserPoolManager;
use crate::utils::error::ContextCreatorError;
use moka::future::Cache;
use std::collections::hash_map::DefaultHasher;
use std::hash::{Hash, Hasher};
use std::path::{Path, PathBuf};
use std::sync::Arc;
use std::time::Duration;
use tokio::time::timeout;
use tree_sitter::Tree;

/// Cache key for AST storage
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
struct CacheKey {
    /// File path (not canonicalized to avoid panics)
    path: PathBuf,
    /// File content hash for validation
    content_hash: u64,
    /// Language of the file
    language: String,
}

impl CacheKey {
    fn new(path: &Path, content: &str, language: &str) -> Self {
        let mut hasher = DefaultHasher::new();
        content.hash(&mut hasher);
        let content_hash = hasher.finish();

        Self {
            path: path.to_path_buf(),
            content_hash,
            language: language.to_string(),
        }
    }
}

/// Cached AST entry
#[derive(Clone)]
struct CacheEntry {
    /// Parsed syntax tree (wrapped in Arc for cheap cloning)
    tree: Arc<Tree>,
    /// Source content (wrapped in Arc for cheap cloning)
    content: Arc<String>,
}

/// Modern async AST cache with bounded memory and timeout protection
#[derive(Clone)]
pub struct AstCacheV2 {
    /// Moka cache with automatic eviction
    cache: Cache<CacheKey, CacheEntry>,
    /// Parser pool manager
    parser_pool: Arc<ParserPoolManager>,
    /// Parsing timeout duration
    parse_timeout: Duration,
}

impl AstCacheV2 {
    /// Create a new AST cache with the specified capacity
    pub fn new(capacity: u64) -> Self {
        let cache = Cache::builder()
            .max_capacity(capacity)
            .time_to_live(Duration::from_secs(3600)) // 1 hour TTL
            .build();

        Self {
            cache,
            parser_pool: Arc::new(ParserPoolManager::new()),
            parse_timeout: Duration::from_secs(30), // 30 second timeout
        }
    }

    /// Create a new AST cache with custom configuration
    pub fn with_config(capacity: u64, ttl: Duration, parse_timeout: Duration) -> Self {
        let cache = Cache::builder()
            .max_capacity(capacity)
            .time_to_live(ttl)
            .build();

        Self {
            cache,
            parser_pool: Arc::new(ParserPoolManager::new()),
            parse_timeout,
        }
    }

    /// Get or parse an AST for the given file
    pub async fn get_or_parse(
        &self,
        path: &Path,
        content: &str,
        language: &str,
    ) -> Result<Arc<Tree>, ContextCreatorError> {
        let key = CacheKey::new(path, content, language);

        // Clone for the async block
        let parser_pool = self.parser_pool.clone();
        let content_clone = content.to_string();
        let language_clone = language.to_string();
        let path_clone = path.to_path_buf();
        let timeout_duration = self.parse_timeout;

        // Use try_get_with for fallible operations
        let entry = self
            .cache
            .try_get_with(key, async move {
                // Parse with timeout protection
                let parse_result = timeout(timeout_duration, async {
                    let mut parser = parser_pool.get_parser(&language_clone).await?;

                    let tree = parser.parse(&content_clone, None).ok_or_else(|| {
                        ContextCreatorError::ParseError(format!(
                            "Failed to parse {} file: {}",
                            language_clone,
                            path_clone.display()
                        ))
                    })?;

                    Ok::<Tree, ContextCreatorError>(tree)
                })
                .await;

                match parse_result {
                    Ok(Ok(tree)) => Ok(CacheEntry {
                        tree: Arc::new(tree),
                        content: Arc::new(content_clone),
                    }),
                    Ok(Err(e)) => Err(e),
                    Err(_) => Err(ContextCreatorError::ParseError(format!(
                        "Parsing timed out after {:?} for file: {}",
                        timeout_duration,
                        path_clone.display()
                    ))),
                }
            })
            .await
            .map_err(|e| {
                ContextCreatorError::ParseError(format!("Failed to cache parse result: {e}"))
            })?;

        Ok(entry.tree.clone())
    }

    /// Get cached content for a file if available
    pub async fn get_content(
        &self,
        path: &Path,
        content_hash: &str,
        language: &str,
    ) -> Option<Arc<String>> {
        // Create a temporary key to check cache
        let mut hasher = DefaultHasher::new();
        content_hash.hash(&mut hasher);
        let hash = hasher.finish();

        let key = CacheKey {
            path: path.to_path_buf(),
            content_hash: hash,
            language: language.to_string(),
        };

        self.cache
            .get(&key)
            .await
            .map(|entry| entry.content.clone())
    }

    /// Clear the cache
    pub async fn clear(&self) {
        self.cache.invalidate_all();
    }

    /// Get current cache size
    pub fn len(&self) -> u64 {
        self.cache.entry_count()
    }

    /// Check if cache is empty
    pub fn is_empty(&self) -> bool {
        self.cache.entry_count() == 0
    }

    /// Get cache statistics
    pub fn stats(&self) -> CacheStats {
        CacheStats {
            hits: 0, // Moka doesn't expose stats in the same way
            misses: 0,
            evictions: 0,
            entry_count: self.cache.entry_count(),
        }
    }
}

/// Cache statistics
#[derive(Debug, Clone)]
pub struct CacheStats {
    pub hits: u64,
    pub misses: u64,
    pub evictions: u64,
    pub entry_count: u64,
}

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

    #[tokio::test]
    async fn test_cache_operations() {
        let cache = AstCacheV2::new(10);

        assert_eq!(cache.len(), 0);
        assert!(cache.is_empty());

        // Parse and cache a file
        let path = Path::new("test.rs");
        let content = "fn main() {}";
        let result = cache.get_or_parse(path, content, "rust").await;
        assert!(result.is_ok());

        // Give cache time to update
        tokio::time::sleep(tokio::time::Duration::from_millis(10)).await;

        // Moka cache has eventual consistency, so len() might not reflect immediately
        // Instead check that we can retrieve the cached item
        let result2 = cache.get_or_parse(path, content, "rust").await;
        assert!(result2.is_ok());

        // Clear cache
        cache.clear().await;
        tokio::time::sleep(tokio::time::Duration::from_millis(10)).await;
    }

    #[tokio::test]
    async fn test_cache_hit() {
        let cache = AstCacheV2::new(10);

        let path = Path::new("test.py");
        let content = "def test(): pass";

        // First call - cache miss
        let result1 = cache.get_or_parse(path, content, "python").await;
        assert!(result1.is_ok());

        // Second call - cache hit (same content)
        let result2 = cache.get_or_parse(path, content, "python").await;
        assert!(result2.is_ok());

        // Trees should be the same (Arc comparison)
        assert!(Arc::ptr_eq(&result1.unwrap(), &result2.unwrap()));
    }

    #[tokio::test]
    async fn test_cache_invalidation_on_content_change() {
        let cache = AstCacheV2::new(10);

        let path = Path::new("test.js");
        let content1 = "function test() {}";
        let content2 = "function test2() {}";

        // Parse with first content
        let result1 = cache.get_or_parse(path, content1, "javascript").await;
        assert!(result1.is_ok());

        // Parse with different content - should not hit cache
        let result2 = cache.get_or_parse(path, content2, "javascript").await;
        assert!(result2.is_ok());

        // Trees should be different
        assert!(!Arc::ptr_eq(&result1.unwrap(), &result2.unwrap()));
    }

    #[tokio::test]
    async fn test_concurrent_parsing() {
        let cache = Arc::new(AstCacheV2::new(100));
        let mut handles = vec![];

        // Spawn multiple tasks parsing the same file
        for _i in 0..10 {
            let cache_clone = cache.clone();
            let handle = tokio::spawn(async move {
                let path = Path::new("concurrent.rs");
                let content = "fn main() { println!(\"test\"); }";
                cache_clone.get_or_parse(path, content, "rust").await
            });
            handles.push(handle);
        }

        // All should succeed
        for handle in handles {
            assert!(handle.await.unwrap().is_ok());
        }

        // Give cache time to update
        tokio::time::sleep(tokio::time::Duration::from_millis(50)).await;

        // With eventual consistency, just verify operations succeeded
        // The important part is that parsing didn't happen 10 times
        assert!(cache.len() <= 10); // At most one per concurrent request
    }

    #[tokio::test]
    async fn test_timeout_configuration() {
        // Create cache with very short timeout
        let cache =
            AstCacheV2::with_config(10, Duration::from_secs(3600), Duration::from_millis(1));

        // This should complete quickly even with short timeout
        let path = Path::new("test.rs");
        let content = "fn main() {}";
        let result = cache.get_or_parse(path, content, "rust").await;

        // Should still succeed as parsing is fast
        assert!(result.is_ok());
    }
}