oxify_connect_vision/

model_loading.rs

//! Memory-mapped model loading for ONNX Runtime.
//!
//! This module provides optimized model loading using memory mapping to reduce
//! memory footprint and improve loading performance for large ONNX models.

use crate::errors::{Result, VisionError};
use std::path::Path;
use std::sync::Arc;

/// Model loading strategy.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum LoadingStrategy {
    /// Standard loading - read entire model into memory
    Standard,
    /// Memory-mapped loading - map model file to virtual memory
    MemoryMapped,
    /// Lazy loading - load model components on demand
    Lazy,
}

/// Configuration for model loading.
#[derive(Debug, Clone)]
pub struct ModelLoadingConfig {
    /// Loading strategy to use
    pub strategy: LoadingStrategy,
    /// Enable model sharing across instances
    pub enable_sharing: bool,
    /// Prefetch model data into page cache
    pub prefetch: bool,
    /// Use huge pages for memory mapping (if available)
    pub use_huge_pages: bool,
}

impl Default for ModelLoadingConfig {
    fn default() -> Self {
        Self {
            strategy: LoadingStrategy::MemoryMapped,
            enable_sharing: true,
            prefetch: true,
            use_huge_pages: false,
        }
    }
}

/// Model loader with memory mapping support.
pub struct ModelLoader {
    config: ModelLoadingConfig,
    #[allow(dead_code)]
    cache: Arc<ModelCache>,
}

impl ModelLoader {
    /// Create a new model loader with default configuration.
    pub fn new() -> Self {
        Self {
            config: ModelLoadingConfig::default(),
            cache: Arc::new(ModelCache::new()),
        }
    }

    /// Create a new model loader with custom configuration.
    pub fn with_config(config: ModelLoadingConfig) -> Self {
        Self {
            config,
            cache: Arc::new(ModelCache::new()),
        }
    }

    /// Load a model from a file path.
    ///
    /// Note: This is a stub implementation. Real implementation would use
    /// platform-specific memory mapping (mmap on Unix, MapViewOfFile on Windows)
    /// and integrate with ONNX Runtime's session options.
    pub fn load_model(&self, model_path: &Path) -> Result<ModelHandle> {
        if !model_path.exists() {
            return Err(VisionError::config(format!(
                "Model file not found: {}",
                model_path.display()
            )));
        }

        match self.config.strategy {
            LoadingStrategy::Standard => self.load_standard(model_path),
            LoadingStrategy::MemoryMapped => self.load_memory_mapped(model_path),
            LoadingStrategy::Lazy => self.load_lazy(model_path),
        }
    }

    /// Load model using standard file reading.
    fn load_standard(&self, model_path: &Path) -> Result<ModelHandle> {
        let file_size = std::fs::metadata(model_path)
            .map_err(|e| VisionError::config(format!("Failed to read model metadata: {}", e)))?
            .len();

        Ok(ModelHandle {
            path: model_path.to_path_buf(),
            size_bytes: file_size,
            strategy: LoadingStrategy::Standard,
            is_loaded: true,
        })
    }

    /// Load model using memory mapping.
    fn load_memory_mapped(&self, model_path: &Path) -> Result<ModelHandle> {
        let file_size = std::fs::metadata(model_path)
            .map_err(|e| VisionError::config(format!("Failed to read model metadata: {}", e)))?
            .len();

        // In a real implementation, this would:
        // 1. Open the file with appropriate flags
        // 2. Create memory mapping using mmap/MapViewOfFile
        // 3. Optionally prefetch pages
        // 4. Configure ONNX Runtime to use the mapped memory

        Ok(ModelHandle {
            path: model_path.to_path_buf(),
            size_bytes: file_size,
            strategy: LoadingStrategy::MemoryMapped,
            is_loaded: true,
        })
    }

    /// Load model using lazy loading.
    fn load_lazy(&self, model_path: &Path) -> Result<ModelHandle> {
        let file_size = std::fs::metadata(model_path)
            .map_err(|e| VisionError::config(format!("Failed to read model metadata: {}", e)))?
            .len();

        Ok(ModelHandle {
            path: model_path.to_path_buf(),
            size_bytes: file_size,
            strategy: LoadingStrategy::Lazy,
            is_loaded: false,
        })
    }

    /// Get memory usage statistics.
    pub fn memory_stats(&self) -> MemoryStats {
        MemoryStats {
            total_mapped_bytes: 0,
            active_models: 0,
            cache_hits: 0,
            cache_misses: 0,
        }
    }
}

impl Default for ModelLoader {
    fn default() -> Self {
        Self::new()
    }
}

/// Handle to a loaded model.
#[derive(Debug, Clone)]
pub struct ModelHandle {
    /// Path to the model file
    pub path: std::path::PathBuf,
    /// Size of the model in bytes
    pub size_bytes: u64,
    /// Loading strategy used
    pub strategy: LoadingStrategy,
    /// Whether the model is currently loaded
    pub is_loaded: bool,
}

impl ModelHandle {
    /// Get model size in megabytes.
    pub fn size_mb(&self) -> f64 {
        self.size_bytes as f64 / (1024.0 * 1024.0)
    }

    /// Unload the model from memory.
    pub fn unload(&mut self) -> Result<()> {
        self.is_loaded = false;
        Ok(())
    }

    /// Reload the model into memory.
    pub fn reload(&mut self) -> Result<()> {
        self.is_loaded = true;
        Ok(())
    }
}

/// Memory usage statistics.
#[derive(Debug, Clone)]
pub struct MemoryStats {
    /// Total bytes currently mapped
    pub total_mapped_bytes: u64,
    /// Number of active model instances
    pub active_models: usize,
    /// Cache hit count
    pub cache_hits: u64,
    /// Cache miss count
    pub cache_misses: u64,
}

impl MemoryStats {
    /// Get total mapped memory in megabytes.
    pub fn total_mapped_mb(&self) -> f64 {
        self.total_mapped_bytes as f64 / (1024.0 * 1024.0)
    }

    /// Get cache hit rate.
    pub fn cache_hit_rate(&self) -> f64 {
        let total = self.cache_hits + self.cache_misses;
        if total > 0 {
            self.cache_hits as f64 / total as f64
        } else {
            0.0
        }
    }
}

/// Model cache for sharing loaded models.
struct ModelCache {
    // In a real implementation, this would maintain weak references to loaded models
    // and allow sharing across provider instances
}

impl ModelCache {
    fn new() -> Self {
        Self {}
    }
}

/// Platform-specific memory mapping utilities.
#[cfg(unix)]
mod platform {
    use super::*;

    /// Create a memory-mapped region for a file (Unix).
    #[allow(dead_code)]
    pub fn create_mmap(_path: &Path, _size: u64) -> Result<()> {
        // Real implementation would use libc::mmap or memmap2 crate
        Ok(())
    }

    /// Prefetch memory pages into cache.
    #[allow(dead_code)]
    pub fn prefetch_pages(_addr: *const u8, _size: usize) -> Result<()> {
        // Real implementation would use libc::madvise with MADV_WILLNEED
        Ok(())
    }

    /// Enable transparent huge pages.
    #[allow(dead_code)]
    pub fn enable_huge_pages(_addr: *const u8, _size: usize) -> Result<()> {
        // Real implementation would use libc::madvise with MADV_HUGEPAGE
        Ok(())
    }
}

#[cfg(windows)]
mod platform {
    use super::*;

    /// Create a memory-mapped region for a file (Windows).
    #[allow(dead_code)]
    pub fn create_mmap(_path: &Path, _size: u64) -> Result<()> {
        // Real implementation would use CreateFileMapping/MapViewOfFile
        Ok(())
    }

    /// Prefetch memory pages into cache.
    #[allow(dead_code)]
    pub fn prefetch_pages(_addr: *const u8, _size: usize) -> Result<()> {
        // Real implementation would use PrefetchVirtualMemory
        Ok(())
    }

    /// Enable large pages (Windows).
    #[allow(dead_code)]
    pub fn enable_large_pages(_addr: *const u8, _size: usize) -> Result<()> {
        // Real implementation would use VirtualAlloc with MEM_LARGE_PAGES
        Ok(())
    }
}

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

    #[test]
    fn test_loading_config_default() {
        let config = ModelLoadingConfig::default();
        assert_eq!(config.strategy, LoadingStrategy::MemoryMapped);
        assert!(config.enable_sharing);
        assert!(config.prefetch);
    }

    #[test]
    fn test_model_handle_size_mb() {
        let handle = ModelHandle {
            path: PathBuf::from("/test/model.onnx"),
            size_bytes: 100 * 1024 * 1024, // 100 MB
            strategy: LoadingStrategy::MemoryMapped,
            is_loaded: true,
        };

        assert_eq!(handle.size_mb(), 100.0);
    }

    #[test]
    fn test_memory_stats_hit_rate() {
        let stats = MemoryStats {
            total_mapped_bytes: 1024 * 1024 * 1024,
            active_models: 2,
            cache_hits: 80,
            cache_misses: 20,
        };

        assert_eq!(stats.cache_hit_rate(), 0.8);
        assert_eq!(stats.total_mapped_mb(), 1024.0);
    }

    #[test]
    fn test_model_handle_unload_reload() {
        let mut handle = ModelHandle {
            path: PathBuf::from("/test/model.onnx"),
            size_bytes: 1024,
            strategy: LoadingStrategy::Standard,
            is_loaded: true,
        };

        assert!(handle.is_loaded);

        handle.unload().unwrap();
        assert!(!handle.is_loaded);

        handle.reload().unwrap();
        assert!(handle.is_loaded);
    }

    #[test]
    fn test_model_loader_creation() {
        let loader = ModelLoader::new();
        assert_eq!(loader.config.strategy, LoadingStrategy::MemoryMapped);

        let custom_config = ModelLoadingConfig {
            strategy: LoadingStrategy::Standard,
            enable_sharing: false,
            prefetch: false,
            use_huge_pages: false,
        };

        let custom_loader = ModelLoader::with_config(custom_config);
        assert_eq!(custom_loader.config.strategy, LoadingStrategy::Standard);
        assert!(!custom_loader.config.enable_sharing);
    }
}