Enhance caching mechanisms and introduce adaptive features

- Updated caching logic to support size-based promotion filtering, ensuring that not all files may be promoted based on size constraints. - Implemented adaptive caching strategies with a new AdaptiveCacheManager to analyze access patterns and adjust caching strategies dynamically. - Introduced predictive caching features with a PredictiveCacheManager to prefetch content based on access patterns. - Added a CacheWarmer to preload popular content into the cache, improving access times for frequently requested files. - Refactored memory management with a DynamicCacheManager to adjust cache sizes based on system memory usage. - Enhanced VFS interface and file metadata handling to support new features and improve performance. - Updated tests to validate new caching behaviors and ensure reliability of the caching system.
2025-09-21 22:47:13 -05:00
parent bbe014e334
commit 45ae234694
12 changed files with 2212 additions and 189 deletions
--- a/vfs/cache/cache.go
+++ b/vfs/cache/cache.go
@@ -6,6 +6,7 @@ import (
 	"s1d3sw1ped/SteamCache2/vfs"
 	"s1d3sw1ped/SteamCache2/vfs/vfserror"
 	"sync"
+	"sync/atomic"
 )

 // TieredCache implements a two-tier cache with fast (memory) and slow (disk) storage
@@ -16,6 +17,12 @@ type TieredCache struct {
 	mu sync.RWMutex
 }

+// LockFreeTieredCache implements a lock-free two-tier cache for better concurrency
+type LockFreeTieredCache struct {
+	fast *atomic.Value // Memory cache (fast) - atomic.Value for lock-free access
+	slow *atomic.Value // Disk cache (slow) - atomic.Value for lock-free access
+}
+
 // New creates a new tiered cache
 func New() *TieredCache {
 	return &TieredCache{}
@@ -53,7 +60,7 @@ func (tc *TieredCache) Create(key string, size int64) (io.WriteCloser, error) {
 	return nil, vfserror.ErrNotFound
 }

-// Open opens a file, checking fast tier first, then slow tier
+// Open opens a file, checking fast tier first, then slow tier with promotion
 func (tc *TieredCache) Open(key string) (io.ReadCloser, error) {
 	tc.mu.RLock()
 	defer tc.mu.RUnlock()
@@ -65,9 +72,30 @@ func (tc *TieredCache) Open(key string) (io.ReadCloser, error) {
 		}
 	}

-	// Fall back to slow tier (disk)
+	// Fall back to slow tier (disk) and promote to fast tier
 	if tc.slow != nil {
-		return tc.slow.Open(key)
+		reader, err := tc.slow.Open(key)
+		if err != nil {
+			return nil, err
+		}
+
+		// If we have both tiers, check if we should promote the file to fast tier
+		if tc.fast != nil {
+			// Check file size before promoting - don't promote if larger than available memory cache space
+			if info, err := tc.slow.Stat(key); err == nil {
+				availableSpace := tc.fast.Capacity() - tc.fast.Size()
+				// Only promote if file fits in available space (with 10% buffer for safety)
+				if info.Size <= int64(float64(availableSpace)*0.9) {
+					// Create a new reader for promotion to avoid interfering with the returned reader
+					promotionReader, err := tc.slow.Open(key)
+					if err == nil {
+						go tc.promoteToFast(key, promotionReader)
+					}
+				}
+			}
+		}
+
+		return reader, nil
 	}

 	return nil, vfserror.ErrNotFound
@@ -151,3 +179,258 @@ func (tc *TieredCache) Capacity() int64 {
 	}
 	return total
 }
+
+// promoteToFast promotes a file from slow tier to fast tier
+func (tc *TieredCache) promoteToFast(key string, reader io.ReadCloser) {
+	defer reader.Close()
+
+	// Get file info from slow tier to determine size
+	tc.mu.RLock()
+	var size int64
+	if tc.slow != nil {
+		if info, err := tc.slow.Stat(key); err == nil {
+			size = info.Size
+		} else {
+			tc.mu.RUnlock()
+			return // Skip promotion if we can't get file info
+		}
+	}
+	tc.mu.RUnlock()
+
+	// Check if file fits in available memory cache space
+	tc.mu.RLock()
+	if tc.fast != nil {
+		availableSpace := tc.fast.Capacity() - tc.fast.Size()
+		// Only promote if file fits in available space (with 10% buffer for safety)
+		if size > int64(float64(availableSpace)*0.9) {
+			tc.mu.RUnlock()
+			return // Skip promotion if file is too large
+		}
+	}
+	tc.mu.RUnlock()
+
+	// Read the entire file content
+	content, err := io.ReadAll(reader)
+	if err != nil {
+		return // Skip promotion if read fails
+	}
+
+	// Create the file in fast tier
+	tc.mu.RLock()
+	if tc.fast != nil {
+		writer, err := tc.fast.Create(key, size)
+		if err == nil {
+			// Write content to fast tier
+			writer.Write(content)
+			writer.Close()
+		}
+	}
+	tc.mu.RUnlock()
+}
+
+// NewLockFree creates a new lock-free tiered cache
+func NewLockFree() *LockFreeTieredCache {
+	return &LockFreeTieredCache{
+		fast: &atomic.Value{},
+		slow: &atomic.Value{},
+	}
+}
+
+// SetFast sets the fast (memory) tier atomically
+func (lftc *LockFreeTieredCache) SetFast(vfs vfs.VFS) {
+	lftc.fast.Store(vfs)
+}
+
+// SetSlow sets the slow (disk) tier atomically
+func (lftc *LockFreeTieredCache) SetSlow(vfs vfs.VFS) {
+	lftc.slow.Store(vfs)
+}
+
+// Create creates a new file, preferring the slow tier for persistence
+func (lftc *LockFreeTieredCache) Create(key string, size int64) (io.WriteCloser, error) {
+	// Try slow tier first (disk) for better testability
+	if slow := lftc.slow.Load(); slow != nil {
+		if vfs, ok := slow.(vfs.VFS); ok {
+			return vfs.Create(key, size)
+		}
+	}
+
+	// Fall back to fast tier (memory)
+	if fast := lftc.fast.Load(); fast != nil {
+		if vfs, ok := fast.(vfs.VFS); ok {
+			return vfs.Create(key, size)
+		}
+	}
+
+	return nil, vfserror.ErrNotFound
+}
+
+// Open opens a file, checking fast tier first, then slow tier with promotion
+func (lftc *LockFreeTieredCache) Open(key string) (io.ReadCloser, error) {
+	// Try fast tier first (memory)
+	if fast := lftc.fast.Load(); fast != nil {
+		if vfs, ok := fast.(vfs.VFS); ok {
+			if reader, err := vfs.Open(key); err == nil {
+				return reader, nil
+			}
+		}
+	}
+
+	// Fall back to slow tier (disk) and promote to fast tier
+	if slow := lftc.slow.Load(); slow != nil {
+		if vfs, ok := slow.(vfs.VFS); ok {
+			reader, err := vfs.Open(key)
+			if err != nil {
+				return nil, err
+			}
+
+			// If we have both tiers, promote the file to fast tier
+			if fast := lftc.fast.Load(); fast != nil {
+				// Create a new reader for promotion to avoid interfering with the returned reader
+				promotionReader, err := vfs.Open(key)
+				if err == nil {
+					go lftc.promoteToFast(key, promotionReader)
+				}
+			}
+
+			return reader, nil
+		}
+	}
+
+	return nil, vfserror.ErrNotFound
+}
+
+// Delete removes a file from all tiers
+func (lftc *LockFreeTieredCache) Delete(key string) error {
+	var lastErr error
+
+	// Delete from fast tier
+	if fast := lftc.fast.Load(); fast != nil {
+		if vfs, ok := fast.(vfs.VFS); ok {
+			if err := vfs.Delete(key); err != nil {
+				lastErr = err
+			}
+		}
+	}
+
+	// Delete from slow tier
+	if slow := lftc.slow.Load(); slow != nil {
+		if vfs, ok := slow.(vfs.VFS); ok {
+			if err := vfs.Delete(key); err != nil {
+				lastErr = err
+			}
+		}
+	}
+
+	return lastErr
+}
+
+// Stat returns file information, checking fast tier first
+func (lftc *LockFreeTieredCache) Stat(key string) (*vfs.FileInfo, error) {
+	// Try fast tier first (memory)
+	if fast := lftc.fast.Load(); fast != nil {
+		if vfs, ok := fast.(vfs.VFS); ok {
+			if info, err := vfs.Stat(key); err == nil {
+				return info, nil
+			}
+		}
+	}
+
+	// Fall back to slow tier (disk)
+	if slow := lftc.slow.Load(); slow != nil {
+		if vfs, ok := slow.(vfs.VFS); ok {
+			return vfs.Stat(key)
+		}
+	}
+
+	return nil, vfserror.ErrNotFound
+}
+
+// Name returns the cache name
+func (lftc *LockFreeTieredCache) Name() string {
+	return "LockFreeTieredCache"
+}
+
+// Size returns the total size across all tiers
+func (lftc *LockFreeTieredCache) Size() int64 {
+	var total int64
+
+	if fast := lftc.fast.Load(); fast != nil {
+		if vfs, ok := fast.(vfs.VFS); ok {
+			total += vfs.Size()
+		}
+	}
+
+	if slow := lftc.slow.Load(); slow != nil {
+		if vfs, ok := slow.(vfs.VFS); ok {
+			total += vfs.Size()
+		}
+	}
+
+	return total
+}
+
+// Capacity returns the total capacity across all tiers
+func (lftc *LockFreeTieredCache) Capacity() int64 {
+	var total int64
+
+	if fast := lftc.fast.Load(); fast != nil {
+		if vfs, ok := fast.(vfs.VFS); ok {
+			total += vfs.Capacity()
+		}
+	}
+
+	if slow := lftc.slow.Load(); slow != nil {
+		if vfs, ok := slow.(vfs.VFS); ok {
+			total += vfs.Capacity()
+		}
+	}
+
+	return total
+}
+
+// promoteToFast promotes a file from slow tier to fast tier (lock-free version)
+func (lftc *LockFreeTieredCache) promoteToFast(key string, reader io.ReadCloser) {
+	defer reader.Close()
+
+	// Get file info from slow tier to determine size
+	var size int64
+	if slow := lftc.slow.Load(); slow != nil {
+		if vfs, ok := slow.(vfs.VFS); ok {
+			if info, err := vfs.Stat(key); err == nil {
+				size = info.Size
+			} else {
+				return // Skip promotion if we can't get file info
+			}
+		}
+	}
+
+	// Check if file fits in available memory cache space
+	if fast := lftc.fast.Load(); fast != nil {
+		if vfs, ok := fast.(vfs.VFS); ok {
+			availableSpace := vfs.Capacity() - vfs.Size()
+			// Only promote if file fits in available space (with 10% buffer for safety)
+			if size > int64(float64(availableSpace)*0.9) {
+				return // Skip promotion if file is too large
+			}
+		}
+	}
+
+	// Read the entire file content
+	content, err := io.ReadAll(reader)
+	if err != nil {
+		return // Skip promotion if read fails
+	}
+
+	// Create the file in fast tier
+	if fast := lftc.fast.Load(); fast != nil {
+		if vfs, ok := fast.(vfs.VFS); ok {
+			writer, err := vfs.Create(key, size)
+			if err == nil {
+				// Write content to fast tier
+				writer.Write(content)
+				writer.Close()
+			}
+		}
+	}
+}