improvements mid apr 2025

cache/cache.go

@@ -23,6 +23,10 @@ type CacheConfig struct {
 		DB       int    `json:"db"`
 		Enable   bool   `json:"enable"`
 	}
+	Memory struct {
+		MaxMemorySize int64 `json:"max_memory_size"` // Maximum memory size in bytes
+		MaxEntries    int64 `json:"max_entries"`     // Maximum number of entries
+	}
 	TTL int `json:"ttl"`
 }
 
@@ -38,6 +42,9 @@ type CacheClient interface {
 	Delete(key string)
 	Clear()
 	CountQueries() int64
+	// Memory usage reporting methods
+	GetMemoryUsage() int64   // Returns current memory usage in bytes
+	GetMaxMemorySize() int64 // Returns max memory size in bytes
 }
 
 var (
@@ -69,8 +76,33 @@ func EnableCache(cfg *CacheConfig) {
 	} else {
 		cfg.Logger.Debug(&libpack_logger.LogMessage{
 			Message: "Using in-memory cache",
+			Pairs: map[string]interface{}{
+				"max_memory_size_bytes": cfg.Memory.MaxMemorySize,
+				"max_entries":           cfg.Memory.MaxEntries,
+			},
 		})
-		cfg.Client = libpack_cache_memory.New(time.Duration(cfg.TTL) * time.Second)
+
+		// Use memory size and entry limits if configured, otherwise use defaults
+		if cfg.Memory.MaxMemorySize > 0 || cfg.Memory.MaxEntries > 0 {
+			maxMemory := cfg.Memory.MaxMemorySize
+			if maxMemory <= 0 {
+				maxMemory = libpack_cache_memory.DefaultMaxMemorySize
+			}
+
+			maxEntries := cfg.Memory.MaxEntries
+			if maxEntries <= 0 {
+				maxEntries = libpack_cache_memory.DefaultMaxCacheSize
+			}
+
+			cfg.Client = libpack_cache_memory.NewWithSize(
+				time.Duration(cfg.TTL)*time.Second,
+				maxMemory,
+				maxEntries,
+			)
+		} else {
+			// Backward compatibility
+			cfg.Client = libpack_cache_memory.New(time.Duration(cfg.TTL) * time.Second)
+		}
 	}
 	config = cfg
 }
@@ -176,6 +208,22 @@ func GetCacheStats() *CacheStats {
 	return cacheStats
 }
 
+// GetCacheMemoryUsage returns the current memory usage of the cache in bytes
+func GetCacheMemoryUsage() int64 {
+	if !IsCacheInitialized() {
+		return 0
+	}
+	return config.Client.GetMemoryUsage()
+}
+
+// GetCacheMaxMemorySize returns the maximum memory size allowed for the cache in bytes
+func GetCacheMaxMemorySize() int64 {
+	if !IsCacheInitialized() {
+		return 0
+	}
+	return config.Client.GetMaxMemorySize()
+}
+
 func ShouldUseRedisCache(cfg *CacheConfig) bool {
 	return cfg.Redis.Enable
 }

cache/memory/compression_test.go

@@ -0,0 +1,218 @@
+package libpack_cache_memory
+
+import (
+	"bytes"
+	"compress/gzip"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+// TestCompressionThreshold tests that values are only compressed when they exceed the threshold
+func TestCompressionThreshold(t *testing.T) {
+	cache := New(5 * time.Second)
+
+	// Create test values
+	smallValue := make([]byte, CompressionThreshold-100) // Below threshold
+	largeValue := make([]byte, CompressionThreshold*2)   // Above threshold
+
+	// Fill values with compressible data (repeating patterns compress well)
+	for i := 0; i < len(smallValue); i++ {
+		smallValue[i] = byte(i % 10)
+	}
+	for i := 0; i < len(largeValue); i++ {
+		largeValue[i] = byte(i % 10)
+	}
+
+	// Test small value
+	cache.Set("small-key", smallValue, 5*time.Second)
+
+	// Extract the entry directly from the cache to check if it's compressed
+	entryRaw, found := cache.entries.Load("small-key")
+	assert.True(t, found, "Entry should exist")
+
+	entry := entryRaw.(CacheEntry)
+	assert.False(t, entry.Compressed, "Small value should not be compressed")
+	assert.Equal(t, smallValue, entry.Value, "Small value should be stored as-is")
+
+	// Test large value
+	cache.Set("large-key", largeValue, 5*time.Second)
+
+	entryRaw, found = cache.entries.Load("large-key")
+	assert.True(t, found, "Entry should exist")
+
+	entry = entryRaw.(CacheEntry)
+	assert.True(t, entry.Compressed, "Large value should be compressed")
+
+	// Ensure the stored value isn't the original
+	assert.NotEqual(t, largeValue, entry.Value, "Large value should not be stored as-is")
+
+	// Verify the value is actually compressed (should be smaller)
+	assert.Less(t, len(entry.Value), len(largeValue), "Compressed value should be smaller than original")
+
+	// Verify we can retrieve the uncompressed value correctly
+	retrievedLarge, found := cache.Get("large-key")
+	assert.True(t, found, "Large value should be retrievable")
+	assert.Equal(t, largeValue, retrievedLarge, "Retrieved large value should match original")
+}
+
+// TestCompressionMemoryUsage tests that memory usage is calculated correctly for compressed entries
+func TestCompressionMemoryUsage(t *testing.T) {
+	cache := New(5 * time.Second)
+
+	// Create a large, highly compressible value
+	valueSize := CompressionThreshold * 4
+	value := make([]byte, valueSize)
+	for i := 0; i < valueSize; i++ {
+		value[i] = byte(i % 2) // Highly compressible pattern (alternating 0s and 1s)
+	}
+
+	// Get initial memory usage
+	initialMemUsage := cache.GetMemoryUsage()
+
+	// Add the value
+	key := "large-compressible-key"
+	cache.Set(key, value, 5*time.Second)
+
+	// Get memory usage after adding
+	newMemUsage := cache.GetMemoryUsage()
+
+	// The memory usage increase should be less than the full value size due to compression
+	memUsageIncrease := newMemUsage - initialMemUsage
+
+	// Extract the entry to check its compressed size
+	entryRaw, found := cache.entries.Load(key)
+	assert.True(t, found, "Entry should exist")
+
+	entry := entryRaw.(CacheEntry)
+	assert.True(t, entry.Compressed, "Value should be compressed")
+
+	// Verify the reported memory usage matches the compressed size + overheads
+	compressedSize := int64(len(entry.Value))
+	keySize := int64(len(key))
+	expectedUsage := compressedSize + keySize + approxEntryOverhead
+
+	// The memory usage should reflect the compressed size, not the original size
+	assert.InDelta(t, expectedUsage, memUsageIncrease, float64(approxEntryOverhead),
+		"Memory usage should be based on compressed size")
+
+	// Verify memory usage is correctly updated after deletion
+	cache.Delete(key)
+	finalMemUsage := cache.GetMemoryUsage()
+	assert.Equal(t, initialMemUsage, finalMemUsage,
+		"Memory usage should return to initial value after deletion")
+}
+
+// TestUncompressibleData tests the case where compression doesn't reduce size
+func TestUncompressibleData(t *testing.T) {
+	cache := New(5 * time.Second)
+
+	// Create a large, random (less compressible) value
+	valueSize := CompressionThreshold * 2
+
+	// Create pseudo-random data that doesn't compress well
+	// Using a custom PRNG for deterministic results across test runs
+	value := make([]byte, valueSize)
+	seed := uint32(42)
+	for i := 0; i < valueSize; i++ {
+		// Simple linear congruential generator
+		seed = seed*1664525 + 1013904223
+		value[i] = byte(seed)
+	}
+
+	// Try to compress it directly to see if it actually would reduce size
+	var buf bytes.Buffer
+	gw := gzip.NewWriter(&buf)
+	gw.Write(value)
+	gw.Close()
+	compressedDirectly := buf.Bytes()
+
+	// Now use the cache's Set method
+	key := "uncompressible-key"
+	cache.Set(key, value, 5*time.Second)
+
+	// Extract the entry to check if it's compressed
+	entryRaw, found := cache.entries.Load(key)
+	assert.True(t, found, "Entry should exist")
+
+	entry := entryRaw.(CacheEntry)
+
+	// If our test data actually compressed to a smaller size, we expect the cache to store it compressed
+	if len(compressedDirectly) < len(value) {
+		assert.True(t, entry.Compressed, "Value should be stored compressed if smaller")
+		assert.Less(t, len(entry.Value), len(value), "Compressed value should be smaller")
+	} else {
+		// Uncommon case: our pseudo-random data actually expanded with gzip
+		// In this case, the cache should store it uncompressed
+		assert.False(t, entry.Compressed, "Value should not be compressed if it would expand")
+		assert.Equal(t, value, entry.Value, "Value should be stored as-is")
+	}
+
+	// Regardless, we should be able to get the correct value back
+	retrievedValue, found := cache.Get(key)
+	assert.True(t, found, "Value should be retrievable")
+	assert.Equal(t, value, retrievedValue, "Retrieved value should match original")
+}
+
+// TestCompressDecompressDirectly tests the compress and decompress methods directly
+func TestCompressDecompressDirectly(t *testing.T) {
+	cache := New(5 * time.Second)
+
+	// Test with various sizes
+	testSizes := []int{
+		100,                      // Small
+		CompressionThreshold - 1, // Just below threshold
+		CompressionThreshold,     // At threshold
+		CompressionThreshold + 1, // Just above threshold
+		CompressionThreshold * 2, // Well above threshold
+	}
+
+	for _, size := range testSizes {
+		t.Run("Size-"+string(rune('A'+len(testSizes)%26)), func(t *testing.T) {
+			// Generate test data with a repeating pattern
+			data := make([]byte, size)
+			for i := 0; i < size; i++ {
+				data[i] = byte(i % 256)
+			}
+
+			// Compress the data
+			compressed, err := cache.compress(data)
+			assert.NoError(t, err, "Compression should not error")
+
+			// Small data may get larger when compressed, larger data should get smaller
+			if size > CompressionThreshold {
+				assert.Less(t, len(compressed), len(data),
+					"Compression should reduce size for data above threshold")
+			}
+
+			// Decompress and verify it matches the original
+			decompressed, err := cache.decompress(compressed)
+			assert.NoError(t, err, "Decompression should not error")
+			assert.Equal(t, data, decompressed, "Data should round-trip correctly through compression")
+		})
+	}
+}
+
+// TestDecompressInvalidData tests handling invalid data in decompress
+func TestDecompressInvalidData(t *testing.T) {
+	cache := New(5 * time.Second)
+
+	// Try to decompress non-gzip data
+	invalidData := []byte("This is not valid gzip data")
+	_, err := cache.decompress(invalidData)
+	assert.Error(t, err, "Decompressing invalid data should return error")
+
+	// Set compressed flag but store invalid data
+	key := "invalid-compressed-key"
+	cache.entries.Store(key, CacheEntry{
+		Value:      invalidData,
+		ExpiresAt:  time.Now().Add(5 * time.Second),
+		Compressed: true, // Flag as compressed even though it's not
+		MemorySize: int64(len(invalidData) + len(key) + approxEntryOverhead),
+	})
+
+	// Try to get it - should fail gracefully
+	_, found := cache.Get(key)
+	assert.False(t, found, "Get should fail gracefully for invalid compressed data")
+}