Refactor Activity Page (#710)

- inference handles to store an activity record for all inference endpoints
- add path, status code, and content type to Activities page
- toggle on/off columns no Activities page 
- add configurable capture level for inference endpoints so large binary blobs are not stored in memory
- store captures in compressed binary format

proxy/cache/cache.go

@@ -0,0 +1,102 @@
+package cache
+
+import (
+	"errors"
+	"sync"
+)
+
+var (
+	ErrExceedsMaxSize = errors.New("item exceeds maximum cache size")
+	ErrNotFound       = errors.New("item not found")
+)
+
+type Cache struct {
+	mu      sync.Mutex
+	items   map[int][]byte
+	order   []int
+	size    int
+	maxSize int
+}
+
+func New(maxBytes int) *Cache {
+	return &Cache{
+		items:   make(map[int][]byte),
+		order:   make([]int, 0),
+		maxSize: maxBytes,
+	}
+}
+
+func (c *Cache) Add(id int, data []byte) error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	dataSize := len(data)
+	if dataSize > c.maxSize {
+		return ErrExceedsMaxSize
+	}
+
+	// If key already exists, remove old entry from size and order
+	if old, exists := c.items[id]; exists {
+		c.size -= len(old)
+		c.removeOrder(id)
+	}
+
+	// Evict oldest (FIFO) until room available
+	for c.size+dataSize > c.maxSize && len(c.order) > 0 {
+		oldestID := c.order[0]
+		c.order = c.order[1:]
+		if evicted, exists := c.items[oldestID]; exists {
+			c.size -= len(evicted)
+			delete(c.items, oldestID)
+		}
+	}
+
+	c.items[id] = data
+	c.order = append(c.order, id)
+	c.size += dataSize
+	return nil
+}
+
+func (c *Cache) removeOrder(id int) {
+	for i, v := range c.order {
+		if v == id {
+			c.order = append(c.order[:i], c.order[i+1:]...)
+			return
+		}
+	}
+}
+
+func (c *Cache) Get(id int) ([]byte, error) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	data, exists := c.items[id]
+	if !exists {
+		return nil, ErrNotFound
+	}
+	return data, nil
+}
+
+func (c *Cache) Has(id int) bool {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	_, exists := c.items[id]
+	return exists
+}
+
+func (c *Cache) Size() int {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	return c.size
+}
+
+func (c *Cache) Clear() {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	c.items = make(map[int][]byte)
+	c.order = c.order[:0]
+	c.size = 0
+}

proxy/cache/cache_test.go

@@ -0,0 +1,130 @@
+package cache
+
+import (
+	"sync"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestCache_Add(t *testing.T) {
+	t.Run("adds and retrieves item", func(t *testing.T) {
+		c := New(1024)
+		data := []byte("hello")
+		require.NoError(t, c.Add(1, data))
+
+		got, err := c.Get(1)
+		require.NoError(t, err)
+		assert.Equal(t, data, got)
+	})
+
+	t.Run("returns error for oversized item", func(t *testing.T) {
+		c := New(10)
+		err := c.Add(1, make([]byte, 20))
+		assert.ErrorIs(t, err, ErrExceedsMaxSize)
+	})
+
+	t.Run("evicts oldest items to make room", func(t *testing.T) {
+		c := New(100)
+
+		require.NoError(t, c.Add(1, make([]byte, 40)))
+		require.NoError(t, c.Add(2, make([]byte, 40)))
+		// Adding item 3 should evict item 1
+		require.NoError(t, c.Add(3, make([]byte, 40)))
+
+		assert.False(t, c.Has(1))
+		assert.True(t, c.Has(2))
+		assert.True(t, c.Has(3))
+	})
+
+	t.Run("overwrites existing key", func(t *testing.T) {
+		c := New(100)
+		require.NoError(t, c.Add(1, []byte("old")))
+		require.NoError(t, c.Add(1, []byte("new")))
+
+		got, err := c.Get(1)
+		require.NoError(t, err)
+		assert.Equal(t, []byte("new"), got)
+		assert.Equal(t, 3, c.Size())
+	})
+}
+
+func TestCache_Get(t *testing.T) {
+	t.Run("returns ErrNotFound for missing key", func(t *testing.T) {
+		c := New(100)
+		_, err := c.Get(99)
+		assert.ErrorIs(t, err, ErrNotFound)
+	})
+}
+
+func TestCache_Has(t *testing.T) {
+	t.Run("returns true for existing key", func(t *testing.T) {
+		c := New(100)
+		require.NoError(t, c.Add(1, []byte("data")))
+		assert.True(t, c.Has(1))
+	})
+
+	t.Run("returns false for missing key", func(t *testing.T) {
+		c := New(100)
+		assert.False(t, c.Has(1))
+	})
+}
+
+func TestCache_Size(t *testing.T) {
+	t.Run("tracks byte usage", func(t *testing.T) {
+		c := New(1000)
+		assert.Equal(t, 0, c.Size())
+
+		require.NoError(t, c.Add(1, make([]byte, 100)))
+		assert.Equal(t, 100, c.Size())
+
+		require.NoError(t, c.Add(2, make([]byte, 200)))
+		assert.Equal(t, 300, c.Size())
+	})
+
+	t.Run("updates on eviction", func(t *testing.T) {
+		c := New(150)
+		require.NoError(t, c.Add(1, make([]byte, 100)))
+		require.NoError(t, c.Add(2, make([]byte, 100)))
+
+		// Item 1 should be evicted, size = 100
+		assert.Equal(t, 100, c.Size())
+	})
+}
+
+func TestCache_Clear(t *testing.T) {
+	t.Run("removes all items and resets size", func(t *testing.T) {
+		c := New(1000)
+		require.NoError(t, c.Add(1, []byte("a")))
+		require.NoError(t, c.Add(2, []byte("b")))
+
+		c.Clear()
+
+		assert.Equal(t, 0, c.Size())
+		assert.False(t, c.Has(1))
+		assert.False(t, c.Has(2))
+	})
+}
+
+func TestCache_Concurrent(t *testing.T) {
+	t.Run("concurrent operations are safe", func(t *testing.T) {
+		c := New(10000)
+
+		var wg sync.WaitGroup
+		for i := 0; i < 10; i++ {
+			wg.Add(1)
+			go func(id int) {
+				defer wg.Done()
+				for j := 0; j < 100; j++ {
+					key := id*100 + j
+					_ = c.Add(key, []byte("data"))
+					_, _ = c.Get(key)
+					_ = c.Has(key)
+					_ = c.Size()
+				}
+			}(i)
+		}
+		wg.Wait()
+	})
+}