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Implement packetcache resizing.
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commit
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2 changed files with 97 additions and 0 deletions
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@ -139,6 +139,9 @@ func (cache *Cache) GetAt(seqno uint16, index uint16, result []byte) uint16 {
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cache.mu.Lock()
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defer cache.mu.Unlock()
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if int(index) > len(cache.entries) {
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return 0
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}
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if cache.entries[index].seqno != seqno {
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return 0
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}
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@ -148,6 +151,57 @@ func (cache *Cache) GetAt(seqno uint16, index uint16, result []byte) uint16 {
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)
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}
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func (cache *Cache) resize(capacity int) {
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if len(cache.entries) == capacity {
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return
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}
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entries := make([]entry, capacity)
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if capacity > len(cache.entries) {
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copy(entries, cache.entries[:cache.tail])
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copy(entries[int(cache.tail)+capacity-len(cache.entries):],
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cache.entries[cache.tail:])
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} else if capacity > int(cache.tail) {
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copy(entries, cache.entries[:cache.tail])
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copy(entries[cache.tail:],
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cache.entries[int(cache.tail)+
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len(cache.entries)-capacity:])
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} else {
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// too bad, invalidate all indices
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copy(entries,
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cache.entries[int(cache.tail)-capacity:cache.tail])
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cache.tail = 0
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}
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cache.entries = entries
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}
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func (cache *Cache) Resize(capacity int) {
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cache.mu.Lock()
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defer cache.mu.Unlock()
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cache.resize(capacity)
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}
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func (cache *Cache) ResizeCond(capacity int) bool {
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cache.mu.Lock()
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defer cache.mu.Unlock()
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current := len(cache.entries)
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if current >= capacity/2 && current < capacity*2 {
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return false
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}
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if int(cache.tail) > current/2 && int(cache.tail) > capacity/2 {
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// bad time to resize, this would invalidate too many indices
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return false
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}
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cache.resize(capacity)
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return true
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}
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// Shift 17 bits out of the bitmap. Return a boolean indicating if any
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// were 0, the index of the first 0 bit, and a bitmap indicating any
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// 0 bits after the first one.
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@ -81,6 +81,49 @@ func TestCacheOverflow(t *testing.T) {
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}
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}
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func TestCacheGrow(t *testing.T) {
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cache := New(16)
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for i := 0; i < 24; i++ {
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cache.Store(uint16(i), []byte{uint8(i)})
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}
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cache.Resize(32)
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for i := 0; i < 32; i++ {
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expected := uint16(0)
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if i < 8 {
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expected = uint16(i + 16)
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}
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if i >= 24 {
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expected = uint16(i - 16)
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}
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if cache.entries[i].seqno != expected {
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t.Errorf("At %v, got %v, expected %v",
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i, cache.entries[i].seqno, expected)
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}
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}
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}
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func TestCacheShrink(t *testing.T) {
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cache := New(16)
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for i := 0; i < 24; i++ {
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cache.Store(uint16(i), []byte{uint8(i)})
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}
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cache.Resize(12)
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for i := 0; i < 12; i++ {
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expected := uint16(i + 16)
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if i >= 8 {
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expected = uint16(i + 4)
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}
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if cache.entries[i].seqno != expected {
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t.Errorf("At %v, got %v, expected %v",
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i, cache.entries[i].seqno, expected)
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}
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}
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}
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func TestBitmap(t *testing.T) {
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value := uint64(0xcdd58f1e035379c0)
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packet := make([]byte, 1)
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