diff options
Diffstat (limited to 'vendor/github.com/go-git/go-git/v5/plumbing/cache/buffer_lru.go')
-rw-r--r-- | vendor/github.com/go-git/go-git/v5/plumbing/cache/buffer_lru.go | 98 |
1 files changed, 98 insertions, 0 deletions
diff --git a/vendor/github.com/go-git/go-git/v5/plumbing/cache/buffer_lru.go b/vendor/github.com/go-git/go-git/v5/plumbing/cache/buffer_lru.go new file mode 100644 index 000000000..acaf19520 --- /dev/null +++ b/vendor/github.com/go-git/go-git/v5/plumbing/cache/buffer_lru.go @@ -0,0 +1,98 @@ +package cache + +import ( + "container/list" + "sync" +) + +// BufferLRU implements an object cache with an LRU eviction policy and a +// maximum size (measured in object size). +type BufferLRU struct { + MaxSize FileSize + + actualSize FileSize + ll *list.List + cache map[int64]*list.Element + mut sync.Mutex +} + +// NewBufferLRU creates a new BufferLRU with the given maximum size. The maximum +// size will never be exceeded. +func NewBufferLRU(maxSize FileSize) *BufferLRU { + return &BufferLRU{MaxSize: maxSize} +} + +// NewBufferLRUDefault creates a new BufferLRU with the default cache size. +func NewBufferLRUDefault() *BufferLRU { + return &BufferLRU{MaxSize: DefaultMaxSize} +} + +type buffer struct { + Key int64 + Slice []byte +} + +// Put puts a buffer into the cache. If the buffer is already in the cache, it +// will be marked as used. Otherwise, it will be inserted. A buffers might +// be evicted to make room for the new one. +func (c *BufferLRU) Put(key int64, slice []byte) { + c.mut.Lock() + defer c.mut.Unlock() + + if c.cache == nil { + c.actualSize = 0 + c.cache = make(map[int64]*list.Element, 1000) + c.ll = list.New() + } + + bufSize := FileSize(len(slice)) + if ee, ok := c.cache[key]; ok { + oldBuf := ee.Value.(buffer) + // in this case bufSize is a delta: new size - old size + bufSize -= FileSize(len(oldBuf.Slice)) + c.ll.MoveToFront(ee) + ee.Value = buffer{key, slice} + } else { + if bufSize > c.MaxSize { + return + } + ee := c.ll.PushFront(buffer{key, slice}) + c.cache[key] = ee + } + + c.actualSize += bufSize + for c.actualSize > c.MaxSize { + last := c.ll.Back() + lastObj := last.Value.(buffer) + lastSize := FileSize(len(lastObj.Slice)) + + c.ll.Remove(last) + delete(c.cache, lastObj.Key) + c.actualSize -= lastSize + } +} + +// Get returns a buffer by its key. It marks the buffer as used. If the buffer +// is not in the cache, (nil, false) will be returned. +func (c *BufferLRU) Get(key int64) ([]byte, bool) { + c.mut.Lock() + defer c.mut.Unlock() + + ee, ok := c.cache[key] + if !ok { + return nil, false + } + + c.ll.MoveToFront(ee) + return ee.Value.(buffer).Slice, true +} + +// Clear the content of this buffer cache. +func (c *BufferLRU) Clear() { + c.mut.Lock() + defer c.mut.Unlock() + + c.ll = nil + c.cache = nil + c.actualSize = 0 +} |