// Put inserts a Block into the Cache, returning the Block that was evicted or
// nil if no eviction was necessary and the Block was retained. Unused Blocks
// are not retained but are returned if the Cache is full.
func (c *FIFO) Put(b bgzf.Block) (evicted bgzf.Block, retained bool) {
c.mu.Lock()
defer c.mu.Unlock()
var d bgzf.Block
if _, ok := c.table[b.Base()]; ok {
return b, false
}
used := b.Used()
if len(c.table) == c.cap {
if !used {
return b, false
}
d = c.root.prev.b
remove(c.root.prev, c.table)
}
n := &node{b: b}
c.table[b.Base()] = n
if used {
insertAfter(&c.root, n)
} else {
insertAfter(c.root.prev, n)
}
return d, true
}
// Put inserts a Block into the Cache, returning the Block that was evicted or
// nil if no eviction was necessary and the Block was retained. Unused Blocks
// are not retained but are returned if the Cache is full.
func (c *Random) Put(b bgzf.Block) (evicted bgzf.Block, retained bool) {
c.mu.Lock()
defer c.mu.Unlock()
var d bgzf.Block
if _, ok := c.table[b.Base()]; ok {
return b, false
}
if len(c.table) == c.cap {
if !b.Used() {
return b, false
}
for k, v := range c.table {
if v.Used() {
continue
}
delete(c.table, k)
d = v
goto done
}
for k, v := range c.table {
delete(c.table, k)
d = v
break
}
done:
}
c.table[b.Base()] = b
return d, true
}
// StatsRecorder allows a bgzf.Cache to capture cache statistics.
type StatsRecorder struct {
bgzf.Cache
mu sync.RWMutex
stats Stats
}
// Stats represents statistics of a bgzf.Cache.
type Stats struct {
Gets int // number of Get operations
Misses int // number of cache misses
Puts int // number of Put operations
Retains int // number of times a Put has resulted in Block retention
Evictions int // number of times a Put has resulted in a Block eviction
}
// Stats returns the current statistics for the cache.
func (s *StatsRecorder) Stats() Stats {
s.mu.RLock()
defer s.mu.RUnlock()
return s.stats
}
// Reset zeros the statistics kept by the StatsRecorder.
func (s *StatsRecorder) Reset() {
s.mu.Lock()
s.stats = Stats{}
s.mu.Unlock()
}
// Get returns the Block in the underlying Cache with the specified base or a nil
// Block if it does not exist. It updates the gets and misses statistics.
func (s *StatsRecorder) Get(base int64) bgzf.Block {
s.mu.Lock()
s.stats.Gets++
blk := s.Cache.Get(base)
if blk == nil {
s.stats.Misses++
}
s.mu.Unlock()
return blk
}
// Put inserts a Block into the underlying Cache, returning the Block and eviction
// status according to the underlying cache behavior. It updates the puts, retains and
// evictions statistics.
func (s *StatsRecorder) Put(b bgzf.Block) (evicted bgzf.Block, retained bool) {
s.mu.Lock()
s.stats.Puts++
blk, retained := s.Cache.Put(b)
if retained {
s.stats.Retains++
if blk != nil {
s.stats.Evictions++
}
}
s.mu.Unlock()
return blk, retained
}
