herald.go/db/stack/stack.go
2022-04-20 18:29:37 +00:00

98 lines
1.7 KiB
Go

package stack
// The db_stack package contains the implementation of a generic slice backed stack
// used for tracking various states in the hub, i.e. headers and txcounts
import (
"sync"
"github.com/lbryio/hub/internal"
)
type SliceBacked struct {
slice []interface{}
len uint32
mut sync.RWMutex
}
func NewSliceBacked(size int) *SliceBacked {
return &SliceBacked{
slice: make([]interface{}, size),
len: 0,
mut: sync.RWMutex{},
}
}
func (s *SliceBacked) Push(v interface{}) {
s.mut.Lock()
defer s.mut.Unlock()
if s.len == uint32(len(s.slice)) {
s.slice = append(s.slice, v)
} else {
s.slice[s.len] = v
}
s.len++
}
func (s *SliceBacked) Pop() interface{} {
s.mut.Lock()
defer s.mut.Unlock()
if s.len == 0 {
return nil
}
s.len--
return s.slice[s.len]
}
func (s *SliceBacked) Get(i uint32) interface{} {
s.mut.RLock()
defer s.mut.RUnlock()
if i >= s.len {
return nil
}
return s.slice[i]
}
func (s *SliceBacked) GetTip() interface{} {
s.mut.RLock()
defer s.mut.RUnlock()
if s.len == 0 {
return nil
}
return s.slice[s.len-1]
}
func (s *SliceBacked) Len() uint32 {
s.mut.RLock()
defer s.mut.RUnlock()
return s.len
}
func (s *SliceBacked) Cap() int {
s.mut.RLock()
defer s.mut.RUnlock()
return cap(s.slice)
}
func (s *SliceBacked) GetSlice() []interface{} {
// This is not thread safe so I won't bother with locking
return s.slice
}
// This function is dangerous because it assumes underlying types
func (s *SliceBacked) TxCountsBisectRight(txNum, rootTxNum uint32) (uint32, uint32) {
s.mut.RLock()
defer s.mut.RUnlock()
txCounts := s.slice[:s.Len()]
height := internal.BisectRight(txCounts, txNum)
createdHeight := internal.BisectRight(txCounts, rootTxNum)
return height, createdHeight
}