ceremonyclient/pebble/metamorphic/utils.go

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2024-01-03 07:31:42 +00:00
// Copyright 2019 The LevelDB-Go and Pebble Authors. All rights reserved. Use
// of this source code is governed by a BSD-style license that can be found in
// the LICENSE file.
package metamorphic
import (
"fmt"
"sort"
"golang.org/x/exp/rand"
)
// objTag identifies the type for an object: DB, Batch, Iter, or Snapshot.
type objTag uint8
const (
dbTag objTag = iota + 1
batchTag
iterTag
snapTag
)
// objID identifies a particular object. The top 4-bits store the tag
// identifying the type of object, while the bottom 28-bits store the slot used
// to index with the test.{batches,iters,snapshots} slices.
type objID uint32
func makeObjID(t objTag, slot uint32) objID {
return objID((uint32(t) << 28) | slot)
}
func (i objID) tag() objTag {
return objTag(i >> 28)
}
func (i objID) slot() uint32 {
return uint32(i) & ((1 << 28) - 1)
}
func (i objID) String() string {
switch i.tag() {
case dbTag:
return fmt.Sprintf("db%d", i.slot())
case batchTag:
return fmt.Sprintf("batch%d", i.slot())
case iterTag:
return fmt.Sprintf("iter%d", i.slot())
case snapTag:
return fmt.Sprintf("snap%d", i.slot())
}
return fmt.Sprintf("unknown%d", i.slot())
}
// objIDSlice is an unordered set of integers used when random selection of an
// element is required.
type objIDSlice []objID
func (s objIDSlice) Len() int { return len(s) }
func (s objIDSlice) Less(i, j int) bool { return s[i] < s[j] }
func (s objIDSlice) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
// Remove removes the specified integer from the set.
//
// TODO(peter): If this proves slow, we can replace this implementation with a
// map and a slice. The slice would provide for random selection of an element,
// while the map would provide quick location of an element to remove.
func (s *objIDSlice) remove(id objID) {
n := len(*s)
for j := 0; j < n; j++ {
if (*s)[j] == id {
(*s)[j], (*s)[n-1] = (*s)[n-1], (*s)[j]
(*s) = (*s)[:n-1]
break
}
}
}
func (s *objIDSlice) rand(rng *rand.Rand) objID {
return (*s)[rng.Intn(len(*s))]
}
// objIDSet is an unordered set of object IDs.
type objIDSet map[objID]struct{}
// sortedKeys returns a sorted slice of the set's keys for deterministic
// iteration.
func (s objIDSet) sorted() []objID {
keys := make(objIDSlice, 0, len(s))
for id := range s {
keys = append(keys, id)
}
sort.Sort(keys)
return keys
}
// firstError returns the first non-nil error of err0 and err1, or nil if both
// are nil.
func firstError(err0, err1 error) error {
if err0 != nil {
return err0
}
return err1
}