131 lines
3.5 KiB
Go
131 lines
3.5 KiB
Go
// Copyright (c) 2020 The Decred developers
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// Use of this source code is governed by an ISC
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// license that can be found in the LICENSE file.
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package database
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import (
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"encoding/binary"
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"encoding/json"
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"fmt"
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"math"
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bolt "go.etcd.io/bbolt"
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)
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// VoteChangeRecord is serialized to json and stored in bbolt db. The json keys
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// are deliberately kept short because they are duplicated many times in the db.
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type VoteChangeRecord struct {
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Request string `json:"req"`
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RequestSignature string `json:"reqs"`
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Response string `json:"rsp"`
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ResponseSignature string `json:"rsps"`
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}
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// SaveVoteChange will insert the provided vote change record into the database,
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// and if this breaches the maximum amount of allowed records, delete the oldest
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// one which is currently stored. Records are stored using a serially increasing
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// integer as the key.
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func (vdb *VspDatabase) SaveVoteChange(ticketHash string, record VoteChangeRecord) error {
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return vdb.db.Update(func(tx *bolt.Tx) error {
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// Serialize record for storage in the database.
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recordBytes, err := json.Marshal(record)
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if err != nil {
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return fmt.Errorf("could not marshal vote change record: %v", err)
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}
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// Create or get a bucket for this ticket.
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bkt, err := tx.Bucket(vspBktK).Bucket(voteChangeBktK).
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CreateBucketIfNotExists([]byte(ticketHash))
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if err != nil {
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return fmt.Errorf("failed to create vote change bucket (ticketHash=%s): %v",
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ticketHash, err)
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}
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// Loop through the bucket to count the records, as well as finding the
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// most recent and the oldest record.
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var count int
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highest := uint32(0)
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lowest := uint32(math.MaxUint32)
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err = bkt.ForEach(func(k, v []byte) error {
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count++
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key := binary.LittleEndian.Uint32(k)
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if key > highest {
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highest = key
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}
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if key < lowest {
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lowest = key
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}
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return nil
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})
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if err != nil {
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return fmt.Errorf("error iterating over vote change bucket: %v", err)
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}
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// If bucket is at (or over) the limit of max allowed records, remove
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// the oldest one.
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if count >= vdb.maxVoteChangeRecords {
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keyBytes := make([]byte, 4)
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binary.LittleEndian.PutUint32(keyBytes, lowest)
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err = bkt.Delete(keyBytes)
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if err != nil {
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return fmt.Errorf("failed to delete old vote change record: %v", err)
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}
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}
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// Insert record with index 0 if the bucket is currently empty,
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// otherwise use most recent + 1.
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var newKey uint32
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if count > 0 {
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newKey = highest + 1
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}
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keyBytes := make([]byte, 4)
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binary.LittleEndian.PutUint32(keyBytes, newKey)
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// Insert record.
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err = bkt.Put(keyBytes, recordBytes)
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if err != nil {
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return fmt.Errorf("could not store vote change record: %v", err)
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}
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return nil
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})
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}
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// GetVoteChanges retrieves all of the stored vote change records for the
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// provided ticket hash.
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func (vdb *VspDatabase) GetVoteChanges(ticketHash string) (map[uint32]VoteChangeRecord, error) {
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records := make(map[uint32]VoteChangeRecord)
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err := vdb.db.View(func(tx *bolt.Tx) error {
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bkt := tx.Bucket(vspBktK).Bucket(voteChangeBktK).
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Bucket([]byte(ticketHash))
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if bkt == nil {
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return nil
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}
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err := bkt.ForEach(func(k, v []byte) error {
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var record VoteChangeRecord
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err := json.Unmarshal(v, &record)
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if err != nil {
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return fmt.Errorf("could not unmarshal vote change record: %v", err)
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}
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records[binary.LittleEndian.Uint32(k)] = record
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return nil
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})
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if err != nil {
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return fmt.Errorf("error iterating over vote change bucket: %v", err)
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}
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return nil
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})
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return records, err
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}
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