/
db.go
201 lines (166 loc) · 4.26 KB
/
db.go
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package kv
import (
"context"
"crypto/rand"
"database/sql"
"github.com/cachecashproject/go-cachecash/dbtx"
"github.com/cachecashproject/go-cachecash/kv/models"
"github.com/pkg/errors"
"github.com/sirupsen/logrus"
"github.com/volatiletech/sqlboiler/boil"
)
// DBDriver is a database driver.
type DBDriver struct {
log *logrus.Logger
}
// NewDBDriver creates a new DBDriver from a db handle.
func NewDBDriver(log *logrus.Logger) Driver {
return &DBDriver{log: log}
}
func randomBuf() ([]byte, error) {
buf := make([]byte, 32)
if _, err := rand.Read(buf); err != nil {
return nil, err
}
return buf, nil
}
func (db *DBDriver) reapTx(tx *sql.Tx) {
if err := tx.Rollback(); err != nil && err != sql.ErrTxDone {
db.log.Errorf("Rollback could not complete: %v", err)
}
}
// tx free get
func (db *DBDriver) get(ctx context.Context, tx *sql.Tx, member, key string) ([]byte, []byte, error) {
record, err := models.Kvstores(
models.KvstoreWhere.Member.EQ(member),
models.KvstoreWhere.Key.EQ(key),
).One(ctx, tx)
if err != nil {
if err == sql.ErrNoRows {
return nil, nil, ErrUnsetValue
}
return nil, nil, err
}
return []byte(record.Value), record.Nonce, nil
}
// Delete removes a key. If a nonce is provided, it will be checked.
func (db *DBDriver) Delete(ctx context.Context, member, key string, nonce []byte) error {
ctx, tx, err := dbtx.BeginTx(ctx)
if err != nil {
return err
}
defer db.reapTx(tx)
var kv models.Kvstore
if nonce != nil {
kv = models.Kvstore{
Member: member,
Key: key,
Nonce: nonce,
}
} else {
kv = models.Kvstore{
Member: member,
Key: key,
}
}
res, err := kv.Delete(ctx, tx)
if err != nil {
return err
}
if res == 0 {
if nonce != nil {
// return not equal here because we're not really sure if we're unset or not.
// Instead of checking twice, this is safe and moderately sane.
return ErrNotEqual
}
return ErrUnsetValue
}
return tx.Commit()
}
// Create creates a key from scratch.
func (db *DBDriver) Create(ctx context.Context, member, key string, value []byte) ([]byte, error) {
buf, err := randomBuf()
if err != nil {
return nil, err
}
ctx, tx, err := dbtx.BeginTx(ctx)
if err != nil {
return nil, err
}
defer db.reapTx(tx)
kv := models.Kvstore{
Member: member,
Key: key,
Value: value,
Nonce: buf,
}
if err := kv.Insert(ctx, tx, boil.Infer()); err != nil {
return nil, errors.Wrap(ErrAlreadySet, err.Error())
}
return buf, tx.Commit()
}
// Get retrieves an item from the store. Users must pass a pointer to the out
// argument so it can be filled by json.Marshal.
func (db *DBDriver) Get(ctx context.Context, member, key string) ([]byte, []byte, error) {
ctx, tx, err := dbtx.BeginTx(ctx)
if err != nil {
return nil, nil, err
}
defer db.reapTx(tx)
return db.get(ctx, tx, member, key)
}
// tx free set
func (db *DBDriver) set(ctx context.Context, tx *sql.Tx, member, key string, value []byte) ([]byte, error) {
buf, err := randomBuf()
if err != nil {
return nil, err
}
kv := models.Kvstore{
Member: member,
Key: key,
Value: value,
Nonce: buf,
}
return buf, kv.Upsert(ctx, tx, true, []string{"member", "key"}, boil.Whitelist("value"), boil.Infer())
}
// Set sets a value in the store
func (db *DBDriver) Set(ctx context.Context, member, key string, value []byte) ([]byte, error) {
ctx, tx, err := dbtx.BeginTx(ctx)
if err != nil {
return nil, err
}
defer db.reapTx(tx)
buf, err := db.set(ctx, tx, member, key, value)
if err != nil {
return nil, err
}
return buf, tx.Commit()
}
// CAS implements a compare-and-swap operation.
func (db *DBDriver) CAS(ctx context.Context, member, key string, nonce, origValue, value []byte) ([]byte, error) {
ctx, tx, err := dbtx.BeginTx(ctx)
if err != nil {
return nil, err
}
defer db.reapTx(tx)
buf, err := randomBuf()
if err != nil {
return nil, err
}
count, err := models.Kvstores(
models.KvstoreWhere.Member.EQ(member),
models.KvstoreWhere.Key.EQ(key),
models.KvstoreWhere.Value.EQ(origValue),
models.KvstoreWhere.Nonce.EQ(nonce),
).UpdateAll(ctx, tx, models.M{"value": value, "nonce": buf})
if err != nil {
return nil, err
}
if count == 0 {
if _, _, err := db.get(ctx, tx, member, key); err != nil {
return nil, err
}
return nil, ErrNotEqual
}
return buf, tx.Commit()
}