func (bs *BlobStore) keyExistsInDb(id *int64, key pandora.Key) (bool, error) {
err := bs.conn.QueryRow("select id from pgstore_blobs_ref where blobid = $1", key.Bytes()).Scan(id)
if err == sql.ErrNoRows {
return false, nil
} else {
if err != nil {
return false, err
}
}
return *id > 0, nil
}
// PutData write the contents of data and return the key used to store the data
func (bs *BlobStore) PutData(k pandora.Key, data []byte) (pandora.Key, error) {
kw := pandora.SHA1KeyWriter{}
kw.Write(data)
actual := kw.Key()
if k != nil && len(k.Bytes()) >= len(actual.Bytes()) {
// avoid allocating outside the stack
copy(k.Bytes(), actual.Bytes())
} else {
// use the heap
k = actual
}
err := bs.insert(k, data)
return k, err
}
func (ms *MessageStore) Ack(mid, lid pandora.Key, status pandora.AckStatus) error {
return doInsideTransaction(ms.conn, func(tx querier) error {
var id int64
switch status {
case pandora.StatusConfirmed, pandora.StatusRejected:
default:
return pandora.ErrUnableToChangeStatus
}
err := tx.QueryRow(`update pgstore_messages
set status = $1, lid = null, leaseuntil = null
where mid = $2 and lid = $3 and leaseuntil >= $4
returning id`, status, mid.Bytes(), lid.Bytes(), time.Now()).Scan(&id)
if err != nil {
return err
}
if id == 0 {
return pandora.ErrUnableToChangeStatus
}
return nil
})
}
// if data have a Bytes() []byte method, then it is used instead of a copy
func (bs *BlobStore) insert(out pandora.Key, data []byte) error {
var id int64
var err error
exists, err := bs.keyExistsInDb(&id, out)
if err != nil {
return err
}
if exists {
return nil
}
return doInsideTransaction(bs.conn, func(tx querier) error {
err := tx.QueryRow(`insert into pgstore_blobs(blobid, data) values ($1, $2) returning id`, out.Bytes(), data).Scan(&id)
if err != nil {
return err
}
_, err = tx.Exec(`insert into pgstore_blobs_ref(id, blobid, delta) values ($1, $2, $3)`, id, out.Bytes(), 0)
if err != nil {
return err
}
return err
})
}
func (bs *BlobStore) UpdateRefCount(k pandora.Key, delta int) error {
var err error
var id int64
exists, err := bs.keyExistsInDb(&id, k)
if !exists {
return ErrKeyNotFound
}
_, err = bs.conn.Exec(`insert into pgstore_blobs_ref(id, blobid, delta) values ($1, $2, $3)`, id, k.Bytes(), delta)
return err
}
// GetData read the contents stored under the k key
func (bs *BlobStore) GetData(out []byte, k pandora.Key) ([]byte, error) {
var id int64
var size int
var err error
exists, err := bs.keyExistsInDb(&id, k)
if !exists {
return nil, ErrKeyNotFound
}
err = bs.conn.QueryRow(`select bs.id, octet_length(bs.data) from pgstore_blobs bs where bs.blobid = $1`, k.Bytes()).Scan(&id, &size)
if err != nil {
return nil, err
}
out = sliceOfSize(out, size)
err = bs.conn.QueryRow(`select bs.data from pgstore_blobs bs where bs.id = $1`, id).Scan(&out)
return out, err
}