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59 lines
1.8 KiB
59 lines
1.8 KiB
package pgsql
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import (
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"database/sql"
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cerrors "github.com/coreos/clair/utils/errors"
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)
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// InsertKeyValue stores (or updates) a single key / value tuple.
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func (pgSQL *pgSQL) InsertKeyValue(key, value string) (err error) {
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if key == "" || value == "" {
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log.Warning("could not insert a flag which has an empty name or value")
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return cerrors.NewBadRequestError("could not insert a flag which has an empty name or value")
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}
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// Upsert.
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//
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// Note: UPSERT works only on >= PostgreSQL 9.5 which is not yet supported by AWS RDS.
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// The best solution is currently the use of http://dba.stackexchange.com/a/13477
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// but the key/value storage doesn't need to be super-efficient and super-safe at the
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// moment so we can just use a client-side solution with transactions, based on
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// http://postgresql.org/docs/current/static/plpgsql-control-structures.html.
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// TODO(Quentin-M): Enable Upsert as soon as 9.5 is stable.
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for {
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// First, try to update.
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r, err := pgSQL.Exec(getQuery("u_keyvalue"), value, key)
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if err != nil {
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return err
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}
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if n, _ := r.RowsAffected(); n > 0 {
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// Updated successfully.
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return nil
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}
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// Try to insert the key.
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// If someone else inserts the same key concurrently, we could get a unique-key violation error.
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_, err = pgSQL.Exec(getQuery("i_keyvalue"), key, value)
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if err != nil {
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if isErrUniqueViolation(err) {
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// Got unique constraint violation, retry.
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continue
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}
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return err
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}
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return nil
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}
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}
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// GetValue reads a single key / value tuple and returns an empty string if the key doesn't exist.
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func (pgSQL *pgSQL) GetKeyValue(key string) (value string, err error) {
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err = pgSQL.QueryRow(getQuery("s_keyvalue"), key).Scan(&value)
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if err == sql.ErrNoRows {
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return "", nil
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}
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return
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}
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