func TestStorage(t *testing.T, ctx context.Context, storage Storage)
TestStorage tests a Storage implementation.
Mem is an in-memory implementation of Storage. It is meant for tests and does not store any data to persistent storage.
The zero value is an empty Mem ready for use.
type Mem struct {
// contains filtered or unexported fields
}
func (m *Mem) ReadOnly(ctx context.Context, f func(context.Context, Transaction) error) error
ReadOnly runs f in a read-only transaction.
func (m *Mem) ReadWrite(ctx context.Context, f func(context.Context, Transaction) error) error
ReadWrite runs f in a read-write transaction.
A Storage is a transaction key-value storage system.
type Storage interface {
// ReadOnly runs f in a read-only transaction.
// It is equivalent to ReadWrite except that the
// transaction's BufferWrite method will fail unconditionally.
// (The implementation may be able to optimize the
// transaction if it knows at the start that no writes will happen.)
ReadOnly(ctx context.Context, f func(context.Context, Transaction) error) error
// ReadWrite runs f in a read-write transaction.
// If f returns an error, the transaction aborts and returns that error.
// If f returns nil, the transaction attempts to commit and then then return nil.
// Otherwise it tries again. Note that f may be called multiple times and that
// the result only describes the effect of the final call to f.
// The caller must take care not to use any state computed during
// earlier calls to f, or even the last call to f when an error is returned.
ReadWrite(ctx context.Context, f func(context.Context, Transaction) error) error
}
A Transaction provides read and write operations within a transaction, as executed by Storage's ReadOnly or ReadWrite methods.
type Transaction interface {
// ReadValue reads the value associated with a single key.
// If there is no value associated with that key, ReadKey returns an empty value.
// An error is only returned for problems accessing the storage.
ReadValue(ctx context.Context, key string) (value string, err error)
// ReadValues reads the values associated with the given keys.
// If there is no value stored for a given key, ReadValues returns an empty value for that key.
// An error is only returned for problems accessing the storage.
ReadValues(ctx context.Context, keys []string) (values []string, err error)
// BufferWrites buffers the given writes,
// to be applied at the end of the transaction.
// BufferWrites panics if this is a ReadOnly transaction.
// It returns an error if it detects any other problems.
// The behavior of multiple writes buffered using the same key
// is undefined: it may return an error or not.
BufferWrites(writes []Write) error
}
A Write is a single change to be applied at the end of a read-write transaction. A Write with an empty value deletes the value associated with the given key.
type Write struct {
Key string
Value string
}