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73f6dc4d44
Previously, it would return an error instead. Now we can distinguish the cases 'error while deleting known key' vs. 'key not in index' without testing for leveldb-internal kinds of errors.
62 lines
2.5 KiB
Go
62 lines
2.5 KiB
Go
// Copyright 2014 The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package index
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import "encoding"
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// KeyValueStore persists key/value pairs. Implementations must be fundamentally
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// goroutine-safe. However, it is the caller's responsibility that keys and
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// values can be safely marshaled and unmarshaled (via the MarshalBinary and
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// UnmarshalBinary methods of the keys and values). For example, if you call the
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// Put method of a KeyValueStore implementation, but the key or the value are
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// modified concurrently while being marshaled into its binary representation,
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// you obviously have a problem. Methods of KeyValueStore return only after
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// (un)marshaling is complete.
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type KeyValueStore interface {
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Put(key, value encoding.BinaryMarshaler) error
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// Get unmarshals the result into value. It returns false if no entry
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// could be found for key. If value is nil, Get behaves like Has.
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Get(key encoding.BinaryMarshaler, value encoding.BinaryUnmarshaler) (bool, error)
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Has(key encoding.BinaryMarshaler) (bool, error)
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// Delete returns (false, nil) if key does not exist.
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Delete(key encoding.BinaryMarshaler) (bool, error)
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NewBatch() Batch
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Commit(b Batch) error
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// ForEach iterates through the complete KeyValueStore and calls the
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// supplied function for each mapping.
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ForEach(func(kv KeyValueAccessor) error) error
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Close() error
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}
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// KeyValueAccessor allows access to the key and value of an entry in a
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// KeyValueStore.
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type KeyValueAccessor interface {
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Key(encoding.BinaryUnmarshaler) error
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Value(encoding.BinaryUnmarshaler) error
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}
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// Batch allows KeyValueStore mutations to be pooled and committed together. An
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// implementation does not have to be goroutine-safe. Never modify a Batch
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// concurrently or commit the same batch multiple times concurrently. Marshaling
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// of keys and values is guaranteed to be complete when the Put or Delete methods
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// have returned.
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type Batch interface {
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Put(key, value encoding.BinaryMarshaler) error
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Delete(key encoding.BinaryMarshaler) error
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Reset()
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}
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