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Diffstat (limited to 'vendor/github.com/couchbase/vellum/vellum.go')
-rw-r--r-- | vendor/github.com/couchbase/vellum/vellum.go | 111 |
1 files changed, 111 insertions, 0 deletions
diff --git a/vendor/github.com/couchbase/vellum/vellum.go b/vendor/github.com/couchbase/vellum/vellum.go new file mode 100644 index 0000000000..b2537b3f00 --- /dev/null +++ b/vendor/github.com/couchbase/vellum/vellum.go @@ -0,0 +1,111 @@ +// Copyright (c) 2017 Couchbase, Inc. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +/* +Package vellum is a library for building, serializing and executing an FST (finite +state transducer). + +There are two distinct phases, building an FST and using it. + +When building an FST, you insert keys ([]byte) and their associated value +(uint64). Insert operations MUST be done in lexicographic order. While +building the FST, data is streamed to an underlying Writer. At the conclusion +of building, you MUST call Close() on the builder. + +After completion of the build phase, you can either Open() the FST if you +serialized it to disk. Alternatively, if you already have the bytes in +memory, you can use Load(). By default, Open() will use mmap to avoid loading +the entire file into memory. + +Once the FST is ready, you can use the Contains() method to see if a keys is +in the FST. You can use the Get() method to see if a key is in the FST and +retrieve it's associated value. And, you can use the Iterator method to +enumerate key/value pairs within a specified range. + +*/ +package vellum + +import ( + "errors" + "io" +) + +// ErrOutOfOrder is returned when values are not inserted in +// lexicographic order. +var ErrOutOfOrder = errors.New("values not inserted in lexicographic order") + +// ErrIteratorDone is returned by Iterator/Next/Seek methods when the +// Current() value pointed to by the iterator is greater than the last +// key in this FST, or outside the configured startKeyInclusive/endKeyExclusive +// range of the Iterator. +var ErrIteratorDone = errors.New("iterator-done") + +// BuilderOpts is a structure to let advanced users customize the behavior +// of the builder and some aspects of the generated FST. +type BuilderOpts struct { + Encoder int + RegistryTableSize int + RegistryMRUSize int +} + +// New returns a new Builder which will stream out the +// underlying representation to the provided Writer as the set is built. +func New(w io.Writer, opts *BuilderOpts) (*Builder, error) { + return newBuilder(w, opts) +} + +// Open loads the FST stored in the provided path +func Open(path string) (*FST, error) { + return open(path) +} + +// Load will return the FST represented by the provided byte slice. +func Load(data []byte) (*FST, error) { + return new(data, nil) +} + +// Merge will iterate through the provided Iterators, merge duplicate keys +// with the provided MergeFunc, and build a new FST to the provided Writer. +func Merge(w io.Writer, opts *BuilderOpts, itrs []Iterator, f MergeFunc) error { + builder, err := New(w, opts) + if err != nil { + return err + } + + itr, err := NewMergeIterator(itrs, f) + for err == nil { + k, v := itr.Current() + err = builder.Insert(k, v) + if err != nil { + return err + } + err = itr.Next() + } + + if err != nil && err != ErrIteratorDone { + return err + } + + err = itr.Close() + if err != nil { + return err + } + + err = builder.Close() + if err != nil { + return err + } + + return nil +} |