inspection.go

// Copyright (c) 2018 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

package fs

// Inspection contains the outcome of a filesystem inspection.
type Inspection struct {
	// SortedCommitLogFiles contains all commitlog filenames that existed
	// before the node began accepting writes.
	SortedCommitLogFiles []string
}

// CommitLogFilesSet generates a set of unique commitlog files.
func (f Inspection) CommitLogFilesSet() map[string]struct{} {
	set := make(map[string]struct{}, len(f.SortedCommitLogFiles))
	for _, file := range f.SortedCommitLogFiles {
		set[file] = struct{}{}
	}

	return set
}

// InspectFilesystem scans the filesystem and generates a Inspection
// which the commitlog bootstrapper needs to avoid reading commitlog files that
// were written *after* the process has already started. I.E in order to distinguish
// between files that were already on disk before the process started, and those that
// were written by the process itself once it started accepting writes (but before
// bootstrapping had complete) we export a function which can be called during node
// startup.
func InspectFilesystem(fsOpts Options) (Inspection, error) {
	path := CommitLogsDirPath(fsOpts.FilePathPrefix())
	files, err := SortedCommitLogFiles(path)
	if err != nil {
		return Inspection{}, err
	}

	return Inspection{
		SortedCommitLogFiles: files,
	}, nil
}