add the bleve check tool

bleve check was a consistency checking tool originally developed
as a part of cbft.  currently it checks that the term dictionary
counts match the number of postings for the term.  in the future
additional checks could be added.  this tool has been back
ported to bleve as we've now adopted a single common tool for
both cbft and bleve.

cmd/bleve/cmd/check.go

@@ -0,0 +1,131 @@
+// Copyright © 2016 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 cmd
+
+import (
+	"fmt"
+	"log"
+
+	"github.com/blevesearch/bleve"
+	"github.com/spf13/cobra"
+)
+
+var checkFieldName string
+var checkCount int
+
+// checkCmd represents the check command
+var checkCmd = &cobra.Command{
+	Use:   "check [index path]",
+	Short: "checks the contents of the index",
+	Long:  `The check command will perform consistency checks on the index.`,
+	RunE: func(cmd *cobra.Command, args []string) error {
+
+		var fieldNames []string
+		var err error
+		if checkFieldName == "" {
+			fieldNames, err = idx.Fields()
+			if err != nil {
+				return err
+			}
+		} else {
+			fieldNames = []string{checkFieldName}
+		}
+		fmt.Printf("checking fields: %v\n", fieldNames)
+
+		totalProblems := 0
+		for _, fieldName := range fieldNames {
+			fmt.Printf("checking field: '%s'\n", fieldName)
+			problems, err := checkField(idx, fieldName)
+			if err != nil {
+				log.Fatal(err)
+			}
+			totalProblems += problems
+		}
+
+		if totalProblems != 0 {
+			return fmt.Errorf("found %d total problems\n", totalProblems)
+		}
+
+		return nil
+	},
+}
+
+func checkField(index bleve.Index, fieldName string) (int, error) {
+	termDictionary, err := getDictionary(index, fieldName)
+	if err != nil {
+		return 0, err
+	}
+	fmt.Printf("field contains %d terms\n", len(termDictionary))
+
+	numTested := 0
+	numProblems := 0
+	for term, count := range termDictionary {
+		fmt.Printf("checked %d terms\r", numTested)
+		if checkCount > 0 && numTested >= checkCount {
+			break
+		}
+
+		tq := bleve.NewTermQuery(term)
+		tq.SetField(fieldName)
+		req := bleve.NewSearchRequest(tq)
+		req.Size = 0
+		res, err := index.Search(req)
+		if err != nil {
+			return 0, err
+		}
+
+		if res.Total != count {
+			fmt.Printf("unexpected mismatch for term '%s', dictionary %d, search hits %d\n", term, count, res.Total)
+			numProblems++
+		}
+
+		numTested++
+	}
+	fmt.Printf("done checking %d terms, found %d problems\n", numTested, numProblems)
+
+	return numProblems, nil
+}
+
+func getDictionary(index bleve.Index, field string) (map[string]uint64, error) {
+	rv := make(map[string]uint64)
+	i, _, err := index.Advanced()
+	if err != nil {
+		log.Fatal(err)
+	}
+	r, err := i.Reader()
+	if err != nil {
+		log.Fatal(err)
+	}
+	d, err := r.FieldDict(field)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	de, err := d.Next()
+	for err == nil && de != nil {
+		rv[de.Term] = de.Count
+		de, err = d.Next()
+	}
+	if err != nil {
+		return nil, err
+	}
+	return rv, nil
+}
+
+func init() {
+	RootCmd.AddCommand(checkCmd)
+	checkCmd.Flags().StringVarP(&checkFieldName, "field", "f", "", "Restrict check to the specified field name, by default check all fields.")
+	checkCmd.Flags().IntVarP(&checkCount, "count", "c", 100, "Check this many terms, default 100.")
+}