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package mongodump
import (
"fmt"
"io"
"github.com/mongodb/mongo-tools/common/bsonutil"
"github.com/mongodb/mongo-tools/common/db"
"github.com/mongodb/mongo-tools/common/intents"
"github.com/mongodb/mongo-tools/common/json"
"github.com/mongodb/mongo-tools/common/log"
"gopkg.in/mgo.v2/bson"
)
// Metadata holds information about a collection's options and indexes.
type Metadata struct {
Options interface{} `json:"options,omitempty"`
Indexes []interface{} `json:"indexes"`
}
// IndexDocumentFromDB is used internally to preserve key ordering.
type IndexDocumentFromDB struct {
Options bson.M `bson:",inline"`
Key bson.D `bson:"key"`
}
// dumpMetadata gets the metadata for a collection and writes it
// in readable JSON format.
func (dump *MongoDump) dumpMetadata(intent *intents.Intent, buffer resettableOutputBuffer) (err error) {
meta := Metadata{
// We have to initialize Indexes to an empty slice, not nil, so that an empty
// array is marshalled into json instead of null. That is, {indexes:[]} is okay
// but {indexes:null} will cause assertions in our legacy C++ mongotools
Indexes: []interface{}{},
}
// The collection options were already gathered while building the list of intents.
// We convert them to JSON so that they can be written to the metadata json file as text.
if intent.Options != nil {
if meta.Options, err = bsonutil.ConvertBSONValueToJSON(*intent.Options); err != nil {
return fmt.Errorf("error converting collection options to JSON: %v", err)
}
} else {
meta.Options = nil
}
// Second, we read the collection's index information by either calling
// listIndexes (pre-2.7 systems) or querying system.indexes.
// We keep a running list of all the indexes
// for the current collection as we iterate over the cursor, and include
// that list as the "indexes" field of the metadata document.
log.Logvf(log.DebugHigh, "\treading indexes for `%v`", intent.Namespace())
session, err := dump.SessionProvider.GetSession()
if err != nil {
return err
}
defer session.Close()
if intent.IsView() {
log.Logvf(log.DebugLow, "not dumping indexes metadata for '%v' because it is a view", intent.Namespace())
} else {
// get the indexes
indexesIter, err := db.GetIndexes(session.DB(intent.DB).C(intent.C))
if err != nil {
return err
}
if indexesIter == nil {
log.Logvf(log.Always, "the collection %v appears to have been dropped after the dump started", intent.Namespace())
return nil
}
indexOpts := &bson.D{}
for indexesIter.Next(indexOpts) {
convertedIndex, err := bsonutil.ConvertBSONValueToJSON(*indexOpts)
if err != nil {
return fmt.Errorf("error converting index (%#v): %v", convertedIndex, err)
}
meta.Indexes = append(meta.Indexes, convertedIndex)
}
if err := indexesIter.Err(); err != nil {
return fmt.Errorf("error getting indexes for collection `%v`: %v", intent.Namespace(), err)
}
}
// Finally, we send the results to the writer as JSON bytes
jsonBytes, err := json.Marshal(meta)
if err != nil {
return fmt.Errorf("error marshalling metadata json for collection `%v`: %v", intent.Namespace(), err)
}
err = intent.MetadataFile.Open()
if err != nil {
return err
}
defer func() {
closeErr := intent.MetadataFile.Close()
if err == nil && closeErr != nil {
err = fmt.Errorf("error writing metadata for collection `%v` to disk: %v", intent.Namespace(), closeErr)
}
}()
var f io.Writer
f = intent.MetadataFile
if buffer != nil {
buffer.Reset(f)
f = buffer
defer func() {
closeErr := buffer.Close()
if err == nil && closeErr != nil {
err = fmt.Errorf("error writing metadata for collection `%v` to disk: %v", intent.Namespace(), closeErr)
}
}()
}
_, err = f.Write(jsonBytes)
if err != nil {
err = fmt.Errorf("error writing metadata for collection `%v` to disk: %v", intent.Namespace(), err)
}
return
}
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