// Create creates a new file with the provided name in the GridFS. If the file
// name already exists, a new version will be inserted with an up-to-date
// uploadDate that will cause it to be atomically visible to the Open and
// OpenId methods. If the file name is not important, an empty name may be
// provided and the file Id used instead.
//
// It's important to Close files whether they are being written to
// or read from, and to check the err result to ensure the operation
// completed successfully.
//
// A simple example inserting a new file:
//
// func check(err os.Error) {
// if err != nil {
// panic(err.String())
// }
// }
// file, err := db.GridFS("fs").Create("myfile.txt")
// check(err)
// n, err := file.Write([]byte("Hello world!")
// check(err)
// err = file.Close()
// check(err)
// fmt.Printf("%d bytes written\n", n)
//
// The io.Writer interface is implemented by *GridFile and may be used to
// help on the file creation. For example:
//
// file, err := db.GridFS("fs").Create("myfile.txt")
// check(err)
// messages, err := os.Open("/var/log/messages")
// check(err)
// defer messages.Close()
// err = io.Copy(file, messages)
// check(err)
// err = file.Close()
// check(err)
//
func (gfs *GridFS) Create(name string) (file *GridFile, err error) {
file = gfs.newFile()
file.mode = gfsWriting
file.wsum = md5.New()
file.doc = gfsFile{Id: bson.NewObjectId(), ChunkSize: 256 * 1024, Filename: name}
return
}
func (file *GridFile) insertChunk(data []byte) {
n := file.chunk
file.chunk++
debugf("GridFile %p: adding to checksum: %q", file, string(data))
file.wsum.Write(data)
for file.doc.ChunkSize*file.wpending >= 1024*1024 {
// Hold on.. we got a MB pending.
file.c.Wait()
if file.err != nil {
return
}
}
file.wpending++
debugf("GridFile %p: inserting chunk %d with %d bytes", file, n, len(data))
// We may not own the memory of data, so rather than
// simply copying it, we'll marshal the document ahead of time.
data, err := bson.Marshal(gfsChunk{bson.NewObjectId(), file.doc.Id, n, data})
if err != nil {
file.err = err
return
}
go func() {
err := file.gfs.Chunks.Insert(bson.Raw{Data: data})
file.m.Lock()
file.wpending--
if err != nil && file.err == nil {
file.err = err
}
file.c.Broadcast()
file.m.Unlock()
}()
}