762 lines
21 KiB
Go
762 lines
21 KiB
Go
// mgo - MongoDB driver for Go
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//
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// Copyright (c) 2010-2012 - Gustavo Niemeyer <gustavo@niemeyer.net>
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//
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are met:
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//
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// 1. Redistributions of source code must retain the above copyright notice, this
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// list of conditions and the following disclaimer.
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// 2. Redistributions in binary form must reproduce the above copyright notice,
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// this list of conditions and the following disclaimer in the documentation
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// and/or other materials provided with the distribution.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
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// ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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package mgo
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import (
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"crypto/md5"
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"encoding/hex"
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"errors"
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"hash"
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"io"
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"os"
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"sync"
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"time"
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"gopkg.in/mgo.v2/bson"
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)
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type GridFS struct {
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Files *Collection
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Chunks *Collection
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}
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type gfsFileMode int
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const (
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gfsClosed gfsFileMode = 0
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gfsReading gfsFileMode = 1
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gfsWriting gfsFileMode = 2
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)
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type GridFile struct {
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m sync.Mutex
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c sync.Cond
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gfs *GridFS
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mode gfsFileMode
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err error
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chunk int
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offset int64
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wpending int
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wbuf []byte
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wsum hash.Hash
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rbuf []byte
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rcache *gfsCachedChunk
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doc gfsFile
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}
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type gfsFile struct {
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Id interface{} "_id"
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ChunkSize int "chunkSize"
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UploadDate time.Time "uploadDate"
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Length int64 ",minsize"
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MD5 string
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Filename string ",omitempty"
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ContentType string "contentType,omitempty"
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Metadata *bson.Raw ",omitempty"
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}
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type gfsChunk struct {
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Id interface{} "_id"
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FilesId interface{} "files_id"
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N int
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Data []byte
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}
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type gfsCachedChunk struct {
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wait sync.Mutex
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n int
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data []byte
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err error
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}
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func newGridFS(db *Database, prefix string) *GridFS {
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return &GridFS{db.C(prefix + ".files"), db.C(prefix + ".chunks")}
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}
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func (gfs *GridFS) newFile() *GridFile {
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file := &GridFile{gfs: gfs}
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file.c.L = &file.m
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//runtime.SetFinalizer(file, finalizeFile)
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return file
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}
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func finalizeFile(file *GridFile) {
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file.Close()
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}
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// Create creates a new file with the provided name in the GridFS. If the file
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// name already exists, a new version will be inserted with an up-to-date
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// uploadDate that will cause it to be atomically visible to the Open and
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// OpenId methods. If the file name is not important, an empty name may be
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// provided and the file Id used instead.
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//
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// It's important to Close files whether they are being written to
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// or read from, and to check the err result to ensure the operation
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// completed successfully.
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//
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// A simple example inserting a new file:
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//
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// func check(err error) {
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// if err != nil {
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// panic(err.String())
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// }
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// }
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// file, err := db.GridFS("fs").Create("myfile.txt")
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// check(err)
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// n, err := file.Write([]byte("Hello world!"))
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// check(err)
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// err = file.Close()
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// check(err)
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// fmt.Printf("%d bytes written\n", n)
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//
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// The io.Writer interface is implemented by *GridFile and may be used to
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// help on the file creation. For example:
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//
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// file, err := db.GridFS("fs").Create("myfile.txt")
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// check(err)
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// messages, err := os.Open("/var/log/messages")
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// check(err)
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// defer messages.Close()
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// err = io.Copy(file, messages)
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// check(err)
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// err = file.Close()
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// check(err)
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//
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func (gfs *GridFS) Create(name string) (file *GridFile, err error) {
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file = gfs.newFile()
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file.mode = gfsWriting
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file.wsum = md5.New()
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file.doc = gfsFile{Id: bson.NewObjectId(), ChunkSize: 255 * 1024, Filename: name}
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return
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}
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// OpenId returns the file with the provided id, for reading.
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// If the file isn't found, err will be set to mgo.ErrNotFound.
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//
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// It's important to Close files whether they are being written to
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// or read from, and to check the err result to ensure the operation
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// completed successfully.
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//
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// The following example will print the first 8192 bytes from the file:
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//
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// func check(err error) {
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// if err != nil {
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// panic(err.String())
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// }
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// }
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// file, err := db.GridFS("fs").OpenId(objid)
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// check(err)
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// b := make([]byte, 8192)
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// n, err := file.Read(b)
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// check(err)
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// fmt.Println(string(b))
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// check(err)
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// err = file.Close()
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// check(err)
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// fmt.Printf("%d bytes read\n", n)
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//
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// The io.Reader interface is implemented by *GridFile and may be used to
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// deal with it. As an example, the following snippet will dump the whole
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// file into the standard output:
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//
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// file, err := db.GridFS("fs").OpenId(objid)
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// check(err)
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// err = io.Copy(os.Stdout, file)
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// check(err)
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// err = file.Close()
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// check(err)
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//
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func (gfs *GridFS) OpenId(id interface{}) (file *GridFile, err error) {
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var doc gfsFile
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err = gfs.Files.Find(bson.M{"_id": id}).One(&doc)
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if err != nil {
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return
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}
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file = gfs.newFile()
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file.mode = gfsReading
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file.doc = doc
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return
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}
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// Open returns the most recently uploaded file with the provided
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// name, for reading. If the file isn't found, err will be set
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// to mgo.ErrNotFound.
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//
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// It's important to Close files whether they are being written to
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// or read from, and to check the err result to ensure the operation
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// completed successfully.
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//
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// The following example will print the first 8192 bytes from the file:
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//
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// file, err := db.GridFS("fs").Open("myfile.txt")
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// check(err)
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// b := make([]byte, 8192)
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// n, err := file.Read(b)
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// check(err)
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// fmt.Println(string(b))
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// check(err)
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// err = file.Close()
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// check(err)
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// fmt.Printf("%d bytes read\n", n)
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//
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// The io.Reader interface is implemented by *GridFile and may be used to
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// deal with it. As an example, the following snippet will dump the whole
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// file into the standard output:
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//
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// file, err := db.GridFS("fs").Open("myfile.txt")
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// check(err)
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// err = io.Copy(os.Stdout, file)
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// check(err)
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// err = file.Close()
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// check(err)
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//
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func (gfs *GridFS) Open(name string) (file *GridFile, err error) {
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var doc gfsFile
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err = gfs.Files.Find(bson.M{"filename": name}).Sort("-uploadDate").One(&doc)
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if err != nil {
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return
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}
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file = gfs.newFile()
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file.mode = gfsReading
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file.doc = doc
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return
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}
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// OpenNext opens the next file from iter for reading, sets *file to it,
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// and returns true on the success case. If no more documents are available
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// on iter or an error occurred, *file is set to nil and the result is false.
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// Errors will be available via iter.Err().
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//
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// The iter parameter must be an iterator on the GridFS files collection.
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// Using the GridFS.Find method is an easy way to obtain such an iterator,
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// but any iterator on the collection will work.
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//
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// If the provided *file is non-nil, OpenNext will close it before attempting
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// to iterate to the next element. This means that in a loop one only
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// has to worry about closing files when breaking out of the loop early
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// (break, return, or panic).
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//
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// For example:
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//
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// gfs := db.GridFS("fs")
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// query := gfs.Find(nil).Sort("filename")
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// iter := query.Iter()
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// var f *mgo.GridFile
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// for gfs.OpenNext(iter, &f) {
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// fmt.Printf("Filename: %s\n", f.Name())
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// }
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// if iter.Close() != nil {
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// panic(iter.Close())
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// }
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//
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func (gfs *GridFS) OpenNext(iter *Iter, file **GridFile) bool {
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if *file != nil {
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// Ignoring the error here shouldn't be a big deal
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// as we're reading the file and the loop iteration
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// for this file is finished.
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_ = (*file).Close()
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}
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var doc gfsFile
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if !iter.Next(&doc) {
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*file = nil
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return false
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}
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f := gfs.newFile()
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f.mode = gfsReading
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f.doc = doc
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*file = f
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return true
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}
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// Find runs query on GridFS's files collection and returns
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// the resulting Query.
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//
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// This logic:
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//
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// gfs := db.GridFS("fs")
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// iter := gfs.Find(nil).Iter()
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//
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// Is equivalent to:
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//
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// files := db.C("fs" + ".files")
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// iter := files.Find(nil).Iter()
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//
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func (gfs *GridFS) Find(query interface{}) *Query {
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return gfs.Files.Find(query)
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}
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// RemoveId deletes the file with the provided id from the GridFS.
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func (gfs *GridFS) RemoveId(id interface{}) error {
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err := gfs.Files.Remove(bson.M{"_id": id})
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if err != nil {
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return err
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}
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_, err = gfs.Chunks.RemoveAll(bson.D{{"files_id", id}})
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return err
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}
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type gfsDocId struct {
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Id interface{} "_id"
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}
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// Remove deletes all files with the provided name from the GridFS.
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func (gfs *GridFS) Remove(name string) (err error) {
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iter := gfs.Files.Find(bson.M{"filename": name}).Select(bson.M{"_id": 1}).Iter()
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var doc gfsDocId
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for iter.Next(&doc) {
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if e := gfs.RemoveId(doc.Id); e != nil {
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err = e
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}
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}
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if err == nil {
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err = iter.Close()
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}
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return err
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}
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func (file *GridFile) assertMode(mode gfsFileMode) {
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switch file.mode {
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case mode:
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return
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case gfsWriting:
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panic("GridFile is open for writing")
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case gfsReading:
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panic("GridFile is open for reading")
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case gfsClosed:
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panic("GridFile is closed")
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default:
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panic("internal error: missing GridFile mode")
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}
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}
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// SetChunkSize sets size of saved chunks. Once the file is written to, it
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// will be split in blocks of that size and each block saved into an
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// independent chunk document. The default chunk size is 255kb.
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//
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// It is a runtime error to call this function once the file has started
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// being written to.
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func (file *GridFile) SetChunkSize(bytes int) {
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file.assertMode(gfsWriting)
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debugf("GridFile %p: setting chunk size to %d", file, bytes)
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file.m.Lock()
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file.doc.ChunkSize = bytes
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file.m.Unlock()
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}
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// Id returns the current file Id.
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func (file *GridFile) Id() interface{} {
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return file.doc.Id
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}
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// SetId changes the current file Id.
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//
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// It is a runtime error to call this function once the file has started
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// being written to, or when the file is not open for writing.
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func (file *GridFile) SetId(id interface{}) {
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file.assertMode(gfsWriting)
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file.m.Lock()
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file.doc.Id = id
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file.m.Unlock()
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}
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// Name returns the optional file name. An empty string will be returned
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// in case it is unset.
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func (file *GridFile) Name() string {
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return file.doc.Filename
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}
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// SetName changes the optional file name. An empty string may be used to
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// unset it.
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//
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// It is a runtime error to call this function when the file is not open
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// for writing.
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func (file *GridFile) SetName(name string) {
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file.assertMode(gfsWriting)
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file.m.Lock()
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file.doc.Filename = name
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file.m.Unlock()
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}
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// ContentType returns the optional file content type. An empty string will be
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// returned in case it is unset.
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func (file *GridFile) ContentType() string {
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return file.doc.ContentType
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}
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// ContentType changes the optional file content type. An empty string may be
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// used to unset it.
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//
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// It is a runtime error to call this function when the file is not open
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// for writing.
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func (file *GridFile) SetContentType(ctype string) {
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file.assertMode(gfsWriting)
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file.m.Lock()
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file.doc.ContentType = ctype
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file.m.Unlock()
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}
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// GetMeta unmarshals the optional "metadata" field associated with the
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// file into the result parameter. The meaning of keys under that field
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// is user-defined. For example:
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//
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// result := struct{ INode int }{}
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// err = file.GetMeta(&result)
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// if err != nil {
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// panic(err.String())
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// }
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// fmt.Printf("inode: %d\n", result.INode)
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//
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func (file *GridFile) GetMeta(result interface{}) (err error) {
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file.m.Lock()
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if file.doc.Metadata != nil {
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err = bson.Unmarshal(file.doc.Metadata.Data, result)
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}
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file.m.Unlock()
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return
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}
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// SetMeta changes the optional "metadata" field associated with the
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// file. The meaning of keys under that field is user-defined.
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// For example:
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//
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// file.SetMeta(bson.M{"inode": inode})
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//
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// It is a runtime error to call this function when the file is not open
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// for writing.
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func (file *GridFile) SetMeta(metadata interface{}) {
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file.assertMode(gfsWriting)
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data, err := bson.Marshal(metadata)
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file.m.Lock()
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if err != nil && file.err == nil {
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file.err = err
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} else {
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file.doc.Metadata = &bson.Raw{Data: data}
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}
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file.m.Unlock()
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}
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// Size returns the file size in bytes.
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func (file *GridFile) Size() (bytes int64) {
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file.m.Lock()
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bytes = file.doc.Length
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file.m.Unlock()
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return
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}
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// MD5 returns the file MD5 as a hex-encoded string.
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func (file *GridFile) MD5() (md5 string) {
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return file.doc.MD5
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}
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// UploadDate returns the file upload time.
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func (file *GridFile) UploadDate() time.Time {
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return file.doc.UploadDate
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}
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// SetUploadDate changes the file upload time.
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//
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// It is a runtime error to call this function when the file is not open
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// for writing.
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func (file *GridFile) SetUploadDate(t time.Time) {
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file.assertMode(gfsWriting)
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file.m.Lock()
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file.doc.UploadDate = t
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file.m.Unlock()
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}
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// Close flushes any pending changes in case the file is being written
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// to, waits for any background operations to finish, and closes the file.
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//
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// It's important to Close files whether they are being written to
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// or read from, and to check the err result to ensure the operation
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// completed successfully.
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func (file *GridFile) Close() (err error) {
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file.m.Lock()
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defer file.m.Unlock()
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if file.mode == gfsWriting {
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if len(file.wbuf) > 0 && file.err == nil {
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file.insertChunk(file.wbuf)
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file.wbuf = file.wbuf[0:0]
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}
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file.completeWrite()
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} else if file.mode == gfsReading && file.rcache != nil {
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file.rcache.wait.Lock()
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file.rcache = nil
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}
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file.mode = gfsClosed
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debugf("GridFile %p: closed", file)
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return file.err
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}
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func (file *GridFile) completeWrite() {
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for file.wpending > 0 {
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debugf("GridFile %p: waiting for %d pending chunks to complete file write", file, file.wpending)
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file.c.Wait()
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}
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if file.err == nil {
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hexsum := hex.EncodeToString(file.wsum.Sum(nil))
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if file.doc.UploadDate.IsZero() {
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file.doc.UploadDate = bson.Now()
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}
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file.doc.MD5 = hexsum
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file.err = file.gfs.Files.Insert(file.doc)
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}
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if file.err != nil {
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file.gfs.Chunks.RemoveAll(bson.D{{"files_id", file.doc.Id}})
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}
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|
if file.err == nil {
|
|
index := Index{
|
|
Key: []string{"files_id", "n"},
|
|
Unique: true,
|
|
}
|
|
file.err = file.gfs.Chunks.EnsureIndex(index)
|
|
}
|
|
}
|
|
|
|
// Abort cancels an in-progress write, preventing the file from being
|
|
// automically created and ensuring previously written chunks are
|
|
// removed when the file is closed.
|
|
//
|
|
// It is a runtime error to call Abort when the file was not opened
|
|
// for writing.
|
|
func (file *GridFile) Abort() {
|
|
if file.mode != gfsWriting {
|
|
panic("file.Abort must be called on file opened for writing")
|
|
}
|
|
file.err = errors.New("write aborted")
|
|
}
|
|
|
|
// Write writes the provided data to the file and returns the
|
|
// number of bytes written and an error in case something
|
|
// wrong happened.
|
|
//
|
|
// The file will internally cache the data so that all but the last
|
|
// chunk sent to the database have the size defined by SetChunkSize.
|
|
// This also means that errors may be deferred until a future call
|
|
// to Write or Close.
|
|
//
|
|
// The parameters and behavior of this function turn the file
|
|
// into an io.Writer.
|
|
func (file *GridFile) Write(data []byte) (n int, err error) {
|
|
file.assertMode(gfsWriting)
|
|
file.m.Lock()
|
|
debugf("GridFile %p: writing %d bytes", file, len(data))
|
|
defer file.m.Unlock()
|
|
|
|
if file.err != nil {
|
|
return 0, file.err
|
|
}
|
|
|
|
n = len(data)
|
|
file.doc.Length += int64(n)
|
|
chunkSize := file.doc.ChunkSize
|
|
|
|
if len(file.wbuf)+len(data) < chunkSize {
|
|
file.wbuf = append(file.wbuf, data...)
|
|
return
|
|
}
|
|
|
|
// First, flush file.wbuf complementing with data.
|
|
if len(file.wbuf) > 0 {
|
|
missing := chunkSize - len(file.wbuf)
|
|
if missing > len(data) {
|
|
missing = len(data)
|
|
}
|
|
file.wbuf = append(file.wbuf, data[:missing]...)
|
|
data = data[missing:]
|
|
file.insertChunk(file.wbuf)
|
|
file.wbuf = file.wbuf[0:0]
|
|
}
|
|
|
|
// Then, flush all chunks from data without copying.
|
|
for len(data) > chunkSize {
|
|
size := chunkSize
|
|
if size > len(data) {
|
|
size = len(data)
|
|
}
|
|
file.insertChunk(data[:size])
|
|
data = data[size:]
|
|
}
|
|
|
|
// And append the rest for a future call.
|
|
file.wbuf = append(file.wbuf, data...)
|
|
|
|
return n, file.err
|
|
}
|
|
|
|
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()
|
|
}()
|
|
}
|
|
|
|
// Seek sets the offset for the next Read or Write on file to
|
|
// offset, interpreted according to whence: 0 means relative to
|
|
// the origin of the file, 1 means relative to the current offset,
|
|
// and 2 means relative to the end. It returns the new offset and
|
|
// an error, if any.
|
|
func (file *GridFile) Seek(offset int64, whence int) (pos int64, err error) {
|
|
file.m.Lock()
|
|
debugf("GridFile %p: seeking for %s (whence=%d)", file, offset, whence)
|
|
defer file.m.Unlock()
|
|
switch whence {
|
|
case os.SEEK_SET:
|
|
case os.SEEK_CUR:
|
|
offset += file.offset
|
|
case os.SEEK_END:
|
|
offset += file.doc.Length
|
|
default:
|
|
panic("unsupported whence value")
|
|
}
|
|
if offset > file.doc.Length {
|
|
return file.offset, errors.New("seek past end of file")
|
|
}
|
|
if offset == file.doc.Length {
|
|
// If we're seeking to the end of the file,
|
|
// no need to read anything. This enables
|
|
// a client to find the size of the file using only the
|
|
// io.ReadSeeker interface with low overhead.
|
|
file.offset = offset
|
|
return file.offset, nil
|
|
}
|
|
chunk := int(offset / int64(file.doc.ChunkSize))
|
|
if chunk+1 == file.chunk && offset >= file.offset {
|
|
file.rbuf = file.rbuf[int(offset-file.offset):]
|
|
file.offset = offset
|
|
return file.offset, nil
|
|
}
|
|
file.offset = offset
|
|
file.chunk = chunk
|
|
file.rbuf = nil
|
|
file.rbuf, err = file.getChunk()
|
|
if err == nil {
|
|
file.rbuf = file.rbuf[int(file.offset-int64(chunk)*int64(file.doc.ChunkSize)):]
|
|
}
|
|
return file.offset, err
|
|
}
|
|
|
|
// Read reads into b the next available data from the file and
|
|
// returns the number of bytes written and an error in case
|
|
// something wrong happened. At the end of the file, n will
|
|
// be zero and err will be set to io.EOF.
|
|
//
|
|
// The parameters and behavior of this function turn the file
|
|
// into an io.Reader.
|
|
func (file *GridFile) Read(b []byte) (n int, err error) {
|
|
file.assertMode(gfsReading)
|
|
file.m.Lock()
|
|
debugf("GridFile %p: reading at offset %d into buffer of length %d", file, file.offset, len(b))
|
|
defer file.m.Unlock()
|
|
if file.offset == file.doc.Length {
|
|
return 0, io.EOF
|
|
}
|
|
for err == nil {
|
|
i := copy(b, file.rbuf)
|
|
n += i
|
|
file.offset += int64(i)
|
|
file.rbuf = file.rbuf[i:]
|
|
if i == len(b) || file.offset == file.doc.Length {
|
|
break
|
|
}
|
|
b = b[i:]
|
|
file.rbuf, err = file.getChunk()
|
|
}
|
|
return n, err
|
|
}
|
|
|
|
func (file *GridFile) getChunk() (data []byte, err error) {
|
|
cache := file.rcache
|
|
file.rcache = nil
|
|
if cache != nil && cache.n == file.chunk {
|
|
debugf("GridFile %p: Getting chunk %d from cache", file, file.chunk)
|
|
cache.wait.Lock()
|
|
data, err = cache.data, cache.err
|
|
} else {
|
|
debugf("GridFile %p: Fetching chunk %d", file, file.chunk)
|
|
var doc gfsChunk
|
|
err = file.gfs.Chunks.Find(bson.D{{"files_id", file.doc.Id}, {"n", file.chunk}}).One(&doc)
|
|
data = doc.Data
|
|
}
|
|
file.chunk++
|
|
if int64(file.chunk)*int64(file.doc.ChunkSize) < file.doc.Length {
|
|
// Read the next one in background.
|
|
cache = &gfsCachedChunk{n: file.chunk}
|
|
cache.wait.Lock()
|
|
debugf("GridFile %p: Scheduling chunk %d for background caching", file, file.chunk)
|
|
// Clone the session to avoid having it closed in between.
|
|
chunks := file.gfs.Chunks
|
|
session := chunks.Database.Session.Clone()
|
|
go func(id interface{}, n int) {
|
|
defer session.Close()
|
|
chunks = chunks.With(session)
|
|
var doc gfsChunk
|
|
cache.err = chunks.Find(bson.D{{"files_id", id}, {"n", n}}).One(&doc)
|
|
cache.data = doc.Data
|
|
cache.wait.Unlock()
|
|
}(file.doc.Id, file.chunk)
|
|
file.rcache = cache
|
|
}
|
|
debugf("Returning err: %#v", err)
|
|
return
|
|
}
|