Update server dependencies

Godeps/_workspace/src/github.com/boltdb/bolt/tx.go

@@ -29,6 +29,14 @@ type Tx struct {
 	pages          map[pgid]*page
 	stats          TxStats
 	commitHandlers []func()
+
+	// WriteFlag specifies the flag for write-related methods like WriteTo().
+	// Tx opens the database file with the specified flag to copy the data.
+	//
+	// By default, the flag is unset, which works well for mostly in-memory
+	// workloads. For databases that are much larger than available RAM,
+	// set the flag to syscall.O_DIRECT to avoid trashing the page cache.
+	WriteFlag int
 }
 
 // init initializes the transaction.
@@ -87,18 +95,21 @@ func (tx *Tx) Stats() TxStats {
 
 // Bucket retrieves a bucket by name.
 // Returns nil if the bucket does not exist.
+// The bucket instance is only valid for the lifetime of the transaction.
 func (tx *Tx) Bucket(name []byte) *Bucket {
 	return tx.root.Bucket(name)
 }
 
 // CreateBucket creates a new bucket.
 // Returns an error if the bucket already exists, if the bucket name is blank, or if the bucket name is too long.
+// The bucket instance is only valid for the lifetime of the transaction.
 func (tx *Tx) CreateBucket(name []byte) (*Bucket, error) {
 	return tx.root.CreateBucket(name)
 }
 
 // CreateBucketIfNotExists creates a new bucket if it doesn't already exist.
 // Returns an error if the bucket name is blank, or if the bucket name is too long.
+// The bucket instance is only valid for the lifetime of the transaction.
 func (tx *Tx) CreateBucketIfNotExists(name []byte) (*Bucket, error) {
 	return tx.root.CreateBucketIfNotExists(name)
 }
@@ -127,7 +138,8 @@ func (tx *Tx) OnCommit(fn func()) {
 }
 
 // Commit writes all changes to disk and updates the meta page.
-// Returns an error if a disk write error occurs.
+// Returns an error if a disk write error occurs, or if Commit is
+// called on a read-only transaction.
 func (tx *Tx) Commit() error {
 	_assert(!tx.managed, "managed tx commit not allowed")
 	if tx.db == nil {
@@ -156,6 +168,8 @@ func (tx *Tx) Commit() error {
 	// Free the old root bucket.
 	tx.meta.root.root = tx.root.root
 
+	opgid := tx.meta.pgid
+
 	// Free the freelist and allocate new pages for it. This will overestimate
 	// the size of the freelist but not underestimate the size (which would be bad).
 	tx.db.freelist.free(tx.meta.txid, tx.db.page(tx.meta.freelist))
@@ -170,6 +184,14 @@ func (tx *Tx) Commit() error {
 	}
 	tx.meta.freelist = p.id
 
+	// If the high water mark has moved up then attempt to grow the database.
+	if tx.meta.pgid > opgid {
+		if err := tx.db.grow(int(tx.meta.pgid+1) * tx.db.pageSize); err != nil {
+			tx.rollback()
+			return err
+		}
+	}
+
 	// Write dirty pages to disk.
 	startTime = time.Now()
 	if err := tx.write(); err != nil {
@@ -203,7 +225,8 @@ func (tx *Tx) Commit() error {
 	return nil
 }
 
-// Rollback closes the transaction and ignores all previous updates.
+// Rollback closes the transaction and ignores all previous updates. Read-only
+// transactions must be rolled back and not committed.
 func (tx *Tx) Rollback() error {
 	_assert(!tx.managed, "managed tx rollback not allowed")
 	if tx.db == nil {
@@ -234,7 +257,8 @@ func (tx *Tx) close() {
 		var freelistPendingN = tx.db.freelist.pending_count()
 		var freelistAlloc = tx.db.freelist.size()
 
-		// Remove writer lock.
+		// Remove transaction ref & writer lock.
+		tx.db.rwtx = nil
 		tx.db.rwlock.Unlock()
 
 		// Merge statistics.
@@ -248,41 +272,47 @@ func (tx *Tx) close() {
 	} else {
 		tx.db.removeTx(tx)
 	}
+
+	// Clear all references.
 	tx.db = nil
+	tx.meta = nil
+	tx.root = Bucket{tx: tx}
+	tx.pages = nil
 }
 
 // Copy writes the entire database to a writer.
-// A reader transaction is maintained during the copy so it is safe to continue
-// using the database while a copy is in progress.
-// Copy will write exactly tx.Size() bytes into the writer.
+// This function exists for backwards compatibility. Use WriteTo() instead.
 func (tx *Tx) Copy(w io.Writer) error {
-	var f *os.File
-	var err error
+	_, err := tx.WriteTo(w)
+	return err
+}
 
-	// Attempt to open reader directly.
-	if f, err = os.OpenFile(tx.db.path, os.O_RDONLY|odirect, 0); err != nil {
-		// Fallback to a regular open if that doesn't work.
-		if f, err = os.OpenFile(tx.db.path, os.O_RDONLY, 0); err != nil {
-			return err
-		}
+// WriteTo writes the entire database to a writer.
+// If err == nil then exactly tx.Size() bytes will be written into the writer.
+func (tx *Tx) WriteTo(w io.Writer) (n int64, err error) {
+	// Attempt to open reader with WriteFlag
+	f, err := os.OpenFile(tx.db.path, os.O_RDONLY|tx.WriteFlag, 0)
+	if err != nil {
+		return 0, err
 	}
+	defer func() { _ = f.Close() }()
 
 	// Copy the meta pages.
 	tx.db.metalock.Lock()
-	_, err = io.CopyN(w, f, int64(tx.db.pageSize*2))
+	n, err = io.CopyN(w, f, int64(tx.db.pageSize*2))
 	tx.db.metalock.Unlock()
 	if err != nil {
-		_ = f.Close()
-		return fmt.Errorf("meta copy: %s", err)
+		return n, fmt.Errorf("meta copy: %s", err)
 	}
 
 	// Copy data pages.
-	if _, err := io.CopyN(w, f, tx.Size()-int64(tx.db.pageSize*2)); err != nil {
-		_ = f.Close()
-		return err
+	wn, err := io.CopyN(w, f, tx.Size()-int64(tx.db.pageSize*2))
+	n += wn
+	if err != nil {
+		return n, err
 	}
 
-	return f.Close()
+	return n, f.Close()
 }
 
 // CopyFile copies the entire database to file at the given path.
@@ -416,15 +446,39 @@ func (tx *Tx) write() error {
 	// Write pages to disk in order.
 	for _, p := range pages {
 		size := (int(p.overflow) + 1) * tx.db.pageSize
-		buf := (*[maxAllocSize]byte)(unsafe.Pointer(p))[:size]
 		offset := int64(p.id) * int64(tx.db.pageSize)
-		if _, err := tx.db.ops.writeAt(buf, offset); err != nil {
-			return err
-		}
 
-		// Update statistics.
-		tx.stats.Write++
+		// Write out page in "max allocation" sized chunks.
+		ptr := (*[maxAllocSize]byte)(unsafe.Pointer(p))
+		for {
+			// Limit our write to our max allocation size.
+			sz := size
+			if sz > maxAllocSize-1 {
+				sz = maxAllocSize - 1
+			}
+
+			// Write chunk to disk.
+			buf := ptr[:sz]
+			if _, err := tx.db.ops.writeAt(buf, offset); err != nil {
+				return err
+			}
+
+			// Update statistics.
+			tx.stats.Write++
+
+			// Exit inner for loop if we've written all the chunks.
+			size -= sz
+			if size == 0 {
+				break
+			}
+
+			// Otherwise move offset forward and move pointer to next chunk.
+			offset += int64(sz)
+			ptr = (*[maxAllocSize]byte)(unsafe.Pointer(&ptr[sz]))
+		}
 	}
+
+	// Ignore file sync if flag is set on DB.
 	if !tx.db.NoSync || IgnoreNoSync {
 		if err := fdatasync(tx.db); err != nil {
 			return err
@@ -461,7 +515,7 @@ func (tx *Tx) writeMeta() error {
 }
 
 // page returns a reference to the page with a given id.
-// If page has been written to then a temporary bufferred page is returned.
+// If page has been written to then a temporary buffered page is returned.
 func (tx *Tx) page(id pgid) *page {
 	// Check the dirty pages first.
 	if tx.pages != nil {