Merge pull request #191 from benbjohnson/win-ftw

Windows Support

Makefile

@@ -38,7 +38,7 @@ build: get
 	@mkdir -p bin
 	@go build -ldflags=$(GOLDFLAGS) -a -o bin/bolt ./cmd/bolt
 
-test: fmt errcheck
+test: fmt
 	@go get github.com/stretchr/testify/assert
 	@echo "=== TESTS ==="
 	@go test -v -cover -test.run=$(TEST)

bolt.go

@@ -1,13 +0,0 @@
-// +build !linux
-
-package bolt
-
-import (
-	"os"
-)
-
-var odirect int
-
-func fdatasync(f *os.File) error {
-	return f.Sync()
-}

bolt_386.go

@@ -0,0 +1,4 @@
+package bolt
+
+// maxMapSize represents the largest mmap size supported by Bolt.
+const maxMapSize = 0xFFFFFFF // 256MB

bolt_amd64.go

@@ -0,0 +1,4 @@
+package bolt
+
+// maxMapSize represents the largest mmap size supported by Bolt.
+const maxMapSize = 0xFFFFFFFFFFFF // 256TB

bolt_darwin.go

@@ -0,0 +1,53 @@
+package bolt
+
+import (
+	"os"
+	"syscall"
+	"unsafe"
+)
+
+var odirect int
+
+// fdatasync flushes written data to a file descriptor.
+func fdatasync(f *os.File) error {
+	return f.Sync()
+}
+
+// flock acquires an advisory lock on a file descriptor.
+func flock(f *os.File) error {
+	return syscall.Flock(int(f.Fd()), syscall.LOCK_EX)
+}
+
+// funlock releases an advisory lock on a file descriptor.
+func funlock(f *os.File) error {
+	return syscall.Flock(int(f.Fd()), syscall.LOCK_UN)
+}
+
+// mmap memory maps a DB's data file.
+func mmap(db *DB, sz int) error {
+	b, err := syscall.Mmap(int(db.file.Fd()), 0, sz, syscall.PROT_READ, syscall.MAP_SHARED)
+	if err != nil {
+		return err
+	}
+
+	// Save the original byte slice and convert to a byte array pointer.
+	db.dataref = b
+	db.data = (*[maxMapSize]byte)(unsafe.Pointer(&b[0]))
+	db.datasz = sz
+	return nil
+}
+
+// munmap unmaps a DB's data file from memory.
+func munmap(db *DB) error {
+	// Ignore the unmap if we have no mapped data.
+	if db.dataref == nil {
+		return nil
+	}
+
+	// Unmap using the original byte slice.
+	err := syscall.Munmap(db.dataref)
+	db.dataref = nil
+	db.data = nil
+	db.datasz = 0
+	return err
+}

bolt_linux.go

@@ -3,10 +3,51 @@ package bolt
 import (
 	"os"
 	"syscall"
+	"unsafe"
 )
 
 var odirect = syscall.O_DIRECT
 
+// fdatasync flushes written data to a file descriptor.
 func fdatasync(f *os.File) error {
 	return syscall.Fdatasync(int(f.Fd()))
 }
+
+// flock acquires an advisory lock on a file descriptor.
+func flock(f *os.File) error {
+	return syscall.Flock(int(f.Fd()), syscall.LOCK_EX)
+}
+
+// funlock releases an advisory lock on a file descriptor.
+func funlock(f *os.File) error {
+	return syscall.Flock(int(f.Fd()), syscall.LOCK_UN)
+}
+
+// mmap memory maps a DB's data file.
+func mmap(db *DB, sz int) error {
+	b, err := syscall.Mmap(int(db.file.Fd()), 0, sz, syscall.PROT_READ, syscall.MAP_SHARED)
+	if err != nil {
+		return err
+	}
+
+	// Save the original byte slice and convert to a byte array pointer.
+	db.dataref = b
+	db.data = (*[maxMapSize]byte)(unsafe.Pointer(&b[0]))
+	db.datasz = sz
+	return nil
+}
+
+// munmap unmaps a DB's data file from memory.
+func munmap(db *DB) error {
+	// Ignore the unmap if we have no mapped data.
+	if db.dataref == nil {
+		return nil
+	}
+
+	// Unmap using the original byte slice.
+	err := syscall.Munmap(db.dataref)
+	db.dataref = nil
+	db.data = nil
+	db.datasz = 0
+	return err
+}

bolt_windows.go

@@ -0,0 +1,73 @@
+package bolt
+
+import (
+	"fmt"
+	"os"
+	"syscall"
+	"unsafe"
+)
+
+var odirect int
+
+// fdatasync flushes written data to a file descriptor.
+func fdatasync(f *os.File) error {
+	return f.Sync()
+}
+
+// flock acquires an advisory lock on a file descriptor.
+func flock(f *os.File) error {
+	return nil
+}
+
+// funlock releases an advisory lock on a file descriptor.
+func funlock(f *os.File) error {
+	return nil
+}
+
+// mmap memory maps a DB's data file.
+// Based on: https://github.com/edsrzf/mmap-go
+func mmap(db *DB, sz int) error {
+	// Truncate the database to the size of the mmap.
+	if err := db.file.Truncate(int64(sz)); err != nil {
+		return fmt.Errorf("truncate: %s", err)
+	}
+
+	// Open a file mapping handle.
+	sizelo := uint32(sz >> 32)
+	sizehi := uint32(sz & 0xffffffff)
+	h, errno := syscall.CreateFileMapping(syscall.Handle(db.file.Fd()), nil, syscall.PAGE_READONLY, sizelo, sizehi, nil)
+	if h == 0 {
+		return os.NewSyscallError("CreateFileMapping", errno)
+	}
+
+	// Create the memory map.
+	addr, errno := syscall.MapViewOfFile(h, syscall.FILE_MAP_READ, 0, 0, uintptr(sz))
+	if addr == 0 {
+		return os.NewSyscallError("MapViewOfFile", errno)
+	}
+
+	// Close mapping handle.
+	if err := syscall.CloseHandle(syscall.Handle(h)); err != nil {
+		return os.NewSyscallError("CloseHandle", err)
+	}
+
+	// Convert to a byte array.
+	db.data = ((*[maxMapSize]byte)(unsafe.Pointer(addr)))
+	db.datasz = sz
+
+	return nil
+}
+
+// munmap unmaps a pointer from a file.
+// Based on: https://github.com/edsrzf/mmap-go
+func munmap(db *DB) error {
+	if db.data == nil {
+		return nil
+	}
+
+	addr := (uintptr)(unsafe.Pointer(&db.data[0]))
+	if err := syscall.UnmapViewOfFile(addr); err != nil {
+		return os.NewSyscallError("UnmapViewOfFile", err)
+	}
+	return nil
+}

db.go

@@ -6,7 +6,6 @@ import (
 	"hash/fnv"
 	"os"
 	"sync"
-	"syscall"
 	"unsafe"
 )
 
@@ -68,7 +67,9 @@ type DB struct {
 
 	path     string
 	file     *os.File
-	data     []byte
+	dataref  []byte
+	data     *[maxMapSize]byte
+	datasz   int
 	meta0    *meta
 	meta1    *meta
 	pageSize int
@@ -120,7 +121,7 @@ func Open(path string, mode os.FileMode) (*DB, error) {
 	// Lock file so that other processes using Bolt cannot use the database
 	// at the same time. This would cause corruption since the two processes
 	// would write meta pages and free pages separately.
-	if err := syscall.Flock(int(db.file.Fd()), syscall.LOCK_EX); err != nil {
+	if err := flock(db.file); err != nil {
 		_ = db.close()
 		return nil, err
 	}
@@ -193,7 +194,7 @@ func (db *DB) mmap(minsz int) error {
 	size = db.mmapSize(size)
 
 	// Memory-map the data file as a byte slice.
-	if db.data, err = syscall.Mmap(int(db.file.Fd()), 0, size, syscall.PROT_READ, syscall.MAP_SHARED); err != nil {
+	if err := mmap(db, size); err != nil {
 		return err
 	}
 
@@ -214,11 +215,8 @@ func (db *DB) mmap(minsz int) error {
 
 // munmap unmaps the data file from memory.
 func (db *DB) munmap() error {
-	if db.data != nil {
-		if err := syscall.Munmap(db.data); err != nil {
-			return fmt.Errorf("unmap error: " + err.Error())
-		}
-		db.data = nil
+	if err := munmap(db); err != nil {
+		return fmt.Errorf("unmap error: " + err.Error())
 	}
 	return nil
 }
@@ -314,7 +312,7 @@ func (db *DB) close() error {
 	// Close file handles.
 	if db.file != nil {
 		// Unlock the file.
-		_ = syscall.Flock(int(db.file.Fd()), syscall.LOCK_UN)
+		_ = funlock(db.file)
 
 		// Close the file descriptor.
 		if err := db.file.Close(); err != nil {
@@ -503,7 +501,7 @@ func (db *DB) Stats() Stats {
 // This is for internal access to the raw data bytes from the C cursor, use
 // carefully, or not at all.
 func (db *DB) Info() *Info {
-	return &Info{db.data, db.pageSize}
+	return &Info{uintptr(unsafe.Pointer(&db.data[0])), db.pageSize}
 }
 
 // page retrieves a page reference from the mmap based on the current page size.
@@ -540,7 +538,7 @@ func (db *DB) allocate(count int) (*page, error) {
 	// Resize mmap() if we're at the end.
 	p.id = db.rwtx.meta.pgid
 	var minsz = int((p.id+pgid(count))+1) * db.pageSize
-	if minsz >= len(db.data) {
+	if minsz >= db.datasz {
 		if err := db.mmap(minsz); err != nil {
 			return nil, fmt.Errorf("mmap allocate error: %s", err)
 		}
@@ -575,7 +573,7 @@ func (s *Stats) add(other *Stats) {
 }
 
 type Info struct {
-	Data     []byte
+	Data     uintptr
 	PageSize int
 }
 

doc.go

@@ -12,6 +12,9 @@ rolled back in the event of a crash.
 
 The design of Bolt is based on Howard Chu's LMDB database project.
 
+Bolt currently works on Windows, Mac OS X, and Linux.
+
+
 Basics
 
 There are only a few types in Bolt: DB, Bucket, Tx, and Cursor. The DB is
@@ -33,7 +36,5 @@ values returned from Bolt cannot be changed. Writing to a read-only byte slice
 will cause Go to panic. If you need to work with data returned from a Get() you
 need to first copy it to a new byte slice.
 
-Bolt currently works on Mac OS and Linux. Windows support is coming soon.
-
 */
 package bolt