proto: make safe for App Engine
Factor unsafe code into its own file that can be replaced with
reflect code when building for App Engine.
benchmark old MB/s new MB/s speedup
BenchmarkMarshal 126.34 120.38 0.95x
BenchmarkUnmarshal 111.84 110.78 0.99x
BenchmarkMarshalBytes 893.70 853.55 0.96x
BenchmarkUnmarshalBytes 615.23 619.73 1.01x
Comparing the two new variants, old = unsafe, new = reflect:
benchmark old MB/s new MB/s speedup
BenchmarkMarshal 120.38 50.52 0.42x
BenchmarkUnmarshal 110.78 20.12 0.18x
BenchmarkMarshalBytes 853.55 182.21 0.21x
BenchmarkUnmarshalBytes 619.73 227.66 0.37x
But really these numbers are unfair since they ignore the
qualitative difference: proto was completely unavailable
on App Engine, and now it can be run there.
R=dsymonds, r
CC=golang-dev
http://codereview.appspot.com/6494085
diff --git a/proto/pointer_unsafe.go b/proto/pointer_unsafe.go
new file mode 100644
index 0000000..817b084
--- /dev/null
+++ b/proto/pointer_unsafe.go
@@ -0,0 +1,218 @@
+// Go support for Protocol Buffers - Google's data interchange format
+//
+// Copyright 2012 Google Inc. All rights reserved.
+// http://code.google.com/p/goprotobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+// * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+// * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+// * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// +build !appengine
+
+// This file contains the implementation of the proto field accesses using package unsafe.
+
+package proto
+
+import (
+ "reflect"
+ "unsafe"
+)
+
+// NOTE: These type_Foo functions would more idiomatically be methods,
+// but Go does not allow methods on pointer types, and we must preserve
+// some pointer type for the garbage collector. We use these
+// funcs with clunky names as our poor approximation to methods.
+//
+// An alternative would be
+// type structPointer struct { p unsafe.Pointer }
+// but that does not registerize as well.
+
+// A structPointer is a pointer to a struct.
+type structPointer unsafe.Pointer
+
+// toStructPointer returns a structPointer equivalent to the given reflect value.
+func toStructPointer(v reflect.Value) structPointer {
+ return structPointer(unsafe.Pointer(v.Pointer()))
+}
+
+// IsNil reports whether p is nil.
+func structPointer_IsNil(p structPointer) bool {
+ return p == nil
+}
+
+// Interface returns the struct pointer, assumed to have element type t,
+// as an interface value.
+func structPointer_Interface(p structPointer, t reflect.Type) interface{} {
+ return reflect.NewAt(t, unsafe.Pointer(p)).Interface()
+}
+
+// A field identifies a field in a struct, accessible from a structPointer.
+// In this implementation, a field is identified by its byte offset from the start of the struct.
+type field uintptr
+
+// toField returns a field equivalent to the given reflect field.
+func toField(f *reflect.StructField) field {
+ return field(f.Offset)
+}
+
+// invalidField is an invalid field identifier.
+const invalidField = ^field(0)
+
+// IsValid reports whether the field identifier is valid.
+func (f field) IsValid() bool {
+ return f != ^field(0)
+}
+
+// Bytes returns the address of a []byte field in the struct.
+func structPointer_Bytes(p structPointer, f field) *[]byte {
+ return (*[]byte)(unsafe.Pointer(uintptr(p) + uintptr(f)))
+}
+
+// BytesSlice returns the address of a [][]byte field in the struct.
+func structPointer_BytesSlice(p structPointer, f field) *[][]byte {
+ return (*[][]byte)(unsafe.Pointer(uintptr(p) + uintptr(f)))
+}
+
+// Bool returns the address of a *bool field in the struct.
+func structPointer_Bool(p structPointer, f field) **bool {
+ return (**bool)(unsafe.Pointer(uintptr(p) + uintptr(f)))
+}
+
+// BoolSlice returns the address of a []bool field in the struct.
+func structPointer_BoolSlice(p structPointer, f field) *[]bool {
+ return (*[]bool)(unsafe.Pointer(uintptr(p) + uintptr(f)))
+}
+
+// String returns the address of a *string field in the struct.
+func structPointer_String(p structPointer, f field) **string {
+ return (**string)(unsafe.Pointer(uintptr(p) + uintptr(f)))
+}
+
+// StringSlice returns the address of a []string field in the struct.
+func structPointer_StringSlice(p structPointer, f field) *[]string {
+ return (*[]string)(unsafe.Pointer(uintptr(p) + uintptr(f)))
+}
+
+// ExtMap returns the address of an extension map field in the struct.
+func structPointer_ExtMap(p structPointer, f field) *map[int32]Extension {
+ return (*map[int32]Extension)(unsafe.Pointer(uintptr(p) + uintptr(f)))
+}
+
+// SetStructPointer writes a *struct field in the struct.
+func structPointer_SetStructPointer(p structPointer, f field, q structPointer) {
+ *(*structPointer)(unsafe.Pointer(uintptr(p) + uintptr(f))) = q
+}
+
+// GetStructPointer reads a *struct field in the struct.
+func structPointer_GetStructPointer(p structPointer, f field) structPointer {
+ return *(*structPointer)(unsafe.Pointer(uintptr(p) + uintptr(f)))
+}
+
+// StructPointerSlice the address of a []*struct field in the struct.
+func structPointer_StructPointerSlice(p structPointer, f field) *structPointerSlice {
+ return (*structPointerSlice)(unsafe.Pointer(uintptr(p) + uintptr(f)))
+}
+
+// A structPointerSlice represents a slice of pointers to structs (themselves submessages or groups).
+type structPointerSlice []structPointer
+
+func (v *structPointerSlice) Len() int { return len(*v) }
+func (v *structPointerSlice) Index(i int) structPointer { return (*v)[i] }
+func (v *structPointerSlice) Append(p structPointer) { *v = append(*v, p) }
+
+// A word32 is the address of a "pointer to 32-bit value" field.
+type word32 **uint32
+
+// IsNil reports whether *v is nil.
+func word32_IsNil(p word32) bool {
+ return *p == nil
+}
+
+// Set sets *v to point at a newly allocated word set to x.
+func word32_Set(p word32, o *Buffer, x uint32) {
+ if len(o.uint32s) == 0 {
+ o.uint32s = make([]uint32, uint32PoolSize)
+ }
+ o.uint32s[0] = x
+ *p = &o.uint32s[0]
+ o.uint32s = o.uint32s[1:]
+}
+
+// Get gets the value pointed at by *v.
+func word32_Get(p word32) uint32 {
+ return **p
+}
+
+// Word32 returns the address of a *int32, *uint32, *float32, or *enum field in the struct.
+func structPointer_Word32(p structPointer, f field) word32 {
+ return word32((**uint32)(unsafe.Pointer(uintptr(p) + uintptr(f))))
+}
+
+// A word32Slice is a slice of 32-bit values.
+type word32Slice []uint32
+
+func (v *word32Slice) Append(x uint32) { *v = append(*v, x) }
+func (v *word32Slice) Len() int { return len(*v) }
+func (v *word32Slice) Index(i int) uint32 { return (*v)[i] }
+
+// Word32Slice returns the address of a []int32, []uint32, []float32, or []enum field in the struct.
+func structPointer_Word32Slice(p structPointer, f field) *word32Slice {
+ return (*word32Slice)(unsafe.Pointer(uintptr(p) + uintptr(f)))
+}
+
+// word64 is like word32 but for 64-bit values.
+type word64 **uint64
+
+func word64_Set(p word64, o *Buffer, x uint64) {
+ if len(o.uint64s) == 0 {
+ o.uint64s = make([]uint64, uint64PoolSize)
+ }
+ o.uint64s[0] = x
+ *p = &o.uint64s[0]
+ o.uint64s = o.uint64s[1:]
+}
+
+func word64_IsNil(p word64) bool {
+ return *p == nil
+}
+
+func word64_Get(p word64) uint64 {
+ return **p
+}
+
+func structPointer_Word64(p structPointer, f field) word64 {
+ return word64((**uint64)(unsafe.Pointer(uintptr(p) + uintptr(f))))
+}
+
+// word64Slice is like word32Slice but for 64-bit values.
+type word64Slice []uint64
+
+func (v *word64Slice) Append(x uint64) { *v = append(*v, x) }
+func (v *word64Slice) Len() int { return len(*v) }
+func (v *word64Slice) Index(i int) uint64 { return (*v)[i] }
+
+func structPointer_Word64Slice(p structPointer, f field) *word64Slice {
+ return (*word64Slice)(unsafe.Pointer(uintptr(p) + uintptr(f)))
+}