mobile/bind: replace seq serialization with direct calls

The seq serialization machinery is a historic artifact from when Go mobile code had to run in a separate process. Now that Go code is running in-process, replace the explicit serialization with direct calls and pass arguments on the stack. The benefits are a much smaller bind runtime, much less garbage (and, in Java, fewer objects with finalizers), less argument copying, and faster cross-language calls. The cost is a more complex generator, because some of the work from the bind runtime is moved to generated code. Generated code now handles conversion between Go and Java/ObjC types, multiple return values and memory management of byte slice and string arguments. To overcome the lack of calling C code between Go packages, all bound packages now end up in the same (fake) package, "gomobile_bind", instead of separate packages (go_<pkgname>). To avoid name clashes, the package name is added as a prefix to generated functions and types. Also, don't copy byte arrays passed to Go, saving call time and allowing read([]byte)-style interfaces to foreign callers (#12113). Finally, add support for nil interfaces and struct pointers to objc. This is a large CL, but most of the changes stem from changing testdata. The full benchcmp output on the CL/20095 benchmarks on my Nexus 5 is reproduced below. Note that the savings for the JavaSlice* benchmarks are skewed because byte slices are no longer copied before passing them to Go. benchmark old ns/op new ns/op delta BenchmarkJavaEmpty 26.0 19.0 -26.92% BenchmarkJavaEmptyDirect 23.0 22.0 -4.35% BenchmarkJavaNoargs 7685 2339 -69.56% BenchmarkJavaNoargsDirect 17405 8041 -53.80% BenchmarkJavaOnearg 26887 2366 -91.20% BenchmarkJavaOneargDirect 34266 7910 -76.92% BenchmarkJavaOneret 38325 2245 -94.14% BenchmarkJavaOneretDirect 46265 7708 -83.34% BenchmarkJavaManyargs 41720 2535 -93.92% BenchmarkJavaManyargsDirect 51026 8373 -83.59% BenchmarkJavaRefjava 38139 21260 -44.26% BenchmarkJavaRefjavaDirect 42706 28150 -34.08% BenchmarkJavaRefgo 34403 6843 -80.11% BenchmarkJavaRefgoDirect 40193 16582 -58.74% BenchmarkJavaStringShort 32366 9323 -71.20% BenchmarkJavaStringShortDirect 41973 19118 -54.45% BenchmarkJavaStringLong 127879 94420 -26.16% BenchmarkJavaStringLongDirect 133776 114760 -14.21% BenchmarkJavaStringShortUnicode 32562 9221 -71.68% BenchmarkJavaStringShortUnicodeDirect 41464 19094 -53.95% BenchmarkJavaStringLongUnicode 131015 89401 -31.76% BenchmarkJavaStringLongUnicodeDirect 134130 90786 -32.31% BenchmarkJavaSliceShort 42462 7538 -82.25% BenchmarkJavaSliceShortDirect 52940 17017 -67.86% BenchmarkJavaSliceLong 138391 8466 -93.88% BenchmarkJavaSliceLongDirect 205804 15666 -92.39% BenchmarkGoEmpty 3.00 3.00 +0.00% BenchmarkGoEmptyDirect 3.00 3.00 +0.00% BenchmarkGoNoarg 40342 13716 -66.00% BenchmarkGoNoargDirect 46691 13569 -70.94% BenchmarkGoOnearg 43529 13757 -68.40% BenchmarkGoOneargDirect 44867 14078 -68.62% BenchmarkGoOneret 45456 13559 -70.17% BenchmarkGoOneretDirect 44694 13442 -69.92% BenchmarkGoRefjava 55111 28071 -49.06% BenchmarkGoRefjavaDirect 60883 26872 -55.86% BenchmarkGoRefgo 57038 29223 -48.77% BenchmarkGoRefgoDirect 56153 27812 -50.47% BenchmarkGoManyargs 67967 17398 -74.40% BenchmarkGoManyargsDirect 60617 16998 -71.96% BenchmarkGoStringShort 57538 22600 -60.72% BenchmarkGoStringShortDirect 52627 22704 -56.86% BenchmarkGoStringLong 128485 52530 -59.12% BenchmarkGoStringLongDirect 138377 52079 -62.36% BenchmarkGoStringShortUnicode 57062 22994 -59.70% BenchmarkGoStringShortUnicodeDirect 62563 22938 -63.34% BenchmarkGoStringLongUnicode 139913 55553 -60.29% BenchmarkGoStringLongUnicodeDirect 150863 57791 -61.69% BenchmarkGoSliceShort 59279 20215 -65.90% BenchmarkGoSliceShortDirect 60160 21136 -64.87% BenchmarkGoSliceLong 411225 301870 -26.59% BenchmarkGoSliceLongDirect 399029 298915 -25.09% Fixes golang/go#12619 Fixes golang/go#12113 Fixes golang/go#13033 Change-Id: I2b45e9e98a1248e3c23a5137f775f7364908bec7 Reviewed-on: https://go-review.googlesource.com/19821 Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
2026-05-22 18:43:29 -07:00 · 2016-03-03 15:03:45 +00:00
parent 988d17d203
commit 6fca37c69e
100 changed files with 6574 additions and 6307 deletions
@@ -0,0 +1,101 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package gomobile_bind
+
+// Go support functions for bindings. This file is copied into the
+// generated gomobile_bind package and compiled along with the
+// generated binding files.
+
+//#cgo LDFLAGS: -llog
+//#include <jni.h>
+//#include <stdint.h>
+//#include <stdlib.h>
+//#include "seq.h"
+import "C"
+import (
+	"unicode/utf16"
+	"unsafe"
+
+	"golang.org/x/mobile/bind/seq"
+)
+
+// DestroyRef is called by Java to inform Go it is done with a reference.
+//export DestroyRef
+func DestroyRef(refnum C.int32_t) {
+	seq.Delete(int32(refnum))
+}
+
+// encodeString encodes a Go string to utf16 and returns a Java string as a nstring
+// containing the jstring.
+// encodeString uses UTF16 as the intermediate format. Note that UTF8 is an obvious
+// alternative, but JNI only supports a C-safe variant of UTF8 (modified UTF8).
+// The returned data is always a copy, regardless of cpy, and will be freed in
+// go_seq_to_java_string.
+func encodeString(s string, cpy bool) C.nstring {
+	n := C.int(len(s))
+	if n == 0 {
+		return C.nstring{}
+	}
+	// Allocate enough for the worst case estimate, every character is a surrogate pair
+	worstCaseLen := 4 * len(s)
+	utf16buf := C.malloc(C.size_t(worstCaseLen))
+	if utf16buf == nil {
+		panic("encodeString: malloc failed")
+	}
+	chars := (*[1<<30 - 1]uint16)(unsafe.Pointer(utf16buf))[:worstCaseLen/2 : worstCaseLen/2]
+	nchars := seq.UTF16Encode(s, chars)
+	return C.nstring{chars: unsafe.Pointer(utf16buf), len: C.jsize(nchars)}
+}
+
+// decodeString decodes a nstring (jstring) to a Go string.
+// If cpy is set, the string contains a copy and is freed.
+func decodeString(str C.nstring, cpy bool) string {
+	if str.chars == nil {
+		return ""
+	}
+	chars := (*[1<<30 - 1]uint16)(unsafe.Pointer(str.chars))[:str.len]
+	s := string(utf16.Decode(chars)) // TODO: avoid the []rune allocation
+	if cpy {
+		C.free(str.chars)
+	}
+	return s
+}
+
+// fromSlice converts a slice to a jbyteArray cast as a nbyteslice. If cpy
+// is set, the returned slice is a copy to be free by go_seq_to_java_bytearray.
+func fromSlice(s []byte, cpy bool) C.nbyteslice {
+	if s == nil || len(s) == 0 {
+		return C.nbyteslice{}
+	}
+	var ptr *C.jbyte
+	n := C.jsize(len(s))
+	if cpy {
+		ptr = (*C.jbyte)(C.malloc(C.size_t(n)))
+		if ptr == nil {
+			panic("fromSlice: malloc failed")
+		}
+		copy((*[1<<31 - 1]byte)(unsafe.Pointer(ptr))[:n], s)
+	} else {
+		ptr = (*C.jbyte)(unsafe.Pointer(&s[0]))
+	}
+	return C.nbyteslice{ptr: unsafe.Pointer(ptr), len: n}
+}
+
+// toSlice takes a nbyteslice (jbyteArray) and returns a byte slice
+// with the data. If cpy is set, the slice contains a copy of the data and is
+// freed.
+func toSlice(s C.nbyteslice, cpy bool) []byte {
+	if s.ptr == nil || s.len == 0 {
+		return nil
+	}
+	var b []byte
+	if cpy {
+		b = C.GoBytes(s.ptr, C.int(s.len))
+		C.free(s.ptr)
+	} else {
+		b = (*[1<<31 - 1]byte)(unsafe.Pointer(s.ptr))[:s.len:s.len]
+	}
+	return b
+}