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9 Commits

Author SHA1 Message Date
Elias Naur
bf31dd1a5e bind,cmd/gomobile: add a new generator for Java API wrappers
Using the new Java class analyzer API, scan the bound packages
for references to Java classes and interfaces and generate Go
wrappers for them.

This is the second part of the implementation of proposal golang/go#16876.

For golang/go#16876

Change-Id: I59ec0ebdae0081a615dc34d450f344c20c03f871
Reviewed-on: https://go-review.googlesource.com/28596
Reviewed-by: David Crawshaw <crawshaw@golang.org>
2016-09-16 17:25:25 +00:00
Elias Naur
80e11ad074 mobile/bind: move generated Java classes to package level
Before this CL, generated Java classes or interfaces were inner
classes to the top package class. That is both unnecessary and creates
ugly class names. Instead, move every generated class and interface to its
own package level class.

NOTE: This is a backwards incompatible change and requires every client
of gomobile APIs to be updated to leave out the package class in the
type names. For example, the Go type

package pkg

type S struct {
}

now generates (with the default java package name go) a Java class named
go.pkg.S. The name before this CL was go.pkg.Pkg.S.

Also, change the custom java package to specify the package prefix and
not the full package as before. This is an unfortunate change needed
to avoid name clashes between two bound packages. On the plus side,
the change brings the custom package case closer to the default behaviour,
which is a commen prefix, "go.", and a distinct java package for every
Go package bound.

Change-Id: Iadfaad56e101d1caf7e2a05006f4d384859a20fe
Reviewed-on: https://go-review.googlesource.com/27436
Reviewed-by: David Crawshaw <crawshaw@golang.org>
2016-08-22 07:41:35 +00:00
Elias Naur
d5b8fb1623 mobile/bind/java: fix compiler warnings
Add a missing #include to declare the exported Go function
setContext, and replace old GNU-style struct initializers.

Change-Id: Id1660559236c39505a47368a700c8e0ad834cf6c
Reviewed-on: https://go-review.googlesource.com/24491
Reviewed-by: David Crawshaw <crawshaw@golang.org>
2016-06-28 17:54:14 +00:00
Elias Naur
a3e0621280 mobile/bind: use objects to pass errors across the language barrier
Gobind uses strings for passing errors across the language barrier.
However, since Gobind doesn't have a concept of a nil string, it
can't separate an empty native string from a nil string.

In turn, that means that empty errors, exceptions or NSError * with
an empty description are treated as no error. With ObjC, empty errors
are replaced with a default string to workaround the issue, while
with Java empty errors are silently ignored.

Fix this by replacing strings with actual error objects, wrapping
the Go error, Java Throwable or ObjC NSError *, and letting the
existing bind machinery take care of passing the references across.

It's a large change for a small corner case, but I believe objects
are a better fit for exception that strings. Error objects also
naturally leads to future additions, for example accessing the
exception class name or chained exception.

Change-Id: Ie03b47cafcb231ad1e12a80195693fa7459c6265
Reviewed-on: https://go-review.googlesource.com/24100
Reviewed-by: David Crawshaw <crawshaw@golang.org>
2016-06-23 18:55:48 +00:00
Elias Naur
5e11c20fc0 mobile/bind: don't force Java classes to extend stub classes
Requiring user code to extend Go interface Stubs to be able to pass
Java objects to Go is clumsy and use up the single extend slot.
Instead, support (and enforce) java classes to implement translated
Go interface directly. This is similar to how ObjC works.

The stub classes are now gone, and users of gobind Java APIs need
to update their code to implement interfaces directly.

Change-Id: I880bb7c8e89d3c21210b2ab2c85ced8d7859ff48
Reviewed-on: https://go-review.googlesource.com/21313
Reviewed-by: David Crawshaw <crawshaw@golang.org>
2016-03-31 07:59:45 +00:00
Elias Naur
07a529f836 mobile/bind: fix a reference count race with the garbage collectors
Each side of the language barrier maintains a map of reference numbers
to objects. Each entry has a reference count that exactly matches
the number of active proxy objects on the other side. When a reference
crosses the barrier, the count is incremented and when a proxy finalizer
is run, the count is decremented. If the count reaches 0, the reference
number and its object are removed from the map.

There is a possibility that a reference number is passed to the other
side, and the last proxy is then immediately garbage collected and
finalized. The reference counter then reaches 0 before the other side has
converted the reference number to its object, crashing the program.

This is possible in both Go/Java/ObjC but is most likely to happen in
ObjC because its own automatic reference count runtime frees objects
as soon as they are statically never referenced again.

Fix the race by always incrementing the reference count before sending
a reference across the barrier. When converting the reference back into
an object on the other side, decrement the counter again.

Only the new ObjC test fails without this fix, but I left the Java
counterpart in for good measure.

Change-Id: I92743aabec275b4a5b82b952052e7e284872ce02
Reviewed-on: https://go-review.googlesource.com/21311
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
2016-03-30 18:24:55 +00:00
Elias Naur
75a1c3da13 mobile/bind: make LOG_FATAL abort() on Android
LOG_FATAL already throws an exception on iOS. Make it abort() on
Android, so that any fatal error will hopefully end up with a useful
log instead of an easily missed message in logcat.

Also, remove return statements after LOG_FATAL on both platforms.
They're unnecessary and confusing and they weren't used consistently
anyway.

Change-Id: I2a8e2e0ac064e95f52ca130de17265c9741cefe4
Reviewed-on: https://go-review.googlesource.com/20257
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
2016-03-06 14:57:14 +00:00
Elias Naur
ba0a725146 mobile/bind: avoid intermediate []rune copy converting Java string to Go
Converting a Go string to a string suitable use a specialized function,
UTF16Encode, that can encode the string directly to a malloc'ed buffer. That
way, only two copies are made when strings are passed from Go to Java; once
for UTF-8 to UTF-16 encoding and once for the creation of the Java String.

This CL implements the same optimization in the other direction, with a
UTF-16 to UTF-8 decoder implemented in C. Unfortunately, while calling into a
Go decoder also saves the extra copy, the Cgo overhead makes the calls much
slower for short strings.

To alleviate the risk of introducing decoding bugs, I've added the tests from
the encoding/utf16 package to SeqTest.

As a sideeffect, both Java and ObjC now always copy strings, regardless of
the argument mode. The cpy argument can therefore be removed from the string
conversion functions. Furthermore, the modeRetained and modeReturned modes
can be collapsed into just one.

While we're here, delete a leftover function from seq/strings.go that
wasn't removed when the old seq buffers went away.

Benchmarks, as compared with benchstat over 5 runs:

name                          old time/op  new time/op  delta
JavaStringShort               11.4µs ±13%  11.6µs ± 4%     ~     (p=0.859 n=10+5)
JavaStringShortDirect         19.5µs ± 9%  20.3µs ± 2%   +3.68%   (p=0.019 n=9+5)
JavaStringLong                 103µs ± 8%    24µs ± 4%  -77.13%   (p=0.001 n=9+5)
JavaStringLongDirect           113µs ± 9%    32µs ± 7%  -71.63%   (p=0.001 n=9+5)
JavaStringShortUnicode        11.1µs ±16%  10.7µs ± 5%     ~      (p=0.190 n=9+5)
JavaStringShortUnicodeDirect  19.6µs ± 7%  20.2µs ± 1%   +2.78%   (p=0.029 n=9+5)
JavaStringLongUnicode         97.1µs ± 9%  28.0µs ± 5%  -71.17%   (p=0.001 n=9+5)
JavaStringLongUnicodeDirect    105µs ±10%    34µs ± 5%  -67.23%   (p=0.002 n=8+5)
JavaStringRetShort            14.2µs ± 2%  13.9µs ± 1%   -2.15%   (p=0.006 n=8+5)
JavaStringRetShortDirect      20.8µs ± 2%  20.4µs ± 2%     ~      (p=0.065 n=8+5)
JavaStringRetLong             42.2µs ± 9%  42.4µs ± 3%     ~      (p=0.190 n=9+5)
JavaStringRetLongDirect       51.2µs ±21%  50.8µs ± 8%     ~      (p=0.518 n=9+5)
GoStringShort                 23.4µs ± 7%  22.5µs ± 3%   -3.55%   (p=0.019 n=9+5)
GoStringLong                  51.9µs ± 9%  53.1µs ± 3%     ~      (p=0.240 n=9+5)
GoStringShortUnicode          24.2µs ± 6%  22.8µs ± 1%   -5.54%   (p=0.002 n=9+5)
GoStringLongUnicode           58.6µs ± 8%  57.6µs ± 3%     ~      (p=0.518 n=9+5)
GoStringRetShort              27.6µs ± 1%  23.2µs ± 2%  -15.87%   (p=0.003 n=7+5)
GoStringRetLong                129µs ±12%    33µs ± 2%  -74.03%  (p=0.001 n=10+5)

Change-Id: Icb9481981493ffca8defed9fb80a9433d6048937
Reviewed-on: https://go-review.googlesource.com/20250
Reviewed-by: David Crawshaw <crawshaw@golang.org>
2016-03-05 10:02:05 +00:00
Elias Naur
6fca37c69e 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>
2016-03-03 15:03:45 +00:00