Java API for mojo system.

mojo/system/android/core_impl.cc

Index: mojo/system/android/core_impl.cc
diff --git a/mojo/system/android/core_impl.cc b/mojo/system/android/core_impl.cc
new file mode 100644
index 0000000000000000000000000000000000000000..3532fc69eb40426cfee0ad7005db0b38391e2099
--- /dev/null
+++ b/mojo/system/android/core_impl.cc
@@ -0,0 +1,290 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "mojo/system/android/core_impl.h"
+
+#include "base/android/base_jni_registrar.h"
+#include "base/android/jni_android.h"
+#include "base/android/jni_registrar.h"
+#include "base/android/library_loader/library_loader_hooks.h"
+#include "base/logging.h"
+#include "jni/CoreImpl_jni.h"
+#include "mojo/embedder/embedder.h"
+#include "mojo/public/c/system/core.h"
+
+namespace mojo {
+
+static void Constructor(JNIEnv* env, jobject jcaller) {
+  mojo::embedder::Init();
+}
+
+static jlong GetTimeTicksNow(JNIEnv* env, jobject jcaller) {
+  return MojoGetTimeTicksNow();
+}
+
+static jint WaitMany(JNIEnv* env,
+                     jobject jcaller,
+                     jobject buffer,
+                     jlong deadline) {
+  // Buffer contains first the list of handles, then the list of flags.
+  const void* buffer_start = env->GetDirectBufferAddress(buffer);
+  DCHECK(buffer_start);

[bulach, 2014/04/14 17:39:56]

probably best as CHECK ?

[qsr, 2014/04/15 08:37:37]

 We do create and provide this buffer in java world. Do we really want to check
this in release mode?

+  const size_t record_size = 8;
+  const size_t buffer_size = env->GetDirectBufferCapacity(buffer);
+  DCHECK_EQ(buffer_size % record_size, 0u);
+
+  const size_t nb_handles = buffer_size / record_size;
+  const MojoHandle* handleStart =

[bulach, 2014/04/14 17:39:56]

nit: handle_start

[qsr, 2014/04/15 08:37:37]

Done.

+      reinterpret_cast<const MojoHandle*>(buffer_start);

[viettrungluu, 2014/04/14 18:02:50]

nit (here and everywhere else): (const) void* -> (const) Foo* only requires a
static_cast, not a reinterpret_cast.

[qsr, 2014/04/15 08:37:37]

Done.

+  const MojoWaitFlags* flagsStart =
+      reinterpret_cast<const MojoWaitFlags*>(handleStart + nb_handles);
+  return MojoWaitMany(handleStart, flagsStart, nb_handles, deadline);
+}
+
+static jobject CreateMessagePipe(JNIEnv* env, jobject jcaller) {
+  MojoHandle handle1, handle2;

[bulach, 2014/04/14 17:39:56]

nit: one per line. also, perhaps input / output?

[qsr, 2014/04/15 08:37:37]

 message pipe are bidi, there is no input output here.

+  MojoResult result = MojoCreateMessagePipe(&handle1, &handle2);
+  return Java_CoreImpl_newNativeCreationResult(env, result, handle1, handle2)
+      .Release();
+}
+
+static jobject CreateDataPipe(JNIEnv* env,
+                              jobject jcaller,
+                              jobject optionsBuffer) {

[bulach, 2014/04/14 17:39:56]

nit: s/sBuffer/s_buffer/

[qsr, 2014/04/15 08:37:37]

Done.

+  const MojoCreateDataPipeOptions* options = NULL;
+  if (optionsBuffer) {
+    const void* buffer_start = env->GetDirectBufferAddress(optionsBuffer);
+    DCHECK(buffer_start);
+    const size_t buffer_size = env->GetDirectBufferCapacity(optionsBuffer);
+    DCHECK_EQ(buffer_size, sizeof(MojoCreateDataPipeOptions));

[bulach, 2014/04/14 17:39:56]

CHECKs ?

[viettrungluu, 2014/04/14 18:02:50]

Note that the various Mojo...Options structures are designed to be extensible,
so you probably shouldn't bother checking very much at this layer.

[qsr, 2014/04/15 08:37:37]

 Well, they are extensible in a C++ word, where the system is an independent
library. In the java world this file lives in, this code is tightly tide to the
java code, and so this should have been compiled at the same time as the java
library. The java library is the one that define the java option class, and that
translate that into the struct it knows about. So there is no extension
possible, and the advantage to have those checks here is that it will force us
to update the java option class and the translation if new options appear.
Unless you have a strong case not wanting this, I think we are better with all
those checks.

[qsr, 2014/04/15 08:37:37]

 Same as above. This is completely on our control. Test should be enough to
catch problems.

+    options = reinterpret_cast<const MojoCreateDataPipeOptions*>(buffer_start);
+    DCHECK_EQ(options->struct_size, buffer_size);

[viettrungluu, 2014/04/14 18:02:50]

Depending on the amount of safety we want to enforce, the correct check might be
to check that |buffer_size >= sizeof(uint32_t) && options->struct_size <=
buffer_size|, and throw MOJO_RESULT_INVALID_ARGUMENT if not.

[qsr, 2014/04/15 08:37:37]

 The buffer creation is done in the java code, translated from a java class. The
user has no control over it at all, so I think DCHECK is the right primitive. If
something is wrong at this level, the error if from us, not from the user of the
library.

+  }
+  MojoHandle handle1, handle2;
+  MojoResult result = MojoCreateDataPipe(options, &handle1, &handle2);
+  return Java_CoreImpl_newNativeCreationResult(env, result, handle1, handle2)
+      .Release();
+}
+
+static jobject CreateSharedBuffer(JNIEnv* env,
+                                  jobject jcaller,
+                                  jobject optionsBuffer,
+                                  jlong numBytes) {

[bulach, 2014/04/14 17:39:56]

nit: s/mBytes/m_bytes/, s/sBuffer/s_buffer/

[qsr, 2014/04/15 08:37:37]

Done.

+  const MojoCreateSharedBufferOptions* options = 0;
+  if (optionsBuffer) {
+    const void* buffer_start = env->GetDirectBufferAddress(optionsBuffer);
+    DCHECK(buffer_start);
+    const size_t buffer_size = env->GetDirectBufferCapacity(optionsBuffer);
+    DCHECK_EQ(buffer_size, sizeof(MojoCreateSharedBufferOptions));
+    options =
+        reinterpret_cast<const MojoCreateSharedBufferOptions*>(buffer_start);
+    DCHECK_EQ(options->struct_size, buffer_size);
+  }
+  MojoHandle handle;
+  MojoResult result = MojoCreateSharedBuffer(options, numBytes, &handle);
+  return Java_CoreImpl_newNativeCreationResult(env, result, handle, 0)
+      .Release();
+}
+
+static jint Close(JNIEnv* env, jobject jcaller, jint mojoHandle) {
+  return MojoClose(mojoHandle);
+}
+
+static jint Wait(JNIEnv* env,
+                 jobject jcaller,
+                 jint mojoHandle,
+                 jint flags,
+                 jlong deadline) {
+  return MojoWait(mojoHandle, flags, deadline);
+}
+
+static jint WriteMessage(JNIEnv* env,
+                         jobject jcaller,
+                         jint mojoHandle,
+                         jobject bytes,
+                         jint numBytes,
+                         jobject handlesBuffer,
+                         jint flags) {
+  const void* buffer_start = 0;
+  uint32_t buffer_size = 0;
+  if (bytes) {
+    buffer_start = env->GetDirectBufferAddress(bytes);
+    DCHECK(buffer_start);
+    DCHECK(env->GetDirectBufferCapacity(bytes) >= numBytes);
+    buffer_size = numBytes;
+  }
+  const MojoHandle* handles = 0;
+  uint32_t num_handles = 0;
+  if (handlesBuffer) {
+    handles = reinterpret_cast<MojoHandle*>(
+        env->GetDirectBufferAddress(handlesBuffer));
+    num_handles = env->GetDirectBufferCapacity(handlesBuffer) / 4;
+  }
+  // Java code will handle invalidating handles if the write succeeded.
+  return MojoWriteMessage(
+      mojoHandle, buffer_start, buffer_size, handles, num_handles, flags);
+}
+
+static jobject ReadMessage(JNIEnv* env,
+                           jobject jcaller,
+                           jint mojoHandle,
+                           jobject bytes,
+                           jobject handlesBuffer,
+                           jint flags) {
+  void* buffer_start = 0;
+  uint32_t buffer_size = 0;
+  if (bytes) {
+    buffer_start = env->GetDirectBufferAddress(bytes);
+    DCHECK(buffer_start);
+    buffer_size = env->GetDirectBufferCapacity(bytes);

[bulach, 2014/04/14 17:39:56]

I'd create a simple java wrapper and use our own JNI..
I suppose some of these "env->" calls could throw exceptions that need to be
checked, etc..

if not a java wrapper, perhaps add in base/android/jni_direct_buffer.h ?

[qsr, 2014/04/15 08:37:37]

 I'm sorry, but I do not understand what you mean. Those methods are not
throwing exceptions. The only one that can, is the NewDirectBuffer, but it can
only throw OOM, and we do not want to catch this one.

 Also, we are already using those methods in the code base.

+  }
+  MojoHandle* handles = 0;
+  uint32_t num_handles = 0;
+  if (handlesBuffer) {
+    handles = reinterpret_cast<MojoHandle*>(
+        env->GetDirectBufferAddress(handlesBuffer));
+    num_handles = env->GetDirectBufferCapacity(handlesBuffer) / 4;
+  }
+  MojoResult result = MojoReadMessage(
+      mojoHandle, buffer_start, &buffer_size, handles, &num_handles, flags);
+  // Jave code will handle taking ownership of any received handle.
+  return Java_CoreImpl_newNativeReadMessageResult(
+             env, result, buffer_size, num_handles).Release();
+}
+
+static jint ReadData(JNIEnv* env,
+                     jobject jcaller,
+                     jint mojoHandle,
+                     jobject elements,
+                     jint flags) {
+  void* buffer_start = 0;
+  uint32_t buffer_size = 0;
+  if (elements) {
+    buffer_start = env->GetDirectBufferAddress(elements);
+    DCHECK(buffer_start);
+    buffer_size = env->GetDirectBufferCapacity(elements);
+  }
+  MojoResult result =
+      MojoReadData(mojoHandle, buffer_start, &buffer_size, flags);
+  if (result < 0) {
+    return result;
+  }
+  return buffer_size;
+}
+
+static jobject BeginReadData(JNIEnv* env,
+                             jobject jcaller,
+                             jint mojoHandle,
+                             jint numBytes,
+                             jint flags) {
+  void const* buffer = 0;
+  uint32_t buffer_size = numBytes;
+  MojoResult result =
+      MojoBeginReadData(mojoHandle, &buffer, &buffer_size, flags);
+  jobject byte_buffer = 0;
+  if (result == MOJO_RESULT_OK) {
+    byte_buffer =
+        env->NewDirectByteBuffer(const_cast<void*>(buffer), buffer_size);
+  }
+  return Java_CoreImpl_newNativeCodeAndBufferResult(env, result, byte_buffer)
+      .Release();
+}
+
+static jint EndReadData(JNIEnv* env,
+                        jobject jcaller,
+                        jint mojoHandle,
+                        jint numBytesRead) {
+  return MojoEndReadData(mojoHandle, numBytesRead);
+}
+
+static jint WriteData(JNIEnv* env,
+                      jobject jcaller,
+                      jint mojoHandle,
+                      jobject elements,
+                      jint limit,
+                      jint flags) {
+  void* buffer_start = env->GetDirectBufferAddress(elements);
+  DCHECK(buffer_start);
+  DCHECK(limit <= env->GetDirectBufferCapacity(elements));
+  uint32_t buffer_size = limit;
+  MojoResult result =
+      MojoWriteData(mojoHandle, buffer_start, &buffer_size, flags);
+  if (result < 0) {
+    return result;
+  }
+  return buffer_size;
+}
+
+static jobject BeginWriteData(JNIEnv* env,
+                              jobject jcaller,
+                              jint mojoHandle,
+                              jint numBytes,
+                              jint flags) {
+  void* buffer = 0;
+  uint32_t buffer_size = numBytes;
+  MojoResult result =
+      MojoBeginWriteData(mojoHandle, &buffer, &buffer_size, flags);
+  jobject byte_buffer = 0;
+  if (result == MOJO_RESULT_OK) {
+    byte_buffer = env->NewDirectByteBuffer(buffer, buffer_size);
+  }
+  return Java_CoreImpl_newNativeCodeAndBufferResult(env, result, byte_buffer)
+      .Release();
+}
+
+static jint EndWriteData(JNIEnv* env,
+                         jobject jcaller,
+                         jint mojoHandle,
+                         jint numBytesWritten) {

[bulach, 2014/04/14 17:39:56]

s/mBytesW/m_bytes_w/ (similarly for other parameters in the functions below..)

[qsr, 2014/04/15 08:37:37]

Done.

+  return MojoEndWriteData(mojoHandle, numBytesWritten);
+}
+
+static jobject Duplicate(JNIEnv* env,
+                         jobject jcaller,
+                         jint mojoHandle,
+                         jobject optionsBuffer) {
+  const MojoDuplicateBufferHandleOptions* options = 0;
+  if (optionsBuffer) {
+    const void* buffer_start = env->GetDirectBufferAddress(optionsBuffer);
+    DCHECK(buffer_start);
+    const size_t buffer_size = env->GetDirectBufferCapacity(optionsBuffer);
+    DCHECK_EQ(buffer_size, sizeof(MojoDuplicateBufferHandleOptions));
+    options =
+        reinterpret_cast<const MojoDuplicateBufferHandleOptions*>(buffer_start);
+    DCHECK_EQ(options->struct_size, buffer_size);
+  }
+  MojoHandle handle;
+  MojoResult result = MojoDuplicateBufferHandle(mojoHandle, options, &handle);
+  return Java_CoreImpl_newNativeCreationResult(env, result, handle, 0)
+      .Release();
+}
+
+static jobject Map(JNIEnv* env,
+                   jobject jcaller,
+                   jint mojoHandle,
+                   jlong offset,
+                   jlong numBytes,
+                   jint flags) {
+  void* buffer = 0;
+  MojoResult result =
+      MojoMapBuffer(mojoHandle, offset, numBytes, &buffer, flags);
+  jobject byte_buffer = 0;
+  if (result == MOJO_RESULT_OK) {
+    byte_buffer = env->NewDirectByteBuffer(buffer, numBytes);
+  }
+  return Java_CoreImpl_newNativeCodeAndBufferResult(env, result, byte_buffer)
+      .Release();
+}
+
+static int Unmap(JNIEnv* env, jobject jcaller, jobject buffer) {
+  void* buffer_start = env->GetDirectBufferAddress(buffer);
+  DCHECK(buffer_start);
+  return MojoUnmapBuffer(buffer_start);
+}
+
+bool RegisterCoreImpl(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+}  // namespace mojo