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cedricfungcedricfung
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Use Binder and ashmem to share memory
1 parent 74c3ca2 commit e475f07

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7 files changed

+224
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7 files changed

+224
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‎.syntastic_cpp_config

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-Ijni
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-Ijni/android/include/system/core/include
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-Ijni/android/include/frameworks/native/include

‎jni/Android.mk

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LOCAL_PATH := $(call my-dir)
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include $(CLEAR_VARS)
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ANDROID_INCLUDE := $(LOCAL_PATH)/android/include
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ANDROID_LIB := $(LOCAL_PATH)/android/lib
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LOCAL_CFLAGS += -DHAVE_PTHREADS -DHAVE_SYS_UIO_H
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LOCAL_C_INCLUDES += $(ANDROID_INCLUDE)/system/core/include
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LOCAL_C_INCLUDES += $(ANDROID_INCLUDE)/frameworks/native/include
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LOCAL_LDLIBS += -L$(ANDROID_LIB)
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LOCAL_LDLIBS += -llog -lutils -lbinder
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LOCAL_SRC_FILES := BinderSHM.cpp
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LOCAL_MODULE := ipc_shared
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include $(BUILD_SHARED_LIBRARY)
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include $(CLEAR_VARS)
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ANDROID_INCLUDE := $(LOCAL_PATH)/android/include
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ANDROID_LIB := $(LOCAL_PATH)/android/lib
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LOCAL_CFLAGS += -DHAVE_PTHREADS -DHAVE_SYS_UIO_H
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LOCAL_C_INCLUDES += $(ANDROID_INCLUDE)/system/core/include
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LOCAL_C_INCLUDES += $(ANDROID_INCLUDE)/frameworks/native/include
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LOCAL_LDLIBS += -L$(ANDROID_LIB)
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LOCAL_LDLIBS += -llog -lutils -lbinder
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LOCAL_SRC_FILES := BinderSHM.cpp
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LOCAL_MODULE := ipc
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include $(BUILD_EXECUTABLE)

‎jni/Application.mk

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NDK_TOOLCHAIN_VERSION=4.8
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APP_ABI := armeabi-v7a
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APP_PLATFORM := android-18
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APP_STL := stlport_static
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APP_CPPFLAGS += -fno-rtti -Wno-psabi -Wno-switch
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STLPORT_FORCE_REBUILD := false

‎jni/BinderSHM.cpp

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#include <jni.h>
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#include <sys/mman.h>
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#include <binder/IInterface.h>
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#include <binder/IBinder.h>
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#include <binder/Binder.h>
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#include <binder/ProcessState.h>
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#include <binder/IServiceManager.h>
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#include <binder/IPCThreadState.h>
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#undef LOG_TAG
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#define LOG_TAG "AndroidIPC::SHM"
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using namespace android;
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// The binder message ids
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enum {
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SET_FD = IBinder::FIRST_CALL_TRANSACTION
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};
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// The interface, binder client and server should both implement it
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class ISHM : public IInterface {
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public:
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virtual status_t setFD(uint32_t fd) = 0;
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DECLARE_META_INTERFACE(SHM);
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};
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// The client interface
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class BpSHM : public BpInterface<ISHM> {
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public:
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BpSHM(const sp<IBinder>& impl) : BpInterface<ISHM>(impl) {
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ALOGD("BpSHM::BpSHM()");
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}
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virtual status_t setFD(uint32_t fd)
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{
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ALOGD("BpSHM::setFD(%u)", fd);
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Parcel data, reply;
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data.writeInterfaceToken(ISHM::getInterfaceDescriptor());
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data.writeFileDescriptor(fd);
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remote()->transact(SET_FD, data, &reply);
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return reply.readInt32();
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}
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};
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IMPLEMENT_META_INTERFACE(SHM, "io.vec.IPC");
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// The server interface
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class BnSHM : public BnInterface<ISHM> {
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virtual status_t onTransact(uint32_t code, const Parcel& data, Parcel* reply, uint32_t flags = 0)
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{
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ALOGD("BnSHM::onTransact(%u)", code);
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CHECK_INTERFACE(IScreenComposer, data, reply);
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switch(code) {
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case SET_FD: {
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reply->writeInt32(setFD(data.readFileDescriptor()));
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return NO_ERROR;
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} break;
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default: {
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return BBinder::onTransact(code, data, reply, flags);
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} break;
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}
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}
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};
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// The server implementation
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class SHM : public BnSHM {
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public:
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status_t setFD(uint32_t fd)
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{
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ALOGD("SHM::setFD(%u)", fd);
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uint8_t *shm = (uint8_t*)mmap(NULL, 1024, PROT_WRITE | PROT_READ, MAP_SHARED, fd, 0);
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if (shm == MAP_FAILED) {
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ALOGE("mmap failed! %d, %s", errno, strerror(errno));
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return UNKNOWN_ERROR;
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}
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ALOGD("mmap %p", shm);
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// Now we can use shm to share data with Java MemoryFile.
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// For this demo, we just release it.
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munmap(shm, 1024);
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return NO_ERROR;
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}
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static void registerService()
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{
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defaultServiceManager()->addService(String16("binder_shm"), new SHM());
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}
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static sp<ISHM> getService()
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{
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sp<IBinder> binder = defaultServiceManager()->getService(String16("binder_shm"));
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return interface_cast<ISHM>(binder);
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}
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};
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// Start the server
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int main(int argc, char const* argv[])
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{
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SHM::registerService();
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android::ProcessState::self()->startThreadPool();
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ALOGI("The SHM service started!");
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IPCThreadState::self()->joinThreadPool();
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return 0;
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}
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// JNI related
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static jboolean jni_setMemoryFile(JNIEnv* env, jclass clz, jobject jmf)
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{
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jclass clsMF = env->FindClass("android/os/MemoryFile");
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jfieldID fldFD = env->GetFieldID(clsMF, "mFD", "Ljava/io/FileDescriptor;");
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jobject objFD = env->GetObjectField(jmf, fldFD);
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jclass clsFD = env->FindClass("java/io/FileDescriptor");
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fldFD = env->GetFieldID(clsFD, "descriptor", "I");
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jint fd = env->GetIntField(objFD, fldFD);
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env->DeleteLocalRef(clsFD);
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env->DeleteLocalRef(objFD);
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env->DeleteLocalRef(clsMF);
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ALOGD("jni_setMemoryFile(%d)", fd);
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sp<ISHM> service = SHM::getService();
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return (service->setFD(fd) == NO_ERROR);
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}
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JNINativeMethod jniMethods[1] = {
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{ "setMemoryFile", "(Landroid/os/MemoryFile;)Z", (void*)jni_setMemoryFile },
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};
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jint JNI_OnLoad(JavaVM* vm, void* reserved)
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{
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JNIEnv* env;
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if (vm->GetEnv(reinterpret_cast<void**>(&env), JNI_VERSION_1_6) != JNI_OK) {
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return -1;
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}
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jclass clz = env->FindClass("io/vec/demo/android/ipc/IPC");
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env->RegisterNatives(clz, jniMethods, sizeof(jniMethods) / sizeof(JNINativeMethod));
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env->DeleteLocalRef(clz);
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return JNI_VERSION_1_6;
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}

‎jni/android/lib/libcutils.so

-53.2 KB
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‎src/io/vec/demo/android/ipc/IPC.java

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package io.vec.demo.android.ipc;
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import android.os.MemoryFile;
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public class IPC {
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public static native boolean setMemoryFile(MemoryFile mfs);
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static {
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System.loadLibrary("ipc_shared");
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}
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}

‎src/io/vec/demo/android/ipc/MainActivity.java

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package io.vec.demo.android.ipc;
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import android.os.Bundle;
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import java.io.IOException;
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import android.app.Activity;
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import android.os.Bundle;
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import android.os.MemoryFile;
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import android.util.Log;
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import android.view.Menu;
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public class MainActivity extends Activity {
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protected void onCreate(Bundle savedInstanceState) {
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super.onCreate(savedInstanceState);
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setContentView(R.layout.activity_main);
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try {
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MemoryFile mf = new MemoryFile("shm-demo", 1024);
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boolean ipcStatus = IPC.setMemoryFile(mf);
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Log.i("AndroidIPC::SHM", "IPC.setMemoryFile " + ipcStatus);
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mf.close();
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} catch (IOException e) {
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e.printStackTrace();
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}
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}
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@Override
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public boolean onCreateOptionsMenu(Menu menu) {
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// Inflate the menu; this adds items to the action bar if it is present.
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getMenuInflater().inflate(R.menu.main, menu);
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return true;
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}

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