oint("/data/zygote.blcr");
registerZygoteSocket();
其中CheckPoint 类是c扩展的java调用接口，通过jni调用checkpoint库函数实现checkpoint动作，下文列出了jni部分内容。该部分仅为一个参考模板，产品化过程应该做更多异常处理和合理化调整工作。
android_blcr_checkpoint.cpp
#define LOG_TAG "BLCR"
namespace android {
static int my_callback(void* arg)
{
int rc;
LOGV(__FUNCTION__);
rc = cr_checkpoint(0);
return 0;
}
static void checkPoint(JNIEnv* env, jobject object,jstring file) {
LOGV(__FUNCTION__);
pid_t my_pid;
int rc,fd;
struct stat s;
cr_checkpoint_handle_t my_handle;
cr_callback_id_t cb_id;
FILE *f;
const jchar* str = env->GetStringCritical(file, 0);
String8 filename;
if (str) {
filename = String8(str, env->GetStringLength(file));
env->ReleaseStringCritical(file, str);
}
else {
LOGE("checkPoint,file name is null");
return;
}
LOGI("checkPoint,filename=%s",filename);
//does the file exist
f = fopen(filename, "r");
if(f==NULL) //create and save checkpoint to it.
{
my_pid = cr_init();
if(my_pid<0)
{
LOGE("cr_init failed,return:%d",my_pid);
return;
}
cb_id = cr_register_callback(my_callback, NULL, CR_SIGNAL_CONTEXT);
if (cb_id < 0)
{
LOGV("cr_register_callback() unexpectedly returned %d\n", cb_id);
return;
}
else
{
LOGV("cr_register_callback() correctly returned %d\n", cb_id);
}
/* Request a checkpoint of ourself */
fd = crut_checkpoint_request(&my_handle, filename);
if (fd < 0)
{
LOGE("crut_checkpoint_request() unexpectedly returned 0x%x\n", fd);
return ;
}
rc = stat(filename, &s);
if (rc) {
LOGE("stat() unexpectedly returned %d\n", rc);
return;
} else {
LOGV("stat(context.%d) correctly returned 0\n", my_pid);
}
if (s.st_size == 0) {
LOGE("context file unexpectedly empty\n");
return;
} else {
LOGV("context.%d is non-empty\n", my_pid);
}
/* Reap the checkpoint request */
rc = crut_checkpoint_wait(&my_handle, fd);
if (rc < 0) {
LOGE("crut_checkpoint_wait() #1 unexpectedly returned 0x%x\n", rc);
return;
} }}
/*
* JNI registration.
*/
static JNINativeMethod gMethods[] = {
/* name, signature, funcPtr */
{"checkPoint", "(Ljava/lang/String;)V", (void *)checkPoint},
};
int register_android_blcr_checkpoint(JNIEnv* env)
{
return jniRegisterNativeMethods(env, "android/blcr/CheckPoint",
gMethods, NELEM(gMethods));
}
}
为了正常使用上面的jni接口，需要把注册函数注册到frameworks/base/core/jni/ AndroidRuntime.cpp，在gRegJNI[]中加入REG_JNI(register_android_blcr_checkpoint)。同时创建CheckPoint.java 文件提供给java调用：
package android.blcr;
public class CheckPoint {
public CheckPoint() {
}
public native void checkPoint(String fileName);
}
正常启动blcr还需要修改init.rc，调整启动zygote的方式。修改点包括载人blcr内核驱动：
insmod /system/lib/modules/blcr_imports.ko
insmod /system/lib/modules/blcr.ko
和启动blcr服务方式，将
service zygote /system/bin/app_process -Xzygote /system/bin --zygote --start-system-server
替换为：service zygote /system/bin/quick.sh -Xzygote /system/bin --zygote --start-system-server
其中quick.sh脚本内容为：
#!/system/b