In Art, DexClassLoader converts dex to the oat file format. dexclassloaderoat

In Art, DexClassLoader converts dex to the oat file format. dexclassloaderoat

After reading the source code DexClassLoader, the native function openDexFileNative in the DexFile class will be called.

Next let's take a look at what the openDexFileNative function has done.

The openDexFileNative function exports the openDexFileNative symbol in the code in the art \ runtime \ native \ dalvik_system_DexFile.cc file.

static JNINativeMethod gMethods[] = {  NATIVE_METHOD(DexFile, closeDexFile, "(I)V"),  NATIVE_METHOD(DexFile, defineClassNative, "(Ljava/lang/String;Ljava/lang/ClassLoader;I)Ljava/lang/Class;"),  NATIVE_METHOD(DexFile, getClassNameList, "(I)[Ljava/lang/String;"),  NATIVE_METHOD(DexFile, isDexOptNeeded, "(Ljava/lang/String;)Z"),  NATIVE_METHOD(DexFile, openDexFileNative, "(Ljava/lang/String;Ljava/lang/String;I)I"),};

By observing the global variables above, we can find that the function represented by openDexFileNative is DexFile_openDexFileNative.

In the DexFile_openDexFileNative function, call the DexFile: GetChecksum function to obtain the checksum of the zip or dex file. If the checksum is obtained, the checksum is saved in the local variable dex_location_checksum.

DexFile::GetChecksum(dex_location, &dex_location_checksum)

If outputName is not NULL, the following code is executed to convert dex to oat.

std::string oat_location(outputName.c_str());dex_file = linker->FindOrCreateOatFileForDexLocation(dex_location, dex_location_checksum, oat_location);

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The FindOrCreateOatFileForDexLocation function is a member function of the ClassLinker class. Let's take a look at what the FindOrCreateOatFileForDexLocation function has done.

The ClassLinker: FindOrCreateOatFileForDexLocation function calls the ClassLinker: FindOrCreateOatFileForDexLocationLocked function.

return FindOrCreateOatFileForDexLocationLocked(dex_location, dex_location_checksum, oat_location);

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ClassLinker: In the FindOrCreateOatFileForDexLocationLocked function.

You can call the ClassLinker: FindDexFileInOatLocation function to determine whether the dex file has been optimized to an oat file.

// Check if we already have an up-to-date output fileconst DexFile* dex_file = FindDexFileInOatLocation(dex_location,                                                     dex_location_checksum,                                                     oat_location);

If dex is not optimized to an oat file, call the ClassLinker: GenerateOatFile function to convert dex to oat.

GenerateOatFile(dex_location, scoped_flock.GetFile().Fd(), oat_location)

In the ClassLinker: GenerateOatFile function, fork is a sub-process. In the sub-process, dex2oat is called to convert dex to oat, and the parent process waits until the sub-process stops running.

// fork and exec dex2oatpid_t pid = fork();

    execl(dex2oat, dex2oat,          "--runtime-arg", "-Xms64m",          "--runtime-arg", "-Xmx64m",          "--runtime-arg", "-classpath",          "--runtime-arg", class_path,          "--runtime-arg", oat_compiler_filter_option,#if !defined(ART_TARGET)          "--host",#endif          boot_image_option,          dex_file_option,          oat_fd_option,          oat_location_option,          NULL);

After the ClassLinker: GenerateOatFile function is executed, the oat_dex_file-> OpenDexFile () function is called to open the dex file in the memory.

const DexFile* result = oat_dex_file->OpenDexFile();

So far, the conversion from dex to oat has been completed.

What is comhtcautotestdlibRecordEngine in loader dalviksystemDexClassLoader @ 406bcc98?

Com. htc. autotest. dlib is a bit like a java package. You can find a file in this directory.