[MTK] 如何在android native code 打callstack

[DESCRIPTION]

 分析native代码流程相关问题时可以用如下方式打出调用栈，适用于Android P及以上

[SOLUTION]

三个步骤

1.找到你需要添加callstack的源代码所在的Android.bp文件

frameworks/av/media/libmedia/Android.bp

2.在Android.bp文件中找到你需要添加callstack的源文件所对应的cc_library name，再在cc_library下面找到"header_libs"和"shared_libs" ，分别添加如下两行代码

在header_libs下面添加"libutils_headers",

在shared_libs下面添加"libutilscallstack",

3.在你需要添加callstack的源文件中引入CallStack的头文件，并在相应代码处添加log即可

#include <utils/CallStack.h>

@@ -378,6 +379,7 @@ status_t MediaPlayer::stop()
status_t MediaPlayer::pause()
{
ALOGV("pause");
+ CallStack stack("pause");

下面以在MediaPlayer.cpp代码的pause()方法和isPlaying()中加callstack为例来做说明，以下内容是git diff文件

 media/libmedia/Android.bp | 2 ++
 media/libmedia/mediaplayer.cpp | 3 +++
 2 files changed, 5 insertions(+)
 mode change 100644 => 100755 media/libmedia/mediaplayer.cpp

diff --git a/media/libmedia/Android.bp b/media/libmedia/Android.bp
index 1d335901c5..c8230645e3 100644
--- a/media/libmedia/Android.bp
+++ b/media/libmedia/Android.bp
@@ -270,6 +270,7 @@ cc_library {
 header_libs: [
 "libstagefright_headers",
 "media_ndk_headers",
+ "libutils_headers",
 ],

 export_header_lib_headers: [
@@ -283,6 +284,7 @@ cc_library {
 "libcutils",
 "libprocessgroup",
 "libutils",
+ "libutilscallstack",
 "libbinder",
 "libsonivox",
 "libandroidicu",
diff --git a/media/libmedia/mediaplayer.cpp b/media/libmedia/mediaplayer.cpp
old mode 100644
new mode 100755
index 6767bba75b..72d65e9564
--- a/media/libmedia/mediaplayer.cpp
+++ b/media/libmedia/mediaplayer.cpp
@@ -45,6 +45,7 @@

 #include <system/audio.h>
 #include <system/window.h>
+#include <utils/CallStack.h>

 namespace android {

@@ -378,6 +379,7 @@ status_t MediaPlayer::stop()
 status_t MediaPlayer::pause()
 {
 ALOGV("pause");
+ CallStack stack("pause");
 Mutex::Autolock _l(mLock);
 if (mCurrentState & (MEDIA_PLAYER_PAUSED|MEDIA_PLAYER_PLAYBACK_COMPLETE))
 return NO_ERROR;
@@ -401,6 +403,7 @@ bool MediaPlayer::isPlaying()
 bool temp = false;
 mPlayer->isPlaying(&temp);
 ALOGV("isPlaying: %d", temp);
+ CallStack stack("isPlaying");
 if ((mCurrentState & MEDIA_PLAYER_STARTED) && ! temp) {
 ALOGE("internal/external state mismatch corrected");
 mCurrentState = MEDIA_PLAYER_PAUSED;
--