Run the metadataretriever at background priority. Bug 2187133.

This change forces metadata retreiver threads to background priority.
Uses an inner class to encapsulate the priority change so that it
automatically restores priority when returning to the client.

media/libmediaplayerservice/MetadataRetrieverClient.cpp

@@ -21,6 +21,7 @@
 
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <sys/resource.h>
 #include <dirent.h>
 #include <unistd.h>
 
@@ -38,6 +39,18 @@
 #include "MidiMetadataRetriever.h"
 #include "MetadataRetrieverClient.h"
 
+/* desktop Linux needs a little help with gettid() */
+#if defined(HAVE_GETTID) && !defined(HAVE_ANDROID_OS)
+#define __KERNEL__
+# include <linux/unistd.h>
+#ifdef _syscall0
+_syscall0(pid_t,gettid)
+#else
+pid_t gettid() { return syscall(__NR_gettid);}
+#endif
+#undef __KERNEL__
+#endif
+
 namespace android {
 
 extern player_type getPlayerType(const char* url);
@@ -212,6 +225,7 @@ sp<IMemory> MetadataRetrieverClient::captureFrame()
 {
     LOGV("captureFrame");
     Mutex::Autolock lock(mLock);
+    Priority priority(ANDROID_PRIORITY_BACKGROUND);
     mThumbnail.clear();
     mThumbnailDealer.clear();
     if (mRetriever == NULL) {
@@ -253,6 +267,7 @@ sp<IMemory> MetadataRetrieverClient::extractAlbumArt()
 {
     LOGV("extractAlbumArt");
     Mutex::Autolock lock(mLock);
+    Priority priority(ANDROID_PRIORITY_BACKGROUND);
     mAlbumArt.clear();
     mAlbumArtDealer.clear();
     if (mRetriever == NULL) {
@@ -294,7 +309,19 @@ const char* MetadataRetrieverClient::extractMetadata(int keyCode)
         LOGE("retriever is not initialized");
         return NULL;
     }
+    Priority priority(ANDROID_PRIORITY_BACKGROUND);
     return mRetriever->extractMetadata(keyCode);
 }
 
+MetadataRetrieverClient::Priority::Priority(int newPriority)
+{
+    mOldPriority = getpriority(PRIO_PROCESS, 0);
+    setpriority(PRIO_PROCESS, 0, newPriority);
+}
+
+MetadataRetrieverClient::Priority::~Priority()
+{
+    setpriority(PRIO_PROCESS, 0, mOldPriority);
+}
+
 }; // namespace android

media/libmediaplayerservice/MetadataRetrieverClient.h

@@ -54,6 +54,16 @@ public:
 private:
     friend class MediaPlayerService;
 
+    class Priority
+    {
+    public:
+        Priority(int newPriority);
+        ~Priority();
+    private:
+        Priority();
+        int         mOldPriority;
+    };
+
     explicit MetadataRetrieverClient(pid_t pid);
     virtual ~MetadataRetrieverClient();