Make MediaScanner skip certain directories

The list of directories to skip are configurable via setprop.
The main motivation is that some test data folder takes long time
to scan, and media scanner may compete for CPU time against perf
tests therefore skewing the results.

Bug: 5263115
Change-Id: I568213e2a4babf6033021c1d336ef0347c0e3315

1 files changed, 59 insertions, 1 deletions

diff --git a/media/libmedia/MediaScanner.cpp b/media/libmedia/MediaScanner.cpp
index 41f8593..19dedfc 100644
--- a/media/libmedia/MediaScanner.cpp
+++ b/media/libmedia/MediaScanner.cpp
@@ -16,6 +16,7 @@
 
 //#define LOG_NDEBUG 0
 #define LOG_TAG "MediaScanner"
+#include <cutils/properties.h>
 #include <utils/Log.h>
 
 #include <media/mediascanner.h>
@@ -26,11 +27,14 @@
 namespace android {
 
 MediaScanner::MediaScanner()
-    : mLocale(NULL) {
+    : mLocale(NULL), mSkipList(NULL), mSkipIndex(NULL) {
+    loadSkipList();
 }
 
 MediaScanner::~MediaScanner() {
     setLocale(NULL);
+    free(mSkipList);
+    free(mSkipIndex);
 }
 
 void MediaScanner::setLocale(const char *locale) {
@@ -47,6 +51,33 @@ const char *MediaScanner::locale() const {
     return mLocale;
 }
 
+void MediaScanner::loadSkipList() {
+    mSkipList = (char *)malloc(PROPERTY_VALUE_MAX * sizeof(char));
+    if (mSkipList) {
+      property_get("testing.mediascanner.skiplist", mSkipList, "");
+    }
+    if (!mSkipList || (strlen(mSkipList) == 0)) {
+        free(mSkipList);
+        mSkipList = NULL;
+        return;
+    }
+    mSkipIndex = (int *)malloc(PROPERTY_VALUE_MAX * sizeof(int));
+    if (mSkipIndex) {
+        // dup it because strtok will modify the string
+        char *skipList = strdup(mSkipList);
+        if (skipList) {
+            char * path = strtok(skipList, ",");
+            int i = 0;
+            while (path) {
+                mSkipIndex[i++] = strlen(path);
+                path = strtok(NULL, ",");
+            }
+            mSkipIndex[i] = -1;
+            free(skipList);
+        }
+    }
+}
+
 MediaScanResult MediaScanner::processDirectory(
         const char *path, MediaScannerClient &client) {
     int pathLength = strlen(path);
@@ -75,12 +106,39 @@ MediaScanResult MediaScanner::processDirectory(
     return result;
 }
 
+bool MediaScanner::shouldSkipDirectory(char *path) {
+    if (path && mSkipList && mSkipIndex) {
+        int len = strlen(path);
+        int idx = 0;
+        // track the start position of next path in the comma
+        // separated list obtained from getprop
+        int startPos = 0;
+        while (mSkipIndex[idx] != -1) {
+            // no point to match path name if strlen mismatch
+            if ((len == mSkipIndex[idx])
+                // pick out the path segment from comma separated list
+                // to compare against current path parameter
+                && (strncmp(path, &mSkipList[startPos], len) == 0)) {
+                return true;
+            }
+            startPos += mSkipIndex[idx] + 1; // extra char for the delimiter
+            idx++;
+        }
+    }
+    return false;
+}
+
 MediaScanResult MediaScanner::doProcessDirectory(
         char *path, int pathRemaining, MediaScannerClient &client, bool noMedia) {
     // place to copy file or directory name
     char* fileSpot = path + strlen(path);
     struct dirent* entry;
 
+    if (shouldSkipDirectory(path)) {
+      LOGD("Skipping: %s", path);
+      return MEDIA_SCAN_RESULT_OK;
+    }
+
     // Treat all files as non-media in directories that contain a  ".nomedia" file
     if (pathRemaining >= 8 /* strlen(".nomedia") */ ) {
         strcpy(fileSpot, ".nomedia");