Fix for b/4165024: Serious Memory leak when playing a WV protected streaming video.

This change allows the WVM extractor to close and reopen when not in use which resolves
the issue with heap fragmentation between plays.

Change-Id: I160ee1e98aada2bfdd0818eeb6300ad50644fb75

media/libstagefright/WVMExtractor.cpp

@@ -33,26 +33,25 @@
 
 #include <utils/Errors.h>
 
-/* The extractor lifetime is short - just long enough to get
- * the media sources constructed - so the shared lib needs to remain open
- * beyond the lifetime of the extractor.  So keep the handle as a global
- * rather than a member of the extractor
- */
-void *gVendorLibHandle = NULL;
-
 namespace android {
 
-static Mutex gWVMutex;
+Mutex WVMExtractor::sMutex;
+uint32_t WVMExtractor::sActiveExtractors = 0;
+void *WVMExtractor::sVendorLibHandle = NULL;
 
 WVMExtractor::WVMExtractor(const sp<DataSource> &source)
     : mDataSource(source) {
     {
-        Mutex::Autolock autoLock(gWVMutex);
-        if (gVendorLibHandle == NULL) {
-            gVendorLibHandle = dlopen("libwvm.so", RTLD_NOW);
+        Mutex::Autolock autoLock(sMutex);
+
+        if (sVendorLibHandle == NULL) {
+            CHECK(sActiveExtractors == 0);
+            sVendorLibHandle = dlopen("libwvm.so", RTLD_NOW);
         }
 
-        if (gVendorLibHandle == NULL) {
+        sActiveExtractors++;
+
+        if (sVendorLibHandle == NULL) {
             LOGE("Failed to open libwvm.so");
             return;
         }
@@ -60,7 +59,7 @@ WVMExtractor::WVMExtractor(const sp<DataSource> &source)
 
     typedef WVMLoadableExtractor *(*GetInstanceFunc)(sp<DataSource>);
     GetInstanceFunc getInstanceFunc =
-        (GetInstanceFunc) dlsym(gVendorLibHandle,
+        (GetInstanceFunc) dlsym(sVendorLibHandle,
                 "_ZN7android11GetInstanceENS_2spINS_10DataSourceEEE");
 
     if (getInstanceFunc) {
@@ -72,6 +71,17 @@ WVMExtractor::WVMExtractor(const sp<DataSource> &source)
 }
 
 WVMExtractor::~WVMExtractor() {
+    Mutex::Autolock autoLock(sMutex);
+
+    CHECK(sActiveExtractors > 0);
+    sActiveExtractors--;
+
+    // Close lib after last use
+    if (sActiveExtractors == 0) {
+        if (sVendorLibHandle != NULL)
+            dlclose(sVendorLibHandle);
+        sVendorLibHandle = NULL;
+    }
 }
 
 size_t WVMExtractor::countTracks() {

media/libstagefright/include/WVMExtractor.h

@@ -18,6 +18,7 @@
 
 #define WVM_EXTRACTOR_H_
 
+#include <media/stagefright/DataSource.h>
 #include <media/stagefright/MediaExtractor.h>
 #include <utils/Errors.h>
 
@@ -67,6 +68,10 @@ private:
 
     WVMExtractor(const WVMExtractor &);
     WVMExtractor &operator=(const WVMExtractor &);
+
+    static Mutex sMutex;
+    static uint32_t sActiveExtractors;
+    static void *sVendorLibHandle;
 };
 
 }  // namespace android