From a4867540534568e3fbd06e142c62834b2bde8834 Mon Sep 17 00:00:00 2001
From: Andreas Huber <andih@google.com>
Date: Tue, 22 Jun 2010 08:57:34 -0700
Subject: [PATCH] Make the prefetcher read packets from the network after a
 keep-alive timeout expires regardless of whether its currently actively
 fetching data or not.

Change-Id: I7d022ac494e1cecdd7f656806b7ed45979c02840
---
 media/libstagefright/NuCachedSource2.cpp       | 18 +++++++++++++++---
 media/libstagefright/include/NuCachedSource2.h | 11 ++++++++---
 2 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/media/libstagefright/NuCachedSource2.cpp b/media/libstagefright/NuCachedSource2.cpp
index f29e7fb180050..c02b7f3c4e7f9 100644
--- a/media/libstagefright/NuCachedSource2.cpp
+++ b/media/libstagefright/NuCachedSource2.cpp
@@ -178,7 +178,8 @@ NuCachedSource2::NuCachedSource2(const sp<DataSource> &source)
       mCacheOffset(0),
       mFinalStatus(OK),
       mLastAccessPos(0),
-      mFetching(true) {
+      mFetching(true),
+      mLastFetchTimeUs(-1) {
     mLooper->registerHandler(mReflector);
     mLooper->start();
 
@@ -259,10 +260,21 @@ void NuCachedSource2::onFetch() {
         mFetching = false;
     }
 
-    if (mFetching) {
+    bool keepAlive =
+        !mFetching
+            && mFinalStatus == OK
+            && ALooper::GetNowUs() >= mLastFetchTimeUs + kKeepAliveIntervalUs;
+
+    if (mFetching || keepAlive) {
+        if (keepAlive) {
+            LOG(INFO) << "Keep alive";
+        }
+
         fetchInternal();
 
-        if (mCache->totalSize() >= kHighWaterThreshold) {
+        mLastFetchTimeUs = ALooper::GetNowUs();
+
+        if (mFetching && mCache->totalSize() >= kHighWaterThreshold) {
             LOG(INFO) << "Cache full, done prefetching for now";
             mFetching = false;
         }
diff --git a/media/libstagefright/include/NuCachedSource2.h b/media/libstagefright/include/NuCachedSource2.h
index c30f02999b1c4..f73e837a2b2f2 100644
--- a/media/libstagefright/include/NuCachedSource2.h
+++ b/media/libstagefright/include/NuCachedSource2.h
@@ -49,9 +49,13 @@ private:
     friend struct AHandlerReflector<NuCachedSource2>;
 
     enum {
-        kPageSize           = 16384,
-        kHighWaterThreshold = 3 * 1024 * 1024,
-        kLowWaterThreshold  = 512 * 1024,
+        kPageSize            = 16384,
+        kHighWaterThreshold  = 3 * 1024 * 1024,
+        kLowWaterThreshold   = 512 * 1024,
+
+        // Read data after a 15 sec timeout whether we're actively
+        // fetching or not.
+        kKeepAliveIntervalUs = 15000000,
     };
 
     enum {
@@ -73,6 +77,7 @@ private:
     off_t mLastAccessPos;
     sp<AMessage> mAsyncResult;
     bool mFetching;
+    int64_t mLastFetchTimeUs;
 
     void onMessageReceived(const sp<AMessage> &msg);
     void onFetch();