1 files changed, 84 insertions, 0 deletions
diff --git a/media/libstagefright/ThrottledSource.cpp b/media/libstagefright/ThrottledSource.cpp
new file mode 100644
index 0000000..b1fcafd
--- /dev/null
+++ b/media/libstagefright/ThrottledSource.cpp
@@ -0,0 +1,84 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "include/ThrottledSource.h"
+
+#include <media/stagefright/foundation/ADebug.h>
+
+namespace android {
+
+static int64_t getNowUs() {
+    struct timeval tv;
+    gettimeofday(&tv, NULL);
+
+    return (int64_t)tv.tv_usec + tv.tv_sec * 1000000ll;
+}
+
+ThrottledSource::ThrottledSource(
+        const sp<DataSource> &source,
+        int32_t bandwidthLimitBytesPerSecond)
+    : mSource(source),
+      mBandwidthLimitBytesPerSecond(bandwidthLimitBytesPerSecond),
+      mStartTimeUs(-1),
+      mTotalTransferred(0) {
+    CHECK(mBandwidthLimitBytesPerSecond > 0);
+}
+
+status_t ThrottledSource::initCheck() const {
+    return mSource->initCheck();
+}
+
+ssize_t ThrottledSource::readAt(off64_t offset, void *data, size_t size) {
+    Mutex::Autolock autoLock(mLock);
+
+    ssize_t n = mSource->readAt(offset, data, size);
+
+    if (n <= 0) {
+        return n;
+    }
+
+    mTotalTransferred += n;
+
+    int64_t nowUs = getNowUs();
+
+    if (mStartTimeUs < 0) {
+        mStartTimeUs = nowUs;
+    }
+
+    // How long would it have taken to transfer everything we ever
+    // transferred given the limited bandwidth.
+    int64_t durationUs =
+        mTotalTransferred * 1000000ll / mBandwidthLimitBytesPerSecond;
+
+    int64_t whenUs = mStartTimeUs + durationUs;
+
+    if (whenUs > nowUs) {
+        usleep(whenUs - nowUs);
+    }
+
+    return n;
+}
+
+status_t ThrottledSource::getSize(off64_t *size) {
+    return mSource->getSize(size);
+}
+
+uint32_t ThrottledSource::flags() {
+    return mSource->flags();
+}
+
+}  // namespace android
+