Limit the total memory usage for Stream instances

content/browser/streams/stream_registry.cc

Index: content/browser/streams/stream_registry.cc
diff --git a/content/browser/streams/stream_registry.cc b/content/browser/streams/stream_registry.cc
index 39d24b39f5f7b505484a472b67a2a490892a3151..3fac83553f3a8d7a5f6e75e9b6a10ed43c9569d2 100644
--- a/content/browser/streams/stream_registry.cc
+++ b/content/browser/streams/stream_registry.cc
@@ -8,7 +8,15 @@
 
 namespace content {
 
-StreamRegistry::StreamRegistry() {
+namespace {
+// The maximum size of memory each StreamRegistry instance is allowed to use
+// for its Stream instances.
+const size_t kDefaultMaxMemoryUsage = 1024 * 1024 * 1024U;  // 1GiB
+}
+
+StreamRegistry::StreamRegistry()
+    : total_memory_usage_(0),
+      max_memory_usage_(kDefaultMaxMemoryUsage) {
 }
 
 StreamRegistry::~StreamRegistry() {
@@ -42,7 +50,35 @@ bool StreamRegistry::CloneStream(const GURL& url, const GURL& src_url) {
 
 void StreamRegistry::UnregisterStream(const GURL& url) {
   DCHECK(CalledOnValidThread());
+
+  StreamMap::iterator iter = streams_.find(url);
+  if (iter == streams_.end())
+    return;
+
+  size_t buffered_bytes = iter->second->last_total_buffered_bytes();
+  DCHECK_LE(buffered_bytes, total_memory_usage_);
+  total_memory_usage_ -= buffered_bytes;
   streams_.erase(url);
 }
 
+bool StreamRegistry::UpdateMemoryUsage(const GURL& url, size_t new_size) {
+  DCHECK(CalledOnValidThread());
+
+  StreamMap::iterator iter = streams_.find(url);
+  // A Stream must be registered with its parent registry to get memory.
+  if (iter == streams_.end())
+    return false;
+
+  size_t last_size = iter->second->last_total_buffered_bytes();
+  DCHECK_LE(last_size, total_memory_usage_);
+  size_t usage_of_others = total_memory_usage_ - last_size;
+
+  if (new_size > std::numeric_limits<size_t>::max() - usage_of_others ||
+      usage_of_others + new_size > max_memory_usage_)

[Charlie Reis, 2013/08/20 22:24:52]

nit: Please change the second half of the check to look more like the first
(i.e., new_size > max_memory_usage_ - usage_of_others).

Why do we need both checks?  Should we just be comparing against
kDefaultMaxMemoryUsage in all the places of this CL rather than max(), or is
there a reason to let things go up to max() in some places?

[tyoshino (SeeGerritForStatus), 2013/08/21 05:37:28]

Oh.. right. Removed numeric_limits check from Stream and StreamRegistry.

+    return false;
+
+  total_memory_usage_ = usage_of_others + new_size;
+  return true;
+}
+
 }  // namespace content