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..e2750d4f3ac3a2aba892a53fb98694606f6ddd1c 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 uint64 kDefaultMaxMemoryUsage = 1024 * 1024 * 1024U;  // 1GiB
+}
+
+StreamRegistry::StreamRegistry()
+    : total_memory_usage_(0),
+      max_memory_usage_(kDefaultMaxMemoryUsage) {
 }
 
 StreamRegistry::~StreamRegistry() {
@@ -42,7 +50,33 @@ 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;
+
+  total_memory_usage_ -= iter->second->last_total_buffered_bytes();

[kinuko, 2013/08/14 09:32:23]

Can we DCHECK this doesn't make total_memory_usage < 0 ?

[tyoshino (SeeGerritForStatus), 2013/08/15 04:15:33]

Done.

   streams_.erase(url);
 }
 
+bool StreamRegistry::CanIncreaseMemoryUsage(
+    const GURL& url, size_t last_size, 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;
+
+  DCHECK_LE(last_size, total_memory_usage_);
+  size_t usage_of_others = total_memory_usage_ - last_size;
+
+  if (std::numeric_limits<size_t>::max() - usage_of_others < new_size ||
+      max_memory_usage_ < usage_of_others + new_size)
+    return false;
+
+  total_memory_usage_ = usage_of_others + new_size;
+  return true;
+}
+
 }  // namespace content