Limit the total memory usage for Stream instances

content/browser/streams/stream_registry.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/streams/stream_registry.h"
 
 #include "content/browser/streams/stream.h"
 
 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() {
 }
 
 void StreamRegistry::RegisterStream(scoped_refptr<Stream> stream) {
   DCHECK(CalledOnValidThread());
   DCHECK(stream.get());
   DCHECK(!stream->url().is_empty());
   streams_[stream->url()] = stream;
@@ skipping 13 matching lines @@
   scoped_refptr<Stream> stream(GetStream(src_url));
   if (stream.get()) {
     streams_[url] = stream;
     return true;
   }
   return false;
 }
 
 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();
   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;

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

nit: using iter->second->last_total_buffered_bytes() for last_size  may feel
slightly more consistent with UnregisterStream.

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

I wondered if either way is better. OK, I'll do so.

Also updated method description and renamed method name to reflect current
implementation.

+
+  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