DNS: Per-network-type and Finch-variable timeouts

net/dns/dns_util.cc

 // Copyright (c) 2011 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 "net/dns/dns_util.h"
 
 #include <errno.h>
 #include <limits.h>
 
 #include <cstring>
 
+#include "base/metrics/field_trial.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/string_split.h"
 #include "build/build_config.h"
 
 #if defined(OS_POSIX)
 #include <netinet/in.h>
 #if !defined(OS_NACL)
 #include <net/if.h>
 #if !defined(OS_ANDROID)
 #include <ifaddrs.h>
 #endif  // !defined(OS_ANDROID)
 #endif  // !defined(OS_NACL)
@@ skipping 123 matching lines @@
 #elif defined(OS_WIN)
   // TODO(wtc): implement with the GetAdaptersAddresses function.
   NOTIMPLEMENTED();
   return false;
 #else
   NOTIMPLEMENTED();
   return false;
 #endif  // defined(various platforms)
 }
 
+#if !defined(OS_NACL)
+namespace {
+
+bool GetTimeDeltaForConnectionTypeFromFieldTrial(
+    const char* field_trial,
+    NetworkChangeNotifier::ConnectionType type_int,

[Randy Smith (Not in Mondays), 2016/03/15 20:12:30]

I mildly object to the naming; other variables of this type are just named
"type", and type"int is in relation to the unusual thing done below (the size_t
version), so I'd rather see that unusual variation named something unusual.

[Deprecated (see juliatuttle), 2016/03/16 16:45:30]

Done.

+    base::TimeDelta* out) {
+  std::string group = base::FieldTrialList::FindFullName(field_trial);
+  std::vector<base::StringPiece> group_parts = base::SplitStringPiece(
+      group, ":", base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
+  if (type_int < 0)
+    return false;
+  size_t type = static_cast<size_t>(type_int);
+  if (type >= group_parts.size())
+    return false;

[Randy Smith (Not in Mondays), 2016/03/15 20:12:30]

Will this catch the case when the field trial isn't set at all?  I'd expect
(haven't checked) group to be the null string in that case, and I'd expect
(haven't checked) SplitStringPiece to return a single entry, so I'd expect a
type of 0 to work when it shoudln't.

[Deprecated (see juliatuttle), 2016/03/16 16:45:30]

Technically, I think StringToInt64 would then fail, but I don't think that's a
proper way to handle it. I'll add a specific check on group at the top.

+  int64_t ms;
+  if (!base::StringToInt64(group_parts[type], &ms))
+    return false;
+  *out = base::TimeDelta::FromMilliseconds(ms);
+  return true;
+}
+
+}  // namespace
+
+base::TimeDelta GetTimeDeltaForConnectionTypeFromFieldTrialOrDefault(
+    const char* field_trial,
+    base::TimeDelta default_delta,
+    NetworkChangeNotifier::ConnectionType type) {
+  base::TimeDelta out;
+  if (!GetTimeDeltaForConnectionTypeFromFieldTrial(field_trial, type, &out))
+    out = default_delta;
+  return out;
+}
+#endif  // !defined(OS_NACL)
+
 }  // namespace net