Limit exponential backoff for broken alternative services.

net/http/http_server_properties_impl.cc

Index: net/http/http_server_properties_impl.cc
diff --git a/net/http/http_server_properties_impl.cc b/net/http/http_server_properties_impl.cc
index f0489c8698671be4b62107d75724afec2fc16a8d..4a4139a0b97e325038bffbc1d4cc6e572c2a1d05 100644
--- a/net/http/http_server_properties_impl.cc
+++ b/net/http/http_server_properties_impl.cc
@@ -23,7 +23,9 @@ namespace net {
 
 namespace {
 
+// kBrokenAlternativeProtocolDelaySecs << (kBrokenDelayMaxShift - 1) ~ 2 days.
 const uint64_t kBrokenAlternativeProtocolDelaySecs = 300;
+const int kBrokenDelayMaxShift = 10;
 
 }  // namespace
 
@@ -472,7 +474,9 @@ void HttpServerPropertiesImpl::MarkAlternativeServiceBroken(
     LOG(DFATAL) << "Trying to mark unknown alternate protocol broken.";
     return;
   }
-  int count = ++recently_broken_alternative_services_[alternative_service];
+  int& count = recently_broken_alternative_services_[alternative_service];
+  if (count < kBrokenDelayMaxShift)
+    ++count;

[Zhongyi Shi, 2016/11/02 20:17:58]

What if the count >= kBrokenDelayMaxShift? I think you might want to then set
the count = kBrokenDelayMaxShift + 1 (note the shift is actually count - 1) to
limit the shift not beyond the range. That also suggests to rename the variable
from count to shift. 

[Bence, 2016/11/07 20:17:24]

Done.

   base::TimeDelta delay =
       base::TimeDelta::FromSeconds(kBrokenAlternativeProtocolDelaySecs);
   base::TimeTicks when = base::TimeTicks::Now() + delay * (1 << (count - 1));