Persist server's crypto config data to disk cache for 0-RTT

net/http/disk_cache_based_quic_server_info.cc

Index: net/http/disk_cache_based_quic_server_info.cc
diff --git a/net/http/disk_cache_based_quic_server_info.cc b/net/http/disk_cache_based_quic_server_info.cc
index aa322ab3f08079a351377e9fe4c948a6a0c025bd..6a6b41c5dcf9f636004eed75478340345e002af1 100644
--- a/net/http/disk_cache_based_quic_server_info.cc
+++ b/net/http/disk_cache_based_quic_server_info.cc
@@ -76,7 +76,8 @@ int DiskCacheBasedQuicServerInfo::WaitForDataReady(
     return OK;
 
   if (!callback.is_null()) {
-    DCHECK(user_callback_.is_null());
+    if (!user_callback_.is_null())
+      return ERR_INVALID_ARGUMENT;

[wtc, 2014/02/07 00:54:11]

Nit: we may want to use a different error code.

Can you explain why you want to allow user_callback_ to be null?

[ramant (doing other things), 2014/02/07 20:30:51]

If user_callback_ not null, then there is a pending callback. Overwriting a
previous user_callback_ with a new callback doesn't seem to be good.

Thought, if we give an error, then caller knows WaitForDataReady has failed and
can handle the error condition, instead of overwriting previous caller's
callback.

Would appreciate if you could recommend a better error code.

     user_callback_ = callback;
   }
 
@@ -85,7 +86,7 @@ int DiskCacheBasedQuicServerInfo::WaitForDataReady(
 
 void DiskCacheBasedQuicServerInfo::Persist() {
   DCHECK(CalledOnValidThread());
-  DCHECK(state_ != GET_BACKEND);
+  DCHECK_NE(state_, GET_BACKEND);
 
   DCHECK(new_data_.empty());
   CHECK(ready_);
@@ -111,6 +112,7 @@ std::string DiskCacheBasedQuicServerInfo::key() const {
 
 void DiskCacheBasedQuicServerInfo::OnIOComplete(CacheOperationDataShim* unused,
                                                 int rv) {
+  DCHECK_NE(state_, NONE);
   rv = DoLoop(rv);
   if (rv != ERR_IO_PENDING && !user_callback_.is_null()) {
     CompletionCallback callback = user_callback_;
@@ -199,6 +201,7 @@ int DiskCacheBasedQuicServerInfo::DoReadComplete(int rv) {
 
 int DiskCacheBasedQuicServerInfo::DoWriteComplete(int rv) {
   state_ = SET_DONE;
+  new_data_.clear();

[wtc, 2014/02/07 00:54:11]

Another good place to do new_data_.clear() is in DoSetDone, because we can also
go to the SET_DONE state from DoCreateOrOpenComplete.

[ramant (doing other things), 2014/02/07 20:30:51]

Done.

   return OK;
 }