RFC: use some in-memory state in SimpleCache to quickly cache-miss some CantConditionalize cases

net/disk_cache/simple/simple_entry_impl.cc

Index: net/disk_cache/simple/simple_entry_impl.cc
diff --git a/net/disk_cache/simple/simple_entry_impl.cc b/net/disk_cache/simple/simple_entry_impl.cc
index afc18852a30f360778f51326459102dec6d7be94..8536ccec11816f3f640699a05f9fc12b31bfa0bf 100644
--- a/net/disk_cache/simple/simple_entry_impl.cc
+++ b/net/disk_cache/simple/simple_entry_impl.cc
@@ -205,6 +205,7 @@ void SimpleEntryImpl::SetActiveEntryProxy(
 }
 
 int SimpleEntryImpl::OpenEntry(Entry** out_entry,
+                               const Backend::OracleCallback& oracle,
                                const CompletionCallback& callback) {
   DCHECK(backend_.get());
 
@@ -219,8 +220,9 @@ int SimpleEntryImpl::OpenEntry(Entry** out_entry,
     INDEX_MAX = 3,
   };
   OpenEntryIndexEnum open_entry_index_enum = INDEX_NOEXIST;
+  uint8_t oracle_byte = 0;
   if (have_index) {
-    if (backend_->index()->Has(entry_hash_))
+    if (backend_->index()->HasWithOracleByte(entry_hash_, &oracle_byte))
       open_entry_index_enum = INDEX_HIT;
     else
       open_entry_index_enum = INDEX_MISS;
@@ -229,6 +231,14 @@ int SimpleEntryImpl::OpenEntry(Entry** out_entry,
                    "OpenEntryIndexState", cache_type_,
                    open_entry_index_enum, INDEX_MAX);
 
+  if (open_entry_index_enum == INDEX_HIT && !oracle.is_null() &&
+      oracle.Run(oracle_byte) == Backend::OracleJudgement::MISS_AND_DOOM) {
+    // ### UMA this.
+    // ### net log.
+    Doom();
+    return net::ERR_FAILED;
+  }
+
   // If entry is not known to the index, initiate fast failover to the network.
   if (open_entry_index_enum == INDEX_MISS) {
     net_log_.AddEventWithNetErrorCode(
@@ -1363,6 +1373,13 @@ void SimpleEntryImpl::UpdateDataFromEntryStat(
   }
 }
 
+void SimpleEntryImpl::SetOracleByte(uint8_t oracle_byte) {
+  DCHECK(io_thread_checker_.CalledOnValidThread());
+  if (!doomed_ && backend_.get()) {
+    backend_->index()->UpdateEntryOracleByte(entry_hash_, oracle_byte);
+  }
+}
+
 int64_t SimpleEntryImpl::GetDiskUsage() const {
   int64_t file_size = 0;
   for (int i = 0; i < kSimpleEntryStreamCount; ++i) {