SimpleCache: open with fewer seeks.

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 48063f7817f7919d15f1dcba8574025fdd4e17d2..5d960a1cfa30f6df4fad731c06ae52c0fb978101 100644
--- a/net/disk_cache/simple/simple_entry_impl.cc
+++ b/net/disk_cache/simple/simple_entry_impl.cc
@@ -696,19 +696,13 @@ void SimpleEntryImpl::OpenEntryInternal(bool have_index,
   std::unique_ptr<SimpleEntryCreationResults> results(
       new SimpleEntryCreationResults(SimpleEntryStat(
           last_used_, last_modified_, data_size_, sparse_data_size_)));
-  Closure task = base::Bind(&SimpleSynchronousEntry::OpenEntry,
-                            cache_type_,
-                            path_,
-                            entry_hash_,
-                            have_index,
-                            results.get());
-  Closure reply = base::Bind(&SimpleEntryImpl::CreationOperationComplete,
-                             this,
-                             callback,
-                             start_time,
-                             base::Passed(&results),
-                             out_entry,
-                             net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_OPEN_END);
+  Closure task =
+      base::Bind(&SimpleSynchronousEntry::OpenEntry, cache_type_, path_, key_,
+                 entry_hash_, have_index, results.get());
+  Closure reply =
+      base::Bind(&SimpleEntryImpl::CreationOperationComplete, this, callback,
+                 start_time, base::Passed(&results), out_entry,
+                 net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_OPEN_END);
   worker_pool_->PostTaskAndReply(FROM_HERE, task, reply);
 }
 
@@ -1147,13 +1141,8 @@ void SimpleEntryImpl::CreationOperationComplete(
     crc32s_[0] = in_results->stream_0_crc32;
     crc32s_end_offset_[0] = in_results->entry_stat.data_size(0);
   }
-  if (key_.empty()) {

[Randy Smith (Not in Mondays), 2016/05/17 20:04:07]

It's not really part of this CL, but I'd value having more documentation on
SimpleEntryImpl about when it can or can't have a key_ and how its behavior
changes in those cases.  Up to you whether to do that while you're here, but
it's not obvious reading the code that key_ (as set through SetKey()) is an
optional useful addition to the SEI).  

[gavinp, 2016/05/18 15:46:00]

Done.

+  if (key_.empty())
     SetKey(synchronous_entry_->key());
-  } else {
-    // This should only be triggered when creating an entry. The key check in
-    // the open case is handled in SimpleBackendImpl.
-    DCHECK_EQ(key_, synchronous_entry_->key());
-  }
   UpdateDataFromEntryStat(in_results->entry_stat);
   SIMPLE_CACHE_UMA(TIMES,
                    "EntryCreationTime", cache_type_,
@@ -1403,7 +1392,7 @@ int64_t SimpleEntryImpl::GetDiskUsage() const {
   int64_t file_size = 0;
   for (int i = 0; i < kSimpleEntryStreamCount; ++i) {
     file_size +=
-        simple_util::GetFileSizeFromKeyAndDataSize(key_, data_size_[i]);
+        simple_util::GetFileSizeFromDataSize(key_.size(), data_size_[i]);
   }
   file_size += sparse_data_size_;
   return file_size;