Revert of Remove void** from disk_cache interface.

net/disk_cache/simple/simple_backend_impl.cc

Index: net/disk_cache/simple/simple_backend_impl.cc
diff --git a/net/disk_cache/simple/simple_backend_impl.cc b/net/disk_cache/simple/simple_backend_impl.cc
index e84211b7c8c997375969cc1835e65f7ef7d8ac86..2e165760b779f69a5807f3476e50561f7eb3d3aa 100644
--- a/net/disk_cache/simple/simple_backend_impl.cc
+++ b/net/disk_cache/simple/simple_backend_impl.cc
@@ -473,78 +473,18 @@
   return DoomEntriesBetween(initial_time, Time(), callback);
 }
 
-class SimpleBackendImpl::SimpleIterator FINAL : public Iterator {
- public:
-  explicit SimpleIterator(base::WeakPtr<SimpleBackendImpl> backend)
-      : backend_(backend),
-        weak_factory_(this) {
-  }
-
-  // From Backend::Iterator:
-  virtual int OpenNextEntry(Entry** next_entry,
-                            const CompletionCallback& callback) OVERRIDE {
-    CompletionCallback open_next_entry_impl =
-        base::Bind(&SimpleIterator::OpenNextEntryImpl,
-                   weak_factory_.GetWeakPtr(), next_entry, callback);
-    return backend_->index_->ExecuteWhenReady(open_next_entry_impl);
-  }
-
-  void OpenNextEntryImpl(Entry** next_entry,
-                         const CompletionCallback& callback,
-                         int index_initialization_error_code) {
-    if (!backend_) {
-      callback.Run(net::ERR_FAILED);
-      return;
-    }
-    if (index_initialization_error_code != net::OK) {
-      callback.Run(index_initialization_error_code);
-      return;
-    }
-    if (!hashes_to_enumerate_)
-      hashes_to_enumerate_ = backend_->index()->GetAllHashes().Pass();
-
-    while (!hashes_to_enumerate_->empty()) {
-      uint64 entry_hash = hashes_to_enumerate_->back();
-      hashes_to_enumerate_->pop_back();
-      if (backend_->index()->Has(entry_hash)) {
-        *next_entry = NULL;
-        CompletionCallback continue_iteration = base::Bind(
-            &SimpleIterator::CheckIterationReturnValue,
-            weak_factory_.GetWeakPtr(),
-            next_entry,
-            callback);
-        int error_code_open = backend_->OpenEntryFromHash(entry_hash,
-                                                          next_entry,
-                                                          continue_iteration);
-        if (error_code_open == net::ERR_IO_PENDING)
-          return;
-        if (error_code_open != net::ERR_FAILED) {
-          callback.Run(error_code_open);
-          return;
-        }
-      }
-    }
-    callback.Run(net::ERR_FAILED);
-  }
-
-  void CheckIterationReturnValue(Entry** entry,
-                                 const CompletionCallback& callback,
-                                 int error_code) {
-    if (error_code == net::ERR_FAILED) {
-      OpenNextEntry(entry, callback);
-      return;
-    }
-    callback.Run(error_code);
-  }
-
- private:
-  base::WeakPtr<SimpleBackendImpl> backend_;
-  scoped_ptr<std::vector<uint64> > hashes_to_enumerate_;
-  base::WeakPtrFactory<SimpleIterator> weak_factory_;
-};
-
-scoped_ptr<Backend::Iterator> SimpleBackendImpl::CreateIterator() {
-  return scoped_ptr<Iterator>(new SimpleIterator(AsWeakPtr()));
+int SimpleBackendImpl::OpenNextEntry(void** iter,
+                                     Entry** next_entry,
+                                     const CompletionCallback& callback) {
+  CompletionCallback get_next_entry =
+      base::Bind(&SimpleBackendImpl::GetNextEntryInIterator, AsWeakPtr(), iter,
+                 next_entry, callback);
+  return index_->ExecuteWhenReady(get_next_entry);
+}
+
+void SimpleBackendImpl::EndEnumeration(void** iter) {
+  active_enumerations_.Remove(IteratorToEnumerationId(iter));
+  *iter = NULL;
 }
 
 void SimpleBackendImpl::GetStats(
@@ -557,6 +497,27 @@
 
 void SimpleBackendImpl::OnExternalCacheHit(const std::string& key) {
   index_->UseIfExists(simple_util::GetEntryHashKey(key));
+}
+
+// static
+SimpleBackendImpl::ActiveEnumerationMap::KeyType
+    SimpleBackendImpl::IteratorToEnumerationId(void** iter) {
+  COMPILE_ASSERT(sizeof(ptrdiff_t) >= sizeof(*iter),
+                 integer_type_must_fit_ptr_type_for_cast_to_be_reversible);
+  const ptrdiff_t ptrdiff_enumeration_id = reinterpret_cast<ptrdiff_t>(*iter);
+  const ActiveEnumerationMap::KeyType enumeration_id = ptrdiff_enumeration_id;
+  DCHECK_EQ(enumeration_id, ptrdiff_enumeration_id);
+  return enumeration_id;
+}
+
+// static
+void* SimpleBackendImpl::EnumerationIdToIterator(
+    ActiveEnumerationMap::KeyType enumeration_id) {
+  const ptrdiff_t ptrdiff_enumeration_id = enumeration_id;
+  DCHECK_EQ(enumeration_id, ptrdiff_enumeration_id);
+  COMPILE_ASSERT(sizeof(ptrdiff_t) >= sizeof(void*),
+                 integer_type_must_fit_ptr_type_for_cast_to_be_reversible);
+  return reinterpret_cast<void*>(ptrdiff_enumeration_id);
 }
 
 void SimpleBackendImpl::InitializeIndex(const CompletionCallback& callback,
@@ -672,6 +633,49 @@
   return net::ERR_IO_PENDING;
 }
 
+void SimpleBackendImpl::GetNextEntryInIterator(
+    void** iter,
+    Entry** next_entry,
+    const CompletionCallback& callback,
+    int error_code) {
+  if (error_code != net::OK) {
+    callback.Run(error_code);
+    return;
+  }
+  std::vector<uint64>* entry_list = NULL;
+  if (*iter == NULL) {
+    const ActiveEnumerationMap::KeyType new_enumeration_id =
+        active_enumerations_.Add(
+            entry_list = index()->GetAllHashes().release());
+    *iter = EnumerationIdToIterator(new_enumeration_id);
+  } else {
+    entry_list = active_enumerations_.Lookup(IteratorToEnumerationId(iter));
+  }
+  while (entry_list->size() > 0) {
+    uint64 entry_hash = entry_list->back();
+    entry_list->pop_back();
+    if (index()->Has(entry_hash)) {
+      *next_entry = NULL;
+      CompletionCallback continue_iteration = base::Bind(
+          &SimpleBackendImpl::CheckIterationReturnValue,
+          AsWeakPtr(),
+          iter,
+          next_entry,
+          callback);
+      int error_code_open = OpenEntryFromHash(entry_hash,
+                                              next_entry,
+                                              continue_iteration);
+      if (error_code_open == net::ERR_IO_PENDING)
+        return;
+      if (error_code_open != net::ERR_FAILED) {
+        callback.Run(error_code_open);
+        return;
+      }
+    }
+  }
+  callback.Run(net::ERR_FAILED);
+}
+
 void SimpleBackendImpl::OnEntryOpenedFromHash(
     uint64 hash,
     Entry** entry,
@@ -725,6 +729,18 @@
   callback.Run(final_code);
 }
 
+void SimpleBackendImpl::CheckIterationReturnValue(
+    void** iter,
+    Entry** entry,
+    const CompletionCallback& callback,
+    int error_code) {
+  if (error_code == net::ERR_FAILED) {
+    OpenNextEntry(iter, entry, callback);
+    return;
+  }
+  callback.Run(error_code);
+}
+
 void SimpleBackendImpl::DoomEntriesComplete(
     scoped_ptr<std::vector<uint64> > entry_hashes,
     const net::CompletionCallback& callback,