Some fleshing out the mojo based localstorage implementation.

content/browser/leveldb_wrapper_impl.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/leveldb_wrapper_impl.h"
 
 #include "base/bind.h"
+#include "mojo/common/common_type_converters.h"
 
 namespace content {
 
 LevelDBWrapperImpl::LevelDBWrapperImpl(
     leveldb::LevelDBDatabase* database,
     const std::string& prefix,
+    size_t max_size,
     const base::Closure& no_bindings_callback)
     : prefix_(prefix),
       no_bindings_callback_(no_bindings_callback),
-      database_(database) {
+      database_(database),
+      bytes_used_(0),
+      max_size_(max_size) {
   bindings_.set_connection_error_handler(base::Bind(
       &LevelDBWrapperImpl::OnConnectionError, base::Unretained(this)));
 }
 
 void LevelDBWrapperImpl::Bind(mojom::LevelDBWrapperRequest request) {
   bindings_.AddBinding(this, std::move(request));
 }
 
+void LevelDBWrapperImpl::AddObserver(mojom::LevelDBObserverPtr observer) {
+  observers_.AddInterfacePtr(std::move(observer));
+}
+
 LevelDBWrapperImpl::~LevelDBWrapperImpl() {}
 
 void LevelDBWrapperImpl::Put(mojo::Array<uint8_t> key,
                              mojo::Array<uint8_t> value,
                              const mojo::String& source,
                              const PutCallback& callback) {
-  NOTIMPLEMENTED();
-  callback.Run(leveldb::DatabaseError::NOT_SUPPORTED);
+  bool has_old_item = false;
+  mojo::Array<uint8_t> old_value;
+  size_t old_item_size = 0;
+  auto found = map_.find(key);
+  if (found != map_.end()) {
+    old_value = std::move(found->second);
+    old_item_size = key.size() + old_value.size();
+    has_old_item = true;
+  }
+  size_t new_item_size = key.size() + value.size();
+  size_t new_bytes_used = bytes_used_ - old_item_size + new_item_size;
+
+  // Only check quota if the size is increasing, this allows
+  // shrinking changes to pre-existing maps that are over budget.
+  if (new_item_size > old_item_size && new_bytes_used > max_size_) {
+    callback.Run(false);
+    return;
+  }
+
+  map_[key.Clone()] = value.Clone();
+  bytes_used_ = new_bytes_used;
+  if (!has_old_item) {
+    // We added a new key/value pair.
+    observers_.ForAllPtrs(
+        [&key, &value, &source](mojom::LevelDBObserver* observer) {
+          observer->KeyAdded(key.Clone(), value.Clone(), source);
+        });
+  } else {
+    // We changed the value for an existing key.
+    observers_.ForAllPtrs(
+        [&key, &value, &source, &old_value](mojom::LevelDBObserver* observer) {
+          observer->KeyChanged(
+              key.Clone(), value.Clone(), old_value.Clone(), source);
+        });
+  }
+  callback.Run(true);
 }
 
 void LevelDBWrapperImpl::Delete(mojo::Array<uint8_t> key,
                                 const mojo::String& source,
                                 const DeleteCallback& callback) {
-  NOTIMPLEMENTED();
-  callback.Run(leveldb::DatabaseError::NOT_SUPPORTED);
+  auto found = map_.find(key);
+  if (found == map_.end()) {
+    callback.Run(true);
+    return;
+  }
+
+  mojo::Array<uint8_t> old_value = std::move(found->second);
+  map_.erase(found);
+  bytes_used_ -= key.size() + old_value.size();
+  observers_.ForAllPtrs(
+      [&key, &source, &old_value](mojom::LevelDBObserver* observer) {
+        observer->KeyDeleted(
+            key.Clone(), old_value.Clone(), source);
+      });
+  callback.Run(true);
 }
 
-void LevelDBWrapperImpl::DeleteAll(mojom::LevelDBObserverPtr observer,
-                                   const mojo::String& source,
+void LevelDBWrapperImpl::DeleteAll(const mojo::String& source,
                                    const DeleteAllCallback& callback) {
-  // TODO(jam): store observer and call it when changes occur.
-  NOTIMPLEMENTED();
-  callback.Run(leveldb::DatabaseError::NOT_SUPPORTED);
+  map_.clear();
+  bytes_used_ = 0;
+  observers_.ForAllPtrs(
+      [&source](mojom::LevelDBObserver* observer) {
+        observer->AllDeleted(source);
+      });
+  callback.Run(true);
 }
 
 void LevelDBWrapperImpl::Get(mojo::Array<uint8_t> key,
                              const GetCallback& callback) {
-  NOTIMPLEMENTED();
-  callback.Run(leveldb::DatabaseError::NOT_SUPPORTED, mojo::Array<uint8_t>());
+  auto found = map_.find(key);
+  if (found == map_.end()) {
+    callback.Run(false, mojo::Array<uint8_t>());
+    return;
+  }
+  callback.Run(true, found->second.Clone());
 }
 
-void LevelDBWrapperImpl::GetAll(mojom::LevelDBObserverPtr observer,
+void LevelDBWrapperImpl::GetAll(const mojo::String& source,
                                 const GetAllCallback& callback) {
-  // TODO(jam): store observer and call it when changes occur.
-  NOTIMPLEMENTED();
-  callback.Run(leveldb::DatabaseError::NOT_SUPPORTED,
-               mojo::Array<mojom::KeyValuePtr>());
+
+  mojo::Array<mojom::KeyValuePtr> all(map_.size());
+  for (const auto& it : map_) {
+    mojom::KeyValuePtr kv = mojom::KeyValue::New();
+    kv->key = it.first.Clone();
+    kv->value = it.second.Clone();
+    all.push_back(std::move(kv));
+  }
+  callback.Run(leveldb::DatabaseError::OK, std::move(all));
+  observers_.ForAllPtrs(
+      [source](mojom::LevelDBObserver* observer) {
+        observer->GetAllComplete(source);
+      });
 }
 
 void LevelDBWrapperImpl::OnConnectionError() {
   if (!bindings_.empty())
     return;
 
   no_bindings_callback_.Run();
 }
 
 }  // namespace content