1 files changed, 292 insertions, 0 deletions
diff --git a/toolkit/components/sessionstore/BrowserSessionStore.cpp b/toolkit/components/sessionstore/BrowserSessionStore.cpp
new file mode 100644
index 0000000000..f4da9646b2
--- /dev/null
+++ b/toolkit/components/sessionstore/BrowserSessionStore.cpp
@@ -0,0 +1,292 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/BrowserSessionStore.h"
+#include <algorithm>
+#include <cstdint>
+#include <functional>
+
+#include "mozilla/AlreadyAddRefed.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/ClearOnShutdown.h"
+#include "mozilla/IntegerRange.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/ScopeExit.h"
+#include "mozilla/StaticPtr.h"
+
+#include "mozilla/dom/BrowserSessionStoreBinding.h"
+#include "mozilla/dom/CanonicalBrowsingContext.h"
+#include "mozilla/dom/SessionStoreFormData.h"
+#include "mozilla/dom/SessionStoreScrollData.h"
+#include "mozilla/dom/WindowGlobalParent.h"
+
+#include "nsTHashMap.h"
+#include "nsHashtablesFwd.h"
+
+#include "js/RootingAPI.h"
+
+using namespace mozilla;
+using namespace mozilla::dom;
+
+static StaticAutoPtr<nsTHashMap<nsUint64HashKey, BrowserSessionStore*>>
+    sSessionStore;
+
+NS_IMPL_CYCLE_COLLECTION(BrowserSessionStore, mBrowsingContext, mFormData,
+                         mScrollData)
+
+/* static */
+already_AddRefed<BrowserSessionStore> BrowserSessionStore::GetOrCreate(
+    CanonicalBrowsingContext* aBrowsingContext) {
+  if (!aBrowsingContext->IsTop()) {
+    return nullptr;
+  }
+
+  if (!sSessionStore) {
+    sSessionStore = new nsTHashMap<nsUint64HashKey, BrowserSessionStore*>();
+    ClearOnShutdown(&sSessionStore);
+  }
+
+  return do_AddRef(sSessionStore->LookupOrInsertWith(
+      aBrowsingContext->Id(),
+      [&] { return new BrowserSessionStore(aBrowsingContext); }));
+}
+
+BrowserSessionStore::BrowserSessionStore(
+    CanonicalBrowsingContext* aBrowsingContext)
+    : mBrowsingContext(aBrowsingContext) {}
+
+SessionStoreFormData* BrowserSessionStore::GetFormdata() { return mFormData; }
+
+SessionStoreScrollData* BrowserSessionStore::GetScroll() { return mScrollData; }
+
+static bool ShouldUpdateSessionStore(CanonicalBrowsingContext* aBrowsingContext,
+                                     uint32_t aEpoch) {
+  if (!aBrowsingContext) {
+    return false;
+  }
+
+  if (aBrowsingContext->Top()->GetSessionStoreEpoch() != aEpoch) {
+    return false;
+  }
+
+  if (aBrowsingContext->IsReplaced()) {
+    return false;
+  }
+
+  if (aBrowsingContext->IsDynamic()) {
+    return false;
+  }
+
+  return true;
+}
+
+// With GetOrCreate we can create either of the weak fields:
+//   WeakPtr<SessionStoreFormData> mFormdata;
+//   WeakPtr<SessionStoreScrollData> mScroll;
+// in CanonicalBrowsingContext. If one already exists, then we return that.
+template <typename T, WeakPtr<T>& (CanonicalBrowsingContext::*GetWeakRef)()>
+static already_AddRefed<T> GetOrCreateEntry(
+    CanonicalBrowsingContext* aBrowsingContext) {
+  typename T::LocationType& location = (aBrowsingContext->*GetWeakRef)();
+  RefPtr<T> entry = location.get();
+  if (!entry) {
+    entry = MakeRefPtr<T>();
+    location = entry;
+  }
+
+  return entry.forget();
+}
+
+// With InsertEntry we can insert an entry in the session store data tree in
+// either of the weak fields:
+//   WeakPtr<SessionStoreFormData> mFormdata;
+//   WeakPtr<SessionStoreScrollData> mScroll;
+// in CanonicalBrowsingContext. If an entry is inserted where there is no parent
+// entry, a spine of entries will be created until one is found, or we reach the
+// top browsing context.
+template <typename T>
+void InsertEntry(BrowsingContext* aBrowsingContext, T* aParent, T* aUpdate) {
+  int32_t offset = aBrowsingContext->ChildOffset();
+  if (offset < 0) {
+    return;
+  }
+
+  aParent->ClearCachedChildren();
+
+  auto& children = aParent->Children();
+
+  children.EnsureLengthAtLeast(offset + 1);
+  if (children[offset] && !aBrowsingContext->Children().IsEmpty()) {
+    children[offset]->ClearCachedChildren();
+    aUpdate->ClearCachedChildren();
+  }
+
+  children[offset] = aUpdate;
+}
+
+// With RemoveEntry we can remove an entry in the session store data tree in
+// either of the weak fields:
+//   WeakPtr<SessionStoreFormData> mFormdata;
+//   WeakPtr<SessionStoreScrollData> mScroll;
+// in CanonicalBrowsingContext. If an entry is removed, where its parent doesn't
+// contain data, we'll remove the parent and repeat until we either find an
+// entry with data or reach the top browsing context.
+template <typename T>
+void RemoveEntry(BrowsingContext* aBrowsingContext, T* aParent) {
+  int32_t offset = aBrowsingContext->ChildOffset();
+  if (offset < 0) {
+    return;
+  }
+
+  if (!aParent) {
+    return;
+  }
+
+  aParent->ClearCachedChildren();
+
+  auto& children = aParent->Children();
+  size_t length = children.Length();
+  if (children.Length() <= static_cast<size_t>(offset)) {
+    // The children array doesn't extend to offset.
+    return;
+  }
+
+  if (static_cast<size_t>(offset) < length - 1) {
+    // offset is before the last item in the children array.
+    children[offset] = nullptr;
+    return;
+  }
+
+  // offset is the last item, find the first non-null item before it
+  // and remove anything after that item.
+  while (offset > 0 && !children[offset - 1]) {
+    --offset;
+  }
+
+  children.TruncateLength(offset);
+}
+
+// With UpdateSessionStoreField we can update an entry in the session store
+// data tree in either of the weak fields:
+//   WeakPtr<SessionStoreFormData> mFormdata;
+//   WeakPtr<SessionStoreScrollData> mScroll;
+// in CanonicalBrowsingContext. UpdateSessionStoreField uses the above
+// functions, `GetOrCreateEntry`, `InsertEntry` and `RemoveEntry` to operate on
+// the weak fields. We return the top-level entry attached to the top browsing
+// context through `aEntry`. If the entire browsing context tree contains no
+// session store data this will be set to nullptr.
+template <typename T, WeakPtr<T>& (CanonicalBrowsingContext::*GetWeakRef)()>
+void UpdateSessionStoreField(CanonicalBrowsingContext* aBrowsingContext,
+                             const typename T::CollectedType& aUpdate,
+                             T** aEntry) {
+  RefPtr<T> currentEntry;
+
+  if (T::HasData(aUpdate)) {
+    currentEntry = GetOrCreateEntry<T, GetWeakRef>(aBrowsingContext);
+    currentEntry->Update(aUpdate);
+
+    CanonicalBrowsingContext* currentBrowsingContext = aBrowsingContext;
+    while (CanonicalBrowsingContext* parent =
+               currentBrowsingContext->GetParent()) {
+      WeakPtr<T>& parentEntry = (parent->*GetWeakRef)();
+      if (parentEntry) {
+        InsertEntry(aBrowsingContext, parentEntry.get(), currentEntry.get());
+        break;
+      }
+
+      RefPtr<T> entry = GetOrCreateEntry<T, GetWeakRef>(parent);
+      InsertEntry(currentBrowsingContext, entry.get(), currentEntry.get());
+
+      currentEntry = entry;
+      currentBrowsingContext = parent;
+    }
+
+    currentEntry = (aBrowsingContext->Top()->*GetWeakRef)().get();
+  } else if ((currentEntry = (aBrowsingContext->*GetWeakRef)())) {
+    currentEntry->Update(aUpdate);
+
+    CanonicalBrowsingContext* currentBrowsingContext = aBrowsingContext;
+    while (CanonicalBrowsingContext* parent =
+               currentBrowsingContext->GetParent()) {
+      if (!currentEntry || !currentEntry->IsEmpty()) {
+        break;
+      }
+
+      T* parentEntry = (parent->*GetWeakRef)().get();
+      RemoveEntry(currentBrowsingContext, parentEntry);
+
+      currentEntry = parentEntry;
+      currentBrowsingContext = parent;
+    }
+
+    if (currentEntry && currentEntry->IsEmpty()) {
+      currentEntry = nullptr;
+    } else {
+      currentEntry = (aBrowsingContext->Top()->*GetWeakRef)().get();
+    }
+  } else {
+    currentEntry = (aBrowsingContext->Top()->*GetWeakRef)().get();
+  }
+
+  *aEntry = currentEntry.forget().take();
+}
+
+void BrowserSessionStore::UpdateSessionStore(
+    CanonicalBrowsingContext* aBrowsingContext,
+    const Maybe<sessionstore::FormData>& aFormData,
+    const Maybe<nsPoint>& aScrollPosition, uint32_t aEpoch) {
+  if (!aFormData && !aScrollPosition) {
+    return;
+  }
+
+  if (!ShouldUpdateSessionStore(aBrowsingContext, aEpoch)) {
+    return;
+  }
+
+  if (aFormData) {
+    UpdateSessionStoreField<
+        SessionStoreFormData,
+        &CanonicalBrowsingContext::GetSessionStoreFormDataRef>(
+        aBrowsingContext, *aFormData, getter_AddRefs(mFormData));
+  }
+
+  if (aScrollPosition) {
+    UpdateSessionStoreField<
+        SessionStoreScrollData,
+        &CanonicalBrowsingContext::GetSessionStoreScrollDataRef>(
+        aBrowsingContext, *aScrollPosition, getter_AddRefs(mScrollData));
+  }
+}
+
+void BrowserSessionStore::RemoveSessionStore(
+    CanonicalBrowsingContext* aBrowsingContext) {
+  if (!aBrowsingContext) {
+    return;
+  }
+
+  CanonicalBrowsingContext* parentContext = aBrowsingContext->GetParent();
+
+  if (parentContext) {
+    RemoveEntry(aBrowsingContext,
+                parentContext->GetSessionStoreFormDataRef().get());
+
+    RemoveEntry(aBrowsingContext,
+                parentContext->GetSessionStoreScrollDataRef().get());
+
+    return;
+  }
+
+  if (aBrowsingContext->IsTop()) {
+    mFormData = nullptr;
+    mScrollData = nullptr;
+  }
+}
+
+BrowserSessionStore::~BrowserSessionStore() {
+  if (sSessionStore) {
+    sSessionStore->Remove(mBrowsingContext->Id());
+  }
+}