Migrate the IndexedDB backend from Blink to Chromium

content/browser/indexed_db/indexed_db_transaction_coordinator.cc

+// Copyright (c) 2013 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/indexed_db/indexed_db_transaction_coordinator.h"
+
+#include "base/logging.h"
+#include "content/browser/indexed_db/indexed_db_transaction.h"
+
+namespace content {
+
+IndexedDBTransactionCoordinator::IndexedDBTransactionCoordinator() {}
+
+IndexedDBTransactionCoordinator::~IndexedDBTransactionCoordinator() {
+  // TODO(jsbell): DCHECK that all queues are empty. http://crbug.com/241821
+}
+
+void IndexedDBTransactionCoordinator::DidCreateTransaction(
+    IndexedDBTransaction* transaction) {
+  DCHECK(transactions_.find(transaction) == transactions_.end());
+  transactions_[transaction] = transaction;
+}
+
+void IndexedDBTransactionCoordinator::DidStartTransaction(
+    IndexedDBTransaction* transaction) {
+  DCHECK(transactions_.find(transaction) != transactions_.end());
+
+  queued_transactions_.insert(transaction);
+  ProcessStartedTransactions();
+}
+
+void IndexedDBTransactionCoordinator::DidFinishTransaction(
+    IndexedDBTransaction* transaction) {
+  DCHECK(transactions_.find(transaction) != transactions_.end());
+
+  if (queued_transactions_.has(transaction)) {
+    DCHECK(started_transactions_.find(transaction) ==
+           started_transactions_.end());
+    queued_transactions_.erase(transaction);
+  } else {
+    if (started_transactions_.find(transaction) != started_transactions_.end())
+      started_transactions_.erase(transaction);
+  }
+  transactions_.erase(transaction);
+
+  ProcessStartedTransactions();
+}
+
+#ifndef NDEBUG
+// Verifies internal consistency while returning whether anything is found.
+bool IndexedDBTransactionCoordinator::IsActive(
+    IndexedDBTransaction* transaction) {
+  bool found = false;
+  if (queued_transactions_.has(transaction))
+    found = true;
+  if (started_transactions_.find(transaction) != started_transactions_.end()) {
+    DCHECK(!found);
+    found = true;
+  }
+  DCHECK_EQ(found, (transactions_.find(transaction) != transactions_.end()));
+  return found;
+}
+#endif
+
+void IndexedDBTransactionCoordinator::ProcessStartedTransactions() {
+  if (queued_transactions_.empty())
+    return;
+
+  DCHECK(started_transactions_.empty() ||
+         (*started_transactions_.begin())->mode() !=
+             indexed_db::TRANSACTION_VERSION_CHANGE);
+
+  list_set<IndexedDBTransaction*>::const_iterator it =
+      queued_transactions_.begin();
+  while (it != queued_transactions_.end()) {
+    IndexedDBTransaction* transaction = *it;
+    ++it;
+    if (CanRunTransaction(transaction)) {
+      queued_transactions_.erase(transaction);
+      started_transactions_.insert(transaction);
+      transaction->Run();
+    }
+  }
+}
+
+static bool DoScopesOverlap(const std::set<int64_t>& scope1,
+                            const std::set<int64_t>& scope2) {
+  for (std::set<int64_t>::const_iterator it = scope1.begin();
+       it != scope1.end();
+       ++it) {
+    if (scope2.find(*it) != scope2.end())
+      return true;
+  }
+  return false;
+}
+
+bool IndexedDBTransactionCoordinator::CanRunTransaction(
+    IndexedDBTransaction* transaction) {
+  DCHECK(queued_transactions_.has(transaction));
+  switch (transaction->mode()) {
+    case indexed_db::TRANSACTION_VERSION_CHANGE:
+      DCHECK(queued_transactions_.size() == 1);
+      DCHECK(started_transactions_.empty());
+      return true;
+
+    case indexed_db::TRANSACTION_READ_ONLY:
+      return true;
+
+    case indexed_db::TRANSACTION_READ_WRITE:
+      for (std::set<IndexedDBTransaction*>::const_iterator it =
+               started_transactions_.begin();
+           it != started_transactions_.end();
+           ++it) {
+        IndexedDBTransaction* other = *it;
+        if (other->mode() == indexed_db::TRANSACTION_READ_WRITE &&
+            DoScopesOverlap(transaction->scope(), other->scope()))
+          return false;
+      }
+      for (list_set<IndexedDBTransaction*>::const_iterator it =
+               queued_transactions_.begin();
+           *it != transaction;
+           ++it) {
+        DCHECK(it != queued_transactions_.end());
+        IndexedDBTransaction* other = *it;
+        if (other->mode() == indexed_db::TRANSACTION_READ_WRITE &&
+            DoScopesOverlap(transaction->scope(), other->scope()))
+          return false;
+      }
+      return true;
+  }
+  NOTREACHED();
+  return false;
+}
+
+}  // namespace content