content/browser/indexed_db/indexed_db_transaction_coordinator.cc

   1 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "content/browser/indexed_db/indexed_db_transaction_coordinator.h"
   6
   7 #include "base/basictypes.h"
   8 #include "base/logging.h"
   9 #include "content/browser/indexed_db/indexed_db_transaction.h"
  10 #include "third_party/WebKit/public/platform/WebIDBTypes.h"
  11
  12 namespace content {
  13
  14 IndexedDBTransactionCoordinator::IndexedDBTransactionCoordinator() {}
  15
  16 IndexedDBTransactionCoordinator::~IndexedDBTransactionCoordinator() {
  17   DCHECK(!queued_transactions_.size());
  18   DCHECK(!started_transactions_.size());
  19 }
  20
  21 void IndexedDBTransactionCoordinator::DidCreateTransaction(
  22     scoped_refptr<IndexedDBTransaction> transaction) {
  23   DCHECK(!queued_transactions_.count(transaction));
  24   DCHECK(!started_transactions_.count(transaction));
  25   DCHECK_EQ(IndexedDBTransaction::CREATED, transaction->state());
  26
  27   queued_transactions_.insert(transaction);
  28   ProcessQueuedTransactions();
  29 }
  30
  31 void IndexedDBTransactionCoordinator::DidFinishTransaction(
  32     IndexedDBTransaction* transaction) {
  33   if (queued_transactions_.count(transaction)) {
  34     DCHECK(!started_transactions_.count(transaction));
  35     queued_transactions_.erase(transaction);
  36   } else {
  37     DCHECK(started_transactions_.count(transaction));
  38     started_transactions_.erase(transaction);
  39   }
  40
  41   ProcessQueuedTransactions();
  42 }
  43
  44 bool IndexedDBTransactionCoordinator::IsRunningVersionChangeTransaction()
  45     const {
  46   return !started_transactions_.empty() &&
  47          (*started_transactions_.begin())->mode() ==
  48              blink::WebIDBTransactionModeVersionChange;
  49 }
  50
  51 #ifndef NDEBUG
  52 // Verifies internal consistency while returning whether anything is found.
  53 bool IndexedDBTransactionCoordinator::IsActive(
  54     IndexedDBTransaction* transaction) {
  55   bool found = false;
  56   if (queued_transactions_.count(transaction))
  57     found = true;
  58   if (started_transactions_.count(transaction)) {
  59     DCHECK(!found);
  60     found = true;
  61   }
  62   return found;
  63 }
  64 #endif
  65
  66 std::vector<const IndexedDBTransaction*>
  67 IndexedDBTransactionCoordinator::GetTransactions() const {
  68   std::vector<const IndexedDBTransaction*> result;
  69
  70   for (const auto& transaction : started_transactions_)
  71     result.push_back(transaction.get());
  72   for (const auto& transaction : queued_transactions_)
  73     result.push_back(transaction.get());
  74
  75   return result;
  76 }
  77
  78 void IndexedDBTransactionCoordinator::ProcessQueuedTransactions() {
  79   if (queued_transactions_.empty())
  80     return;
  81
  82   DCHECK(!IsRunningVersionChangeTransaction());
  83
  84   // The locked_scope set accumulates the ids of object stores in the scope of
  85   // running read/write transactions. Other read-write transactions with
  86   // stores in this set may not be started. Read-only transactions may start,
  87   // taking a snapshot of the database, which does not include uncommitted
  88   // data. ("Version change" transactions are exclusive, but handled by the
  89   // connection sequencing in IndexedDBDatabase.)
  90   std::set<int64> locked_scope;
  91   for (const auto& transaction : started_transactions_) {
  92     if (transaction->mode() == blink::WebIDBTransactionModeReadWrite) {
  93       // Started read/write transactions have exclusive access to the object
  94       // stores within their scopes.
  95       locked_scope.insert(transaction->scope().begin(),
  96                           transaction->scope().end());
  97     }
  98   }
  99
 100   TransactionSet::const_iterator it = queued_transactions_.begin();
 101   while (it != queued_transactions_.end()) {
 102     scoped_refptr<IndexedDBTransaction> transaction = *it;
 103     ++it;
 104     if (CanStartTransaction(transaction.get(), locked_scope)) {
 105       DCHECK_EQ(IndexedDBTransaction::CREATED, transaction->state());
 106       queued_transactions_.erase(transaction);
 107       started_transactions_.insert(transaction);
 108       transaction->Start();
 109       DCHECK_EQ(IndexedDBTransaction::STARTED, transaction->state());
 110     }
 111     if (transaction->mode() == blink::WebIDBTransactionModeReadWrite) {
 112       // Either the transaction started, so it has exclusive access to the
 113       // stores in its scope, or per the spec the transaction which was
 114       // created first must get access first, so the stores are also locked.
 115       locked_scope.insert(transaction->scope().begin(),
 116                           transaction->scope().end());
 117     }
 118   }
 119 }
 120
 121 template<typename T>
 122 static bool DoSetsIntersect(const std::set<T>& set1,
 123                             const std::set<T>& set2) {
 124   typename std::set<T>::const_iterator it1 = set1.begin();
 125   typename std::set<T>::const_iterator it2 = set2.begin();
 126   while (it1 != set1.end() && it2 != set2.end()) {
 127     if (*it1 < *it2)
 128       ++it1;
 129     else if (*it2 < *it1)
 130       ++it2;
 131     else
 132       return true;
 133   }
 134   return false;
 135 }
 136
 137 bool IndexedDBTransactionCoordinator::CanStartTransaction(
 138     IndexedDBTransaction* const transaction,
 139     const std::set<int64>& locked_scope) const {
 140   DCHECK(queued_transactions_.count(transaction));
 141   switch (transaction->mode()) {
 142     case blink::WebIDBTransactionModeVersionChange:
 143       DCHECK_EQ(1u, queued_transactions_.size());
 144       DCHECK(started_transactions_.empty());
 145       DCHECK(locked_scope.empty());
 146       return true;
 147
 148     case blink::WebIDBTransactionModeReadOnly:
 149     case blink::WebIDBTransactionModeReadWrite:
 150       return !DoSetsIntersect(transaction->scope(), locked_scope);
 151   }
 152   NOTREACHED();
 153   return false;
 154 }
 155
 156 }  // namespace content