storage/StatementCache.h
author Brian Stack <bstack@mozilla.com>
Wed, 12 Apr 2017 21:01:46 -0700
changeset 404168 5748607f3014e8cec573fccebce5dcbf83b6ffd6
parent 320276 d5722e7de045a82cfbcb74b1c818e239ae63001a
child 508163 6f3709b3878117466168c40affa7bca0b60cf75b
permissions -rw-r--r--
Bug 591688 - Notify when decision task fails r=dustin,gps This uses the email provided by mozilla-taskcluster to find who to email about failed decision tasks. It also adds some validation of the try syntax that we've previously ignored. Any platforms or build types specified in try sytax that don't exist in the full task graph will throw an error. MozReview-Commit-ID: JOKkLle7hEe

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * vim: sw=2 ts=2 et lcs=trail\:.,tab\:>~ :
 * 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/. */

#ifndef mozilla_storage_StatementCache_h
#define mozilla_storage_StatementCache_h

#include "mozIStorageConnection.h"
#include "mozIStorageStatement.h"
#include "mozIStorageAsyncStatement.h"

#include "nsAutoPtr.h"
#include "nsHashKeys.h"
#include "nsInterfaceHashtable.h"

namespace mozilla {
namespace storage {

/**
 * Class used to cache statements (mozIStorageStatement or
 * mozIStorageAsyncStatement).
 */
template<typename StatementType>
class StatementCache {
public:
  /**
   * Constructor for the cache.
   *
   * @note a connection can have more than one cache.
   *
   * @param aConnection
   *        A reference to the nsCOMPtr for the connection this cache is to be
   *        used for.  This nsCOMPtr must at least live as long as this class,
   *        otherwise crashes will happen.
   */
  explicit StatementCache(nsCOMPtr<mozIStorageConnection>& aConnection)
  : mConnection(aConnection)
  {
  }

  /**
   * Obtains a cached statement.  If this statement is not yet created, it will
   * be created and stored for later use.
   *
   * @param aQuery
   *        The SQL string (either a const char [] or nsACString) to get a
   *        cached query for.
   * @return the cached statement, or null upon error.
   */
  inline
  already_AddRefed<StatementType>
  GetCachedStatement(const nsACString& aQuery)
  {
    nsCOMPtr<StatementType> stmt;
    if (!mCachedStatements.Get(aQuery, getter_AddRefs(stmt))) {
      stmt = CreateStatement(aQuery);
      NS_ENSURE_TRUE(stmt, nullptr);

      mCachedStatements.Put(aQuery, stmt);
    }
    return stmt.forget();
  }

  template<int N>
  MOZ_ALWAYS_INLINE already_AddRefed<StatementType>
  GetCachedStatement(const char (&aQuery)[N])
  {
    nsDependentCString query(aQuery, N - 1);
    return GetCachedStatement(query);
  }

  /**
   * Finalizes all cached statements so the database can be safely closed.  The
   * behavior of this cache is unspecified after this method is called.
   */
  inline
  void
  FinalizeStatements()
  {
    for (auto iter = mCachedStatements.Iter(); !iter.Done(); iter.Next()) {
      (void)iter.Data()->Finalize();
    }

    // Clear the cache at this time too!
    (void)mCachedStatements.Clear();
  }

private:
  inline
  already_AddRefed<StatementType>
  CreateStatement(const nsACString& aQuery);

  nsInterfaceHashtable<nsCStringHashKey, StatementType> mCachedStatements;
  nsCOMPtr<mozIStorageConnection>& mConnection;
};

template< >
inline
already_AddRefed<mozIStorageStatement>
StatementCache<mozIStorageStatement>::CreateStatement(const nsACString& aQuery)
{
  NS_ENSURE_TRUE(mConnection, nullptr);

  nsCOMPtr<mozIStorageStatement> stmt;
  nsresult rv = mConnection->CreateStatement(aQuery, getter_AddRefs(stmt));
  if (NS_FAILED(rv)) {
    nsCString error;
    error.AppendLiteral("The statement '");
    error.Append(aQuery);
    error.AppendLiteral("' failed to compile with the error message '");
    nsCString msg;
    (void)mConnection->GetLastErrorString(msg);
    error.Append(msg);
    error.AppendLiteral("'.");
    NS_ERROR(error.get());
  }
  NS_ENSURE_SUCCESS(rv, nullptr);

  return stmt.forget();
}

template< >
inline
already_AddRefed<mozIStorageAsyncStatement>
StatementCache<mozIStorageAsyncStatement>::CreateStatement(const nsACString& aQuery)
{
  NS_ENSURE_TRUE(mConnection, nullptr);

  nsCOMPtr<mozIStorageAsyncStatement> stmt;
  nsresult rv = mConnection->CreateAsyncStatement(aQuery, getter_AddRefs(stmt));
  NS_ENSURE_SUCCESS(rv, nullptr);

  return stmt.forget();
}

} // namespace storage
} // namespace mozilla

#endif // mozilla_storage_StatementCache_h