StorageBaseStatementInternal.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * vim: sw=2 ts=2 sts=2 expandtab
 * 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 "StorageBaseStatementInternal.h"

#include "nsProxyRelease.h"

#include "mozStorageBindingParamsArray.h"
#include "mozStorageStatementData.h"
#include "mozStorageAsyncStatementExecution.h"

namespace mozilla {
namespace storage {

////////////////////////////////////////////////////////////////////////////////
//// Local Classes

/**
 * Used to finalize an asynchronous statement on the background thread.
 */
class AsyncStatementFinalizer : public nsRunnable
{
public:
  /**
   * Constructor for the event.
   *
   * @param aStatement
   *        We need the AsyncStatement to be able to get at the sqlite3_stmt;
   *        we only access/create it on the async thread.
   * @param aConnection
   *        We need the connection to know what thread to release the statement
   *        on.  We release the statement on that thread since releasing the
   *        statement might end up releasing the connection too.
   */
  AsyncStatementFinalizer(StorageBaseStatementInternal *aStatement,
                          Connection *aConnection)
  : mStatement(aStatement)
  , mConnection(aConnection)
  {
  }

  NS_IMETHOD Run()
  {
    if (mStatement->mAsyncStatement) {
      (void)::sqlite3_finalize(mStatement->mAsyncStatement);
      mStatement->mAsyncStatement = nullptr;
    }
    (void)::NS_ProxyRelease(mConnection->threadOpenedOn, mStatement);
    return NS_OK;
  }
private:
  nsRefPtr<StorageBaseStatementInternal> mStatement;
  nsRefPtr<Connection> mConnection;
};

/**
 * Finalize a sqlite3_stmt on the background thread for a statement whose
 * destructor was invoked and the statement was non-null.
 */
class LastDitchSqliteStatementFinalizer : public nsRunnable
{
public:
  /**
   * Event constructor.
   *
   * @param aConnection
   *        Used to keep the connection alive.  If we failed to do this, it
   *        is possible that the statement going out of scope invoking us
   *        might have the last reference to the connection and so trigger
   *        an attempt to close the connection which is doomed to fail
   *        (because the asynchronous execution thread must exist which will
   *        trigger the failure case).
   * @param aStatement
   *        The sqlite3_stmt to finalize.  This object takes ownership /
   *        responsibility for the instance and all other references to it
   *        should be forgotten.
   */
  LastDitchSqliteStatementFinalizer(nsRefPtr<Connection> &aConnection,
                                    sqlite3_stmt *aStatement)
  : mConnection(aConnection)
  , mAsyncStatement(aStatement)
  {
    NS_PRECONDITION(aConnection, "You must provide a Connection");
  }

  NS_IMETHOD Run()
  {
    (void)::sqlite3_finalize(mAsyncStatement);
    mAsyncStatement = nullptr;

    // Because of our ambiguous nsISupports we cannot use the NS_ProxyRelease
    // template helpers.
    Connection *rawConnection = nullptr;
    mConnection.swap(rawConnection);
    (void)::NS_ProxyRelease(
      rawConnection->threadOpenedOn,
      NS_ISUPPORTS_CAST(mozIStorageConnection *, rawConnection));
    return NS_OK;
  }
private:
  nsRefPtr<Connection> mConnection;
  sqlite3_stmt *mAsyncStatement;
};

////////////////////////////////////////////////////////////////////////////////
//// StorageBaseStatementInternal

StorageBaseStatementInternal::StorageBaseStatementInternal()
: mAsyncStatement(NULL)
{
}

void
StorageBaseStatementInternal::asyncFinalize()
{
  nsIEventTarget *target = mDBConnection->getAsyncExecutionTarget();
  if (!target) {
    // If we cannot get the background thread, we have to assume it has been
    // shutdown (or is in the process of doing so).  As a result, we should
    // just finalize it here and now.
    destructorAsyncFinalize();
  }
  else {
    nsCOMPtr<nsIRunnable> event =
      new AsyncStatementFinalizer(this, mDBConnection);

    // If the dispatching did not go as planned, finalize now.
    if (NS_FAILED(target->Dispatch(event, NS_DISPATCH_NORMAL))) {
      destructorAsyncFinalize();
    }
  }
}

void
StorageBaseStatementInternal::destructorAsyncFinalize()
{
  if (!mAsyncStatement)
    return;

  nsIEventTarget *target = mDBConnection->getAsyncExecutionTarget();
  if (target) {
    nsCOMPtr<nsIRunnable> event =
      new LastDitchSqliteStatementFinalizer(mDBConnection, mAsyncStatement);
    if (NS_SUCCEEDED(target->Dispatch(event, NS_DISPATCH_NORMAL))) {
      mAsyncStatement = nullptr;
      return;
    }
  }
  // (no async thread remains or we could not dispatch to it)
  (void)::sqlite3_finalize(mAsyncStatement);
  mAsyncStatement = nullptr;
}

NS_IMETHODIMP
StorageBaseStatementInternal::NewBindingParamsArray(
  mozIStorageBindingParamsArray **_array
)
{
  nsCOMPtr<mozIStorageBindingParamsArray> array = new BindingParamsArray(this);
  NS_ENSURE_TRUE(array, NS_ERROR_OUT_OF_MEMORY);

  array.forget(_array);
  return NS_OK;
}

NS_IMETHODIMP
StorageBaseStatementInternal::ExecuteAsync(
  mozIStorageStatementCallback *aCallback,
  mozIStoragePendingStatement **_stmt
)
{
  // We used to call Connection::ExecuteAsync but it takes a
  // mozIStorageBaseStatement signature because it is also a public API.  Since
  // our 'this' has no static concept of mozIStorageBaseStatement and Connection
  // would just QI it back across to a StorageBaseStatementInternal and the
  // actual logic is very simple, we now roll our own.
  nsTArray<StatementData> stmts(1);
  StatementData data;
  nsresult rv = getAsynchronousStatementData(data);
  NS_ENSURE_SUCCESS(rv, rv);
  NS_ENSURE_TRUE(stmts.AppendElement(data), NS_ERROR_OUT_OF_MEMORY);

  // Dispatch to the background
  return AsyncExecuteStatements::execute(stmts, mDBConnection, aCallback,
                                         _stmt);
}

NS_IMETHODIMP
StorageBaseStatementInternal::EscapeStringForLIKE(
  const nsAString &aValue,
  const PRUnichar aEscapeChar,
  nsAString &_escapedString
)
{
  const PRUnichar MATCH_ALL('%');
  const PRUnichar MATCH_ONE('_');

  _escapedString.Truncate(0);

  for (uint32_t i = 0; i < aValue.Length(); i++) {
    if (aValue[i] == aEscapeChar || aValue[i] == MATCH_ALL ||
        aValue[i] == MATCH_ONE) {
      _escapedString += aEscapeChar;
    }
    _escapedString += aValue[i];
  }
  return NS_OK;
}

} // namespace storage
} // namespace mozilla