storage/StorageBaseStatementInternal.cpp
author Chris H-C <chutten@mozilla.com>
Mon, 04 Jul 2016 11:16:05 -0400
changeset 312997 df28918fe2361f0b54ca9ce4773a29c4c0675d06
parent 308876 b09d90288666fb3afb11877fc45527b904ef23db
permissions -rw-r--r--
bug 1218576 - Support remote accumulation via JS histograms. r=gfritzsche The JS histograms, too, need to dispatch their accumulations from child to parent. JSHistograms_Add now only supports histograms that are in gHistogramsMap or that were created in the parent process. After bug 1288745, maybe we'll be able to change this to be less convoluted. MozReview-Commit-ID: 3qTH89YKbGP

/* -*- 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 Runnable
{
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() override
  {
    if (mStatement->mAsyncStatement) {
      sqlite3_finalize(mStatement->mAsyncStatement);
      mStatement->mAsyncStatement = nullptr;
    }

    nsCOMPtr<nsIThread> targetThread(mConnection->threadOpenedOn);
    NS_ProxyRelease(targetThread, mStatement.forget());
    return NS_OK;
  }
private:
  RefPtr<StorageBaseStatementInternal> mStatement;
  RefPtr<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 Runnable
{
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(RefPtr<Connection> &aConnection,
                                    sqlite3_stmt *aStatement)
  : mConnection(aConnection)
  , mAsyncStatement(aStatement)
  {
    NS_PRECONDITION(aConnection, "You must provide a Connection");
  }

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

    nsCOMPtr<nsIThread> target(mConnection->threadOpenedOn);
    (void)::NS_ProxyRelease(target, mConnection.forget());
    return NS_OK;
  }
private:
  RefPtr<Connection> mConnection;
  sqlite3_stmt *mAsyncStatement;
};

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

StorageBaseStatementInternal::StorageBaseStatementInternal()
: mAsyncStatement(nullptr)
{
}

void
StorageBaseStatementInternal::asyncFinalize()
{
  nsIEventTarget *target = mDBConnection->getAsyncExecutionTarget();
  if (target) {
    // Attempt to finalize asynchronously
    nsCOMPtr<nsIRunnable> event =
      new AsyncStatementFinalizer(this, mDBConnection);

    // Dispatch. Note that dispatching can fail, typically if
    // we have a race condition with asyncClose(). It's ok,
    // let asyncClose() win.
    (void)target->Dispatch(event, NS_DISPATCH_NORMAL);
  }
  // If we cannot get the background thread,
  // mozStorageConnection::AsyncClose() has already been called and
  // the statement either has been or will be cleaned up by
  // internalClose().
}

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

  // If we reach this point, our owner has not finalized this
  // statement, yet we are being destructed. If possible, we want to
  // auto-finalize it early, to release the resources early.
  nsIEventTarget *target = mDBConnection->getAsyncExecutionTarget();
  if (target) {
    // If we can get the async execution target, we can indeed finalize
    // the statement, as the connection is still open.
    bool isAsyncThread = false;
    (void)target->IsOnCurrentThread(&isAsyncThread);

    nsCOMPtr<nsIRunnable> event =
      new LastDitchSqliteStatementFinalizer(mDBConnection, mAsyncStatement);
    if (isAsyncThread) {
      (void)event->Run();
    } else {
      (void)target->Dispatch(event, NS_DISPATCH_NORMAL);
    }
  }

  // We might not be able to dispatch to the background thread,
  // presumably because it is being shutdown. Since said shutdown will
  // finalize the statement, we just need to clean-up around here.
  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,
                                         mNativeConnection, aCallback, _stmt);
}

NS_IMETHODIMP
StorageBaseStatementInternal::EscapeStringForLIKE(
  const nsAString &aValue,
  const char16_t aEscapeChar,
  nsAString &_escapedString
)
{
  const char16_t MATCH_ALL('%');
  const char16_t 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