storage/mozStorageStatementData.h
author Chris H-C <chutten@mozilla.com>
Mon, 04 Jul 2016 11:16:05 -0400
changeset 312997 df28918fe2361f0b54ca9ce4773a29c4c0675d06
parent 283951 c75f253f4335d4069676dd3a978940716508d9fb
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 et
 * 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 mozStorageStatementData_h
#define mozStorageStatementData_h

#include "sqlite3.h"

#include "nsAutoPtr.h"
#include "nsTArray.h"
#include "nsIEventTarget.h"
#include "MainThreadUtils.h"

#include "mozStorageBindingParamsArray.h"
#include "mozIStorageBaseStatement.h"
#include "mozStorageConnection.h"
#include "StorageBaseStatementInternal.h"

struct sqlite3_stmt;

namespace mozilla {
namespace storage {

class StatementData
{
public:
  StatementData(sqlite3_stmt *aStatement,
                already_AddRefed<BindingParamsArray> aParamsArray,
                StorageBaseStatementInternal *aStatementOwner)
  : mStatement(aStatement)
  , mParamsArray(aParamsArray)
  , mStatementOwner(aStatementOwner)
  {
    NS_PRECONDITION(mStatementOwner, "Must have a statement owner!");
  }
  StatementData(const StatementData &aSource)
  : mStatement(aSource.mStatement)
  , mParamsArray(aSource.mParamsArray)
  , mStatementOwner(aSource.mStatementOwner)
  {
    NS_PRECONDITION(mStatementOwner, "Must have a statement owner!");
  }
  StatementData()
  : mStatement(nullptr)
  {
  }
  ~StatementData()
  {
    // We need to ensure that mParamsArray is released on the main thread,
    // as the binding arguments may be XPConnect values, which are safe
    // to release only on the main thread.
    NS_ReleaseOnMainThread(mParamsArray.forget());
  }

  /**
   * Return the sqlite statement, fetching it from the storage statement.  In
   * the case of AsyncStatements this may actually create the statement 
   */
  inline int getSqliteStatement(sqlite3_stmt **_stmt)
  {
    if (!mStatement) {
      int rc = mStatementOwner->getAsyncStatement(&mStatement);
      NS_ENSURE_TRUE(rc == SQLITE_OK, rc);
    }
    *_stmt = mStatement;
    return SQLITE_OK;
  }

  operator BindingParamsArray *() const { return mParamsArray; }

  /**
   * NULLs out our sqlite3_stmt (it is held by the owner) after reseting it and
   * clear all bindings to it.  This is expected to occur on the async thread.
   */
  inline void reset()
  {
    NS_PRECONDITION(mStatementOwner, "Must have a statement owner!");
#ifdef DEBUG
    {
      nsCOMPtr<nsIEventTarget> asyncThread =
        mStatementOwner->getOwner()->getAsyncExecutionTarget();
      // It's possible that we are shutting down the async thread, and this
      // method would return nullptr as a result.
      if (asyncThread) {
        bool onAsyncThread;
        NS_ASSERTION(NS_SUCCEEDED(asyncThread->IsOnCurrentThread(&onAsyncThread)) && onAsyncThread,
                     "This should only be running on the async thread!");
      }
    }
#endif
    // In the AsyncStatement case we may never have populated mStatement if the
    // AsyncExecuteStatements got canceled or a failure occurred in constructing
    // the statement.
    if (mStatement) {
      (void)::sqlite3_reset(mStatement);
      (void)::sqlite3_clear_bindings(mStatement);
      mStatement = nullptr;
    }
  }

  /**
   * Indicates if this statement has parameters to be bound before it is
   * executed.
   *
   * @return true if the statement has parameters to bind against, false
   *         otherwise.
   */
  inline bool hasParametersToBeBound() const { return !!mParamsArray; }
  /**
   * Indicates the number of implicit statements generated by this statement
   * requiring a transaction for execution.  For example a single statement
   * with N BindingParams will execute N implicit staments.
   *
   * @return number of statements requiring a transaction for execution.
   *
   * @note In the case of AsyncStatements this may actually create the
   *       statement.
   */
  inline uint32_t needsTransaction()
  {
    MOZ_ASSERT(!NS_IsMainThread());
    // Be sure to use the getSqliteStatement helper, since sqlite3_stmt_readonly
    // can only analyze prepared statements and AsyncStatements are prepared
    // lazily.
    sqlite3_stmt *stmt;
    int rc = getSqliteStatement(&stmt);
    if (SQLITE_OK != rc || ::sqlite3_stmt_readonly(stmt)) {
      return 0;
    }
    return mParamsArray ? mParamsArray->length() : 1;
  }

private:
  sqlite3_stmt *mStatement;
  RefPtr<BindingParamsArray> mParamsArray;

  /**
   * We hold onto a reference of the statement's owner so it doesn't get
   * destroyed out from under us.
   */
  nsCOMPtr<StorageBaseStatementInternal> mStatementOwner;
};

} // namespace storage
} // namespace mozilla

#endif // mozStorageStatementData_h