mozStorageStatementData.h

/* -*- 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) {
    MOZ_ASSERT(mStatementOwner, "Must have a statement owner!");
  }
  StatementData(const StatementData& aSource)
      : mStatement(aSource.mStatement),
        mParamsArray(aSource.mParamsArray),
        mStatementOwner(aSource.mStatementOwner) {
    MOZ_ASSERT(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_ReleaseOnMainThreadSystemGroup("StatementData::mParamsArray",
                                      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() {
    MOZ_ASSERT(mStatementOwner, "Must have a statement owner!");
    // 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