storage/mozStorageStatementData.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
   2  * vim: sw=2 ts=2 sts=2 et
   3  * This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef mozStorageStatementData_h
   8 #define mozStorageStatementData_h
   9
  10 #include "sqlite3.h"
  11
  12 #include "nsAutoPtr.h"
  13 #include "nsTArray.h"
  14 #include "nsIEventTarget.h"
  15 #include "MainThreadUtils.h"
  16
  17 #include "mozStorageBindingParamsArray.h"
  18 #include "mozIStorageBaseStatement.h"
  19 #include "mozStorageConnection.h"
  20 #include "StorageBaseStatementInternal.h"
  21
  22 struct sqlite3_stmt;
  23
  24 namespace mozilla {
  25 namespace storage {
  26
  27 class StatementData
  28 {
  29 public:
  30   StatementData(sqlite3_stmt *aStatement,
  31                 already_AddRefed<BindingParamsArray> aParamsArray,
  32                 StorageBaseStatementInternal *aStatementOwner)
  33   : mStatement(aStatement)
  34   , mParamsArray(aParamsArray)
  35   , mStatementOwner(aStatementOwner)
  36   {
  37     MOZ_ASSERT(mStatementOwner, "Must have a statement owner!");
  38   }
  39   StatementData(const StatementData &aSource)
  40   : mStatement(aSource.mStatement)
  41   , mParamsArray(aSource.mParamsArray)
  42   , mStatementOwner(aSource.mStatementOwner)
  43   {
  44     MOZ_ASSERT(mStatementOwner, "Must have a statement owner!");
  45   }
  46   StatementData()
  47   : mStatement(nullptr)
  48   {
  49   }
  50   ~StatementData()
  51   {
  52     // We need to ensure that mParamsArray is released on the main thread,
  53     // as the binding arguments may be XPConnect values, which are safe
  54     // to release only on the main thread.
  55     NS_ReleaseOnMainThreadSystemGroup("StatementData::mParamsArray",
  56                                       mParamsArray.forget());
  57   }
  58
  59   /**
  60    * Return the sqlite statement, fetching it from the storage statement.  In
  61    * the case of AsyncStatements this may actually create the statement
  62    */
  63   inline int getSqliteStatement(sqlite3_stmt **_stmt)
  64   {
  65     if (!mStatement) {
  66       int rc = mStatementOwner->getAsyncStatement(&mStatement);
  67       NS_ENSURE_TRUE(rc == SQLITE_OK, rc);
  68     }
  69     *_stmt = mStatement;
  70     return SQLITE_OK;
  71   }
  72
  73   operator BindingParamsArray *() const { return mParamsArray; }
  74
  75   /**
  76    * NULLs out our sqlite3_stmt (it is held by the owner) after reseting it and
  77    * clear all bindings to it.  This is expected to occur on the async thread.
  78    */
  79   inline void reset()
  80   {
  81     MOZ_ASSERT(mStatementOwner, "Must have a statement owner!");
  82     // In the AsyncStatement case we may never have populated mStatement if the
  83     // AsyncExecuteStatements got canceled or a failure occurred in constructing
  84     // the statement.
  85     if (mStatement) {
  86       (void)::sqlite3_reset(mStatement);
  87       (void)::sqlite3_clear_bindings(mStatement);
  88       mStatement = nullptr;
  89     }
  90   }
  91
  92   /**
  93    * Indicates if this statement has parameters to be bound before it is
  94    * executed.
  95    *
  96    * @return true if the statement has parameters to bind against, false
  97    *         otherwise.
  98    */
  99   inline bool hasParametersToBeBound() const { return !!mParamsArray; }
 100   /**
 101    * Indicates the number of implicit statements generated by this statement
 102    * requiring a transaction for execution.  For example a single statement
 103    * with N BindingParams will execute N implicit staments.
 104    *
 105    * @return number of statements requiring a transaction for execution.
 106    *
 107    * @note In the case of AsyncStatements this may actually create the
 108    *       statement.
 109    */
 110   inline uint32_t needsTransaction()
 111   {
 112     MOZ_ASSERT(!NS_IsMainThread());
 113     // Be sure to use the getSqliteStatement helper, since sqlite3_stmt_readonly
 114     // can only analyze prepared statements and AsyncStatements are prepared
 115     // lazily.
 116     sqlite3_stmt *stmt;
 117     int rc = getSqliteStatement(&stmt);
 118     if (SQLITE_OK != rc || ::sqlite3_stmt_readonly(stmt)) {
 119       return 0;
 120     }
 121     return mParamsArray ? mParamsArray->length() : 1;
 122   }
 123
 124 private:
 125   sqlite3_stmt *mStatement;
 126   RefPtr<BindingParamsArray> mParamsArray;
 127
 128   /**
 129    * We hold onto a reference of the statement's owner so it doesn't get
 130    * destroyed out from under us.
 131    */
 132   nsCOMPtr<StorageBaseStatementInternal> mStatementOwner;
 133 };
 134
 135 } // namespace storage
 136 } // namespace mozilla
 137
 138 #endif // mozStorageStatementData_h