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  public:
  29   StatementData(sqlite3_stmt *aStatement,
  30                 already_AddRefed<BindingParamsArray> aParamsArray,
  31                 StorageBaseStatementInternal *aStatementOwner)
  32       : mStatement(aStatement),
  33         mParamsArray(aParamsArray),
  34         mStatementOwner(aStatementOwner) {
  35     MOZ_ASSERT(mStatementOwner, "Must have a statement owner!");
  36   }
  37   StatementData(const StatementData &aSource)
  38       : mStatement(aSource.mStatement),
  39         mParamsArray(aSource.mParamsArray),
  40         mStatementOwner(aSource.mStatementOwner) {
  41     MOZ_ASSERT(mStatementOwner, "Must have a statement owner!");
  42   }
  43   StatementData() : mStatement(nullptr) {}
  44   ~StatementData() {
  45     // We need to ensure that mParamsArray is released on the main thread,
  46     // as the binding arguments may be XPConnect values, which are safe
  47     // to release only on the main thread.
  48     NS_ReleaseOnMainThreadSystemGroup("StatementData::mParamsArray",
  49                                       mParamsArray.forget());
  50   }
  51
  52   /**
  53    * Return the sqlite statement, fetching it from the storage statement.  In
  54    * the case of AsyncStatements this may actually create the statement
  55    */
  56   inline int getSqliteStatement(sqlite3_stmt **_stmt) {
  57     if (!mStatement) {
  58       int rc = mStatementOwner->getAsyncStatement(&mStatement);
  59       NS_ENSURE_TRUE(rc == SQLITE_OK, rc);
  60     }
  61     *_stmt = mStatement;
  62     return SQLITE_OK;
  63   }
  64
  65   operator BindingParamsArray *() const { return mParamsArray; }
  66
  67   /**
  68    * NULLs out our sqlite3_stmt (it is held by the owner) after reseting it and
  69    * clear all bindings to it.  This is expected to occur on the async thread.
  70    */
  71   inline void reset() {
  72     MOZ_ASSERT(mStatementOwner, "Must have a statement owner!");
  73     // In the AsyncStatement case we may never have populated mStatement if the
  74     // AsyncExecuteStatements got canceled or a failure occurred in constructing
  75     // the statement.
  76     if (mStatement) {
  77       (void)::sqlite3_reset(mStatement);
  78       (void)::sqlite3_clear_bindings(mStatement);
  79       mStatement = nullptr;
  80     }
  81   }
  82
  83   /**
  84    * Indicates if this statement has parameters to be bound before it is
  85    * executed.
  86    *
  87    * @return true if the statement has parameters to bind against, false
  88    *         otherwise.
  89    */
  90   inline bool hasParametersToBeBound() const { return !!mParamsArray; }
  91   /**
  92    * Indicates the number of implicit statements generated by this statement
  93    * requiring a transaction for execution.  For example a single statement
  94    * with N BindingParams will execute N implicit staments.
  95    *
  96    * @return number of statements requiring a transaction for execution.
  97    *
  98    * @note In the case of AsyncStatements this may actually create the
  99    *       statement.
 100    */
 101   inline uint32_t needsTransaction() {
 102     MOZ_ASSERT(!NS_IsMainThread());
 103     // Be sure to use the getSqliteStatement helper, since sqlite3_stmt_readonly
 104     // can only analyze prepared statements and AsyncStatements are prepared
 105     // lazily.
 106     sqlite3_stmt *stmt;
 107     int rc = getSqliteStatement(&stmt);
 108     if (SQLITE_OK != rc || ::sqlite3_stmt_readonly(stmt)) {
 109       return 0;
 110     }
 111     return mParamsArray ? mParamsArray->length() : 1;
 112   }
 113
 114  private:
 115   sqlite3_stmt *mStatement;
 116   RefPtr<BindingParamsArray> mParamsArray;
 117
 118   /**
 119    * We hold onto a reference of the statement's owner so it doesn't get
 120    * destroyed out from under us.
 121    */
 122   nsCOMPtr<StorageBaseStatementInternal> mStatementOwner;
 123 };
 124
 125 }  // namespace storage
 126 }  // namespace mozilla
 127
 128 #endif  // mozStorageStatementData_h