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comparison: storage/public/mozStorageHelper.h
storage/public/mozStorageHelper.h
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| -1:000000000000 | 0:736a3eafbf84 |
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| 1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ | |
| 2 /* This Source Code Form is subject to the terms of the Mozilla Public | |
| 3 * License, v. 2.0. If a copy of the MPL was not distributed with this | |
| 4 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ | |
| 5 | |
| 6 #ifndef MOZSTORAGEHELPER_H | |
| 7 #define MOZSTORAGEHELPER_H | |
| 8 | |
| 9 #include "nsAutoPtr.h" | |
| 10 | |
| 11 #include "mozIStorageAsyncConnection.h" | |
| 12 #include "mozIStorageConnection.h" | |
| 13 #include "mozIStorageStatement.h" | |
| 14 #include "nsError.h" | |
| 15 | |
| 16 /** | |
| 17 * This class wraps a transaction inside a given C++ scope, guaranteeing that | |
| 18 * the transaction will be completed even if you have an exception or | |
| 19 * return early. | |
| 20 * | |
| 21 * aCommitOnComplete controls whether the transaction is committed or rolled | |
| 22 * back when it goes out of scope. A common use is to create an instance with | |
| 23 * commitOnComplete = FALSE (rollback), then call Commit on this object manually | |
| 24 * when your function completes successfully. | |
| 25 * | |
| 26 * Note that nested transactions are not supported by sqlite, so if a transaction | |
| 27 * is already in progress, this object does nothing. Note that in this case, | |
| 28 * you may not get the transaction type you ask for, and you won't be able | |
| 29 * to rollback. | |
| 30 * | |
| 31 * Note: This class is templatized to be also usable with internal data | |
| 32 * structures. External users of this class should generally use | |
| 33 * |mozStorageTransaction| instead. | |
| 34 */ | |
| 35 template<typename T, typename U> | |
| 36 class mozStorageTransactionBase | |
| 37 { | |
| 38 public: | |
| 39 mozStorageTransactionBase(T* aConnection, | |
| 40 bool aCommitOnComplete, | |
| 41 int32_t aType = mozIStorageConnection::TRANSACTION_DEFERRED) | |
| 42 : mConnection(aConnection), | |
| 43 mHasTransaction(false), | |
| 44 mCommitOnComplete(aCommitOnComplete), | |
| 45 mCompleted(false) | |
| 46 { | |
| 47 // We won't try to get a transaction if one is already in progress. | |
| 48 if (mConnection) | |
| 49 mHasTransaction = NS_SUCCEEDED(mConnection->BeginTransactionAs(aType)); | |
| 50 } | |
| 51 ~mozStorageTransactionBase() | |
| 52 { | |
| 53 if (mConnection && mHasTransaction && ! mCompleted) { | |
| 54 if (mCommitOnComplete) | |
| 55 mConnection->CommitTransaction(); | |
| 56 else | |
| 57 mConnection->RollbackTransaction(); | |
| 58 } | |
| 59 } | |
| 60 | |
| 61 /** | |
| 62 * Commits the transaction if one is in progress. If one is not in progress, | |
| 63 * this is a NOP since the actual owner of the transaction outside of our | |
| 64 * scope is in charge of finally comitting or rolling back the transaction. | |
| 65 */ | |
| 66 nsresult Commit() | |
| 67 { | |
| 68 if (!mConnection || mCompleted) | |
| 69 return NS_OK; // no connection, or already done | |
| 70 mCompleted = true; | |
| 71 if (! mHasTransaction) | |
| 72 return NS_OK; // transaction not ours, ignore | |
| 73 nsresult rv = mConnection->CommitTransaction(); | |
| 74 if (NS_SUCCEEDED(rv)) | |
| 75 mHasTransaction = false; | |
| 76 | |
| 77 return rv; | |
| 78 } | |
| 79 | |
| 80 /** | |
| 81 * Rolls back the transaction in progress. You should only call this function | |
| 82 * if this object has a real transaction (HasTransaction() = true) because | |
| 83 * otherwise, there is no transaction to roll back. | |
| 84 */ | |
| 85 nsresult Rollback() | |
| 86 { | |
| 87 if (!mConnection || mCompleted) | |
| 88 return NS_OK; // no connection, or already done | |
| 89 mCompleted = true; | |
| 90 if (! mHasTransaction) | |
| 91 return NS_ERROR_FAILURE; | |
| 92 | |
| 93 // It is possible that a rollback will return busy, so we busy wait... | |
| 94 nsresult rv = NS_OK; | |
| 95 do { | |
| 96 rv = mConnection->RollbackTransaction(); | |
| 97 if (rv == NS_ERROR_STORAGE_BUSY) | |
| 98 (void)PR_Sleep(PR_INTERVAL_NO_WAIT); | |
| 99 } while (rv == NS_ERROR_STORAGE_BUSY); | |
| 100 | |
| 101 if (NS_SUCCEEDED(rv)) | |
| 102 mHasTransaction = false; | |
| 103 | |
| 104 return rv; | |
| 105 } | |
| 106 | |
| 107 /** | |
| 108 * Returns whether this object wraps a real transaction. False means that | |
| 109 * this object doesn't do anything because there was already a transaction in | |
| 110 * progress when it was created. | |
| 111 */ | |
| 112 bool HasTransaction() | |
| 113 { | |
| 114 return mHasTransaction; | |
| 115 } | |
| 116 | |
| 117 /** | |
| 118 * This sets the default action (commit or rollback) when this object goes | |
| 119 * out of scope. | |
| 120 */ | |
| 121 void SetDefaultAction(bool aCommitOnComplete) | |
| 122 { | |
| 123 mCommitOnComplete = aCommitOnComplete; | |
| 124 } | |
| 125 | |
| 126 protected: | |
| 127 U mConnection; | |
| 128 bool mHasTransaction; | |
| 129 bool mCommitOnComplete; | |
| 130 bool mCompleted; | |
| 131 }; | |
| 132 | |
| 133 /** | |
| 134 * An instance of the mozStorageTransaction<> family dedicated | |
| 135 * to |mozIStorageConnection|. | |
| 136 */ | |
| 137 typedef mozStorageTransactionBase<mozIStorageConnection, | |
| 138 nsCOMPtr<mozIStorageConnection> > | |
| 139 mozStorageTransaction; | |
| 140 | |
| 141 | |
| 142 | |
| 143 /** | |
| 144 * This class wraps a statement so that it is guaraneed to be reset when | |
| 145 * this object goes out of scope. | |
| 146 * | |
| 147 * Note that this always just resets the statement. If the statement doesn't | |
| 148 * need resetting, the reset operation is inexpensive. | |
| 149 */ | |
| 150 class MOZ_STACK_CLASS mozStorageStatementScoper | |
| 151 { | |
| 152 public: | |
| 153 mozStorageStatementScoper(mozIStorageStatement* aStatement) | |
| 154 : mStatement(aStatement) | |
| 155 { | |
| 156 } | |
| 157 ~mozStorageStatementScoper() | |
| 158 { | |
| 159 if (mStatement) | |
| 160 mStatement->Reset(); | |
| 161 } | |
| 162 | |
| 163 /** | |
| 164 * Call this to make the statement not reset. You might do this if you know | |
| 165 * that the statement has been reset. | |
| 166 */ | |
| 167 void Abandon() | |
| 168 { | |
| 169 mStatement = nullptr; | |
| 170 } | |
| 171 | |
| 172 protected: | |
| 173 nsCOMPtr<mozIStorageStatement> mStatement; | |
| 174 }; | |
| 175 | |
| 176 // Use this to make queries uniquely identifiable in telemetry | |
| 177 // statistics, especially PRAGMAs. We don't include __LINE__ so that | |
| 178 // queries are stable in the face of source code changes. | |
| 179 #define MOZ_STORAGE_UNIQUIFY_QUERY_STR "/* " __FILE__ " */ " | |
| 180 | |
| 181 #endif /* MOZSTORAGEHELPER_H */ |
