diff options
Diffstat (limited to 'src/mongo/client/read_preference.h')
| -rw-r--r-- | src/mongo/client/read_preference.h | 231 |
1 files changed, 119 insertions, 112 deletions
diff --git a/src/mongo/client/read_preference.h b/src/mongo/client/read_preference.h index 5b23335bf31..161cfc0f241 100644 --- a/src/mongo/client/read_preference.h +++ b/src/mongo/client/read_preference.h @@ -31,118 +31,125 @@ #include "mongo/db/jsobj.h" namespace mongo { - template <typename T> class StatusWith; - - enum class ReadPreference { - /** - * Read from primary only. All operations produce an error (throw an exception where - * applicable) if primary is unavailable. Cannot be combined with tags. - */ - PrimaryOnly = 0, - - /** - * Read from primary if available, otherwise a secondary. Tags will only be applied in the - * event that the primary is unavailable and a secondary is read from. In this event only - * secondaries matching the tags provided would be read from. - */ - PrimaryPreferred, - - /** - * Read from secondary if available, otherwise error. - */ - SecondaryOnly, - - /** - * Read from a secondary if available, otherwise read from the primary. - */ - SecondaryPreferred, - - /** - * Read from any member. - */ - Nearest, - }; +template <typename T> +class StatusWith; +enum class ReadPreference { /** - * A simple object for representing the list of tags requested by a $readPreference. + * Read from primary only. All operations produce an error (throw an exception where + * applicable) if primary is unavailable. Cannot be combined with tags. */ - class TagSet { - public: - /** - * Creates a TagSet that matches any nodes. This is the TagSet represented by the BSON - * array containing a single empty document - [{}]. - * - * Do not call during static init. - */ - TagSet(); - - /** - * Returns an empty TagSet. This is the TagSet represented by the empty BSON array - []. - * This TagSet must be associated with ReadPreference::PrimaryOnly. - * ReadPreference::Primary. - */ - static TagSet primaryOnly(); - - /** - * Creates a TagSet from a BSONArray of tags. - * - * @param tags the list of tags associated with this option. This object - * will get a shared copy of the list. Therefore, it is important - * for the the given tag to live longer than the created tag set. - */ - explicit TagSet(const BSONArray& tags) : _tags(tags) {} - - /** - * Returns the BSONArray listing all tags that should be accepted. - */ - const BSONArray& getTagBSON() const { return _tags; } - - bool operator==(const TagSet& other) const { return _tags == other._tags; } - bool operator!=(const TagSet& other) const { return !(*this == other); } - - private: - BSONArray _tags; - }; - - struct ReadPreferenceSetting { - /** - * @param pref the read preference mode. - * @param tag the tag set. Note that this object will have the - * tag set will have this in a reset state (meaning, this - * object's copy of tag will have the iterator in the initial - * position). - */ - ReadPreferenceSetting(ReadPreference pref, TagSet tags); - - // TODO: remove when StatusWith supports non-default constructible types (SERVER-18007) - ReadPreferenceSetting() = default; - - inline bool equals(const ReadPreferenceSetting& other) const { - return (pref == other.pref) && (tags == other.tags); - } - - /** - * Serializes this ReadPreferenceSetting as a BSON document. - */ - BSONObj toBSON() const; - - /** - * Describes this ReadPreferenceSetting as a string. - */ - std::string toString() const; - - /** - * Parses a ReadPreferenceSetting from a BSON document of the form: - * { mode: <mode>, tags: <array of tags> }. The 'mode' element must a string equal to either - * "primary", "primaryPreferred", "secondary", "secondaryPreferred", or "nearest". Although - * the tags array is intended to be an array of unique BSON documents, no further validation - * is performed on it other than checking that it is an array, and that it is empty if - * 'mode' is 'primary'. - */ - static StatusWith<ReadPreferenceSetting> fromBSON(const BSONObj& readPrefSettingObj); - - ReadPreference pref{ReadPreference::PrimaryOnly}; - TagSet tags{TagSet::primaryOnly()}; - }; - -} // namespace mongo + PrimaryOnly = 0, + + /** + * Read from primary if available, otherwise a secondary. Tags will only be applied in the + * event that the primary is unavailable and a secondary is read from. In this event only + * secondaries matching the tags provided would be read from. + */ + PrimaryPreferred, + + /** + * Read from secondary if available, otherwise error. + */ + SecondaryOnly, + + /** + * Read from a secondary if available, otherwise read from the primary. + */ + SecondaryPreferred, + + /** + * Read from any member. + */ + Nearest, +}; + +/** + * A simple object for representing the list of tags requested by a $readPreference. + */ +class TagSet { +public: + /** + * Creates a TagSet that matches any nodes. This is the TagSet represented by the BSON + * array containing a single empty document - [{}]. + * + * Do not call during static init. + */ + TagSet(); + + /** + * Returns an empty TagSet. This is the TagSet represented by the empty BSON array - []. + * This TagSet must be associated with ReadPreference::PrimaryOnly. + * ReadPreference::Primary. + */ + static TagSet primaryOnly(); + + /** + * Creates a TagSet from a BSONArray of tags. + * + * @param tags the list of tags associated with this option. This object + * will get a shared copy of the list. Therefore, it is important + * for the the given tag to live longer than the created tag set. + */ + explicit TagSet(const BSONArray& tags) : _tags(tags) {} + + /** + * Returns the BSONArray listing all tags that should be accepted. + */ + const BSONArray& getTagBSON() const { + return _tags; + } + + bool operator==(const TagSet& other) const { + return _tags == other._tags; + } + bool operator!=(const TagSet& other) const { + return !(*this == other); + } + +private: + BSONArray _tags; +}; + +struct ReadPreferenceSetting { + /** + * @param pref the read preference mode. + * @param tag the tag set. Note that this object will have the + * tag set will have this in a reset state (meaning, this + * object's copy of tag will have the iterator in the initial + * position). + */ + ReadPreferenceSetting(ReadPreference pref, TagSet tags); + + // TODO: remove when StatusWith supports non-default constructible types (SERVER-18007) + ReadPreferenceSetting() = default; + + inline bool equals(const ReadPreferenceSetting& other) const { + return (pref == other.pref) && (tags == other.tags); + } + + /** + * Serializes this ReadPreferenceSetting as a BSON document. + */ + BSONObj toBSON() const; + + /** + * Describes this ReadPreferenceSetting as a string. + */ + std::string toString() const; + + /** + * Parses a ReadPreferenceSetting from a BSON document of the form: + * { mode: <mode>, tags: <array of tags> }. The 'mode' element must a string equal to either + * "primary", "primaryPreferred", "secondary", "secondaryPreferred", or "nearest". Although + * the tags array is intended to be an array of unique BSON documents, no further validation + * is performed on it other than checking that it is an array, and that it is empty if + * 'mode' is 'primary'. + */ + static StatusWith<ReadPreferenceSetting> fromBSON(const BSONObj& readPrefSettingObj); + + ReadPreference pref{ReadPreference::PrimaryOnly}; + TagSet tags{TagSet::primaryOnly()}; +}; + +} // namespace mongo |