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-rw-r--r--src/mongo/client/dbclientcursor.h484
1 files changed, 260 insertions, 224 deletions
diff --git a/src/mongo/client/dbclientcursor.h b/src/mongo/client/dbclientcursor.h
index 1e110a4d317..c10f4adf8ff 100644
--- a/src/mongo/client/dbclientcursor.h
+++ b/src/mongo/client/dbclientcursor.h
@@ -39,238 +39,274 @@
namespace mongo {
- class AScopedConnection;
+class AScopedConnection;
- /** for mock purposes only -- do not create variants of DBClientCursor, nor hang code here
- @see DBClientMockCursor
+/** for mock purposes only -- do not create variants of DBClientCursor, nor hang code here
+ @see DBClientMockCursor
+ */
+class DBClientCursorInterface {
+ MONGO_DISALLOW_COPYING(DBClientCursorInterface);
+
+public:
+ virtual ~DBClientCursorInterface() {}
+ virtual bool more() = 0;
+ virtual BSONObj next() = 0;
+ // TODO bring more of the DBClientCursor interface to here
+protected:
+ DBClientCursorInterface() {}
+};
+
+/** Queries return a cursor object */
+class DBClientCursor : public DBClientCursorInterface {
+ MONGO_DISALLOW_COPYING(DBClientCursor);
+
+public:
+ /** If true, safe to call next(). Requests more from server if necessary. */
+ bool more();
+
+ /** If true, there is more in our local buffers to be fetched via next(). Returns
+ false when a getMore request back to server would be required. You can use this
+ if you want to exhaust whatever data has been fetched to the client already but
+ then perhaps stop.
+ */
+ int objsLeftInBatch() const {
+ _assertIfNull();
+ return _putBack.size() + batch.nReturned - batch.pos;
+ }
+ bool moreInCurrentBatch() {
+ return objsLeftInBatch() > 0;
+ }
+
+ /** next
+ @return next object in the result cursor.
+ on an error at the remote server, you will get back:
+ { $err: <std::string> }
+ if you do not want to handle that yourself, call nextSafe().
+
+ Warning: The returned BSONObj will become invalid after the next batch
+ is fetched or when this cursor is destroyed.
+ */
+ BSONObj next();
+
+ /**
+ restore an object previously returned by next() to the cursor
*/
- class DBClientCursorInterface {
- MONGO_DISALLOW_COPYING(DBClientCursorInterface);
- public:
- virtual ~DBClientCursorInterface() {}
- virtual bool more() = 0;
- virtual BSONObj next() = 0;
- // TODO bring more of the DBClientCursor interface to here
- protected:
- DBClientCursorInterface() {}
- };
+ void putBack(const BSONObj& o) {
+ _putBack.push(o.getOwned());
+ }
- /** Queries return a cursor object */
- class DBClientCursor : public DBClientCursorInterface {
- MONGO_DISALLOW_COPYING(DBClientCursor);
- public:
- /** If true, safe to call next(). Requests more from server if necessary. */
- bool more();
-
- /** If true, there is more in our local buffers to be fetched via next(). Returns
- false when a getMore request back to server would be required. You can use this
- if you want to exhaust whatever data has been fetched to the client already but
- then perhaps stop.
- */
- int objsLeftInBatch() const { _assertIfNull(); return _putBack.size() + batch.nReturned - batch.pos; }
- bool moreInCurrentBatch() { return objsLeftInBatch() > 0; }
-
- /** next
- @return next object in the result cursor.
- on an error at the remote server, you will get back:
- { $err: <std::string> }
- if you do not want to handle that yourself, call nextSafe().
-
- Warning: The returned BSONObj will become invalid after the next batch
- is fetched or when this cursor is destroyed.
- */
- BSONObj next();
-
- /**
- restore an object previously returned by next() to the cursor
- */
- void putBack( const BSONObj &o ) { _putBack.push( o.getOwned() ); }
-
- /** throws AssertionException if get back { $err : ... } */
- BSONObj nextSafe();
-
- /** peek ahead at items buffered for future next() calls.
- never requests new data from the server. so peek only effective
- with what is already buffered.
- WARNING: no support for _putBack yet!
- */
- void peek(std::vector<BSONObj>&, int atMost);
-
- // Peeks at first element, if exists
- BSONObj peekFirst();
-
- /**
- * peek ahead and see if an error occurred, and get the error if so.
- */
- bool peekError(BSONObj* error = NULL);
-
- /**
- iterate the rest of the cursor and return the number if items
- */
- int itcount() {
- int c = 0;
- while ( more() ) {
- next();
- c++;
- }
- return c;
- }
+ /** throws AssertionException if get back { $err : ... } */
+ BSONObj nextSafe();
- /** cursor no longer valid -- use with tailable cursors.
- note you should only rely on this once more() returns false;
- 'dead' may be preset yet some data still queued and locally
- available from the dbclientcursor.
- */
- bool isDead() const { return cursorId == 0; }
-
- bool tailable() const { return (opts & QueryOption_CursorTailable) != 0; }
-
- /** see ResultFlagType (constants.h) for flag values
- mostly these flags are for internal purposes -
- ResultFlag_ErrSet is the possible exception to that
- */
- bool hasResultFlag( int flag ) {
- _assertIfNull();
- return (resultFlags & flag) != 0;
- }
+ /** peek ahead at items buffered for future next() calls.
+ never requests new data from the server. so peek only effective
+ with what is already buffered.
+ WARNING: no support for _putBack yet!
+ */
+ void peek(std::vector<BSONObj>&, int atMost);
- /// Change batchSize after construction. Can change after requesting first batch.
- void setBatchSize(int newBatchSize) { batchSize = newBatchSize; }
-
- DBClientCursor(DBClientBase* client,
- const std::string& ns,
- const BSONObj& query,
- int nToReturn,
- int nToSkip,
- const BSONObj* fieldsToReturn,
- int queryOptions,
- int bs);
-
- DBClientCursor(DBClientBase* client,
- const std::string& ns,
- long long cursorId,
- int nToReturn,
- int options );
-
- virtual ~DBClientCursor();
-
- long long getCursorId() const { return cursorId; }
-
- /** by default we "own" the cursor and will send the server a KillCursor
- message when ~DBClientCursor() is called. This function overrides that.
- */
- void decouple() { _ownCursor = false; }
-
- void attach( AScopedConnection * conn );
-
- std::string originalHost() const { return _originalHost; }
-
- std::string getns() const { return ns; }
-
- Message* getMessage(){ return batch.m.get(); }
-
- /**
- * Used mainly to run commands on connections that doesn't support lazy initialization and
- * does not support commands through the call interface.
- *
- * @param cmd The BSON representation of the command to send.
- *
- * @return true if command was sent successfully
- */
- bool initCommand();
-
- /**
- * actually does the query
- */
- bool init();
-
- void initLazy( bool isRetry = false );
- bool initLazyFinish( bool& retry );
-
- class Batch {
- MONGO_DISALLOW_COPYING(Batch);
- friend class DBClientCursor;
- std::unique_ptr<Message> m;
- int nReturned;
- int pos;
- const char *data;
- public:
- Batch() : m( new Message() ), nReturned(), pos(), data() { }
- };
-
- /**
- * For exhaust. Used in DBClientConnection.
- */
- void exhaustReceiveMore();
-
- private:
- DBClientCursor(DBClientBase* client,
- const std::string& ns,
- const BSONObj& query,
- long long cursorId,
- int nToReturn,
- int nToSkip,
- const BSONObj* fieldsToReturn,
- int queryOptions,
- int bs);
-
- int nextBatchSize();
-
- Batch batch;
- DBClientBase* _client;
- std::string _originalHost;
- const std::string ns;
- const bool _isCommand;
- BSONObj query;
- int nToReturn;
- bool haveLimit;
- int nToSkip;
- const BSONObj *fieldsToReturn;
- int opts;
- int batchSize;
- std::stack< BSONObj > _putBack;
- int resultFlags;
- long long cursorId;
- bool _ownCursor; // see decouple()
- std::string _scopedHost;
- std::string _lazyHost;
- bool wasError;
-
- void dataReceived() { bool retry; std::string lazyHost; dataReceived( retry, lazyHost ); }
- void dataReceived( bool& retry, std::string& lazyHost );
-
- /**
- * Called by dataReceived when the query was actually a command. Parses the command reply
- * according to the RPC protocol used to send it, and then fills in the internal field
- * of this cursor with the received data.
- */
- void commandDataReceived();
-
- void requestMore();
-
- // Don't call from a virtual function
- void _assertIfNull() const { uassert(13348, "connection died", this); }
-
- // init pieces
- void _assembleInit( Message& toSend );
- };
+ // Peeks at first element, if exists
+ BSONObj peekFirst();
- /** iterate over objects in current batch only - will not cause a network call
+ /**
+ * peek ahead and see if an error occurred, and get the error if so.
*/
- class DBClientCursorBatchIterator {
- public:
- DBClientCursorBatchIterator( DBClientCursor &c ) : _c( c ), _n() {}
- bool moreInCurrentBatch() { return _c.moreInCurrentBatch(); }
- BSONObj nextSafe() {
- massert( 13383, "BatchIterator empty", moreInCurrentBatch() );
- ++_n;
- return _c.nextSafe();
+ bool peekError(BSONObj* error = NULL);
+
+ /**
+ iterate the rest of the cursor and return the number if items
+ */
+ int itcount() {
+ int c = 0;
+ while (more()) {
+ next();
+ c++;
}
- int n() const { return _n; }
- private:
- DBClientCursor &_c;
- int _n;
+ return c;
+ }
+
+ /** cursor no longer valid -- use with tailable cursors.
+ note you should only rely on this once more() returns false;
+ 'dead' may be preset yet some data still queued and locally
+ available from the dbclientcursor.
+ */
+ bool isDead() const {
+ return cursorId == 0;
+ }
+
+ bool tailable() const {
+ return (opts & QueryOption_CursorTailable) != 0;
+ }
+
+ /** see ResultFlagType (constants.h) for flag values
+ mostly these flags are for internal purposes -
+ ResultFlag_ErrSet is the possible exception to that
+ */
+ bool hasResultFlag(int flag) {
+ _assertIfNull();
+ return (resultFlags & flag) != 0;
+ }
+
+ /// Change batchSize after construction. Can change after requesting first batch.
+ void setBatchSize(int newBatchSize) {
+ batchSize = newBatchSize;
+ }
+
+ DBClientCursor(DBClientBase* client,
+ const std::string& ns,
+ const BSONObj& query,
+ int nToReturn,
+ int nToSkip,
+ const BSONObj* fieldsToReturn,
+ int queryOptions,
+ int bs);
+
+ DBClientCursor(DBClientBase* client,
+ const std::string& ns,
+ long long cursorId,
+ int nToReturn,
+ int options);
+
+ virtual ~DBClientCursor();
+
+ long long getCursorId() const {
+ return cursorId;
+ }
+
+ /** by default we "own" the cursor and will send the server a KillCursor
+ message when ~DBClientCursor() is called. This function overrides that.
+ */
+ void decouple() {
+ _ownCursor = false;
+ }
+
+ void attach(AScopedConnection* conn);
+
+ std::string originalHost() const {
+ return _originalHost;
+ }
+
+ std::string getns() const {
+ return ns;
+ }
+
+ Message* getMessage() {
+ return batch.m.get();
+ }
+
+ /**
+ * Used mainly to run commands on connections that doesn't support lazy initialization and
+ * does not support commands through the call interface.
+ *
+ * @param cmd The BSON representation of the command to send.
+ *
+ * @return true if command was sent successfully
+ */
+ bool initCommand();
+
+ /**
+ * actually does the query
+ */
+ bool init();
+
+ void initLazy(bool isRetry = false);
+ bool initLazyFinish(bool& retry);
+
+ class Batch {
+ MONGO_DISALLOW_COPYING(Batch);
+ friend class DBClientCursor;
+ std::unique_ptr<Message> m;
+ int nReturned;
+ int pos;
+ const char* data;
+
+ public:
+ Batch() : m(new Message()), nReturned(), pos(), data() {}
};
-} // namespace mongo
+ /**
+ * For exhaust. Used in DBClientConnection.
+ */
+ void exhaustReceiveMore();
+
+private:
+ DBClientCursor(DBClientBase* client,
+ const std::string& ns,
+ const BSONObj& query,
+ long long cursorId,
+ int nToReturn,
+ int nToSkip,
+ const BSONObj* fieldsToReturn,
+ int queryOptions,
+ int bs);
+
+ int nextBatchSize();
+
+ Batch batch;
+ DBClientBase* _client;
+ std::string _originalHost;
+ const std::string ns;
+ const bool _isCommand;
+ BSONObj query;
+ int nToReturn;
+ bool haveLimit;
+ int nToSkip;
+ const BSONObj* fieldsToReturn;
+ int opts;
+ int batchSize;
+ std::stack<BSONObj> _putBack;
+ int resultFlags;
+ long long cursorId;
+ bool _ownCursor; // see decouple()
+ std::string _scopedHost;
+ std::string _lazyHost;
+ bool wasError;
+
+ void dataReceived() {
+ bool retry;
+ std::string lazyHost;
+ dataReceived(retry, lazyHost);
+ }
+ void dataReceived(bool& retry, std::string& lazyHost);
+
+ /**
+ * Called by dataReceived when the query was actually a command. Parses the command reply
+ * according to the RPC protocol used to send it, and then fills in the internal field
+ * of this cursor with the received data.
+ */
+ void commandDataReceived();
+
+ void requestMore();
+
+ // Don't call from a virtual function
+ void _assertIfNull() const {
+ uassert(13348, "connection died", this);
+ }
+ // init pieces
+ void _assembleInit(Message& toSend);
+};
+
+/** iterate over objects in current batch only - will not cause a network call
+ */
+class DBClientCursorBatchIterator {
+public:
+ DBClientCursorBatchIterator(DBClientCursor& c) : _c(c), _n() {}
+ bool moreInCurrentBatch() {
+ return _c.moreInCurrentBatch();
+ }
+ BSONObj nextSafe() {
+ massert(13383, "BatchIterator empty", moreInCurrentBatch());
+ ++_n;
+ return _c.nextSafe();
+ }
+ int n() const {
+ return _n;
+ }
+
+private:
+ DBClientCursor& _c;
+ int _n;
+};
+
+} // namespace mongo
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