SERVER-35115 Separate dbclientinterface.h into several parts, one per class.

1 files changed, 310 insertions, 0 deletions

diff --git a/src/mongo/client/dbclient_cursor.h b/src/mongo/client/dbclient_cursor.h
new file mode 100644
index 00000000000..36f5c20452a
--- /dev/null
+++ b/src/mongo/client/dbclient_cursor.h
@@ -0,0 +1,310 @@
+// file dbclientcursor.h
+
+/*    Copyright 2009 10gen Inc.
+ *
+ *    This program is free software: you can redistribute it and/or  modify
+ *    it under the terms of the GNU Affero General Public License, version 3,
+ *    as published by the Free Software Foundation.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU Affero General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Affero General Public License
+ *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the GNU Affero General Public License in all respects
+ *    for all of the code used other than as permitted herein. If you modify
+ *    file(s) with this exception, you may extend this exception to your
+ *    version of the file(s), but you are not obligated to do so. If you do not
+ *    wish to do so, delete this exception statement from your version. If you
+ *    delete this exception statement from all source files in the program,
+ *    then also delete it in the license file.
+ */
+
+#pragma once
+
+#include <stack>
+
+#include "mongo/base/disallow_copying.h"
+#include "mongo/db/dbmessage.h"
+#include "mongo/db/jsobj.h"
+#include "mongo/db/json.h"
+#include "mongo/db/namespace_string.h"
+#include "mongo/rpc/message.h"
+
+namespace mongo {
+
+class AScopedConnection;
+class DBClientBase;
+
+/** Queries return a cursor object */
+class DBClientCursor {
+    MONGO_DISALLOW_COPYING(DBClientCursor);
+
+public:
+    /** If true, safe to call next().  Requests more from server if necessary. */
+    virtual 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 {
+        return _putBack.size() + batch.objs.size() - 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().
+    */
+    virtual 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;
+    }
+
+    /** 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) {
+        return (resultFlags & flag) != 0;
+    }
+
+    /// Change batchSize after construction. Can change after requesting first batch.
+    void setBatchSize(int newBatchSize) {
+        batchSize = newBatchSize;
+    }
+
+
+    /**
+     * Fold this in with queryOptions to force the use of legacy query operations.
+     * This flag is never sent over the wire and is only used locally.
+     */
+    enum { QueryOptionLocal_forceOpQuery = 1 << 30 };
+
+    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,
+                   std::vector<BSONObj> initialBatch = {});
+
+    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.ns();
+    }
+
+    /**
+     * actually does the query
+     */
+    bool init();
+
+    void initLazy(bool isRetry = false);
+    bool initLazyFinish(bool& retry);
+
+    /**
+     * For exhaust. Used in DBClientConnection.
+     */
+    void exhaustReceiveMore();
+
+    /**
+     * Marks this object as dead and sends the KillCursors message to the server.
+     *
+     * Any errors that result from this are swallowed since this is typically performed as part of
+     * cleanup and a failure to kill the cursor should not result in a failure of the operation
+     * using the cursor.
+     *
+     * Killing an already killed or exhausted cursor does nothing, so it is safe to always call this
+     * if you want to ensure that a cursor is killed.
+     */
+    void kill();
+
+    /**
+     * Returns true if the connection this cursor is using has pending replies.
+     *
+     * If true, you should not try to use the connection for any other purpose or return it to a
+     * pool.
+     *
+     * This can happen if either initLazy() was called without initLazyFinish() or an exhaust query
+     * was started but not completed.
+     */
+    bool connectionHasPendingReplies() const {
+        return _connectionHasPendingReplies;
+    }
+
+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,
+                   std::vector<BSONObj> initialBatch);
+
+    int nextBatchSize();
+
+    struct Batch {
+        // TODO remove constructors after c++17 toolchain upgrade
+        Batch() = default;
+        Batch(std::vector<BSONObj> initial, size_t initialPos = 0)
+            : objs(std::move(initial)), pos(initialPos) {}
+        std::vector<BSONObj> objs;
+        size_t pos = 0;
+    };
+
+    Batch batch;
+    DBClientBase* _client;
+    std::string _originalHost;
+    NamespaceString 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;
+    BSONVersion _enabledBSONVersion;
+    bool _useFindCommand = true;
+    bool _connectionHasPendingReplies = false;
+    int _lastRequestId = 0;
+
+    void dataReceived(const Message& reply) {
+        bool retry;
+        std::string lazyHost;
+        dataReceived(reply, retry, lazyHost);
+    }
+    void dataReceived(const Message& reply, bool& retry, std::string& lazyHost);
+
+    /**
+     * Parses and returns command replies regardless of which command protocol was used.
+     * Does *not* parse replies from non-command OP_QUERY finds.
+     */
+    BSONObj commandDataReceived(const Message& reply);
+
+    void requestMore();
+
+    // init pieces
+    Message _assembleInit();
+    Message _assembleGetMore();
+};
+
+/** 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