Imported Upstream version 1.3.1

1 files changed, 55 insertions, 0 deletions

diff --git a/client/examples/tail.cpp b/client/examples/tail.cpp
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+// tail.cpp
+
+/*    Copyright 2009 10gen Inc.
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ */
+
+/* example of using a tailable cursor */
+
+#include "../../client/dbclient.h"
+#include "../../util/goodies.h"
+
+using namespace mongo;
+
+void foo() { }
+
+/* "tail" the specified namespace, outputting elements as they are added. 
+   _id values must be inserted in increasing order for this to work. (Some other 
+   field could also be used.)
+
+   Note: one could use a capped collection and $natural order to do something 
+         similar, using sort({$natural:1}), and then not need to worry about 
+	 _id's being in order.
+*/
+void tail(DBClientBase& conn, const char *ns) {
+  conn.ensureIndex(ns, fromjson("{_id:1}"));
+  BSONElement lastId;
+  Query query = Query().sort("_id");
+  while( 1 ) {
+    auto_ptr<DBClientCursor> c = conn.query(ns, query, 0, 0, 0, Option_CursorTailable);
+    while( 1 ) {
+      if( !c->more() ) { 
+	if( c->isDead() ) {
+	  // we need to requery
+	  break;
+	}
+	sleepsecs(1);
+      }
+      BSONObj o = c->next();
+      lastId = o["_id"];
+      cout << o.toString() << endl;
+    }
+    query = QUERY( "_id" << GT << lastId ).sort("_id");
+  }
+}