QtCassandra 程序1

/*
* Text:
*      read_write_data.cpp
*
* Description:
*      Create a context with a table, then try to read and write data to
*      the Cassandra cluster.
*
* Documentation:
*      Run with no options.
*      Fails if the test cannot create the context, create the table,
*      read or write the data.
*
* License:
*      Copyright (c) 2011 Made to Order Software Corp.
*
*      http://snapwebsites.org/
*      [e-mail]
*
*      Permission is hereby granted, free of charge, to any person obtaining a
*      copy of this software and associated documentation files (the
*      "Software"), to deal in the Software without restriction, including
*      without limitation the rights to use, copy, modify, merge, publish,
*      distribute, sublicense, and/or sell copies of the Software, and to
*      permit persons to whom the Software is furnished to do so, subject to
*      the following conditions:
*
*      The above copyright notice and this permission notice shall be included
*      in all copies or substantial portions of the Software.
*
*      THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
*      OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
*      MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
*      IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
*      CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
*      TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
*      SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

#include <QtCassandra/QCassandra.h>
#include <QtCore/QDebug>
#include <thrift-gencpp-cassandra/cassandra_types.h>

int main(int argc, char *argv[])
{
    QtCassandra::QCassandra     cassandra;//定义一个数据库

    cassandra.connect();//链接数据库
qDebug() << "Working on Cassandra Cluster Named" << cassandra.clusterName();
    qDebug() << "Working on Cassandra Protocol Version" << cassandra.protocolVersion();

    QSharedPointer<QtCassandra::QCassandraContext> context(cassandra.context("qt_cassandra_test_rw"));//创建一个keyspace 名字为qt_cassandra_test_rw.
    context->setStrategyClass("SimpleStrategy"); // default is LocalStrategy  副本放置策略为简单策略，一个数据中心内放置副本
    //context->setDurableWrites(false); // by default this is 'true'
    context->setReplicationFactor(1); // by default this is undefined 副本因子为1，只在当前节点上存储数据，不在集群中的其他节点上存储数据

    QSharedPointer<QtCassandra::QCassandraTable> table(context->table("qt_cassandra_test_table"));//创建列族，columnfamily 的名字为qt_cassandra_test_table
    //table->setComment("Our test table.");//注释信息，列族定义中的重要信息，字符串形式的人类可读的任意注释语言
    table->setColumnType("Standard"); // Standard or Super  普通列族 或者是 超级列族
    table->setKeyValidationClass("BytesType");
    table->setDefaultValidationClass("BytesType");
    table->setComparatorType("BytesType");// 按照 bytetype进行排序
    table->setKeyCacheSavePeriodInSeconds(14400);
    table->setMemtableFlushAfterMins(60);
    //table->setMemtableThroughputInMb(247);
    //table->setMemtableOperationsInMillions(1.1578125);
    //table->setGcGraceSeconds(864000); // 10 days (default)
    table->setGcGraceSeconds(3600); // 1h.
    table->setMinCompactionThreshold(4);
    table->setMaxCompactionThreshold(22);
    table->setReplicateOnWrite(1);

//column_type:标准列族或者超级列族

//colck_type:唯一合法的值就是 Timestamp

//comparator:按照什么类型进行排序

//subcomparator:当column是超级列时，子列使用的比较器

//recociler:当列的版本发生冲突时，进行协调的类的名字，目前唯一合法的是Timestamp

//rows_cached:要缓存的行数量

//preload_row_cache:把这个选项设置为true,可以自动加载行缓存

//key_cache_size:放入缓存中键值数量

//read_repair_chance:合法值区间为0.0-1.0

// Cluster->keyspace->columnfamily->column

//对应Qt的库为:

//Cluster->Contexts->tables->ColumnDefintions   

//QCassandra->QCassandraContexts->QCassandraTable->QCassandraRow->QCassandraCell

//row为 列族中的一行数据，而cell则指的是某个数据，这个cell可以是column的key或者 value

//多个cell构成了 row

    try {
        context->create();//创建keyspace和 列族
        qDebug() << "Context and its table were created!";
    }
    catch(org::apache::cassandra::InvalidRequestException& e) {
        qDebug() << "Exception is [" << e.why.c_str() << "]";
    }

    //try {  // by default the rest should not generate an exception
    // now that it's created, we can access it with the [] operator

    QtCassandra::QCassandraValue value1(-55);//插入一条数据，
    cassandra["qt_cassandra_test_rw"]["qt_cassandra_test_table"][QString("http://www.snapwebsites.org/page/3")][QString("size")] = value1;

//参数为，1，keyspace   2,columnfamily  3,rowkey  4,columnkey  5,columnvalue
    QtCassandra::QCassandraValue value2(1000000);
    cassandra["qt_cassandra_test_rw"]["qt_cassandra_test_table"][QString("http://www.snapwebsites.org/page/3")][QString("million")] = value2;

    // binary
    QByteArray bin;
    bin.append((char)1);
    bin.append((char)255);
    bin.append('G');
    bin.append('I');
    bin.append('F');
    bin.append('.');
    bin.append((char)32);
    bin.append((char)7);
    bin.append((char)0xC0); // 192
    //bin.clear();  // here you can test that empty values are acceptable by Cassandra
    QtCassandra::QCassandraValue value3(bin);
    QByteArray row_key;
    row_key.append((char)0);
    row_key.append((char)255);
    row_key.append((char)9);
    row_key.append((char)25);
    row_key.append((char)0);
    QByteArray column_key;
    column_key.append((char)0);
    column_key.append((char)1);
    column_key.append((char)15);
    column_key.append((char)0);
    column_key.append((char)255);
    cassandra["qt_cassandra_test_rw"]["qt_cassandra_test_table"][row_key][column_key] = value3;

    // read this one from the memory cache
    QtCassandra::QCassandraValue v1 = cassandra["qt_cassandra_test_rw"]["qt_cassandra_test_table"][QString("http://www.snapwebsites.org/page/3")][QString("size")];
    if(v1.int32Value() != -55) {
        qDebug() << "Reading the size value failed. Got" << v1.int32Value() << "instead of -55";
    }

    // clear the cache
    cassandra["qt_cassandra_test_rw"]["qt_cassandra_test_table"].clearCache();
    if(cassandra["qt_cassandra_test_rw"]["qt_cassandra_test_table"][QString("http://www.snapwebsites.org/page/3")].exists(QString("size"))) {
        qDebug() << "Yeah! exists(\"size\") worked! (from Cassandra)";
    }
    else {
        qDebug() << "Could not find \"size\" which should be defined";
    }

    // clear the cache
    cassandra["qt_cassandra_test_rw"]["qt_cassandra_test_table"].clearCache();
    if(cassandra["qt_cassandra_test_rw"]["qt_cassandra_test_table"].exists(QString("http://www.snapwebsites.org/page/3"))) {
        qDebug() << "Yeah! exists(\"http://www.snapwebsites.org/page/3\") worked! (from Cassandra)";
    }
    else {
        qDebug() << "Could not find \"http://www.snapwebsites.org/page/3\" which should be defined";
    }

    if(cassandra["qt_cassandra_test_rw"]["qt_cassandra_test_table"].exists(QString("unknown row"))) {
        qDebug() << "Hmmm... exists(\"unknown row\") worked... (from Cassandra)";
    }
    else {
        qDebug() << "Could not find \"unknown row\" which was expected!";
    }

    // clear the cache
    cassandra["qt_cassandra_test_rw"]["qt_cassandra_test_table"].clearCache();

    // re-read this one from Cassandra

//读取一条数据
    QtCassandra::QCassandraValue v1b = cassandra["qt_cassandra_test_rw"]["qt_cassandra_test_table"][QString("http://www.snapwebsites.org/page/3")][QString("size")];

    if(v1b.int32Value() != -55) {
        qDebug() << "Reading the size value failed. Got" << v1b.int32Value() << "instead of -55";
    }

    QtCassandra::QCassandraValue v2 = cassandra["qt_cassandra_test_rw"]["qt_cassandra_test_table"][QString("http://www.snapwebsites.org/page/3")][QString("million")];
    if(v2.int32Value() != 1000000) {
        qDebug() << "Reading the size value failed. Got" << v2.int32Value() << "instead of -55";
    }

    if(cassandra["qt_cassandra_test_rw"]["qt_cassandra_test_table"][QString("http://www.snapwebsites.org/page/3")].exists(QString("million"))) {
        qDebug() << "Yeah! exists(\"million\") worked! (from memory)";
    }
    else {
        qDebug() << "Could not find \"million\" which should be defined";
    }

    // undefined cell...
    if(cassandra["qt_cassandra_test_rw"]["qt_cassandra_test_table"][QString("http://www.snapwebsites.org/page/3")].exists(QString("this one"))) {
        qDebug() << "Somehow \"this one\" exists!";
    }
    else {
        qDebug() << "Could not find \"this one\" as expected";
    }

    // clear the cache, test that we can find all the cells
    cassandra["qt_cassandra_test_rw"]["qt_cassandra_test_table"].clearCache();
    QtCassandra::QCassandraColumnPredicate column_predicate;
    cassandra["qt_cassandra_test_rw"]["qt_cassandra_test_table"][QString("http://www.snapwebsites.org/page/3")].readCells(column_predicate);

    const QtCassandra::QCassandraCells& cells(cassandra["qt_cassandra_test_rw"]["qt_cassandra_test_table"][QString("http://www.snapwebsites.org/page/3")].cells());

//读取所有 keyspace是 qt_cassandra_test_rw，列族是qt_cassandra_test_table中的数据
    qDebug() << "cells in 1st row" << cells.size();
    for(QtCassandra::QCassandraCells::const_iterator it = cells.begin(); it != cells.end(); ++it) {
        qDebug() << "  name" << (*it)->columnName();
    }

    qDebug() << "cellCount()" << cassandra["qt_cassandra_test_rw"]["qt_cassandra_test_table"][QString("http://www.snapwebsites.org/page/3")].cellCount();

    // remove one of the cells
    cassandra["qt_cassandra_test_rw"]["qt_cassandra_test_table"][QString("http://www.snapwebsites.org/page/3")].dropCell(QString("million"));

    // clear the cache, test that we can find all the cells
    cassandra["qt_cassandra_test_rw"]["qt_cassandra_test_table"].clearCache();
    cassandra["qt_cassandra_test_rw"]["qt_cassandra_test_table"][QString("http://www.snapwebsites.org/page/3")].readCells(column_predicate);
    const QtCassandra::QCassandraCells& cells2(cassandra["qt_cassandra_test_rw"]["qt_cassandra_test_table"][QString("http://www.snapwebsites.org/page/3")].cells());
    qDebug() << "AFTER REMOVE: cells in 1st row" << cells.size();
    for(QtCassandra::QCassandraCells::const_iterator it = cells2.begin(); it != cells2.end(); ++it) {
        qDebug() << "  name" << (*it)->columnName();
    }

    qDebug() << "cellCount()" << cassandra["qt_cassandra_test_rw"]["qt_cassandra_test_table"][QString("http://www.snapwebsites.org/page/3")].cellCount();

    cassandra["qt_cassandra_test_rw"]["qt_cassandra_test_table"].dropRow(QString("http://www.snapwebsites.org/page/3"), QtCassandra::QCassandraValue::TIMESTAMP_MODE_DEFINED, QtCassandra::QCassandra::timeofday() + 10000000, QtCassandra::CONSISTENCY_LEVEL_ONE);
    //if(cassandra["qt_cassandra_test_rw"]["qt_cassandra_test_table"].exists(QString("http://www.snapwebsites.org/page/3"))) {
    //    qDebug() << "error: dropped row still exists...";
    //}
    //else {
    //    qDebug() << "dropped row does not exist anymore";
    //}

    //}
    //catch(org::apache::cassandra::InvalidRequestException& e) {
    //    qDebug() << "While Working: exception is [" << e.why.c_str() << "]";
    //}

    //context->drop();
}

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