Cassandra Java Client

前回 Cassandra Thrift APIのConsistencyLevel と内容的に前後してしまいますが、Cassandra APIのテストコードを一応載せておきます。データ操作(取得/登録/削除)に関するAPIはひととおり使用してあるので、コードを見ればだいたいの使い方は理解できると思います。また、各APIのシグネチャはCassandraのホームディレクトリにjavadocディレクトリがあるのでそこで確認できます。
(org.apache.cassandra.thrift.CassandraServer を参照)

以下のコードは、例としてブログ記事をデータとして扱っています。
・ColumnFamily は Entry
・entry* という key は title、category、tag の３つをcolumnを持つ

import java.util.*;
import java.io.UnsupportedEncodingException;
import org.apache.cassandra.thrift.*;
import org.apache.thrift.protocol.TBinaryProtocol;
import org.apache.thrift.protocol.TProtocol;
import org.apache.thrift.transport.TSocket;
import org.apache.thrift.transport.TTransport;
import org.apache.thrift.TException;
import org.apache.thrift.transport.TTransportException;

public class TestClient {
  private static final String KEYSPACE = "Keyspace1";
  private static final String COLUMN_FAMILY = "Entry";
  private TTransport transport = null;
  private Cassandra.Client client = null;
  TestClient() {
    client = getConnection();
  }
  private Cassandra.Client getConnection() {
    try {
      transport = new TSocket("localhost", 9160);
      TProtocol protocol = new TBinaryProtocol(transport);
      Cassandra.Client client = new Cassandra.Client(protocol);
      transport.open();
      return client;
    }catch(TTransportException e) {
      e.printStackTrace();
    }
    return null;
  }
  private void closeConnection() {
    try {
      transport.flush();
      transport.close();
    }catch(TTransportException e) {
      e.printStackTrace();
    }
  }
  private void selectEntry(String key) {
    try {
      SlicePredicate slicePredicate = new SlicePredicate();
      SliceRange sliceRange = new SliceRange();
      sliceRange.setStart(new byte[] {});
      sliceRange.setFinish(new byte[] {});
      slicePredicate.setSlice_range(sliceRange);
      ColumnParent columnParent = new ColumnParent(COLUMN_FAMILY);
      List<ColumnOrSuperColumn> results = client.get_slice(KEYSPACE, key, columnParent, slicePredicate, ConsistencyLevel.ONE);
      printData(key, results);
    }catch(Exception e) {
      e.printStackTrace();
    }
  }
  private void selectAllEntry() {
    try {
      KeyRange keyRange = new KeyRange();
      keyRange.setStart_key("");
      keyRange.setEnd_key("");
      SliceRange sliceRange = new SliceRange();
      sliceRange.setStart(new byte[] {});
      sliceRange.setFinish(new byte[] {});
      SlicePredicate slicePredicate = new SlicePredicate();
      slicePredicate.setSlice_range(sliceRange);
      ColumnParent columnParent = new ColumnParent(COLUMN_FAMILY);
      List<KeySlice> keySlices = client.get_range_slices(KEYSPACE, columnParent, slicePredicate, keyRange, ConsistencyLevel.ONE);
      for(KeySlice keySlice : keySlices) {
        printData(keySlice.getKey(), keySlice.getColumns());
      }
    }catch(Exception e) {
      e.printStackTrace();
    }
  }
  private void insertEntry(String key, Map<String, String> data) {
    try {
      Map<String, List<ColumnOrSuperColumn>> cfmap = new HashMap<String, List<ColumnOrSuperColumn>>();
      List<ColumnOrSuperColumn> columns = new ArrayList<ColumnOrSuperColumn>();
      Column column;
      ColumnOrSuperColumn columnOrSuperColumn;
      long timestamp = System.currentTimeMillis();
      for(Map.Entry<String, String> e : data.entrySet()) {
        column = new Column(e.getKey().getBytes("utf-8"), e.getValue().getBytes("utf-8"), timestamp);
        columnOrSuperColumn = new ColumnOrSuperColumn();
        columnOrSuperColumn.setColumn(column);
        columns.add(columnOrSuperColumn);
      }
      cfmap.put(COLUMN_FAMILY, columns);
      client.batch_insert(KEYSPACE, key, cfmap, ConsistencyLevel.ALL);
    }catch(Exception e) {
      e.printStackTrace();
    }
  }
  private void deleteEntry(String key) {
    try {
      ColumnPath columnPath = new ColumnPath(COLUMN_FAMILY);
      client.remove(KEYSPACE, key, columnPath, System.currentTimeMillis(), ConsistencyLevel.ALL);
    }catch(Exception e) {
      e.printStackTrace();
    }
  }
  private void updateEntry(String key, Map<String, String> data) {
    try {
      Map<String, Map<String, List<Mutation>>> mutationMap = new HashMap<String, Map<String, List<Mutation>>>();
      List<Mutation> mutations = new ArrayList<Mutation>();
      Column column;
      ColumnOrSuperColumn columnOrSuperColumn;
      Mutation mutation;
      long timestamp = System.currentTimeMillis();
      for(Map.Entry<String, String> e : data.entrySet()) {            
        column = new Column(e.getKey().getBytes("utf-8"), e.getValue().getBytes("utf-8"), timestamp);
        columnOrSuperColumn = new ColumnOrSuperColumn();
        columnOrSuperColumn.setColumn(column);
        mutation = new Mutation();
        mutation.setColumn_or_supercolumn(columnOrSuperColumn);
        mutations.add(mutation);
      }
      Map<String, List<Mutation>> mutationsForColumnFamily = new HashMap<String, List<Mutation>>();
      mutationsForColumnFamily.put(COLUMN_FAMILY, mutations);
      mutationMap.put(key, mutationsForColumnFamily);
      client.batch_mutate(KEYSPACE, mutationMap, ConsistencyLevel.ALL);
    }catch(Exception e) {
      e.printStackTrace();
    }
  }
  private void printData(String key, List<ColumnOrSuperColumn> results) {
    try {
      System.out.println("Key: '" + key + "'");
      for(ColumnOrSuperColumn c : results) {
        if(c.getColumn() != null) {
          String name = new String(c.getColumn().getName(), "utf-8");
          String value = new String(c.getColumn().getValue(), "utf-8");
          long timestamp = c.getColumn().getTimestamp();
          System.out.println("  name: '" + name + "', value: '" + value + "', timestamp: " + timestamp);
        }
      }
    }catch(UnsupportedEncodingException e) {
      e.printStackTrace();
    }
  }
  /**
   * test cassandra api.
   */
  public static void main(String args[]) {
    TestClient c = new TestClient();
    // insert entry1
    Map<String, String> data = new HashMap<String, String>();
    data.put("title", "Cassandra Java Client");
    data.put("category", "tech/study");
    data.put("tag", "database");
    c.insertEntry("entry1", data);
    // insert entry2
    data = new HashMap<String, String>();
    data.put("title", "OpenCV 2.1 is out!");
    data.put("category", "tech/study");
    data.put("tag", "cv/im");
    c.insertEntry("entry2", data);
    // select entries
    System.out.println("select entries, using selectEntry()");
    c.selectEntry("entry1");
    c.selectEntry("entry2");
    // delete entry2
    System.out.println("delete entry2");
    c.deleteEntry("entry2");
    System.out.println("select entries, using selectEntry()");
    c.selectEntry("entry1");
    c.selectEntry("entry2");
    // update entry1
    System.out.println("update entry1: title, category");
    Map<String, String> updateData = new HashMap<String, String>();
    updateData.put("title", "change title");
    updateData.put("category", "change category");
    c.updateEntry("entry1", updateData);
    System.out.println("select entry1, using selectEntry()");
    c.selectEntry("entry1");
    // insert entry3
    c.insertEntry("entry3", data);
    // select all entries
    System.out.println("select all entries from Entry, using selectAllEntry()");
    c.selectAllEntry();
    c.closeConnection();
  }
}

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

137

138

139

140

141

142

143

144

145

146

147

148

149

150

151

152

153

154

155

156

157

158

159

160

161

162

163

164

165

166

167

168

169

170

171

172

173

174

175

176

177

178

179

180

import java.util.*;

import java.io.UnsupportedEncodingException;

import org.apache.cassandra.thrift.*;

import org.apache.thrift.protocol.TBinaryProtocol;

import org.apache.thrift.protocol.TProtocol;

import org.apache.thrift.transport.TSocket;

import org.apache.thrift.transport.TTransport;

import org.apache.thrift.TException;

import org.apache.thrift.transport.TTransportException;

public class TestClient {

private static final String KEYSPACE = "Keyspace1";

private static final String COLUMN_FAMILY = "Entry";

private TTransport transport = null;

private Cassandra.Client client = null;

TestClient() {

client = getConnection();

}

private Cassandra.Client getConnection() {

try {

transport = new TSocket("localhost", 9160);

TProtocol protocol = new TBinaryProtocol(transport);

Cassandra.Client client = new Cassandra.Client(protocol);

transport.open();

return client;

}catch(TTransportException e) {

e.printStackTrace();

}

return null;

}

private void closeConnection() {

try {

transport.flush();

transport.close();

}catch(TTransportException e) {

e.printStackTrace();

}

private void selectEntry(String key) {

try {

SlicePredicate slicePredicate = new SlicePredicate();

SliceRange sliceRange = new SliceRange();

sliceRange.setStart(new byte[] {});

sliceRange.setFinish(new byte[] {});

slicePredicate.setSlice_range(sliceRange);

ColumnParent columnParent = new ColumnParent(COLUMN_FAMILY);

List<ColumnOrSuperColumn> results = client.get_slice(KEYSPACE, key, columnParent, slicePredicate, ConsistencyLevel.ONE);

printData(key, results);

}catch(Exception e) {

e.printStackTrace();

}

private void selectAllEntry() {

try {

KeyRange keyRange = new KeyRange();

keyRange.setStart_key("");

keyRange.setEnd_key("");

SliceRange sliceRange = new SliceRange();

sliceRange.setStart(new byte[] {});

sliceRange.setFinish(new byte[] {});

SlicePredicate slicePredicate = new SlicePredicate();

slicePredicate.setSlice_range(sliceRange);

ColumnParent columnParent = new ColumnParent(COLUMN_FAMILY);

List<KeySlice> keySlices = client.get_range_slices(KEYSPACE, columnParent, slicePredicate, keyRange, ConsistencyLevel.ONE);

for(KeySlice keySlice : keySlices) {

printData(keySlice.getKey(), keySlice.getColumns());

}

}catch(Exception e) {

e.printStackTrace();

}

private void insertEntry(String key, Map<String, String> data) {

try {

Map<String, List<ColumnOrSuperColumn>> cfmap = new HashMap<String, List<ColumnOrSuperColumn>>();

List<ColumnOrSuperColumn> columns = new ArrayList<ColumnOrSuperColumn>();

Column column;

ColumnOrSuperColumn columnOrSuperColumn;

long timestamp = System.currentTimeMillis();

for(Map.Entry<String, String> e : data.entrySet()) {

column = new Column(e.getKey().getBytes("utf-8"), e.getValue().getBytes("utf-8"), timestamp);

columnOrSuperColumn = new ColumnOrSuperColumn();

columnOrSuperColumn.setColumn(column);

columns.add(columnOrSuperColumn);

}

cfmap.put(COLUMN_FAMILY, columns);

client.batch_insert(KEYSPACE, key, cfmap, ConsistencyLevel.ALL);

}catch(Exception e) {

e.printStackTrace();

}

private void deleteEntry(String key) {

try {

ColumnPath columnPath = new ColumnPath(COLUMN_FAMILY);

client.remove(KEYSPACE, key, columnPath, System.currentTimeMillis(), ConsistencyLevel.ALL);

}catch(Exception e) {

e.printStackTrace();

}

private void updateEntry(String key, Map<String, String> data) {

try {

Map<String, Map<String, List<Mutation>>> mutationMap = new HashMap<String, Map<String, List<Mutation>>>();

List<Mutation> mutations = new ArrayList<Mutation>();

Column column;

ColumnOrSuperColumn columnOrSuperColumn;

Mutation mutation;

long timestamp = System.currentTimeMillis();

for(Map.Entry<String, String> e : data.entrySet()) {

column = new Column(e.getKey().getBytes("utf-8"), e.getValue().getBytes("utf-8"), timestamp);

columnOrSuperColumn = new ColumnOrSuperColumn();

columnOrSuperColumn.setColumn(column);

mutation = new Mutation();

mutation.setColumn_or_supercolumn(columnOrSuperColumn);

mutations.add(mutation);

}

Map<String, List<Mutation>> mutationsForColumnFamily = new HashMap<String, List<Mutation>>();

mutationsForColumnFamily.put(COLUMN_FAMILY, mutations);

mutationMap.put(key, mutationsForColumnFamily);

client.batch_mutate(KEYSPACE, mutationMap, ConsistencyLevel.ALL);

}catch(Exception e) {

e.printStackTrace();

}

private void printData(String key, List<ColumnOrSuperColumn> results) {

try {

System.out.println("Key: '" + key + "'");

for(ColumnOrSuperColumn c : results) {

if(c.getColumn() != null) {

String name = new String(c.getColumn().getName(), "utf-8");

String value = new String(c.getColumn().getValue(), "utf-8");

long timestamp = c.getColumn().getTimestamp();

System.out.println(" name: '" + name + "', value: '" + value + "', timestamp: " + timestamp);

}

}catch(UnsupportedEncodingException e) {

e.printStackTrace();

}

/**

* test cassandra api.

public static void main(String args[]) {

TestClient c = new TestClient();

// insert entry1

Map<String, String> data = new HashMap<String, String>();

data.put("title", "Cassandra Java Client");

data.put("category", "tech/study");

data.put("tag", "database");

c.insertEntry("entry1", data);

// insert entry2

data = new HashMap<String, String>();

data.put("title", "OpenCV 2.1 is out!");

data.put("category", "tech/study");

data.put("tag", "cv/im");

c.insertEntry("entry2", data);

// select entries

System.out.println("select entries, using selectEntry()");

c.selectEntry("entry1");

c.selectEntry("entry2");

// delete entry2

System.out.println("delete entry2");

c.deleteEntry("entry2");

System.out.println("select entries, using selectEntry()");

c.selectEntry("entry1");

c.selectEntry("entry2");

// update entry1

System.out.println("update entry1: title, category");

Map<String, String> updateData = new HashMap<String, String>();

updateData.put("title", "change title");

updateData.put("category", "change category");

c.updateEntry("entry1", updateData);

System.out.println("select entry1, using selectEntry()");

c.selectEntry("entry1");

// insert entry3

c.insertEntry("entry3", data);

// select all entries

System.out.println("select all entries from Entry, using selectAllEntry()");

c.selectAllEntry();

c.closeConnection();

}

データ登録では Cassandra.Client.batch_insert を使って複数のcolumnを一度にwriteしてますが、Cassandra.Client.insert という単一のcolumnをwriteするメソッドもあります。writeするcolumnが複数ある場合、その数だけ insert を呼ぶより batch_insert で一度にwriteした方が高速です。ただし、”Deprecated in 0.6 – use batch_mutate instead” とAPIリファレンスに書いてあるように、データ登録時も Cassandra.Client.batch_mutate の利用が推奨されているようです。

CassandraのクライアントはThriftを利用しているので多言語対応していますが、やはり個人的にはJavaから操作するのがいいかなと思います。プロトタイピングでは Net::Cassandra(Perlの場合)などでさっと作って検証してから、Javaでじっくり書き直す感じになるでしょうか。

Cassandra Java Client

あわせて読む:

コメントを残す