Kohei Nozaki's blog 

• jQuery DataTables plugin can delegate some data processing to server-side with interaction with JSON[2].
  • It's efficient way when we have to go with large data sets.
• So I have tried it with JAX-RS.

Environment

• DataTables 1.9.4
• WildFly 8.0.0.Final
• Oracle JDK8
• PostgreSQL 9.2.4

Sample data

• In this example, we use some tables on PostgreSQL as the data source.
  • These tables are parts of the job repository of jBeret (jBatch implementation of WildFly).
• We will execute a SQL which returns data set like this:

 jobexecutionid | jobname |        starttime        |         endtime         | batchstatus 
----------------+---------+-------------------------+-------------------------+-------------
           2167 | myjob   | 2014-03-19 14:31:13.343 |                         | STARTING
           2166 | myjob   | 2014-03-19 14:14:38.158 | 2014-03-19 14:14:59.388 | FAILED
           2165 | myjob   | 2014-03-19 14:13:24.104 | 2014-03-19 14:14:25.59  | STOPPED
           2164 | myjob   | 2014-03-19 14:11:32.238 |                         | STARTING
           2163 | myjob   | 2014-03-19 14:03:41.07  | 2014-03-19 14:10:29.391 | STOPPED
           2162 | myjob   | 2014-03-19 13:54:41.017 | 2014-03-19 13:56:55.365 | STOPPED
           2161 | myjob   | 2014-03-19 13:54:26.902 | 2014-03-19 13:54:38.077 | STOPPED
           2160 | myjob   | 2014-03-19 13:53:49.291 | 2014-03-19 13:54:22.496 | STOPPED
(8 rows)

jbatch=# 

Resources

JobExecutionReportService.java

• Make sure a datasource named “java:jboss/jdbc/JBatchDS” configured correctly on the application server.

package org.nailedtothex.jaxrs_datatables;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import javax.ejb.Stateless;
import javax.sql.DataSource;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.QueryParam;
import javax.ws.rs.core.MediaType;
import java.sql.*;
import java.text.Format;
import java.text.MessageFormat;
import java.util.*;

@Stateless
@Path("/JobExecutionReportService")
public class JobExecutionReportService {
    private static final String SQL_COUNT = "SELECT COUNT(1) FROM job_execution";
    private static final String SQL_FETCH = "SELECT\n" +
            "    e.jobexecutionid,\n" +
            "    i.jobname,\n" +
            "    e.starttime,\n" +
            "    e.endtime,\n" +
            "    e.batchstatus\n" +
            "FROM\n" +
            "    job_execution e\n" +
            "    LEFT JOIN job_instance i ON e.jobinstanceid = i.jobinstanceid\n" +
            "ORDER BY\n" +
            "    e.jobexecutionid {0}\n" +
            "LIMIT ?\n" +
            "OFFSET ?";
    private static final Set<String> VALID_SORT_DIR = Collections.unmodifiableSet(new HashSet<>(Arrays.asList("asc", "desc")));

    @Resource(lookup = "java:jboss/jdbc/JBatchDS")
    private DataSource ds;
    private Format sqlFormat;

    @PostConstruct
    protected void init() {
        sqlFormat = new MessageFormat(SQL_FETCH);
    }

    @GET
    @Produces(MediaType.APPLICATION_JSON)
    public DataTablesBean getJobExecutionReport(
            @QueryParam("sEcho") Integer sEcho,
            @QueryParam("iDisplayLength") Integer iDisplayLength,
            @QueryParam("iDisplayStart") Integer iDisplayStart,
            @QueryParam("sSortDir_0") String sSortDir_0) throws SQLException {

        final Long count;
        try (Connection cn = ds.getConnection();
             Statement st = cn.createStatement();
             ResultSet rs = st.executeQuery(SQL_COUNT);) {
            rs.next();
            count = rs.getLong(1);
        }

        if (sSortDir_0 == null || !VALID_SORT_DIR.contains(sSortDir_0)) {
            throw new IllegalArgumentException(sSortDir_0);
        }

        final String sql = sqlFormat.format(new Object[]{sSortDir_0});
        final List<List<String>> aaData = new ArrayList<>();

        try (Connection cn = ds.getConnection();
             PreparedStatement ps = cn.prepareStatement(sql)) {
            ps.setInt(1, iDisplayLength);
            ps.setInt(2, iDisplayStart);
            try (ResultSet rs = ps.executeQuery()) {
                final int columns = rs.getMetaData().getColumnCount();
                while (rs.next()) {
                    List<String> data = new ArrayList<>(columns);
                    for (int i = 1; i <= columns; i++) {
                        data.add(rs.getString(i));
                    }
                    aaData.add(data);
                }
            }
        }

        final DataTablesBean bean = new DataTablesBean();
        bean.setsEcho(sEcho);
        bean.setiTotalDisplayRecords(String.valueOf(count));
        bean.setiTotalRecords(String.valueOf(count));
        bean.setAaData(aaData);
        return bean;
    }

}

DataTablesBean.java

package org.nailedtothex.jaxrs_datatables;

import java.util.List;

public class DataTablesBean {
    private Integer sEcho;
    private String iTotalRecords;
    private String iTotalDisplayRecords;
    private List<List<String>> aaData;

    public String getiTotalRecords() {
        return iTotalRecords;
    }

    public void setiTotalRecords(String iTotalRecords) {
        this.iTotalRecords = iTotalRecords;
    }

    public String getiTotalDisplayRecords() {
        return iTotalDisplayRecords;
    }

    public void setiTotalDisplayRecords(String iTotalDisplayRecords) {
        this.iTotalDisplayRecords = iTotalDisplayRecords;
    }

    public List<List<String>> getAaData() {
        return aaData;
    }

    public void setAaData(List<List<String>> aaData) {
        this.aaData = aaData;
    }

    public Integer getsEcho() {
        return sEcho;
    }

    public void setsEcho(Integer sEcho) {
        this.sEcho = sEcho;
    }
}

index.html

<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <link rel="stylesheet" type="text/css"
          href="http://ajax.aspnetcdn.com/ajax/jquery.dataTables/1.9.4/css/jquery.dataTables.css">
    <script type="text/javascript" charset="utf8"
            src="http://ajax.aspnetcdn.com/ajax/jQuery/jquery-1.8.2.min.js"></script>
    <script type="text/javascript" charset="utf8"
            src="http://ajax.aspnetcdn.com/ajax/jquery.dataTables/1.9.4/jquery.dataTables.min.js"></script>
    <script>
        $(document).ready(function () {
            $('#example').dataTable({
                "bFilter": false,
                "sPaginationType": "full_numbers",
                "aaSorting": [
                    [ 0, "desc" ]
                ],
                "aoColumns": [
                    { "bSortable": true },
                    { "bSortable": false },
                    { "bSortable": false },
                    { "bSortable": false },
                    { "bSortable": false }
                ],
                "bProcessing": true,
                "bServerSide": true,
                "sAjaxSource": "webapi/JobExecutionReportService"
            });
        });
    </script>
    <title></title>
</head>
<body>
<table id="example">
    <thead>
    <tr>
        <th>id</th>
        <th>jobName</th>
        <th>startTime</th>
        <th>endTime</th>
        <th>batchStatus</th>
    </tr>
    </thead>
    <tbody>
    </tbody>
</table>
</body>
</html>

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.nailedtothex</groupId>
    <artifactId>jaxrs-datatables</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>war</packaging>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>

    <dependencies>
        <dependency>
            <groupId>javax</groupId>
            <artifactId>javaee-api</artifactId>
            <version>7.0</version>
        </dependency>
    </dependencies>

</project>

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
          http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
         version="3.0">
    <servlet-mapping>
        <servlet-name>javax.ws.rs.core.Application</servlet-name>
        <url-pattern>/webapi/*</url-pattern>
    </servlet-mapping>
    <welcome-file-list>
        <welcome-file>index.html</welcome-file>
    </welcome-file-list>
</web-app>

In action

• Pagination and sorting with id are working correctly.

References

1. The Java EE 7 Tutorial:Building RESTful Web Services with JAX-RS | Java EE Documentation
2. DataTables - Usage
3. DataTables example

dump data

hogedb=# copy (select * from hogetable where basedate between '20070101' and '20070131') TO '/tmp/1month.sql';
COPY 561368
hogedb=# 

dump schema

pg_dump --schema-only -t hogetable hogedb > /tmp/1month.ddl

restore schema

hogedb=# \i /tmp/1month.ddl 
SET
SET
SET
SET
SET
SET
SET
SET
CREATE TABLE
ALTER TABLE
ALTER TABLE
ALTER TABLE
CREATE INDEX
CREATE INDEX
hogedb=# 

restore data

hogedb=# copy hogetable from '/tmp/1month.sql';
COPY 561368
hogedb=#

References

1. COPY

• Bulk fetching is difficult with standard JPA API, but provider-specific functions make it easy.
• This is a example of such provider-specific bulk fetching function of Hibernate with JSR352.

According to JSR 352 Implementation - Connection close probl… | Community, this example seems to be wrong. every cursors need to be opened and closed in a transaction. so another approach is required, e.g. fetch primary keys in open(), then fetch each rows in readItem().

Environment

• WildFly8.0.0.Final
• Hibernate 4.3.1.Final
• Oracle JDK7u51
• PostgreSQL 9.2.4

Example

ItemReader

package org.nailedtothex.jbatch.example.chunk;

@Named
public class ChunkItemReader extends AbstractItemReader {
    @PersistenceContext
    EntityManager em;
    ScrollableResults scroll;
    StatelessSession ss;
    Session session;

    @Override
    public void open(Serializable checkpoint) throws Exception {
        session = em.unwrap(Session.class);
        ss = session.getSessionFactory().openStatelessSession();
        scroll = ss.createQuery("SELECT c FROM ChunkInputItem c ORDER BY c.id").scroll(ScrollMode.FORWARD_ONLY);
    }

    @Override
    public Object readItem() throws Exception {
        if (!scroll.next()) {
            return null;
        }

        return scroll.get(0);
    }

    @Override
    public void close() throws Exception {
        try {
            scroll.close();
        } catch (Exception e) {
        }
        try {
            ss.close();
        } catch (Exception e) {
        }
        try {
            session.close();
        } catch (Exception e) {
        }
    }
}

• I'm not sure that close() procedures are mandatory or not.

ItemWriter

package org.nailedtothex.jbatch.example.chunk;

@Named
public class ChunkItemWriter extends AbstractItemWriter {
    private static final Logger log = Logger.getLogger(ChunkItemWriter.class.getName());

    @Override
    public void writeItems(List<Object> items) throws Exception {
        log.log(Level.FINE, "chunkItemWriter#writeItems(): {0}", new Object[] { items });
    }
}

persistence.xml

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.1"
    xmlns="http://xmlns.jcp.org/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd">
    <persistence-unit name="jbatchsls">
        <provider>org.hibernate.ejb.HibernatePersistence</provider>
        <jta-data-source>java:jboss/jdbc/JBatchTestDS</jta-data-source>
        <properties>
            <property name="javax.persistence.schema-generation.database.action" value="none" />
            <property name="hibernate.connection.release_mode" value="on_close"/>  
        </properties>
    </persistence-unit>
</persistence>

• “hibernate.connection.release_mode” property is necessary.
  • NOTE: use of this declaration is highly discouraged. see the additional note in the bottom of this article which explains the another way to realize it.
• If this is not set, then you will get:

15:24:59,047 INFO  [org.hibernate.engine.jdbc.internal.JdbcCoordinatorImpl] (batch-batch - 19) HHH000106: Forcing container resource cleanup on transaction completion
15:24:59,048 WARN  [org.hibernate.engine.jdbc.spi.SqlExceptionHelper] (batch-batch - 19) SQL Error: 0, SQLState: null
15:24:59,048 ERROR [org.hibernate.engine.jdbc.spi.SqlExceptionHelper] (batch-batch - 19) The result set is closed.
15:24:59,048 ERROR [org.jberet] (batch-batch - 19) JBERET000007: Failed to run job chunk, doChunk, org.jberet.job.model.Chunk@16d1364: org.hibernate.exception.GenericJDBCException: could not advance using next()
    at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:54) [hibernate-core-4.3.1.Final.jar:4.3.1.Final]
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:126) [hibernate-core-4.3.1.Final.jar:4.3.1.Final]
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:112) [hibernate-core-4.3.1.Final.jar:4.3.1.Final]
    at org.hibernate.internal.ScrollableResultsImpl.next(ScrollableResultsImpl.java:125) [hibernate-core-4.3.1.Final.jar:4.3.1.Final]
    at org.nailedtothex.jbatch.example.chunk.ChunkItemReader.readItem(ChunkItemReader.java:31) [classes:]
    at org.jberet.runtime.runner.ChunkRunner.readItem(ChunkRunner.java:343) [jberet-core-1.0.1.Beta-SNAPSHOT.jar:1.0.1.Beta-SNAPSHOT]
    at org.jberet.runtime.runner.ChunkRunner.readProcessWriteItems(ChunkRunner.java:288) [jberet-core-1.0.1.Beta-SNAPSHOT.jar:1.0.1.Beta-SNAPSHOT]
    at org.jberet.runtime.runner.ChunkRunner.run(ChunkRunner.java:190) [jberet-core-1.0.1.Beta-SNAPSHOT.jar:1.0.1.Beta-SNAPSHOT]
    at org.jberet.runtime.runner.StepExecutionRunner.runBatchletOrChunk(StepExecutionRunner.java:204) [jberet-core-1.0.1.Beta-SNAPSHOT.jar:1.0.1.Beta-SNAPSHOT]
    at org.jberet.runtime.runner.StepExecutionRunner.run(StepExecutionRunner.java:131) [jberet-core-1.0.1.Beta-SNAPSHOT.jar:1.0.1.Beta-SNAPSHOT]
    at org.jberet.runtime.runner.CompositeExecutionRunner.runStep(CompositeExecutionRunner.java:162) [jberet-core-1.0.1.Beta-SNAPSHOT.jar:1.0.1.Beta-SNAPSHOT]
    at org.jberet.runtime.runner.CompositeExecutionRunner.runFromHeadOrRestartPoint(CompositeExecutionRunner.java:88) [jberet-core-1.0.1.Beta-SNAPSHOT.jar:1.0.1.Beta-SNAPSHOT]
    at org.jberet.runtime.runner.JobExecutionRunner.run(JobExecutionRunner.java:58) [jberet-core-1.0.1.Beta-SNAPSHOT.jar:1.0.1.Beta-SNAPSHOT]
    at org.wildfly.jberet.services.BatchEnvironmentService$WildFlyBatchEnvironment$1.run(BatchEnvironmentService.java:149) [wildfly-jberet-8.0.0.Final.jar:8.0.0.Final]
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471) [rt.jar:1.7.0_51]
    at java.util.concurrent.FutureTask.run(FutureTask.java:262) [rt.jar:1.7.0_51]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) [rt.jar:1.7.0_51]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) [rt.jar:1.7.0_51]
    at java.lang.Thread.run(Thread.java:744) [rt.jar:1.7.0_51]
    at org.jboss.threads.JBossThread.run(JBossThread.java:122)
Caused by: java.sql.SQLException: The result set is closed.
    at org.jboss.jca.adapters.jdbc.WrappedResultSet.checkState(WrappedResultSet.java:4081)
    at org.jboss.jca.adapters.jdbc.WrappedResultSet.next(WrappedResultSet.java:1855)
    at org.hibernate.internal.ScrollableResultsImpl.next(ScrollableResultsImpl.java:120) [hibernate-core-4.3.1.Final.jar:4.3.1.Final]
    ... 16 more

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>jbatchsls</groupId>
    <artifactId>jbatchsls</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>war</packaging>
    <properties>
        <maven.compiler.source>1.7</maven.compiler.source>
        <maven.compiler.target>1.7</maven.compiler.target>
        <failOnMissingWebXml>false</failOnMissingWebXml>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.nailedtothex</groupId>
            <artifactId>jbatchif</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </dependency>
        <dependency>
            <groupId>javax</groupId>
            <artifactId>javaee-api</artifactId>
            <version>7.0</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>4.3.1.Final</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.hamcrest</groupId>
            <artifactId>hamcrest-core</artifactId>
            <version>1.3</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.jboss</groupId>
            <artifactId>jboss-remote-naming</artifactId>
            <version>2.0.0.Final</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.jboss.xnio</groupId>
            <artifactId>xnio-nio</artifactId>
            <version>3.2.0.Final</version>
            <scope>test</scope>
        </dependency>
    </dependencies>
</project>

ChunkInputItem

package org.nailedtothex.jbatch.example.chunk;

import java.io.Serializable;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;

@Entity
public class ChunkInputItem implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(nullable = false)
    private Long id;

    @Column
    private Integer input;

    @Column
    private Boolean processed;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public Integer getInput() {
        return input;
    }

    public void setInput(Integer input) {
        this.input = input;
    }

    public Boolean getProcessed() {
        return processed;
    }

    public void setProcessed(Boolean processed) {
        this.processed = processed;
    }

    @Override
    public String toString() {
        return "ChunkInputItem [id=" + id + ", input=" + input + ", processed=" + processed + "]";
    }
}

Test data

jbatcharts=# select * from chunkinputitem ;
 id | input | processed 
----+-------+-----------
  0 |     0 | f
  1 |    10 | f
  2 |    20 | f
  3 |    30 | f
  4 |    40 | f
  5 |    50 | f
  6 |    60 | f
  7 |    70 | f
  8 |    80 | f
  9 |    90 | f
(10 rows)

jbatcharts=# 

Log

15:29:03,916 DEBUG [org.hibernate.SQL] (batch-batch - 20) select chunkinput0_.id as id1_0_, chunkinput0_.input as input2_0_, chunkinput0_.processed as processe3_0_ from ChunkInputItem chunkinput0_ order by chunkinput0_.id
15:29:03,918 FINE  [org.nailedtothex.jbatch.example.chunk.ChunkItemWriter] (batch-batch - 20) chunkItemWriter#writeItems(): [ChunkInputItem [id=0, input=0, processed=false], ChunkInputItem [id=1, input=10, processed=false], ChunkInputItem [id=2, input=20, processed=false]]
15:29:03,920 FINE  [org.nailedtothex.jbatch.example.chunk.ChunkItemWriter] (batch-batch - 20) chunkItemWriter#writeItems(): [ChunkInputItem [id=3, input=30, processed=false], ChunkInputItem [id=4, input=40, processed=false], ChunkInputItem [id=5, input=50, processed=false]]
15:29:03,922 FINE  [org.nailedtothex.jbatch.example.chunk.ChunkItemWriter] (batch-batch - 20) chunkItemWriter#writeItems(): [ChunkInputItem [id=6, input=60, processed=false], ChunkInputItem [id=7, input=70, processed=false], ChunkInputItem [id=8, input=80, processed=false]]
15:29:03,925 FINE  [org.nailedtothex.jbatch.example.chunk.ChunkItemWriter] (batch-batch - 20) chunkItemWriter#writeItems(): [ChunkInputItem [id=9, input=90, processed=false]]

A way to avoid “hibernate.connection.release_mode=on_close”

• ItemReader like this works with no declaration of “hibernate.connection.release_mode=on_close” which highly discouraged[2].

public abstract class AbstractHibernateItemReader extends AbstractItemReader {
    @PersistenceContext
    EntityManager em;
    @Resource
    DataSource ds;
    Connection cn;
    ScrollableResults scroll;
    StatelessSession ss;
    Session session;

    @Override
    public void open(Serializable checkpoint) throws Exception {
        cn = ds.getConnection();
        cn.setHoldability(ResultSet.HOLD_CURSORS_OVER_COMMIT);
        session = em.unwrap(Session.class);
        ss = session.getSessionFactory().openStatelessSession(cn);
        scroll = ss.createQuery("SELECT c FROM ChunkInputItem c ORDER BY c.id").scroll(ScrollMode.FORWARD_ONLY);
    }
...
    @Override
    public void close() throws Exception {
        try {
            scroll.close();
        } catch (Exception e) {
        }
        try {
            ss.close();
        } catch (Exception e) {
        }
        try {
            session.close();
        } catch (Exception e) {
        }
        try {
            cn.close();
        } catch (Exception e) {
        }
    }
...

• Ugly but I guess that it would be better for some occasions.
• There's no proper way to set holdability of resultset with StatelessSession[3].
• Configure through Session#doWork() and SessionImpl#connection() didn't worked as expectedly.
  • Both of them brings “The result set is closed”.

References

1. Bulk fetching with Hibernate | Java Code Geeks
2. 11.5. Connection Release Modes
3. [HHH-2820] Can not set HOLD_CURSORS_OVER_COMMIT when creating ScrollableResults - Hibernate JIRA

Make multi commits to one commit with rebase

Commit

kyle-no-MacBook:hello kyle$ echo commit1 >> README.md
kyle-no-MacBook:hello kyle$ git commit -am 'commit1'
[b4 2447554] commit1
 1 file changed, 1 insertion(+)
kyle-no-MacBook:hello kyle$ echo commit2 >> README.md
kyle-no-MacBook:hello kyle$ git commit -am 'commit2'
[b4 50e8dee] commit2
 1 file changed, 1 insertion(+)
kyle-no-MacBook:hello kyle$ git log -2
commit 50e8deed471c20abc9b86eb1cb7d6b6af4c9fcfd
Author: lbtc-xxx <lbtc-xxx@example.com>
Date:   Sun Mar 9 20:17:23 2014 +0900

    commit2

commit 2447554c8495ff5f407b4dffb84278840d7fdba6
Author: lbtc-xxx <lbtc-xxx@example.com>
Date:   Sun Mar 9 20:17:15 2014 +0900

    commit1

Rebase

• Exec this (number 2 means how many commits to be one commit):

git rebase -i HEAD~2

• Editor launches with this text:

pick 2447554 commit1
pick 50e8dee commit2

# Rebase 9ccae64..50e8dee onto 9ccae64
#
# Commands:
#  p, pick = use commit
#  r, reword = use commit, but edit the commit message
#  e, edit = use commit, but stop for amending
#  s, squash = use commit, but meld into previous commit
#  f, fixup = like "squash", but discard this commit's log message
#  x, exec = run command (the rest of the line) using shell
#
# These lines can be re-ordered; they are executed from top to bottom.
#
# If you remove a line here THAT COMMIT WILL BE LOST.
#
# However, if you remove everything, the rebase will be aborted.
#
# Note that empty commits are commented out

• Edit to:

pick 2447554 commit1
squash 50e8dee commit2

• Another editor will launch so that we can edit commit message:

# This is a combination of 2 commits.
# The first commit's message is:

commit1

# This is the 2nd commit message:

commit2

# Please enter the commit message for your changes. Lines starting
# with '#' will be ignored, and an empty message aborts the commit.
# HEAD detached at 2447554
# You are currently editing a commit while rebasing branch 'b4' on '9ccae64'.
#
# Changes to be committed:
#   (use "git reset HEAD^1 <file>..." to unstage)
#
#       modified:   README.md
#

• Gone like this:

kyle-no-MacBook:hello kyle$ git rebase -i HEAD~2
[detached HEAD ada1147] commit1
 1 file changed, 2 insertions(+)
Successfully rebased and updated refs/heads/b4.
kyle-no-MacBook:hello kyle$ 

• Log:

kyle-no-MacBook:hello kyle$ git log -2
commit ada114798c5727e8461afc36a10ad0b36e5e214a
Author: lbtc-xxx <lbtc-xxx@example.com>
Date:   Sun Mar 9 20:17:15 2014 +0900

    commit1

    commit2

commit 9ccae643e8ceee10c5f7bcb4103857bc1a38cdd4
Author: lbtc-xxx <lbtc-xxx@example.com>
Date:   Sun Mar 9 19:09:56 2014 +0900

    cancel
kyle-no-MacBook:hello kyle$ 

• README.md

kyle-no-MacBook:hello kyle$ cat README.md 
b4-local1
CANCEL
commit1
commit2
kyle-no-MacBook:hello kyle$ 

Cancel a commit

kyle-no-MacBook:hello kyle$ echo CANCEL >> README.md 
kyle-no-MacBook:hello kyle$ git commit -am 'cancel'
[b4 8c2027b] cancel
 1 file changed, 1 insertion(+)
kyle-no-MacBook:hello kyle$ 

• Cancel:

kyle-no-MacBook:hello kyle$ git reset HEAD^
Unstaged changes after reset:
M   README.md
kyle-no-MacBook:hello kyle$ git status
# On branch b4
# Changes not staged for commit:
#   (use "git add <file>..." to update what will be committed)
#   (use "git checkout -- <file>..." to discard changes in working directory)
#
#   modified:   README.md
#
no changes added to commit (use "git add" and/or "git commit -a")
kyle-no-MacBook:hello kyle$ git log
commit 75dc62abde6e533a5aef8ecab248ed4f3bbfe43a
Author: lbtc-xxx <lbtc-xxx@example.com>
Date:   Sun Mar 9 17:40:57 2014 +0900

    local1-b4

• If you want to commit again, just do this:

git commit -am 'cancel'

Cancel a push

kyle-no-MacBook:hello kyle$ git push
warning: push.default is unset; its implicit value is changing in
...
Counting objects: 10, done.
Delta compression using up to 8 threads.
Compressing objects: 100% (3/3), done.
Writing objects: 100% (6/6), 498 bytes | 0 bytes/s, done.
Total 6 (delta 1), reused 0 (delta 0)
To git@github.com:lbtc-xxx/hello.git
   bdbe00c..c107ca9  b1 -> b1
   75dc62a..9ccae64  b4 -> b4
   059de38..30254fe  master -> master
kyle-no-MacBook:hello kyle$ 

• Now b4 is:

• Cancelling:

kyle-no-MacBook:hello kyle$ git push -f origin HEAD^:b4
Total 0 (delta 0), reused 0 (delta 0)
To git@github.com:lbtc-xxx/hello.git
 + 9ccae64...75dc62a HEAD^ -> b4 (forced update)
kyle-no-MacBook:hello kyle$ 

• Roll-backed:

References

1. git reset についてもまとめてみる - murankの日記