Merge pull request #21 from qq254963746/develop

采用CAS 来减小 mysql  queue 情况下 dead lock 的概率

Author: qq254963746

job-example/src/main/java/com/lts/job/example/api/JobTrackerTest.java

@@ -12,9 +12,9 @@ public class JobTrackerTest {
     public static void main(String[] args) {
 
         // 1. 使用mongo做任务队列
-        testMongoQueue();
+//        testMongoQueue();
         // 2. 使用mysql做任务队列
-//        testMysqlQueue();
+        testMysqlQueue();
     }
 
     /**

job-example/src/main/java/com/lts/job/example/support/TestJobRunner.java

@@ -24,7 +24,7 @@ public void run(Job job) throws Throwable {
         bizLogger.info("测试，业务日志啊啊啊啊啊");
 
         try {
-            Thread.sleep(1000L);
+            Thread.sleep(100L);
         } catch (InterruptedException e) {
             e.printStackTrace();
         }

job-queue/job-queue-mysql/src/main/java/com/lts/job/queue/mysql/MysqlExecutableJobQueue.java

@@ -8,10 +8,8 @@
 import com.lts.job.queue.domain.JobPo;
 import com.lts.job.queue.exception.JobQueueException;
 import com.lts.job.queue.mysql.support.ResultSetHandlerHolder;
-import com.lts.job.store.jdbc.SqlExecutor;
 
 import java.io.InputStream;
-import java.sql.Connection;
 import java.sql.SQLException;
 import java.util.List;
 
@@ -62,41 +60,83 @@ public boolean add(JobPo jobPo) {
 
     @Override
     public JobPo take(final String taskTrackerNodeGroup, final String taskTrackerIdentity) {
-        return getSqlTemplate().executeInTransaction(new SqlExecutor<JobPo>() {
-            @Override
-            public JobPo run(Connection conn) throws SQLException {
-                Long now = System.currentTimeMillis();
-                // select for update
-                String selectForUpdateSql = "SELECT *" +
-                        " FROM `{tableName}` " +
-                        " WHERE is_running = ? " +
-                        " AND `trigger_time` < ? " +
-                        " ORDER BY `trigger_time` ASC, `priority` ASC, `gmt_created` ASC " +
-                        " LIMIT 0, 1 FOR UPDATE";
-                Object[] selectParams = new Object[]{false, now};
-                JobPo jobPo = getSqlTemplate().query(conn, getRealSql(selectForUpdateSql, taskTrackerNodeGroup),
-                        ResultSetHandlerHolder.JOB_PO_RESULT_SET_HANDLER, selectParams
-                );
-                if (jobPo != null) {
-                    String updateSql = "UPDATE `{tableName}` SET " +
-                            "`is_running` = ?, " +
-                            "`task_tracker_identity` = ?, " +
-                            "`gmt_modified` = ?," +
-                            "`prev_exe_time` = ? " +
-                            " WHERE job_id = ?";
-                    Object[] params = new Object[]{
-                            true, taskTrackerIdentity, now, now, jobPo.getJobId()
-                    };
-                    getSqlTemplate().update(conn, getRealSql(updateSql, taskTrackerNodeGroup), params);
+        /**
+         * 这里从SELECT FOR UPDATE 优化为 CAS 乐观锁
+         */
+        Long now = DateUtils.currentTimeMillis();
+        String selectSql = "SELECT *" +
+                " FROM `{tableName}` " +
+                " WHERE is_running = ? " +
+                " AND `trigger_time` < ? " +
+                " ORDER BY `trigger_time` ASC, `priority` ASC, `gmt_created` ASC " +
+                " LIMIT 0, 1";
+        Object[] selectParams = new Object[]{false, now};
 
-                    jobPo.setIsRunning(true);
-                    jobPo.setTaskTrackerIdentity(taskTrackerIdentity);
-                    jobPo.setGmtModified(now);
-                    jobPo.setPrevExeTime(now);
-                }
+        try {
+            JobPo jobPo = getSqlTemplate().query(getRealSql(selectSql, taskTrackerNodeGroup),
+                    ResultSetHandlerHolder.JOB_PO_RESULT_SET_HANDLER, selectParams);
+            if (jobPo == null) {
+                return null;
+            }
+
+            String updateSql = "UPDATE `{tableName}` SET " +
+                    "`is_running` = ?, " +
+                    "`task_tracker_identity` = ?, " +
+                    "`gmt_modified` = ?," +
+                    "`prev_exe_time` = ? " +
+                    " WHERE job_id = ? AND is_running = ?";
+            Object[] params = new Object[]{
+                    true, taskTrackerIdentity, now, now, jobPo.getJobId(), false
+            };
+            // 返回影响的行数
+            int affectedRow = getSqlTemplate().update(getRealSql(updateSql, taskTrackerNodeGroup), params);
+            if (affectedRow == 0) {
+                return take(taskTrackerNodeGroup, taskTrackerIdentity);
+            } else {
+                jobPo.setIsRunning(true);
+                jobPo.setTaskTrackerIdentity(taskTrackerIdentity);
+                jobPo.setGmtModified(now);
+                jobPo.setPrevExeTime(now);
                 return jobPo;
             }
-        });
+        } catch (SQLException e) {
+            throw new JobQueueException(e);
+        }
+//        return getSqlTemplate().executeInTransaction(new SqlExecutor<JobPo>() {
+//            @Override
+//            public JobPo run(Connection conn) throws SQLException {
+//                Long now = System.currentTimeMillis();
+//                // select for update
+//                String selectForUpdateSql = "SELECT *" +
+//                        " FROM `{tableName}` " +
+//                        " WHERE is_running = ? " +
+//                        " AND `trigger_time` < ? " +
+//                        " ORDER BY `trigger_time` ASC, `priority` ASC, `gmt_created` ASC " +
+//                        " LIMIT 0, 1 FOR UPDATE";
+//                Object[] selectParams = new Object[]{false, now};
+//                JobPo jobPo = getSqlTemplate().query(conn, getRealSql(selectForUpdateSql, taskTrackerNodeGroup),
+//                        ResultSetHandlerHolder.JOB_PO_RESULT_SET_HANDLER, selectParams
+//                );
+//                if (jobPo != null) {
+//                    String updateSql = "UPDATE `{tableName}` SET " +
+//                            "`is_running` = ?, " +
+//                            "`task_tracker_identity` = ?, " +
+//                            "`gmt_modified` = ?," +
+//                            "`prev_exe_time` = ? " +
+//                            " WHERE job_id = ?";
+//                    Object[] params = new Object[]{
+//                            true, taskTrackerIdentity, now, now, jobPo.getJobId()
+//                    };
+//                    getSqlTemplate().update(conn, getRealSql(updateSql, taskTrackerNodeGroup), params);
+//
+//                    jobPo.setIsRunning(true);
+//                    jobPo.setTaskTrackerIdentity(taskTrackerIdentity);
+//                    jobPo.setGmtModified(now);
+//                    jobPo.setPrevExeTime(now);
+//                }
+//                return jobPo;
+//            }
+//        });
     }
 
     @Override