a little improvement for DatabaseTableMeta

parse/src/main/java/com/alibaba/otter/canal/parse/inbound/mysql/tsdb/DatabaseTableMeta.java

@@ -10,6 +10,8 @@ import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.ThreadFactory;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.locks.ReadWriteLock;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
 import java.util.regex.Pattern;
 
 import org.apache.commons.beanutils.BeanUtils;
@@ -57,6 +59,7 @@ public class DatabaseTableMeta implements TableMetaTSDB {
             return thread;
         }
     });
+    private ReadWriteLock             lock             = new ReentrantReadWriteLock();
     private String                    destination;
     private MemoryTableMeta           memoryTableMeta;
     private MysqlConnection           connection;                                                                 // 查询meta信息的链接
@@ -129,15 +132,19 @@ public class DatabaseTableMeta implements TableMetaTSDB {
 
     @Override
     public TableMeta find(String schema, String table) {
-        synchronized (memoryTableMeta) {
+        lock.readLock().lock();
+        try{
             return memoryTableMeta.find(schema, table);
+        }finally {
+            lock.readLock().unlock();
         }
     }
 
     @Override
     public boolean apply(EntryPosition position, String schema, String ddl, String extra) {
         // 首先记录到内存结构
-        synchronized (memoryTableMeta) {
+        lock.writeLock().lock();
+        try{
             if (memoryTableMeta.apply(position, schema, ddl, extra)) {
                 this.lastPosition = position;
                 this.hasNewDdl = true;
@@ -146,6 +153,8 @@ public class DatabaseTableMeta implements TableMetaTSDB {
             } else {
                 throw new RuntimeException("apply to memory is failed");
             }
+        }finally {
+            lock.writeLock().unlock();
         }
     }
 
@@ -269,18 +278,22 @@ public class DatabaseTableMeta implements TableMetaTSDB {
      */
     private boolean applySnapshotToDB(EntryPosition position, boolean init) {
         // 获取一份快照
-        MemoryTableMeta tmpMemoryTableMeta = new MemoryTableMeta();
         Map<String, String> schemaDdls = null;
-        synchronized (memoryTableMeta) {
+        lock.readLock().lock();
+        try{
             if (!init && !hasNewDdl) {
                 // 如果是持续构建,则识别一下是否有DDL变更过,如果没有就忽略了
                 return false;
             }
             this.hasNewDdl = false;
             schemaDdls = memoryTableMeta.snapshot();
-            for (Map.Entry<String, String> entry : schemaDdls.entrySet()) {
-                tmpMemoryTableMeta.apply(position, entry.getKey(), entry.getValue(), null);
-            }
+        }finally{
+            lock.readLock().unlock();
+        }
+
+        MemoryTableMeta tmpMemoryTableMeta = new MemoryTableMeta();
+        for (Map.Entry<String, String> entry : schemaDdls.entrySet()) {
+            tmpMemoryTableMeta.apply(position, entry.getKey(), entry.getValue(), null);
         }
 
         // 基于临时内存对象进行对比