fixing schema copy

CHANGELOG.md

@@ -1,6 +1,10 @@
+## [16.3.2] - 2020-10-27
+### Fixed
+* Issue where external AVRO schemas generated lots of copy jobs. See [#203](https://github.com/HotelsDotCom/circus-train/issues/203).
+
 ## [16.3.1] - 2020-09-15
 ### Changed
-* Added fields `sourceTable` and `sourcePartitions` to the `CopierContext` class. 
+* Added fields `sourceTable` and `sourcePartitions` to the `CopierContext` class.
 
 ## [16.3.0] - 2020-09-01
 ### Added

circus-train-avro/src/main/java/com/hotels/bdp/circustrain/avro/util/SchemaCopier.java

@@ -17,17 +17,20 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
+import java.io.IOException;
 import java.util.HashMap;
 import java.util.Map;
 
 import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.Path;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.context.annotation.Profile;
 import org.springframework.stereotype.Component;
 
+import com.hotels.bdp.circustrain.api.CircusTrainException;
 import com.hotels.bdp.circustrain.api.Modules;
 import com.hotels.bdp.circustrain.api.conf.TableReplication;
 import com.hotels.bdp.circustrain.api.copier.Copier;
@@ -45,15 +48,18 @@ public class SchemaCopier {
   private static final Logger LOG = LoggerFactory.getLogger(SchemaCopier.class);
 
   private final Configuration sourceHiveConf;
+  private final Configuration replicaHiveConf;
   private final CopierFactoryManager copierFactoryManager;
   private final CopierOptions globalCopierOptions;
 
   @Autowired
   public SchemaCopier(
       Configuration sourceHiveConf,
+      Configuration replicaHiveConf,
       CopierFactoryManager copierFactoryManager,
       CopierOptions globalCopierOptions) {
     this.sourceHiveConf = sourceHiveConf;
+    this.replicaHiveConf = replicaHiveConf;
     this.copierFactoryManager = copierFactoryManager;
     this.globalCopierOptions = globalCopierOptions;
   }
@@ -68,20 +74,32 @@ public Path copy(String source, String destination, EventTableReplication eventT
     sourceLocation = sourceFileSystemPathResolver.resolveNameServices(sourceLocation);
 
     Path destinationSchemaFile = new Path(destination, sourceLocation.getName());
+    try {
+      FileSystem targetFileSystem = destinationSchemaFile.getFileSystem(replicaHiveConf);
+      if (targetFileSystem.exists(destinationSchemaFile)) {
+        LOG
+            .info("Avro schema has already been copied from '{}' to '{}', skipping schema copy step.", sourceLocation,
+                destinationSchemaFile);
+      } else {
+        Map<String, Object> mergedCopierOptions = new HashMap<>(TableReplication
+            .getMergedCopierOptions(globalCopierOptions.getCopierOptions(), eventTableReplication.getCopierOptions()));
 
-    Map<String, Object> mergedCopierOptions = new HashMap<>(TableReplication
-        .getMergedCopierOptions(globalCopierOptions.getCopierOptions(), eventTableReplication.getCopierOptions()));
-    mergedCopierOptions.put(CopierOptions.COPY_DESTINATION_IS_FILE, "true");
-    CopierFactory copierFactory = copierFactoryManager
-        .getCopierFactory(sourceLocation, destinationSchemaFile, mergedCopierOptions);
-    LOG.info("Replicating Avro schema from '{}' to '{}'", sourceLocation, destinationSchemaFile);
-    CopierContext copierContext = new CopierContext(eventId, sourceLocation, destinationSchemaFile, mergedCopierOptions);
-    Copier copier = copierFactory.newInstance(copierContext);
-    Metrics metrics = copier.copy();
+        mergedCopierOptions.put(CopierOptions.COPY_DESTINATION_IS_FILE, "true");
+        CopierFactory copierFactory = copierFactoryManager
+            .getCopierFactory(sourceLocation, destinationSchemaFile, mergedCopierOptions);
+        LOG.info("Replicating Avro schema from '{}' to '{}'", sourceLocation, destinationSchemaFile);
+        CopierContext copierContext = new CopierContext(eventId, sourceLocation, destinationSchemaFile,
+            mergedCopierOptions);
+        Copier copier = copierFactory.newInstance(copierContext);
+        Metrics metrics = copier.copy();
 
-    LOG
-        .info("Avro schema '{} bytes' has been copied from '{}' to '{}'", metrics.getBytesReplicated(), sourceLocation,
-            destinationSchemaFile);
+        LOG
+            .info("Avro schema '{} bytes' has been copied from '{}' to '{}'", metrics.getBytesReplicated(),
+                sourceLocation, destinationSchemaFile);
+      }
+    } catch (IOException e) {
+      throw new CircusTrainException("Could not check target FileSystem:", e);
+    }
     return destinationSchemaFile;
   }
 }

circus-train-avro/src/test/java/com/hotels/bdp/circustrain/avro/util/SchemaCopierTest.java

@@ -19,6 +19,7 @@
 import static org.junit.Assert.assertThat;
 import static org.mockito.Matchers.any;
 import static org.mockito.Matchers.eq;
+import static org.mockito.Mockito.verifyZeroInteractions;
 import static org.mockito.Mockito.when;
 
 import java.io.File;
@@ -36,6 +37,8 @@
 import org.mockito.Mock;
 import org.mockito.runners.MockitoJUnitRunner;
 
+import com.google.common.io.Files;
+
 import com.hotels.bdp.circustrain.api.copier.Copier;
 import com.hotels.bdp.circustrain.api.copier.CopierContext;
 import com.hotels.bdp.circustrain.api.copier.CopierFactory;
@@ -60,7 +63,7 @@ public class SchemaCopierTest {
 
   @Before
   public void setUp() {
-    schemaCopier = new SchemaCopier(new HiveConf(), copierFactoryManager, copierOptions);
+    schemaCopier = new SchemaCopier(new HiveConf(), new HiveConf(), copierFactoryManager, copierOptions);
   }
 
   @Test
@@ -79,6 +82,20 @@ public void copiedToCorrectDestination() throws IOException {
     assertThat(result, is(targetFile));
   }
 
+  @Test
+  public void skipCopyIfDestinationExists() throws IOException {
+    Path source = new Path(temporaryFolder.newFile("test.txt").toURI());
+    File destination = temporaryFolder.newFolder();
+    Path targetFile = new Path(destination.toString(), "test.txt");
+    Files.touch(new File(targetFile.toUri().toString()));
+    Map<String, Object> copierOptionsMap = new HashMap<>();
+    copierOptionsMap.put(CopierOptions.COPY_DESTINATION_IS_FILE, "true");
+
+    Path result = schemaCopier.copy(source.toString(), destination.toString(), eventTableReplication, eventId);
+    assertThat(result, is(targetFile));
+    verifyZeroInteractions(copierFactoryManager, copierFactory, copier, metrics);
+  }
+
   @Test(expected = NullPointerException.class)
   public void copyWithNullSourceParamThrowsException() throws IOException {
     File destination = temporaryFolder.newFolder();