[GitHub] [flink-table-store] JingsongLi commented on a diff in pull request #101: [FLINK-27366] Record schema on filesystem path

[GitBox <gi...@apache.org>]

JingsongLi commented on code in PR #101:
URL: https://github.com/apache/flink-table-store/pull/101#discussion_r874562026


##########
flink-table-store-core/src/main/java/org/apache/flink/table/store/file/schema/SchemaManager.java:
##########
@@ -0,0 +1,144 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.table.store.file.schema;
+
+import org.apache.flink.core.fs.Path;
+import org.apache.flink.table.store.file.operation.Lock;
+import org.apache.flink.table.store.file.utils.FileUtils;
+import org.apache.flink.table.store.file.utils.JsonSerdeUtil;
+import org.apache.flink.table.types.logical.RowType;
+import org.apache.flink.util.Preconditions;
+
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.UUID;
+import java.util.concurrent.Callable;
+
+import static org.apache.flink.table.store.file.utils.FileUtils.listVersionedFiles;
+
+/** Schema Manager to manage schema versions. */
+public class SchemaManager {
+
+    private static final String SCHEMA_PREFIX = "schema-";
+
+    private final Path tableRoot;
+
+    /** Default no lock. */
+    private Lock lock = Callable::call;
+
+    public SchemaManager(Path tableRoot) {
+        this.tableRoot = tableRoot;
+    }
+
+    public SchemaManager withLock(Lock lock) {
+        this.lock = lock;
+        return this;
+    }
+
+    /** @return latest schema. */
+    public Optional<Schema> latest() {
+        try {
+            return listVersionedFiles(schemaDirectory(), SCHEMA_PREFIX)
+                    .reduce(Math::max)
+                    .map(this::schema);
+        } catch (IOException e) {
+            throw new UncheckedIOException(e);
+        }
+    }
+
+    /** Create a new schema from {@link UpdateSchema}. */
+    public Schema commitNewVersion(UpdateSchema updateSchema) throws Exception {
+        RowType rowType = updateSchema.rowType();
+        List<String> partitionKeys = updateSchema.partitionKeys();
+        List<String> primaryKeys = updateSchema.primaryKeys();
+        Map<String, String> options = updateSchema.options();
+
+        while (true) {
+            long id;
+            int highestFieldId;
+            List<DataField> fields;
+            Optional<Schema> latest = latest();
+            if (latest.isPresent()) {
+                Schema oldSchema = latest.get();
+                Preconditions.checkArgument(
+                        oldSchema.primaryKeys().equals(primaryKeys),
+                        "Primary key modification is not supported, "
+                                + "old primaryKeys is %s, new primaryKeys is %s",
+                        oldSchema.primaryKeys(),
+                        primaryKeys);
+
+                if (!updateSchema
+                                .rowType()
+                                .getFields()
+                                .equals(oldSchema.logicalRowType().getFields())
+                        || !updateSchema.partitionKeys().equals(oldSchema.partitionKeys())) {
+                    throw new UnsupportedOperationException(
+                            "TODO: support update field types and partition keys. ");
+                }
+
+                fields = oldSchema.fields();
+                id = oldSchema.id() + 1;
+                highestFieldId = oldSchema.highestFieldId();
+            } else {
+                fields = Schema.newFields(rowType);
+                highestFieldId = Schema.currentHighestFieldId(fields);
+                id = 0;
+            }
+
+            Schema schema =
+                    new Schema(id, fields, highestFieldId, partitionKeys, primaryKeys, options);
+
+            Path temp = toTmpSchemaPath(id);
+            Path finalFile = toSchemaPath(id);
+            FileUtils.writeFileUtf8(temp, schema.toString());
+
+            Boolean success = lock.runWithLock(() -> temp.getFileSystem().rename(temp, finalFile));
+            if (success) {
+                return schema;
+            } else {
+                // retry
+                FileUtils.deleteOrWarn(temp);

Review Comment:
   Yes, but we dont have other solutions.



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