This is an automated email from the ASF dual-hosted git repository. jackietien pushed a commit to branch snapshot/2.0.0-250109 in repository https://gitbox.apache.org/repos/asf/tsfile.git
commit 1ad55931758e5ad86ca4882958c83f6dcbf78723 Author: shuwenwei <[email protected]> AuthorDate: Thu Jan 9 12:15:49 2025 +0800 add cache table schema map option (#369) * add cache table schema map option * modify method name * fix ut --- .../tsfile/compatibility/CompatibilityUtils.java | 2 ++ .../tsfile/compatibility/DeserializeConfig.java | 4 ++- .../tsfile/file/metadata/TsFileMetadata.java | 26 +++++++++++++-- .../apache/tsfile/read/TsFileSequenceReader.java | 39 ++++++++++++++++++++-- .../tsfile/read/controller/IMetadataQuerier.java | 3 ++ .../read/controller/MetadataQuerierByFileImpl.java | 9 +++++ .../read/query/executor/TableQueryExecutor.java | 2 +- .../tsfile/read/v4/DeviceTableModelReader.java | 10 +++--- .../org/apache/tsfile/utils/TsFileSketchTool.java | 9 ++--- .../tsfile/file/metadata/TsFileMetadataTest.java | 2 +- .../tsfile/read/TsFileSequenceReaderTest.java | 37 ++++++++++++++++++++ .../apache/tsfile/write/TsFileWriteApiTest.java | 2 +- 12 files changed, 123 insertions(+), 22 deletions(-) diff --git a/java/tsfile/src/main/java/org/apache/tsfile/compatibility/CompatibilityUtils.java b/java/tsfile/src/main/java/org/apache/tsfile/compatibility/CompatibilityUtils.java index ec0102c5..f8d2ca5d 100644 --- a/java/tsfile/src/main/java/org/apache/tsfile/compatibility/CompatibilityUtils.java +++ b/java/tsfile/src/main/java/org/apache/tsfile/compatibility/CompatibilityUtils.java @@ -42,6 +42,8 @@ public class CompatibilityUtils { org.apache.tsfile.common.conf.TSFileConfig.VERSION_NUMBER_V3; v3DeserializeConfig.tsFileMetadataBufferDeserializer = CompatibilityUtils::deserializeTsFileMetadataFromV3; + v3DeserializeConfig.cacheTableSchemaMapTsFileMetadataBufferDeserializer = + CompatibilityUtils::deserializeTsFileMetadataFromV3; v3DeserializeConfig.deviceIDBufferDeserializer = ((buffer, context) -> { final PlainDeviceID deviceID = PlainDeviceID.deserialize(buffer); diff --git a/java/tsfile/src/main/java/org/apache/tsfile/compatibility/DeserializeConfig.java b/java/tsfile/src/main/java/org/apache/tsfile/compatibility/DeserializeConfig.java index b9228bd0..c11225f9 100644 --- a/java/tsfile/src/main/java/org/apache/tsfile/compatibility/DeserializeConfig.java +++ b/java/tsfile/src/main/java/org/apache/tsfile/compatibility/DeserializeConfig.java @@ -36,7 +36,9 @@ import java.nio.ByteBuffer; public class DeserializeConfig { public byte versionNumber = org.apache.tsfile.common.conf.TSFileConfig.VERSION_NUMBER; public BufferDeserializer<TsFileMetadata> tsFileMetadataBufferDeserializer = - TsFileMetadata::deserializeFrom; + TsFileMetadata::deserializeWithoutCacheTableSchemaMap; + public BufferDeserializer<TsFileMetadata> cacheTableSchemaMapTsFileMetadataBufferDeserializer = + TsFileMetadata::deserializeAndCacheTableSchemaMap; public BufferDeserializer<MetadataIndexNode> deviceMetadataIndexNodeBufferDeserializer = (buffer, context) -> MetadataIndexNode.deserializeFrom(buffer, true, context); diff --git a/java/tsfile/src/main/java/org/apache/tsfile/file/metadata/TsFileMetadata.java b/java/tsfile/src/main/java/org/apache/tsfile/file/metadata/TsFileMetadata.java index 16f1da5d..d7ac19bb 100644 --- a/java/tsfile/src/main/java/org/apache/tsfile/file/metadata/TsFileMetadata.java +++ b/java/tsfile/src/main/java/org/apache/tsfile/file/metadata/TsFileMetadata.java @@ -46,6 +46,7 @@ public class TsFileMetadata { // List of <name, offset, childMetadataIndexType> private Map<String, MetadataIndexNode> tableMetadataIndexNodeMap; private Map<String, TableSchema> tableSchemaMap; + private boolean hasTableSchemaMapCache; private Map<String, String> tsFileProperties; // offset of MetaMarker.SEPARATOR @@ -57,13 +58,24 @@ public class TsFileMetadata { private String encryptType; + public static TsFileMetadata deserializeAndCacheTableSchemaMap( + ByteBuffer buffer, DeserializeConfig context) { + return deserializeFrom(buffer, context, true); + } + + public static TsFileMetadata deserializeWithoutCacheTableSchemaMap( + ByteBuffer buffer, DeserializeConfig context) { + return deserializeFrom(buffer, context, false); + } + /** * deserialize data from the buffer. * * @param buffer -buffer use to deserialize * @return -an instance of TsFileMetaData */ - public static TsFileMetadata deserializeFrom(ByteBuffer buffer, DeserializeConfig context) { + public static TsFileMetadata deserializeFrom( + ByteBuffer buffer, DeserializeConfig context, boolean needTableSchemaMap) { TsFileMetadata fileMetaData = new TsFileMetadata(); int startPos = buffer.position(); @@ -84,10 +96,13 @@ public class TsFileMetadata { for (int i = 0; i < tableSchemaNum; i++) { String tableName = ReadWriteIOUtils.readVarIntString(buffer); TableSchema tableSchema = context.tableSchemaBufferDeserializer.deserialize(buffer, context); - tableSchema.setTableName(tableName); - tableSchemaMap.put(tableName, tableSchema); + if (needTableSchemaMap) { + tableSchema.setTableName(tableName); + tableSchemaMap.put(tableName, tableSchema); + } } fileMetaData.setTableSchemaMap(tableSchemaMap); + fileMetaData.hasTableSchemaMapCache = needTableSchemaMap; // metaOffset long metaOffset = ReadWriteIOUtils.readLong(buffer); @@ -267,6 +282,7 @@ public class TsFileMetadata { public void setTableSchemaMap(Map<String, TableSchema> tableSchemaMap) { this.tableSchemaMap = tableSchemaMap; + this.hasTableSchemaMapCache = true; } public Map<String, MetadataIndexNode> getTableMetadataIndexNodeMap() { @@ -281,6 +297,10 @@ public class TsFileMetadata { return metadataIndexNode; } + public boolean hasTableSchemaMapCache() { + return hasTableSchemaMapCache; + } + public Map<String, TableSchema> getTableSchemaMap() { return tableSchemaMap; } diff --git a/java/tsfile/src/main/java/org/apache/tsfile/read/TsFileSequenceReader.java b/java/tsfile/src/main/java/org/apache/tsfile/read/TsFileSequenceReader.java index 127630f3..3f7a171b 100644 --- a/java/tsfile/src/main/java/org/apache/tsfile/read/TsFileSequenceReader.java +++ b/java/tsfile/src/main/java/org/apache/tsfile/read/TsFileSequenceReader.java @@ -22,6 +22,7 @@ package org.apache.tsfile.read; import org.apache.tsfile.common.conf.TSFileConfig; import org.apache.tsfile.common.conf.TSFileDescriptor; import org.apache.tsfile.common.constant.TsFileConstant; +import org.apache.tsfile.compatibility.BufferDeserializer; import org.apache.tsfile.compatibility.CompatibilityUtils; import org.apache.tsfile.compatibility.DeserializeConfig; import org.apache.tsfile.compress.IUnCompressor; @@ -52,6 +53,7 @@ import org.apache.tsfile.file.metadata.ITimeSeriesMetadata; import org.apache.tsfile.file.metadata.MeasurementMetadataIndexEntry; import org.apache.tsfile.file.metadata.MetadataIndexNode; import org.apache.tsfile.file.metadata.TableDeviceMetadata; +import org.apache.tsfile.file.metadata.TableSchema; import org.apache.tsfile.file.metadata.TimeseriesMetadata; import org.apache.tsfile.file.metadata.TsFileMetadata; import org.apache.tsfile.file.metadata.enums.CompressionType; @@ -134,6 +136,7 @@ public class TsFileSequenceReader implements AutoCloseable { private byte fileVersion; private DeserializeConfig deserializeConfig = new DeserializeConfig(); + private volatile boolean cacheTableSchemaMap = false; /** * Create a file reader of the given file. The reader will read the tail of the file to get the @@ -285,6 +288,10 @@ public class TsFileSequenceReader implements AutoCloseable { } } + public void setEnableCacheTableSchemaMap() { + this.cacheTableSchemaMap = true; + } + public void loadMetadataSize() throws IOException { loadMetadataSize(null); } @@ -394,9 +401,7 @@ public class TsFileSequenceReader implements AutoCloseable { if (tsFileMetaData == null) { synchronized (this) { if (tsFileMetaData == null) { - tsFileMetaData = - deserializeConfig.tsFileMetadataBufferDeserializer.deserialize( - readData(fileMetadataPos, fileMetadataSize, ioSizeRecorder), deserializeConfig); + tsFileMetaData = forceReadFileMetadata(cacheTableSchemaMap, ioSizeRecorder); } } } @@ -409,6 +414,34 @@ public class TsFileSequenceReader implements AutoCloseable { return tsFileMetaData; } + public Map<String, TableSchema> getTableSchemaMap() throws IOException { + return getTableSchemaMap(null); + } + + public Map<String, TableSchema> getTableSchemaMap(LongConsumer ioSizeRecorder) + throws IOException { + if (tsFileMetaData != null && tsFileMetaData.hasTableSchemaMapCache()) { + return tsFileMetaData.getTableSchemaMap(); + } + TsFileMetadata tempTsFileMetadata = forceReadFileMetadata(true, ioSizeRecorder); + if (cacheTableSchemaMap) { + synchronized (this) { + this.tsFileMetaData = tempTsFileMetadata; + } + } + return tempTsFileMetadata.getTableSchemaMap(); + } + + private TsFileMetadata forceReadFileMetadata( + boolean needTableSchemaMap, LongConsumer ioSizeRecorder) throws IOException { + ByteBuffer buffer = readData(fileMetadataPos, fileMetadataSize, ioSizeRecorder); + BufferDeserializer<TsFileMetadata> deserializer = + needTableSchemaMap + ? deserializeConfig.cacheTableSchemaMapTsFileMetadataBufferDeserializer + : deserializeConfig.tsFileMetadataBufferDeserializer; + return deserializer.deserialize(buffer, deserializeConfig); + } + /** * This function does not modify the position of the file reader. * diff --git a/java/tsfile/src/main/java/org/apache/tsfile/read/controller/IMetadataQuerier.java b/java/tsfile/src/main/java/org/apache/tsfile/read/controller/IMetadataQuerier.java index b6d9654a..3503e49e 100644 --- a/java/tsfile/src/main/java/org/apache/tsfile/read/controller/IMetadataQuerier.java +++ b/java/tsfile/src/main/java/org/apache/tsfile/read/controller/IMetadataQuerier.java @@ -24,6 +24,7 @@ import org.apache.tsfile.exception.write.NoMeasurementException; import org.apache.tsfile.file.metadata.IChunkMetadata; import org.apache.tsfile.file.metadata.IDeviceID; import org.apache.tsfile.file.metadata.MetadataIndexNode; +import org.apache.tsfile.file.metadata.TableSchema; import org.apache.tsfile.file.metadata.TsFileMetadata; import org.apache.tsfile.read.common.Path; import org.apache.tsfile.read.common.TimeRange; @@ -55,6 +56,8 @@ public interface IMetadataQuerier { TsFileMetadata getWholeFileMetadata(); + Map<String, TableSchema> getTableSchemaMap(); + /** * this will load all chunk metadata of given paths into cache. * diff --git a/java/tsfile/src/main/java/org/apache/tsfile/read/controller/MetadataQuerierByFileImpl.java b/java/tsfile/src/main/java/org/apache/tsfile/read/controller/MetadataQuerierByFileImpl.java index 47888d01..ae7fb9ee 100644 --- a/java/tsfile/src/main/java/org/apache/tsfile/read/controller/MetadataQuerierByFileImpl.java +++ b/java/tsfile/src/main/java/org/apache/tsfile/read/controller/MetadataQuerierByFileImpl.java @@ -27,6 +27,7 @@ import org.apache.tsfile.file.metadata.IChunkMetadata; import org.apache.tsfile.file.metadata.IDeviceID; import org.apache.tsfile.file.metadata.ITimeSeriesMetadata; import org.apache.tsfile.file.metadata.MetadataIndexNode; +import org.apache.tsfile.file.metadata.TableSchema; import org.apache.tsfile.file.metadata.TimeseriesMetadata; import org.apache.tsfile.file.metadata.TsFileMetadata; import org.apache.tsfile.read.TsFileSequenceReader; @@ -60,11 +61,14 @@ public class MetadataQuerierByFileImpl implements IMetadataQuerier { private LRUCache<Pair<IDeviceID, String>, List<IChunkMetadata>> deviceIdChunkMetadataCache; private TsFileSequenceReader tsFileReader; + private Map<String, TableSchema> tableSchemaMap; /** Constructor of MetadataQuerierByFileImpl. */ public MetadataQuerierByFileImpl(TsFileSequenceReader tsFileReader) throws IOException { this.tsFileReader = tsFileReader; + this.tsFileReader.setEnableCacheTableSchemaMap(); this.fileMetaData = tsFileReader.readFileMetadata(); + this.tableSchemaMap = tsFileReader.getTableSchemaMap(); deviceIdChunkMetadataCache = new LRUCache<Pair<IDeviceID, String>, List<IChunkMetadata>>(CACHED_ENTRY_NUMBER) { @Override @@ -127,6 +131,11 @@ public class MetadataQuerierByFileImpl implements IMetadataQuerier { return fileMetaData; } + @Override + public Map<String, TableSchema> getTableSchemaMap() { + return tableSchemaMap; + } + @Override @SuppressWarnings("squid:S3776") // Suppress high Cognitive Complexity warning public void loadChunkMetaDatas(List<Path> paths) throws IOException { diff --git a/java/tsfile/src/main/java/org/apache/tsfile/read/query/executor/TableQueryExecutor.java b/java/tsfile/src/main/java/org/apache/tsfile/read/query/executor/TableQueryExecutor.java index 82c59890..8d178aa4 100644 --- a/java/tsfile/src/main/java/org/apache/tsfile/read/query/executor/TableQueryExecutor.java +++ b/java/tsfile/src/main/java/org/apache/tsfile/read/query/executor/TableQueryExecutor.java @@ -76,7 +76,7 @@ public class TableQueryExecutor { throws ReadProcessException { TsFileMetadata fileMetadata = metadataQuerier.getWholeFileMetadata(); MetadataIndexNode tableRoot = fileMetadata.getTableMetadataIndexNode(tableName); - TableSchema tableSchema = fileMetadata.getTableSchemaMap().get(tableName); + TableSchema tableSchema = metadataQuerier.getTableSchemaMap().get(tableName); if (tableRoot == null || tableSchema == null) { return new EmptyTsBlockReader(); } diff --git a/java/tsfile/src/main/java/org/apache/tsfile/read/v4/DeviceTableModelReader.java b/java/tsfile/src/main/java/org/apache/tsfile/read/v4/DeviceTableModelReader.java index f9c9870a..894353fa 100644 --- a/java/tsfile/src/main/java/org/apache/tsfile/read/v4/DeviceTableModelReader.java +++ b/java/tsfile/src/main/java/org/apache/tsfile/read/v4/DeviceTableModelReader.java @@ -25,7 +25,6 @@ import org.apache.tsfile.exception.read.ReadProcessException; import org.apache.tsfile.exception.write.NoMeasurementException; import org.apache.tsfile.exception.write.NoTableException; import org.apache.tsfile.file.metadata.TableSchema; -import org.apache.tsfile.file.metadata.TsFileMetadata; import org.apache.tsfile.read.TsFileSequenceReader; import org.apache.tsfile.read.controller.CachedChunkLoaderImpl; import org.apache.tsfile.read.controller.IChunkLoader; @@ -57,6 +56,7 @@ public class DeviceTableModelReader implements ITsFileReader { public DeviceTableModelReader(File file) throws IOException { this.fileReader = new TsFileSequenceReader(file.getPath()); + this.fileReader.setEnableCacheTableSchemaMap(); this.metadataQuerier = new MetadataQuerierByFileImpl(fileReader); this.chunkLoader = new CachedChunkLoaderImpl(fileReader); this.queryExecutor = @@ -66,14 +66,13 @@ public class DeviceTableModelReader implements ITsFileReader { @TsFileApi public List<TableSchema> getAllTableSchema() throws IOException { - Map<String, TableSchema> tableSchemaMap = fileReader.readFileMetadata().getTableSchemaMap(); + Map<String, TableSchema> tableSchemaMap = fileReader.getTableSchemaMap(); return new ArrayList<>(tableSchemaMap.values()); } @TsFileApi public Optional<TableSchema> getTableSchemas(String tableName) throws IOException { - TsFileMetadata tsFileMetadata = fileReader.readFileMetadata(); - Map<String, TableSchema> tableSchemaMap = tsFileMetadata.getTableSchemaMap(); + Map<String, TableSchema> tableSchemaMap = fileReader.getTableSchemaMap(); return Optional.ofNullable(tableSchemaMap.get(tableName.toLowerCase())); } @@ -81,8 +80,7 @@ public class DeviceTableModelReader implements ITsFileReader { public ResultSet query(String tableName, List<String> columnNames, long startTime, long endTime) throws IOException, NoTableException, NoMeasurementException, ReadProcessException { String lowerCaseTableName = tableName.toLowerCase(); - TsFileMetadata tsFileMetadata = fileReader.readFileMetadata(); - TableSchema tableSchema = tsFileMetadata.getTableSchemaMap().get(lowerCaseTableName); + TableSchema tableSchema = fileReader.getTableSchemaMap().get(lowerCaseTableName); if (tableSchema == null) { throw new NoTableException(tableName); } diff --git a/java/tsfile/src/main/java/org/apache/tsfile/utils/TsFileSketchTool.java b/java/tsfile/src/main/java/org/apache/tsfile/utils/TsFileSketchTool.java index e7ce355a..2bf2fd5e 100644 --- a/java/tsfile/src/main/java/org/apache/tsfile/utils/TsFileSketchTool.java +++ b/java/tsfile/src/main/java/org/apache/tsfile/utils/TsFileSketchTool.java @@ -202,13 +202,10 @@ public class TsFileSketchTool { } // table schema - printlnBoth( - pw, - String.format("%20s", pos) - + "|\tTableSchemaCnt=" - + tsFileMetaData.getTableSchemaMap().size()); + Map<String, TableSchema> tableSchemaMap = reader.getTableSchemaMap(); + printlnBoth(pw, String.format("%20s", pos) + "|\tTableSchemaCnt=" + tableSchemaMap.size()); pos += Integer.BYTES; - for (Entry<String, TableSchema> entry : tsFileMetaData.getTableSchemaMap().entrySet()) { + for (Entry<String, TableSchema> entry : tableSchemaMap.entrySet()) { final String tableName = entry.getKey(); final TableSchema tableSchema = entry.getValue(); diff --git a/java/tsfile/src/test/java/org/apache/tsfile/file/metadata/TsFileMetadataTest.java b/java/tsfile/src/test/java/org/apache/tsfile/file/metadata/TsFileMetadataTest.java index 03e22e27..dcf34391 100644 --- a/java/tsfile/src/test/java/org/apache/tsfile/file/metadata/TsFileMetadataTest.java +++ b/java/tsfile/src/test/java/org/apache/tsfile/file/metadata/TsFileMetadataTest.java @@ -72,7 +72,7 @@ public class TsFileMetadataTest { ByteBuffer buffer = ByteBuffer.allocate((int) channel.size()); channel.read(buffer); buffer.rewind(); - metaData = TsFileMetadata.deserializeFrom(buffer, deserializeConfig); + metaData = TsFileMetadata.deserializeAndCacheTableSchemaMap(buffer, deserializeConfig); return metaData; } catch (IOException e) { e.printStackTrace(); diff --git a/java/tsfile/src/test/java/org/apache/tsfile/read/TsFileSequenceReaderTest.java b/java/tsfile/src/test/java/org/apache/tsfile/read/TsFileSequenceReaderTest.java index 14e97de3..854e80ac 100644 --- a/java/tsfile/src/test/java/org/apache/tsfile/read/TsFileSequenceReaderTest.java +++ b/java/tsfile/src/test/java/org/apache/tsfile/read/TsFileSequenceReaderTest.java @@ -32,6 +32,7 @@ import org.apache.tsfile.file.metadata.ChunkMetadata; import org.apache.tsfile.file.metadata.IChunkMetadata; import org.apache.tsfile.file.metadata.IDeviceID; import org.apache.tsfile.file.metadata.IDeviceID.Factory; +import org.apache.tsfile.file.metadata.TableSchema; import org.apache.tsfile.file.metadata.enums.TSEncoding; import org.apache.tsfile.read.common.Path; import org.apache.tsfile.utils.BloomFilter; @@ -40,10 +41,13 @@ import org.apache.tsfile.utils.Pair; import org.apache.tsfile.utils.TsFileGeneratorUtils; import org.apache.tsfile.write.TsFileWriter; import org.apache.tsfile.write.record.TSRecord; +import org.apache.tsfile.write.record.Tablet; import org.apache.tsfile.write.record.datapoint.DoubleDataPoint; import org.apache.tsfile.write.schema.IMeasurementSchema; import org.apache.tsfile.write.schema.MeasurementSchema; import org.apache.tsfile.write.schema.Schema; +import org.apache.tsfile.write.v4.ITsFileWriter; +import org.apache.tsfile.write.v4.TsFileWriterBuilder; import org.junit.After; import org.junit.Assert; @@ -53,7 +57,9 @@ import org.junit.Test; import java.io.File; import java.io.IOException; import java.nio.ByteBuffer; +import java.nio.file.Files; import java.util.ArrayList; +import java.util.Collections; import java.util.HashMap; import java.util.List; import java.util.Map; @@ -225,4 +231,35 @@ public class TsFileSequenceReaderTest { reader.selfCheck(new Schema(), new ArrayList<>(), false)); } } + + @Test + public void testGetTableSchemaMap() throws IOException, WriteProcessException { + File file = new File(FILE_PATH); + try { + tsFile.close(); + Files.deleteIfExists(file.toPath()); + } catch (IOException ignored) { + } + TableSchema tableSchema = + new TableSchema( + "t1", + Collections.singletonList(new MeasurementSchema("s1", TSDataType.INT32)), + Collections.singletonList(Tablet.ColumnCategory.FIELD)); + try (ITsFileWriter writer = + new TsFileWriterBuilder().tableSchema(tableSchema).file(file).build()) { + Tablet tablet = + new Tablet(Collections.singletonList("s1"), Collections.singletonList(TSDataType.INT32)); + tablet.addTimestamp(0, 1); + tablet.addValue("s1", 0, 1); + writer.write(tablet); + } + try (TsFileSequenceReader reader = new TsFileSequenceReader(FILE_PATH)) { + Assert.assertFalse(reader.readFileMetadata().hasTableSchemaMapCache()); + Assert.assertEquals(1, reader.getTableSchemaMap().size()); + Assert.assertFalse(reader.readFileMetadata().hasTableSchemaMapCache()); + reader.setEnableCacheTableSchemaMap(); + Assert.assertEquals(1, reader.getTableSchemaMap().size()); + Assert.assertTrue(reader.readFileMetadata().hasTableSchemaMapCache()); + } + } } diff --git a/java/tsfile/src/test/java/org/apache/tsfile/write/TsFileWriteApiTest.java b/java/tsfile/src/test/java/org/apache/tsfile/write/TsFileWriteApiTest.java index 160866e4..c5ecab75 100644 --- a/java/tsfile/src/test/java/org/apache/tsfile/write/TsFileWriteApiTest.java +++ b/java/tsfile/src/test/java/org/apache/tsfile/write/TsFileWriteApiTest.java @@ -923,7 +923,7 @@ public class TsFileWriteApiTest { writer.writeTable(tablet); } try (TsFileSequenceReader reader = new TsFileSequenceReader(f.getPath())) { - Map<String, TableSchema> tableSchemaMap = reader.readFileMetadata().getTableSchemaMap(); + Map<String, TableSchema> tableSchemaMap = reader.getTableSchemaMap(); TableSchema tableSchemaInTsFile = tableSchemaMap.get("table1"); Assert.assertNotNull(tableSchemaInTsFile); for (IMeasurementSchema columnSchema : tableSchemaInTsFile.getColumnSchemas()) {
