RATIS-1734. Separate state machine snapshot install path

ratis-server-api/src/main/java/org/apache/ratis/statemachine/StateMachineStorage.java

@@ -17,10 +17,11 @@
  */
 package org.apache.ratis.statemachine;
 
-import java.io.IOException;
-
 import org.apache.ratis.server.storage.RaftStorage;
 
+import java.io.File;
+import java.io.IOException;
+
 public interface StateMachineStorage {
 
   void init(RaftStorage raftStorage) throws IOException;
@@ -38,4 +39,14 @@ public interface StateMachineStorage {
   void format() throws IOException;
 
   void cleanupOldSnapshots(SnapshotRetentionPolicy snapshotRetentionPolicy) throws IOException;
+
+  /** @return the state machine directory. */
+  default File getSnapshotDir() {
+    return null;
+  }
+
+  /** @return the temporary directory. */
+  default File getTmpDir() {
+    return null;
+  }
 }

ratis-server/src/main/java/org/apache/ratis/server/impl/ServerState.java

@@ -116,7 +116,14 @@ class ServerState {
     this.raftStorage = MemoizedCheckedSupplier.valueOf(
         () -> StorageImplUtils.initRaftStorage(storageDirName, option, prop));
 
-    this.snapshotManager = StorageImplUtils.newSnapshotManager(id);
+    this.snapshotManager = StorageImplUtils.newSnapshotManager(id, () -> {
+          try {
+            return raftStorage.get().getStorageDir();
+          } catch (IOException e) {
+            throw new IllegalStateException("RaftStorageDirectory is not properly initialized " + storageDirName, e);
+          }
+        },
+        stateMachine.getStateMachineStorage());
 
     // On start the leader is null, start the clock now
     this.leaderId = null;

ratis-server/src/main/java/org/apache/ratis/server/leader/InstallSnapshotRequests.java

@@ -25,16 +25,21 @@
 import org.apache.ratis.server.RaftServer;
 import org.apache.ratis.server.storage.FileChunkReader;
 import org.apache.ratis.server.storage.FileInfo;
+import org.apache.ratis.server.storage.RaftStorageDirectory;
 import org.apache.ratis.statemachine.SnapshotInfo;
 import org.apache.ratis.util.JavaUtils;
 
+import java.io.File;
 import java.io.IOException;
+import java.nio.file.Path;
 import java.util.Iterator;
 import java.util.NoSuchElementException;
+import java.util.Optional;
+import java.util.function.Function;
 
 /**
  * An {@link Iterable} of {@link InstallSnapshotRequestProto} for sending a snapshot.
- *
+ * <p>
  * The snapshot is sent by one or more requests, where
  * a snapshot has one or more files, and
  * a file is sent by one or more chunks.
@@ -43,6 +48,7 @@
 class InstallSnapshotRequests implements Iterable<InstallSnapshotRequestProto> {
   private final RaftServer.Division server;
   private final RaftPeerId followerId;
+  private final Function<FileInfo, Path> getRelativePath;
 
   /** The snapshot to be sent. */
   private final SnapshotInfo snapshot;
@@ -71,6 +77,21 @@ class InstallSnapshotRequests implements Iterable<InstallSnapshotRequestProto> {
     this.snapshotChunkMaxSize = snapshotChunkMaxSize;
     this.totalSize = snapshot.getFiles().stream().mapToLong(FileInfo::getFileSize).reduce(Long::sum).orElseThrow(
             () -> new IllegalStateException("Failed to compute total size for snapshot " + snapshot));
+
+    final File snapshotDir = server.getStateMachine().getStateMachineStorage().getSnapshotDir();
+    final Function<Path, Path> relativize;
+    if (snapshotDir != null) {
+      final Path dir = snapshotDir.toPath();
+      // add STATE_MACHINE_DIR_NAME for compatibility.
+      relativize = p -> new File(RaftStorageDirectory.STATE_MACHINE_DIR_NAME, dir.relativize(p).toString()).toPath();
+    } else {
+      final Path dir = server.getRaftStorage().getStorageDir().getRoot().toPath();
+      relativize = dir::relativize;
+    }
+    this.getRelativePath = info -> Optional.of(info.getPath())
+        .filter(Path::isAbsolute)
+        .map(relativize)
+        .orElseGet(info::getPath);
   }
 
   @Override
@@ -97,7 +118,7 @@ private InstallSnapshotRequestProto nextInstallSnapshotRequestProto() {
     final FileInfo info = snapshot.getFiles().get(fileIndex);
     try {
       if (current == null) {
-        current = new FileChunkReader(info, server.getRaftStorage().getStorageDir());
+        current = new FileChunkReader(info, getRelativePath.apply(info));
       }
       final FileChunkProto chunk = current.readFileChunk(snapshotChunkMaxSize);
       if (chunk.getDone()) {

ratis-server/src/main/java/org/apache/ratis/server/storage/FileChunkReader.java

@@ -30,7 +30,6 @@
 import java.nio.file.Path;
 import java.security.DigestInputStream;
 import java.security.MessageDigest;
-import java.util.Optional;
 
 /** Read {@link FileChunkProto}s from a file. */
 public class FileChunkReader implements Closeable {
@@ -47,15 +46,12 @@ public class FileChunkReader implements Closeable {
    * Construct a reader from a file specified by the given {@link FileInfo}.
    *
    * @param info the information of the file.
-   * @param directory the directory where the file is stored.
+   * @param relativePath the relative path of the file.
    * @throws IOException if it failed to open the file.
    */
-  public FileChunkReader(FileInfo info, RaftStorageDirectory directory) throws IOException {
+  public FileChunkReader(FileInfo info, Path relativePath) throws IOException {
     this.info = info;
-    this.relativePath = Optional.of(info.getPath())
-        .filter(Path::isAbsolute)
-        .map(p -> directory.getRoot().toPath().relativize(p))
-        .orElse(info.getPath());
+    this.relativePath = relativePath;
     final File f = info.getPath().toFile();
     if (info.getFileDigest() == null) {
       digester = MD5Hash.getDigester();

ratis-server/src/main/java/org/apache/ratis/server/storage/SnapshotManager.java

@@ -17,32 +17,35 @@
  */
 package org.apache.ratis.server.storage;
 
-import java.io.File;
-import java.io.FileOutputStream;
-import java.io.IOException;
-import java.nio.channels.FileChannel;
-import java.nio.file.Path;
-import java.security.DigestOutputStream;
-import java.security.MessageDigest;
-import java.util.function.Supplier;
-
 import org.apache.ratis.io.CorruptedFileException;
 import org.apache.ratis.io.MD5Hash;
-import org.apache.ratis.protocol.RaftPeerId;
 import org.apache.ratis.proto.RaftProtos.FileChunkProto;
 import org.apache.ratis.proto.RaftProtos.InstallSnapshotRequestProto;
+import org.apache.ratis.protocol.RaftPeerId;
 import org.apache.ratis.server.util.ServerStringUtils;
 import org.apache.ratis.statemachine.SnapshotInfo;
 import org.apache.ratis.statemachine.StateMachine;
+import org.apache.ratis.statemachine.StateMachineStorage;
 import org.apache.ratis.util.FileUtils;
 import org.apache.ratis.util.IOUtils;
 import org.apache.ratis.util.JavaUtils;
 import org.apache.ratis.util.MD5FileUtil;
+import org.apache.ratis.util.MemoizedSupplier;
 import org.apache.ratis.util.Preconditions;
 import org.apache.ratis.util.StringUtils;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.nio.channels.FileChannel;
+import java.security.DigestOutputStream;
+import java.security.MessageDigest;
+import java.util.Optional;
+import java.util.function.Function;
+import java.util.function.Supplier;
+
 /**
  * Manage snapshots of a raft peer.
  * TODO: snapshot should be treated as compaction log thus can be merged into
@@ -55,10 +58,22 @@ public class SnapshotManager {
   private static final String TMP = ".tmp";
 
   private final RaftPeerId selfId;
+
+  private final Supplier<File> snapshotDir;
+  private final Supplier<File> tmp;
+  private final Function<FileChunkProto, String> getRelativePath;
   private final Supplier<MessageDigest> digester = JavaUtils.memoize(MD5Hash::getDigester);
 
-  SnapshotManager(RaftPeerId selfId) {
+  SnapshotManager(RaftPeerId selfId, Supplier<RaftStorageDirectory> dir, StateMachineStorage smStorage) {
     this.selfId = selfId;
+    this.snapshotDir = MemoizedSupplier.valueOf(
+        () -> Optional.ofNullable(smStorage.getSnapshotDir()).orElseGet(() -> dir.get().getStateMachineDir()));
+    this.tmp = MemoizedSupplier.valueOf(
+        () -> Optional.ofNullable(smStorage.getTmpDir()).orElseGet(() -> dir.get().getTmpDir()));
+
+    this.getRelativePath =
+        c -> dir.get().getStateMachineDir().toPath()
+            .relativize(new File(dir.get().getRoot(), c.getFilename()).toPath()).toString();
   }
 
   public void installSnapshot(InstallSnapshotRequestProto request, StateMachine stateMachine, RaftStorageDirectory dir)
@@ -67,7 +82,7 @@ public void installSnapshot(InstallSnapshotRequestProto request, StateMachine st
     final long lastIncludedIndex = snapshotChunkRequest.getTermIndex().getIndex();
 
     // create a unique temporary directory
-    final File tmpDir =  new File(dir.getTmpDir(), "snapshot-" + snapshotChunkRequest.getRequestId());
+    final File tmpDir =  new File(tmp.get(), "snapshot-" + snapshotChunkRequest.getRequestId());
     FileUtils.createDirectories(tmpDir);
     tmpDir.deleteOnExit();
 
@@ -77,7 +92,6 @@ public void installSnapshot(InstallSnapshotRequestProto request, StateMachine st
     // TODO: Make sure that subsequent requests for the same installSnapshot are coming in order,
     // and are not lost when whole request cycle is done. Check requestId and requestIndex here
 
-    final Path stateMachineDir = dir.getStateMachineDir().toPath();
     for (FileChunkProto chunk : snapshotChunkRequest.getFileChunksList()) {
       SnapshotInfo pi = stateMachine.getLatestSnapshot();
       if (pi != null && pi.getTermIndex().getIndex() >= lastIncludedIndex) {
@@ -86,9 +100,7 @@ public void installSnapshot(InstallSnapshotRequestProto request, StateMachine st
             + " with endIndex >= lastIncludedIndex " + lastIncludedIndex);
       }
 
-      String fileName = chunk.getFilename(); // this is relative to the root dir
-      final Path relative = stateMachineDir.relativize(new File(dir.getRoot(), fileName).toPath());
-      final File tmpSnapshotFile = new File(tmpDir, relative.toString());
+      final File tmpSnapshotFile = new File(tmpDir, getRelativePath.apply(chunk));
       FileUtils.createDirectories(tmpSnapshotFile);
 
       FileOutputStream out = null;
@@ -147,7 +159,7 @@ public void installSnapshot(InstallSnapshotRequestProto request, StateMachine st
     }
 
     if (snapshotChunkRequest.getDone()) {
-      rename(tmpDir, dir.getStateMachineDir());
+      rename(tmpDir, snapshotDir.get());
     }
   }
 

ratis-server/src/main/java/org/apache/ratis/server/storage/StorageImplUtils.java

@@ -22,6 +22,7 @@
 import org.apache.ratis.server.RaftServerConfigKeys;
 import org.apache.ratis.server.RaftServerConfigKeys.Log;
 import org.apache.ratis.server.storage.RaftStorage.StartupOption;
+import org.apache.ratis.statemachine.StateMachineStorage;
 import org.apache.ratis.util.SizeInBytes;
 
 import java.io.File;
@@ -31,6 +32,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
+import java.util.function.Supplier;
 import java.util.stream.Collectors;
 
 import static org.apache.ratis.server.RaftServer.Division.LOG;
@@ -42,8 +44,9 @@ private StorageImplUtils() {
     //Never constructed
   }
 
-  public static SnapshotManager newSnapshotManager(RaftPeerId id) {
-    return new SnapshotManager(id);
+  public static SnapshotManager newSnapshotManager(RaftPeerId id,
+                                                   Supplier<RaftStorageDirectory> dir, StateMachineStorage smStorage) {
+    return new SnapshotManager(id, dir, smStorage);
   }
 
   /** Create a {@link RaftStorageImpl}. */