1 files changed, 61 insertions, 0 deletions
diff --git a/airlift-zstd/src/main/java/ai/vespa/airlift/zstd/HuffmanCompressionContext.java b/airlift-zstd/src/main/java/ai/vespa/airlift/zstd/HuffmanCompressionContext.java
new file mode 100644
index 00000000000..a651ea2a625
--- /dev/null
+++ b/airlift-zstd/src/main/java/ai/vespa/airlift/zstd/HuffmanCompressionContext.java
@@ -0,0 +1,61 @@
+/*
+ * Licensed 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 ai.vespa.airlift.zstd;
+
+class HuffmanCompressionContext
+{
+    private final HuffmanTableWriterWorkspace tableWriterWorkspace = new HuffmanTableWriterWorkspace();
+    private final HuffmanCompressionTableWorkspace compressionTableWorkspace = new HuffmanCompressionTableWorkspace();
+
+    private HuffmanCompressionTable previousTable = new HuffmanCompressionTable(Huffman.MAX_SYMBOL_COUNT);
+    private HuffmanCompressionTable temporaryTable = new HuffmanCompressionTable(Huffman.MAX_SYMBOL_COUNT);
+
+    private HuffmanCompressionTable previousCandidate = previousTable;
+    private HuffmanCompressionTable temporaryCandidate = temporaryTable;
+
+    public HuffmanCompressionTable getPreviousTable()
+    {
+        return previousTable;
+    }
+
+    public HuffmanCompressionTable borrowTemporaryTable()
+    {
+        previousCandidate = temporaryTable;
+        temporaryCandidate = previousTable;
+
+        return temporaryTable;
+    }
+
+    public void discardTemporaryTable()
+    {
+        previousCandidate = previousTable;
+        temporaryCandidate = temporaryTable;
+    }
+
+    public void saveChanges()
+    {
+        temporaryTable = temporaryCandidate;
+        previousTable = previousCandidate;
+    }
+
+    public HuffmanCompressionTableWorkspace getCompressionTableWorkspace()
+    {
+        return compressionTableWorkspace;
+    }
+
+    public HuffmanTableWriterWorkspace getTableWriterWorkspace()
+    {
+        return tableWriterWorkspace;
+    }
+}