feat: implement java bindings

.github/workflows/bump-version/action.yml

@@ -20,7 +20,6 @@ runs:
       cargo install cargo-bump
       cargo bump ${{ inputs.part }}
   - name: Synchronize rust version
-    working-directory: rust
     shell: bash
     run: |
       cargo install cargo-workspaces --version 0.2.44

.github/workflows/java.yml

@@ -0,0 +1,66 @@
+name: Build and Run Java JNI Tests
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    paths:
+      - java/**
+      - rust/**
+      - .github/workflows/java.yml
+env:
+  # This env var is used by Swatinem/rust-cache@v2 for the cache
+  # key, so we set it to make sure it is always consistent.
+  CARGO_TERM_COLOR: always
+  # Disable full debug symbol generation to speed up CI build and keep memory down
+  # "1" means line tables only, which is useful for panic tracebacks.
+  RUSTFLAGS: "-C debuginfo=1"
+  RUST_BACKTRACE: "1"
+  # according to: https://matklad.github.io/2021/09/04/fast-rust-builds.html
+  # CI builds are faster with incremental disabled.
+  CARGO_INCREMENTAL: "0"
+  CARGO_BUILD_JOBS: "1"
+jobs:
+  linux-build:
+    runs-on: ubuntu-22.04
+    name: ubuntu-22.04 + Java 11 & 17
+    defaults:
+      run:
+        working-directory: ./java
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+      - uses: Swatinem/rust-cache@v2
+        with:
+          workspaces: java/java-jni
+      - name: Run cargo fmt
+        run: cargo fmt --check
+        working-directory: ./java/lance-jni
+      - name: Install dependencies
+        run: |
+          sudo apt update
+          sudo apt install -y protobuf-compiler libssl-dev
+      - name: Install Java 17
+        uses: actions/setup-java@v4
+        with:
+          distribution: temurin
+          java-version: 17
+          cache: "maven"
+      - run: echo "JAVA_17=$JAVA_HOME" >> $GITHUB_ENV
+      - name: Install Java 11
+        uses: actions/setup-java@v4
+        with:
+          distribution: temurin
+          java-version: 11
+          cache: "maven"
+      - name: Java Style Check
+        run: mvn checkstyle:check
+      - name: Rust Clippy
+        working-directory: java/lance-jni
+        run: cargo clippy --all-targets -- -D warnings
+      - name: Build with Maven with Java 11
+        run: mvn package -DskipTests=true
+      - name: Running tests with Java 11
+        run: mvn test
+      - name: Running tests with Java 17
+        run: JAVA_HOME=$JAVA_17 JAVA_TOOL_OPTIONS="--add-opens=java.base/java.nio=ALL-UNNAMED" mvn test

.github/workflows/rust.yml

@@ -35,9 +35,6 @@ jobs:
         toolchain:
           - stable
           - nightly
-    defaults:
-      run:
-        working-directory: ./rust
     steps:
       - uses: actions/checkout@v4
       - uses: Swatinem/rust-cache@v2
@@ -73,9 +70,6 @@ jobs:
   linux-arm:
     runs-on: buildjet-4vcpu-ubuntu-2204-arm
     timeout-minutes: 30
-    defaults:
-      run:
-        working-directory: ./rust
     steps:
       - uses: actions/checkout@v4
       - uses: Swatinem/rust-cache@v2
@@ -94,9 +88,6 @@ jobs:
   clippy:
     runs-on: ubuntu-22.04
     timeout-minutes: 30
-    defaults:
-      run:
-        working-directory: ./rust
     steps:
       - uses: actions/checkout@v4
       - uses: Swatinem/rust-cache@v2

rust/Cargo.toml → Cargo.toml

@@ -1,17 +1,19 @@
 [workspace]
 members = [
-    "lance-arrow",
-    "lance-core",
-    "lance-datagen",
-    "lance-file",
-    "lance-index",
-    "lance-io",
-    "lance-linalg",
-    "lance-table",
-    "lance-testing",
-    "lance-test-macros",
-    "lance",
+    "java/lance-jni",
+    "rust/lance",
+    "rust/lance-arrow",
+    "rust/lance-core",
+    "rust/lance-datagen",
+    "rust/lance-file",
+    "rust/lance-index",
+    "rust/lance-io",
+    "rust/lance-linalg",
+    "rust/lance-table",
+    "rust/lance-test-macros",
+    "rust/lance-testing",
 ]
+exclude = ["python"]
 # Python package needs to be built by maturin.
 resolver = "2"
 
@@ -39,18 +41,18 @@ categories = [
 rust-version = "1.75"
 
 [workspace.dependencies]
-lance = { version = "=0.10.0", path = "./lance" }
-lance-arrow = { version = "=0.10.0", path = "./lance-arrow" }
-lance-core = { version = "=0.10.0", path = "./lance-core" }
-lance-datafusion = { version = "=0.10.0", path = "./lance-datafusion" }
-lance-datagen = { version = "=0.10.0", path = "./lance-datagen" }
-lance-file = { version = "=0.10.0", path = "./lance-file" }
-lance-index = { version = "=0.10.0", path = "./lance-index" }
-lance-io = { version = "=0.10.0", path = "./lance-io" }
-lance-linalg = { version = "=0.10.0", path = "./lance-linalg" }
-lance-table = { version = "=0.10.0", path = "./lance-table" }
-lance-test-macros = { version = "=0.10.0", path = "./lance-test-macros" }
-lance-testing = { version = "=0.10.0", path = "./lance-testing" }
+lance = { version = "=0.10.0", path = "./rust/lance" }
+lance-arrow = { version = "=0.10.0", path = "./rust/lance-arrow" }
+lance-core = { version = "=0.10.0", path = "./rust/lance-core" }
+lance-datafusion = { version = "=0.10.0", path = "./rust/lance-datafusion" }
+lance-datagen = { version = "=0.10.0", path = "./rust/lance-datagen" }
+lance-file = { version = "=0.10.0", path = "./rust/lance-file" }
+lance-index = { version = "=0.10.0", path = "./rust/lance-index" }
+lance-io = { version = "=0.10.0", path = "./rust/lance-io" }
+lance-linalg = { version = "=0.10.0", path = "./rust/lance-linalg" }
+lance-table = { version = "=0.10.0", path = "./rust/lance-table" }
+lance-test-macros = { version = "=0.10.0", path = "./rust/lance-test-macros" }
+lance-testing = { version = "=0.10.0", path = "./rust/lance-testing" }
 approx = "0.5.1"
 # Note that this one does not include pyarrow
 arrow = { version = "50.0.0", optional = false, features = ["prettyprint"] }

java/.gitignore

@@ -0,0 +1 @@
+*.iml

java/lance-jni/Cargo.toml

@@ -0,0 +1,21 @@
+[package]
+name = "lance-jni"
+version.workspace = true
+edition.workspace = true
+repository.workspace = true
+readme.workspace = true
+license.workspace = true
+description = "JNI bindings for Lance Columnar format"
+keywords.workspace = true
+categories.workspace = true
+
+[lib]
+crate-type = ["cdylib"]
+
+[dependencies]
+lance.workspace = true
+arrow = { workspace = true, features = ["ffi"] }
+tokio = { workspace = true }
+jni = "0.21.1"
+snafu.workspace = true
+lazy_static.workspace = true

java/lance-jni/src/blocking_dataset.rs

@@ -0,0 +1,46 @@
+// Copyright 2023 Lance Developers.
+//
+// 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.
+
+use arrow::array::RecordBatchReader;
+
+use lance::dataset::{Dataset, WriteParams};
+use lance::Result;
+
+use crate::RT;
+
+pub struct BlockingDataset {
+    inner: Dataset,
+}
+
+impl BlockingDataset {
+    pub fn write(
+        reader: impl RecordBatchReader + Send + 'static,
+        uri: &str,
+        params: Option<WriteParams>,
+    ) -> Result<Self> {
+        let inner = RT.block_on(Dataset::write(reader, uri, params))?;
+        Ok(Self { inner })
+    }
+
+    pub fn open(uri: &str) -> Result<Self> {
+        let inner = RT.block_on(Dataset::open(uri))?;
+        Ok(Self { inner })
+    }
+
+    pub fn count_rows(&self) -> Result<usize> {
+        RT.block_on(self.inner.count_rows())
+    }
+
+    pub fn close(&self) {}
+}

java/lance-jni/src/jni_helpers.rs

@@ -0,0 +1,87 @@
+// Copyright 2023 Lance Developers.
+//
+// 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.
+
+use jni::objects::{JMap, JObject, JString};
+use jni::JNIEnv;
+
+pub fn throw_java_exception(env: &mut JNIEnv, err_msg: &str) {
+    env.throw_new("java/lang/RuntimeException", err_msg)
+        .expect("Error throwing exception");
+}
+
+pub fn extract_path_str(env: &mut JNIEnv, path: &JString) -> Result<String, String> {
+    match env.get_string(path) {
+        Ok(path) => Ok(path.into()),
+        Err(err) => Err(format!("Invalid path string: {}", err)),
+    }
+}
+
+pub trait ExtractJniValue {
+    // extract JNI JObject to rust type
+    fn extract(env: &mut JNIEnv, obj: JObject) -> Result<Self, String>
+    where
+        Self: Sized;
+}
+
+impl ExtractJniValue for i32 {
+    fn extract(env: &mut JNIEnv, obj: JObject) -> Result<Self, String> {
+        env.call_method(obj, "intValue", "()I", &[])
+            .and_then(|jvalue| jvalue.i())
+            .map_err(|e| e.to_string())
+    }
+}
+
+impl ExtractJniValue for i64 {
+    fn extract(env: &mut JNIEnv, obj: JObject) -> Result<Self, String> {
+        env.call_method(obj, "longValue", "()J", &[])
+            .and_then(|jvalue| jvalue.j())
+            .map_err(|e| e.to_string())
+    }
+}
+
+impl ExtractJniValue for String {
+    fn extract(env: &mut JNIEnv, obj: JObject) -> Result<Self, String> {
+        env.get_string(&JString::from(obj))
+            .map(|jstr| jstr.into())
+            .map_err(|e| e.to_string())
+    }
+}
+
+pub fn extract_and_process_jni_map_value<T, F>(
+    env: &mut JNIEnv,
+    map: &JMap,
+    key: &str,
+    mut process: F,
+) -> Result<(), String>
+where
+    T: ExtractJniValue,
+    F: FnMut(T) -> Result<(), String>, // func to apply to return value
+{
+    let key_obj = env
+        .new_string(key)
+        .map(JObject::from)
+        .map_err(|e| e.to_string())?;
+
+    match map.get(env, &key_obj) {
+        Ok(Some(value_obj)) => {
+            if !value_obj.is_null() {
+                let value = T::extract(env, value_obj)?;
+                process(value)?;
+            }
+            Ok(())
+        }
+        Ok(None) => Ok(()), // Key is not present in the map, so we do nothing
+        Err(e) => Err(e.to_string()),
+    }
+}