make CUDA and Flash Attention 2 optional features (#511)

Signed-off-by: OneZero-Y <[email protected]>

Author: OneZero-Y

candle-binding/Cargo.toml

@@ -10,18 +10,19 @@ name = "candle_semantic_router"
 crate-type = ["staticlib", "cdylib"]
 
 [features]
-default = ["cuda"]
+default = []
+# CUDA support (enables GPU acceleration)
 cuda = ["candle-core/cuda", "candle-nn/cuda", "candle-transformers/cuda"]
 # Flash Attention 2 support (requires CUDA and compatible GPU)
 # Enable with: cargo build --features flash-attn
 # Note: Requires CUDA Compute Capability >= 8.0 (Ampere or newer)
-flash-attn = ["candle-flash-attn"]
+flash-attn = ["cuda", "candle-flash-attn"]
 
 [dependencies]
 anyhow = { version = "1", features = ["backtrace"] }
-candle-core = { version = "0.8.4", features = ["cuda"] }
-candle-nn = { version = "0.8.4", features = ["cuda"] }
-candle-transformers = { version = "0.8.4", features = ["cuda"] }
+candle-core = "0.8.4"
+candle-nn = "0.8.4"
+candle-transformers = "0.8.4"
 # Flash Attention 2 (optional, requires CUDA)
 # Reference: https://github.com/huggingface/candle/tree/main/candle-flash-attn
 candle-flash-attn = { version = "0.8.4", optional = true }

tools/make/rust.mk

@@ -13,6 +13,17 @@ test-rust: rust
 	@echo "Running Rust unit tests (release mode, sequential on GPU $(TEST_GPU_DEVICE))"
 	@cd candle-binding && CUDA_VISIBLE_DEVICES=$(TEST_GPU_DEVICE) cargo test --release --lib -- --test-threads=1 --nocapture
 
+# Test Flash Attention（requires GPU and CUDA environment configured in system）
+# Note: Ensure CUDA paths are set in your shell environment (e.g., ~/.bashrc)
+#   - PATH should include nvcc (e.g., /usr/local/cuda/bin)
+#   - LD_LIBRARY_PATH should include CUDA libs (e.g., /usr/local/cuda/lib64, /usr/lib/wsl/lib for WSL)
+#   - CUDA_HOME, CUDA_PATH should point to CUDA installation
+# Note: Uses TEST_GPU_DEVICE env var (default: 2) to avoid GPU 0/1 which may be busy
+test-rust-flash-attn: rust-flash-attn
+	@$(LOG_TARGET)
+	@echo "Running Rust unit tests with Flash Attention 2 (GPU $(TEST_GPU_DEVICE))"
+	@cd candle-binding && CUDA_VISIBLE_DEVICES=$(TEST_GPU_DEVICE) cargo test --release --features flash-attn --lib -- --test-threads=1 --nocapture
+
 # Test specific Rust module (with release optimization for performance)
 #   Example: make test-rust-module MODULE=classifiers::lora::pii_lora_test
 #   Example: make test-rust-module MODULE=classifiers::lora::pii_lora_test::test_pii_lora_pii_lora_classifier_new
@@ -26,6 +37,19 @@ test-rust-module: rust
 	@echo "Running Rust tests for module: $(MODULE) (release mode, GPU $(TEST_GPU_DEVICE))"
 	@cd candle-binding && CUDA_VISIBLE_DEVICES=$(TEST_GPU_DEVICE) cargo test --release $(MODULE) --lib -- --test-threads=1 --nocapture
 
+# Test specific Flash Attention module (requires GPU and CUDA environment)
+#   Example: make test-rust-flash-attn-module MODULE=model_architectures::embedding::qwen3_embedding_test
+#   Example: make test-rust-flash-attn-module MODULE=model_architectures::embedding::qwen3_embedding_test::test_qwen3_embedding_forward
+test-rust-flash-attn-module: rust-flash-attn
+	@$(LOG_TARGET)
+	@if [ -z "$(MODULE)" ]; then \
+		echo "Usage: make test-rust-flash-attn-module MODULE=<module_name>"; \
+		echo "Example: make test-rust-flash-attn-module MODULE=model_architectures::embedding::qwen3_embedding_test"; \
+		exit 1; \
+	fi
+	@echo "Running Rust Flash Attention tests for module: $(MODULE) (GPU $(TEST_GPU_DEVICE))"
+	@cd candle-binding && CUDA_VISIBLE_DEVICES=$(TEST_GPU_DEVICE) cargo test --release --features flash-attn $(MODULE) --lib -- --nocapture
+
 # Test the Rust library (conditionally use rust-ci in CI environments)
 test-binding: $(if $(CI),rust-ci,rust) ## Run Go tests with the Rust static library
 	@$(LOG_TARGET)
@@ -83,3 +107,14 @@ rust-ci: ## Build the Rust library without CUDA support (for GitHub Actions/CI)
 	fi && \
 	echo "Building Rust library without CUDA (CPU-only)..." && \
 	cd candle-binding && cargo build --release --no-default-features'
+
+rust-flash-attn: ## Build Rust library with Flash Attention 2 (requires CUDA environment)
+	@$(LOG_TARGET)
+	@echo "Building Rust library with Flash Attention 2 (requires CUDA)..."
+	@if command -v nvcc >/dev/null 2>&1; then \
+		echo "✅ nvcc found: $$(nvcc --version | grep release)"; \
+	else \
+		echo "❌ nvcc not found in PATH. Please configure CUDA environment."; \
+		exit 1; \
+	fi
+	@cd candle-binding && cargo build --release --features flash-attn