GH-51663: [C++][Gandiva] Race condition with Gandiva expressions

cpp/src/gandiva/engine.cc

@@ -304,9 +304,14 @@ void RemoveBuildTargetAttributes(llvm::Module& module) {
 
 }  // namespace
 
-Status Engine::SetLLVMObjectCache(GandivaObjectCache& object_cache) {
-  auto cached_buffer = object_cache.getObject(nullptr);
-  if (cached_buffer) {
+Status Engine::SetLLVMObjectCache(
+    const std::shared_ptr<llvm::MemoryBuffer>& prev_cached_obj) {
+  if (prev_cached_obj) {
+    // Copy rather than hand over the cache's own buffer -- addObjectFile takes
+    // ownership and may free it, but the shared cache map holds a reference to the
+    // same object too.
+    auto cached_buffer = prev_cached_obj->getMemBufferCopy(
+        prev_cached_obj->getBuffer(), prev_cached_obj->getBufferIdentifier());
     auto error = lljit_->addObjectFile(std::move(cached_buffer));
     if (error) {
       return Status::CodeGenError("Failed to add cached object file to LLJIT: ",

cpp/src/gandiva/engine.h

@@ -74,8 +74,12 @@ class GANDIVA_EXPORT Engine {
   /// Optimise and compile the module.
   Status FinalizeModule();
 
-  /// Set LLVM ObjectCache.
-  Status SetLLVMObjectCache(GandivaObjectCache& object_cache);
+  /// Pre-load the LLJIT with an already-compiled object for the current module, if
+  /// one was found by the caller's own cache lookup. Takes the lookup result directly
+  /// rather than re-querying the cache, so this can never disagree with the \p cached
+  /// flag passed to \p Make -- avoiding the load being based on a newer cache state
+  /// than the one that decided whether Make() would still build (and load) fresh IR.
+  Status SetLLVMObjectCache(const std::shared_ptr<llvm::MemoryBuffer>& prev_cached_obj);
 
   /// Get the compiled function corresponding to the irfunction.
   Result<void*> CompiledFunction(const std::string& function);

cpp/src/gandiva/filter.cc

@@ -76,8 +76,11 @@ Status Filter::Make(SchemaPtr schema, ConditionPtr condition,
     ARROW_RETURN_NOT_OK(expr_validator.Validate(condition));
   }
 
-  // Set the object cache for LLVM
-  ARROW_RETURN_NOT_OK(llvm_gen->SetLLVMObjectCache(obj_cache));
+  // Pre-load the already-compiled object from the cache lookup above, if there was
+  // one. Reuses prev_cached_obj instead of letting SetLLVMObjectCache re-query the
+  // shared cache, so this can never disagree with the is_cached snapshot that
+  // decided whether Build() below still compiles fresh IR (see GH-601).
+  ARROW_RETURN_NOT_OK(llvm_gen->SetLLVMObjectCache(prev_cached_obj));
 
   ARROW_RETURN_NOT_OK(llvm_gen->Build({condition}, SelectionVector::Mode::MODE_NONE));
 

cpp/src/gandiva/llvm_generator.cc

@@ -64,8 +64,9 @@ LLVMGenerator::GetCache() {
   return shared_cache;
 }
 
-Status LLVMGenerator::SetLLVMObjectCache(GandivaObjectCache& object_cache) {
-  return engine_->SetLLVMObjectCache(object_cache);
+Status LLVMGenerator::SetLLVMObjectCache(
+    const std::shared_ptr<llvm::MemoryBuffer>& prev_cached_obj) {
+  return engine_->SetLLVMObjectCache(prev_cached_obj);
 }
 
 Status LLVMGenerator::Add(const ExpressionPtr expr, const FieldDescriptorPtr output) {

cpp/src/gandiva/llvm_generator.h

@@ -58,8 +58,11 @@ class GANDIVA_EXPORT LLVMGenerator {
   static std::shared_ptr<Cache<ExpressionCacheKey, std::shared_ptr<llvm::MemoryBuffer>>>
   GetCache();
 
-  /// \brief Set LLVM ObjectCache.
-  Status SetLLVMObjectCache(GandivaObjectCache& object_cache);
+  /// \brief Pre-load the engine with an already-compiled object for the current
+  /// module, if the caller's own cache lookup found one. See the equivalent Engine
+  /// method for why this takes the lookup result directly instead of re-querying
+  /// the cache.
+  Status SetLLVMObjectCache(const std::shared_ptr<llvm::MemoryBuffer>& prev_cached_obj);
 
   /// \brief Build the code for the expression trees for default mode with a LLVM
   /// ObjectCache. Each element in the vector represents an expression tree

cpp/src/gandiva/projector.cc

@@ -94,8 +94,11 @@ Status Projector::Make(SchemaPtr schema, const ExpressionVector& exprs,
     }
   }
 
-  // Set the object cache for LLVM
-  ARROW_RETURN_NOT_OK(llvm_gen->SetLLVMObjectCache(obj_cache));
+  // Pre-load the already-compiled object from the cache lookup above, if there was
+  // one. Reuses prev_cached_obj instead of letting SetLLVMObjectCache re-query the
+  // shared cache, so this can never disagree with the is_cached snapshot that
+  // decided whether Build() below still compiles fresh IR (see GH-601).
+  ARROW_RETURN_NOT_OK(llvm_gen->SetLLVMObjectCache(prev_cached_obj));
 
   ARROW_RETURN_NOT_OK(llvm_gen->Build(exprs, selection_vector_mode));
 

cpp/src/gandiva/tests/CMakeLists.txt

@@ -19,6 +19,7 @@ add_gandiva_test(projector-test
                  SOURCES
                  binary_test.cc
                  boolean_expr_test.cc
+                 concurrent_make_test.cc
                  date_time_test.cc
                  decimal_alignment_test.cc
                  decimal_single_test.cc

cpp/src/gandiva/tests/concurrent_make_test.cc

@@ -0,0 +1,206 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you 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.
+
+// Regression tests for GH-601: concurrent Projector::Make()/Filter::Make() calls for the
+// *same* expression cache key.
+//
+// Before the fix, Make() read the shared object cache once to decide `is_cached`, then
+// SetLLVMObjectCache() performed a second, independent read of the same key. A thread
+// that saw a miss on the first read and a hit on the second one would both pre-load the
+// cached object (defining e.g. "expr_0_0" in its JITDylib) *and* add its own freshly
+// compiled IR module defining the same symbol, so LLVM ORC's duplicate-symbol detection
+// fired and Make() returned "Failed to add IR module to LLJIT: Duplicate definition of
+// symbol".
+//
+// Note that this surfaces as a returned Status rather than a crash, so every Make() below
+// must be asserted on -- that is precisely what the pre-existing Java-side repro
+// (ProjectorTest#testMakeProjectorParallel) failed to do.
+
+#include <gtest/gtest.h>
+
+#include <condition_variable>
+#include <memory>
+#include <mutex>
+#include <string>
+#include <thread>
+#include <vector>
+
+#include "arrow/memory_pool.h"
+#include "gandiva/filter.h"
+#include "gandiva/projector.h"
+#include "gandiva/tests/test_util.h"
+#include "gandiva/tree_expr_builder.h"
+
+namespace gandiva {
+
+using arrow::int32;
+
+namespace {
+
+// Releases every waiting thread at once, so the racing Make() calls actually overlap
+// instead of trickling in as each thread is spawned. Hand-rolled rather than std::latch
+// to avoid depending on the standard library's C++20 <latch> support.
+class StartGate {
+ public:
+  void Wait() {
+    std::unique_lock<std::mutex> lock(mutex_);
+    cv_.wait(lock, [this] { return open_; });
+  }
+
+  void Open() {
+    {
+      std::lock_guard<std::mutex> lock(mutex_);
+      open_ = true;
+    }
+    cv_.notify_all();
+  }
+
+ private:
+  std::mutex mutex_;
+  std::condition_variable cv_;
+  bool open_ = false;
+};
+
+int NumThreads() {
+  auto hw = static_cast<int>(std::thread::hardware_concurrency());
+  return std::max(8, 2 * std::max(1, hw));
+}
+
+// Each iteration needs a cache key that has never been built before, so that every thread
+// in that iteration genuinely starts from a miss. Note that TestConfiguration() returns
+// the *same* shared Configuration instance every call, and ExpressionCacheKey compares
+// configurations by pointer identity, so varying the configuration would not produce a
+// miss -- vary the schema instead.
+constexpr int kIterations = 25;
+
+}  // namespace
+
+class TestConcurrentMake : public ::testing::Test {
+ public:
+  void SetUp() { pool_ = arrow::default_memory_pool(); }
+
+ protected:
+  arrow::MemoryPool* pool_;
+};
+
+TEST_F(TestConcurrentMake, TestProjectorMakeSameCacheKey) {
+  const int num_threads = NumThreads();
+
+  for (int iter = 0; iter < kIterations; ++iter) {
+    // Unique per iteration => guaranteed cache miss for the first thread to get there.
+    auto field0 = field("f0_" + std::to_string(iter), int32());
+    auto field1 = field("f1_" + std::to_string(iter), int32());
+    auto schema = arrow::schema({field0, field1});
+    auto field_sum = field("add_" + std::to_string(iter), int32());
+    auto sum_expr = TreeExprBuilder::MakeExpression("add", {field0, field1}, field_sum);
+    auto configuration = TestConfiguration();
+
+    StartGate gate;
+    std::vector<std::thread> threads;
+    std::vector<Status> statuses(num_threads);
+    std::vector<std::shared_ptr<Projector>> projectors(num_threads);
+
+    threads.reserve(num_threads);
+    for (int i = 0; i < num_threads; ++i) {
+      threads.emplace_back([&, i] {
+        gate.Wait();
+        statuses[i] = Projector::Make(schema, {sum_expr}, configuration, &projectors[i]);
+      });
+    }
+    gate.Open();
+    for (auto& thread : threads) {
+      thread.join();
+    }
+
+    // Create a row-batch with some sample data.
+    int num_records = 4;
+    auto array0 = MakeArrowArrayInt32({1, 2, 3, 4}, {true, true, true, true});
+    auto array1 = MakeArrowArrayInt32({11, 13, 15, 17}, {true, true, true, true});
+    auto exp_sum = MakeArrowArrayInt32({12, 15, 18, 21}, {true, true, true, true});
+    auto in_batch = arrow::RecordBatch::Make(schema, num_records, {array0, array1});
+
+    for (int i = 0; i < num_threads; ++i) {
+      ASSERT_OK(statuses[i]) << "iteration " << iter << ", thread " << i;
+      ASSERT_NE(projectors[i], nullptr) << "iteration " << iter << ", thread " << i;
+
+      // Every projector must evaluate correctly, including the ones built from the cache
+      // hit path. No pre-existing test evaluates a cache-hit projector, so a
+      // corrupt-but-non-null cached module would otherwise go unnoticed.
+      arrow::ArrayVector outputs;
+      ASSERT_OK(projectors[i]->Evaluate(*in_batch, pool_, &outputs))
+          << "iteration " << iter << ", thread " << i;
+      EXPECT_ARROW_ARRAY_EQUALS(exp_sum, outputs.at(0));
+    }
+  }
+}
+
+TEST_F(TestConcurrentMake, TestFilterMakeSameCacheKey) {
+  const int num_threads = NumThreads();
+
+  for (int iter = 0; iter < kIterations; ++iter) {
+    auto field0 = field("g0_" + std::to_string(iter), int32());
+    auto field1 = field("g1_" + std::to_string(iter), int32());
+    auto schema = arrow::schema({field0, field1});
+
+    // Condition: f0 + f1 < 10
+    auto node_f0 = TreeExprBuilder::MakeField(field0);
+    auto node_f1 = TreeExprBuilder::MakeField(field1);
+    auto sum_func =
+        TreeExprBuilder::MakeFunction("add", {node_f0, node_f1}, arrow::int32());
+    auto literal_10 = TreeExprBuilder::MakeLiteral(static_cast<int32_t>(10));
+    auto less_than_10 = TreeExprBuilder::MakeFunction("less_than", {sum_func, literal_10},
+                                                      arrow::boolean());
+    auto condition = TreeExprBuilder::MakeCondition(less_than_10);
+    auto configuration = TestConfiguration();
+
+    StartGate gate;
+    std::vector<std::thread> threads;
+    std::vector<Status> statuses(num_threads);
+    std::vector<std::shared_ptr<Filter>> filters(num_threads);
+
+    threads.reserve(num_threads);
+    for (int i = 0; i < num_threads; ++i) {
+      threads.emplace_back([&, i] {
+        gate.Wait();
+        statuses[i] = Filter::Make(schema, condition, configuration, &filters[i]);
+      });
+    }
+    gate.Open();
+    for (auto& thread : threads) {
+      thread.join();
+    }
+
+    int num_records = 5;
+    auto array0 = MakeArrowArrayInt32({1, 2, 3, 4, 6}, {true, true, true, false, true});
+    auto array1 = MakeArrowArrayInt32({5, 9, 6, 17, 3}, {true, true, false, true, true});
+    auto exp = MakeArrowArrayUint16({0, 4});
+    auto in_batch = arrow::RecordBatch::Make(schema, num_records, {array0, array1});
+
+    for (int i = 0; i < num_threads; ++i) {
+      ASSERT_OK(statuses[i]) << "iteration " << iter << ", thread " << i;
+      ASSERT_NE(filters[i], nullptr) << "iteration " << iter << ", thread " << i;
+
+      std::shared_ptr<SelectionVector> selection_vector;
+      ASSERT_OK(SelectionVector::MakeInt16(num_records, pool_, &selection_vector));
+      ASSERT_OK(filters[i]->Evaluate(*in_batch, selection_vector))
+          << "iteration " << iter << ", thread " << i;
+      EXPECT_ARROW_ARRAY_EQUALS(exp, selection_vector->ToArray());
+    }
+  }
+}
+
+}  // namespace gandiva