Clean Up Nimble Flush Policy Code (#235)

Summary:
Pull Request resolved: #235

As preparation for our [Nimble chunked encoding](https://fburl.com/gdoc/zjck7lo6) work, we decided to clean up the previous contract to remove unused methods and attributes. Should be a no-op since these methods and attributes were not used. We also clarified the naming of some attributes.

Reviewed By: sdruzkin, helfman

Differential Revision: D81514657

fbshipit-source-id: 3575af8e7689c8ad28befa4195356c955e7e1279

Author: macvincent

.pre-commit-config.yaml

@@ -16,7 +16,7 @@
 
 repos:
   - repo: https://github.com/pre-commit/mirrors-clang-format
-    rev: v18.1.3
+    rev: v21.1.0
     hooks:
       - id: clang-format
   - repo: https://github.com/BlankSpruce/gersemi

dwio/nimble/velox/FlushPolicy.cpp

@@ -17,14 +17,10 @@
 
 namespace facebook::nimble {
 
-FlushDecision RawStripeSizeFlushPolicy::shouldFlush(
+FlushDecision StripeRawSizeFlushPolicy::shouldFlush(
     const StripeProgress& stripeProgress) {
-  return stripeProgress.rawStripeSize >= rawStripeSize_ ? FlushDecision::Stripe
+  return stripeProgress.stripeRawSize >= stripeRawSize_ ? FlushDecision::Stripe
                                                         : FlushDecision::None;
 }
 
-void RawStripeSizeFlushPolicy::onClose() {
-  // No-op
-}
-
 } // namespace facebook::nimble

dwio/nimble/velox/FlushPolicy.h

@@ -22,11 +22,9 @@ namespace facebook::nimble {
 
 struct StripeProgress {
   // Size of the stripe data when it's fully decompressed and decoded
-  const uint64_t rawStripeSize;
+  const uint64_t stripeRawSize;
   // Size of the stripe after buffered data is encoded and optionally compressed
-  const uint64_t stripeSize;
-  // Size of the allocated buffer in the writer
-  const uint64_t bufferSize;
+  const uint64_t stripeEncodedSize;
 };
 
 enum class FlushDecision : uint8_t {
@@ -39,38 +37,29 @@ class FlushPolicy {
  public:
   virtual ~FlushPolicy() = default;
   virtual FlushDecision shouldFlush(const StripeProgress& stripeProgress) = 0;
-  // Required for memory pressure coordination for now. Will remove in the
-  // future.
-  virtual void onClose() = 0;
 };
 
-class RawStripeSizeFlushPolicy final : public FlushPolicy {
+class StripeRawSizeFlushPolicy final : public FlushPolicy {
  public:
-  explicit RawStripeSizeFlushPolicy(uint64_t rawStripeSize)
-      : rawStripeSize_{rawStripeSize} {}
+  explicit StripeRawSizeFlushPolicy(uint64_t stripeRawSize)
+      : stripeRawSize_{stripeRawSize} {}
 
   FlushDecision shouldFlush(const StripeProgress& stripeProgress) override;
 
-  void onClose() override;
-
  private:
-  const uint64_t rawStripeSize_;
+  const uint64_t stripeRawSize_;
 };
 
 class LambdaFlushPolicy : public FlushPolicy {
  public:
   explicit LambdaFlushPolicy(
       std::function<FlushDecision(const StripeProgress&)> lambda)
-      : lambda_{lambda} {}
+      : lambda_{std::move(lambda)} {}
 
   FlushDecision shouldFlush(const StripeProgress& stripeProgress) override {
     return lambda_(stripeProgress);
   }
 
-  void onClose() override {
-    // No-op
-  }
-
  private:
   std::function<FlushDecision(const StripeProgress&)> lambda_;
 };

dwio/nimble/velox/VeloxWriter.cpp

@@ -33,7 +33,6 @@
 #include "dwio/nimble/velox/SchemaSerialization.h"
 #include "dwio/nimble/velox/SchemaTypes.h"
 #include "dwio/nimble/velox/StatsGenerated.h"
-#include "folly/ScopeGuard.h"
 #include "velox/common/time/CpuWallTimer.h"
 #include "velox/dwio/common/ExecutorBarrier.h"
 #include "velox/type/Type.h"
@@ -552,8 +551,6 @@ void VeloxWriter::close() {
 
   if (file_) {
     try {
-      auto exitGuard =
-          folly::makeGuard([this]() { context_->flushPolicy->onClose(); });
       flush();
       root_->close();
 
@@ -847,11 +844,8 @@ bool VeloxWriter::tryWriteStripe(bool force) {
   auto shouldFlush = [&]() {
     return context_->flushPolicy->shouldFlush(
         StripeProgress{
-            .rawStripeSize = context_->memoryUsed,
-            .stripeSize = context_->stripeSize,
-            .bufferSize =
-                static_cast<uint64_t>(context_->bufferMemoryPool->usedBytes()),
-        });
+            .stripeRawSize = context_->memoryUsed,
+            .stripeEncodedSize = context_->stripeSize});
   };
 
   auto decision = force ? FlushDecision::Stripe : shouldFlush();

dwio/nimble/velox/VeloxWriterOptions.h

@@ -109,7 +109,7 @@ struct VeloxWriterOptions {
   // Provides policy that controls stripe sizes and memory footprint.
   std::function<std::unique_ptr<FlushPolicy>()> flushPolicyFactory = []() {
     // Buffering 256MB data before encoding stripes.
-    return std::make_unique<RawStripeSizeFlushPolicy>(256 << 20);
+    return std::make_unique<StripeRawSizeFlushPolicy>(256 << 20);
   };
 
   // When the writer needs to buffer data, and internal buffers don't have

dwio/nimble/velox/tests/VeloxWriterTests.cpp

@@ -297,21 +297,21 @@ std::vector<velox::RowVectorPtr> generateBatches(
 }
 } // namespace
 
-struct RawStripeSizeFlushPolicyTestCase {
+struct StripeRawSizeFlushPolicyTestCase {
   const size_t batchCount;
   const uint32_t rawStripeSize;
   const uint32_t stripeCount;
 };
 
-class RawStripeSizeFlushPolicyTest
+class StripeRawSizeFlushPolicyTest
     : public VeloxWriterTests,
-      public ::testing::WithParamInterface<RawStripeSizeFlushPolicyTestCase> {};
+      public ::testing::WithParamInterface<StripeRawSizeFlushPolicyTestCase> {};
 
-TEST_P(RawStripeSizeFlushPolicyTest, RawStripeSizeFlushPolicy) {
+TEST_P(StripeRawSizeFlushPolicyTest, StripeRawSizeFlushPolicy) {
   auto type = velox::ROW({{"simple", velox::INTEGER()}});
   nimble::VeloxWriterOptions writerOptions{.flushPolicyFactory = []() {
     // Buffering 256MB data before encoding stripes.
-    return std::make_unique<nimble::RawStripeSizeFlushPolicy>(
+    return std::make_unique<nimble::StripeRawSizeFlushPolicy>(
         GetParam().rawStripeSize);
   }};
 
@@ -385,7 +385,7 @@ TEST_F(VeloxWriterTests, MemoryReclaimPath) {
 
 TEST_F(VeloxWriterTests, FlushHugeStrings) {
   nimble::VeloxWriterOptions writerOptions{.flushPolicyFactory = []() {
-    return std::make_unique<nimble::RawStripeSizeFlushPolicy>(1 * 1024 * 1024);
+    return std::make_unique<nimble::StripeRawSizeFlushPolicy>(1 * 1024 * 1024);
   }};
 
   velox::test::VectorMaker vectorMaker{leafPool_.get()};
@@ -1953,26 +1953,26 @@ TEST_F(VeloxWriterTests, RawSizeWritten) {
 }
 
 INSTANTIATE_TEST_CASE_P(
-    RawStripeSizeFlushPolicyTestSuite,
-    RawStripeSizeFlushPolicyTest,
+    StripeRawSizeFlushPolicyTestSuite,
+    StripeRawSizeFlushPolicyTest,
     ::testing::Values(
-        RawStripeSizeFlushPolicyTestCase{
+        StripeRawSizeFlushPolicyTestCase{
             .batchCount = 50,
             .rawStripeSize = 256 << 10,
             .stripeCount = 4},
-        RawStripeSizeFlushPolicyTestCase{
+        StripeRawSizeFlushPolicyTestCase{
             .batchCount = 100,
             .rawStripeSize = 256 << 10,
             .stripeCount = 7},
-        RawStripeSizeFlushPolicyTestCase{
+        StripeRawSizeFlushPolicyTestCase{
             .batchCount = 100,
             .rawStripeSize = 256 << 11,
             .stripeCount = 4},
-        RawStripeSizeFlushPolicyTestCase{
+        StripeRawSizeFlushPolicyTestCase{
             .batchCount = 100,
             .rawStripeSize = 256 << 12,
             .stripeCount = 2},
-        RawStripeSizeFlushPolicyTestCase{
+        StripeRawSizeFlushPolicyTestCase{
             .batchCount = 100,
             .rawStripeSize = 256 << 20,
             .stripeCount = 1}));