From 19b3424a3c351ccab40c56988d8521d0e855a7e7 Mon Sep 17 00:00:00 2001
From: Marcus Holland-Moritz <github@mhxnet.de>
Date: Tue, 15 Aug 2023 17:48:50 +0200
Subject: [PATCH] Add constrained_block_size to granularity policy

---
 src/dwarfs/segmenter.cpp | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/src/dwarfs/segmenter.cpp b/src/dwarfs/segmenter.cpp
index 53a2add6..75ba427a 100644
--- a/src/dwarfs/segmenter.cpp
+++ b/src/dwarfs/segmenter.cpp
@@ -283,6 +283,13 @@ class ConstantGranularityPolicy : private GranularityPolicyBase {
                    chunkable_size_fail_message(size, kGranularity));
     }
   }
+
+  static size_t constrained_block_size(size_t size) {
+    if constexpr (kGranularity > 1) {
+      size -= size % kGranularity;
+    }
+    return size;
+  }
 };
 
 class VariableGranularityPolicy : private GranularityPolicyBase {
@@ -309,6 +316,13 @@ class VariableGranularityPolicy : private GranularityPolicyBase {
     }
   }
 
+  size_t constrained_block_size(size_t size) const {
+    if (granularity_ > 1) {
+      size -= size % granularity_;
+    }
+    return size;
+  }
+
  private:
   uint_fast32_t const granularity_;
 };
@@ -395,7 +409,7 @@ class segmenter_ final : public segmenter::impl, private GranularityPolicy {
       , block_ready_{std::move(block_ready)}
       , window_size_{window_size(cfg)}
       , window_step_{window_step(cfg)}
-      , block_size_{block_size(cfg)}
+      , block_size_{this->constrained_block_size(block_size(cfg))}
       , filter_{bloom_filter_size(cfg)}
       , match_counts_{1, 0, 128} {
     if (segmentation_enabled()) {