From 0a6bf2b7f5088f17cee9f29b0aca9ad15f028b89 Mon Sep 17 00:00:00 2001 From: nivy Date: Mon, 13 Jul 2026 22:31:39 -0700 Subject: [PATCH 1/2] Allow setCompressedReadAheadBufferSizeInKb(0) to disable RAB --- .../cassandra/config/DatabaseDescriptor.java | 4 ++-- .../config/DatabaseDescriptorTest.java | 24 +++++++++++++++++++ 2 files changed, 26 insertions(+), 2 deletions(-) diff --git a/src/java/org/apache/cassandra/config/DatabaseDescriptor.java b/src/java/org/apache/cassandra/config/DatabaseDescriptor.java index c0fb8bc200e0..9477c2547826 100644 --- a/src/java/org/apache/cassandra/config/DatabaseDescriptor.java +++ b/src/java/org/apache/cassandra/config/DatabaseDescriptor.java @@ -3067,8 +3067,8 @@ public static int getCompressedReadAheadBufferSizeInKB() public static void setCompressedReadAheadBufferSizeInKb(int sizeInKb) { - if (sizeInKb < 256) - throw new IllegalArgumentException("compressed_read_ahead_buffer_size_in_kb must be at least 256KiB"); + if (sizeInKb != 0 && sizeInKb < 256) + throw new IllegalArgumentException("compressed_read_ahead_buffer_size_in_kb must be at least 256KiB (set to 0 to disable)"); conf.compressed_read_ahead_buffer_size = createIntKibibyteBoundAndEnsureItIsValidForByteConversion(sizeInKb, "compressed_read_ahead_buffer_size"); } diff --git a/test/unit/org/apache/cassandra/config/DatabaseDescriptorTest.java b/test/unit/org/apache/cassandra/config/DatabaseDescriptorTest.java index 5796c4032f4a..041e312a43f1 100644 --- a/test/unit/org/apache/cassandra/config/DatabaseDescriptorTest.java +++ b/test/unit/org/apache/cassandra/config/DatabaseDescriptorTest.java @@ -1190,4 +1190,28 @@ public void testGetDirectIOWritePaths() throws IOException conf.local_system_data_file_directory = savedLocalSystemDir; } } + + @Test + public void testSetCompressedReadAheadBufferSizeInKb() + { + int original = DatabaseDescriptor.getCompressedReadAheadBufferSizeInKB(); + try + { + // 0 should be a legal value, and represents disabling read-ahead buffer + DatabaseDescriptor.setCompressedReadAheadBufferSizeInKb(0); + assertEquals(0, DatabaseDescriptor.getCompressedReadAheadBufferSizeInKB()); + assertEquals(0, DatabaseDescriptor.getCompressedReadAheadBufferSize()); + + Assertions.assertThatThrownBy(() -> DatabaseDescriptor.setCompressedReadAheadBufferSizeInKb(255)) + .isInstanceOf(IllegalArgumentException.class) + .hasMessage("compressed_read_ahead_buffer_size_in_kb must be at least 256KiB (set to 0 to disable)"); + + DatabaseDescriptor.setCompressedReadAheadBufferSizeInKb(256); + assertEquals(256, DatabaseDescriptor.getCompressedReadAheadBufferSizeInKB()); + } + finally + { + DatabaseDescriptor.setCompressedReadAheadBufferSizeInKb(original); + } + } } From c919bcde522ff13728336b726c12de4525962f74 Mon Sep 17 00:00:00 2001 From: nivy Date: Tue, 14 Jul 2026 11:01:18 -0700 Subject: [PATCH 2/2] Disallow negative buffer sizes --- src/java/org/apache/cassandra/config/DatabaseDescriptor.java | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/java/org/apache/cassandra/config/DatabaseDescriptor.java b/src/java/org/apache/cassandra/config/DatabaseDescriptor.java index 9477c2547826..abff357737f0 100644 --- a/src/java/org/apache/cassandra/config/DatabaseDescriptor.java +++ b/src/java/org/apache/cassandra/config/DatabaseDescriptor.java @@ -3067,7 +3067,7 @@ public static int getCompressedReadAheadBufferSizeInKB() public static void setCompressedReadAheadBufferSizeInKb(int sizeInKb) { - if (sizeInKb != 0 && sizeInKb < 256) + if (sizeInKb < 0 || (sizeInKb > 0 && sizeInKb < 256)) throw new IllegalArgumentException("compressed_read_ahead_buffer_size_in_kb must be at least 256KiB (set to 0 to disable)"); conf.compressed_read_ahead_buffer_size = createIntKibibyteBoundAndEnsureItIsValidForByteConversion(sizeInKb, "compressed_read_ahead_buffer_size");