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Allow setCompressedReadAheadBufferSizeInKb(0) to disable RAB #4940

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Allow setCompressedReadAheadBufferSizeInKb(0) to disable RAB #4940

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0a6bf2b
Allow setCompressedReadAheadBufferSizeInKb(0) to disable RAB
Jul 14, 2026
c919bcd
Disallow negative buffer sizes
Jul 14, 2026
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4 changes: 2 additions & 2 deletions src/java/org/apache/cassandra/config/DatabaseDescriptor.java
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Original file line number Diff line number Diff line change
Expand Up @@ -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 > 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");
}
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24 changes: 24 additions & 0 deletions test/unit/org/apache/cassandra/config/DatabaseDescriptorTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -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);
}
}
}