make bloomfilter constants settable by envvar at compile time

responder-common/Cargo.toml

@@ -9,3 +9,6 @@ user = []
 
 [lib]
 path = "src/lib.rs"
+
+[dependencies]
+konst = { version = "0.3", features = ["parsing"] }

responder-common/src/lib.rs

@@ -1,7 +1,12 @@
 #![no_std]
 
 pub mod bloom_filter {
-    pub const BITS: usize = 0x400_00000; // 128MB
+    use konst::primitive::{parse_usize, parse_u32};
+    use konst::unwrap_ctx;
+    use konst::option::unwrap_or;
+
+    pub const ADDRESS_BITS: usize = unwrap_ctx!(parse_usize(unwrap_or!(option_env!("BLOOMFILTER_ADDRESS_BITS"), "30"))); // default = 0x1E = 30
+    pub const BITS: usize = 1 << ADDRESS_BITS; // default = 0x40_000_000 = 128MB
     pub const ADDRESS_MASK: usize = BITS - 1;
 
     pub const WORD_BITS: usize = 0x8; // 8
@@ -9,17 +14,17 @@ pub mod bloom_filter {
     pub const ADDRESS_BITS_WORD: usize = 0x3; // log_2(0x8)
     pub const ADDRESS_MASK_WORD: usize = WORD_BITS - 1; // 0x7
 
-    pub const CHUNK_BITS: usize = 0x40000;
+    pub const ADDRESS_BITS_CHUNK: usize = unwrap_ctx!(parse_usize(unwrap_or!(option_env!("BLOOMFILTER_ADDRESS_BITS_CHUNK"), "18"))); // default = 0x12 = 18 = log_2(32KB)
+    pub const CHUNK_BITS: usize = 1 << ADDRESS_BITS_CHUNK; // default = 0x40000  = 32KB (per-cpu map value size limit)
     pub const CHUNK_BYTES: usize = CHUNK_BITS >> 0x3;
     pub const CHUNK_SIZE: usize = CHUNK_BITS >> ADDRESS_BITS_WORD; // WORD_SIZE * CHUNK_SIZE = 32Kb
     pub type ChunkType = [WordType; CHUNK_SIZE];
-    pub const ADDRESS_BITS_CHUNK: usize = 0x12; // = log_2(CHUNK_SIZE)
     pub const ADDRESS_MASK_CHUNK: usize = CHUNK_BITS - 1;
 
     pub const BUFFER_SIZE: usize = BITS >> ADDRESS_BITS_WORD; // 0x20_0000
     pub const MAP_SIZE: usize = BITS >> ADDRESS_BITS_CHUNK;
 
-    pub const HASH_COUNT: u32 = 10;
+    pub const HASH_COUNT: u32 = unwrap_ctx!(parse_u32(unwrap_or!(option_env!("BLOOMFILTER_HASH_COUNT"), "10")));
     // Hashing based on jhash.h from kernel // TODO improve reference
     const HASH_INITVAL: u32 = 0xdeadbeef;