feat: make rocksdb optional when using sqlite feature

- Make rocksdb dependency optional in both lib and bin crates
- Add feature flags to properly control backend selection
- Update conditional compilation to check for rocksdb feature
- Add proper error variants for each backend (rocksdb, sqlite, indexdb)
- Disable default features for ckb-light-client-lib dependency

This allows building with --features sqlite --no-default-features
to completely exclude rocksdb from the dependency tree.

Author: quake

light-client-bin/Cargo.toml

@@ -19,7 +19,7 @@ ckb-types = "1"
 ckb-traits = "1"
 ckb-systemtime = "1"
 
-ckb-light-client-lib = { path = "../light-client-lib" }
+ckb-light-client-lib = { path = "../light-client-lib", default-features = false }
 clap = { version = "4", features = ["cargo"] }
 log = "0.4"
 ctrlc = { version = "3.2.1", features = ["termination"] }
@@ -29,7 +29,7 @@ jsonrpc-http-server = "18.0"
 jsonrpc-server-utils = "18.0"
 rocksdb = { package = "ckb-rocksdb", version = "=0.21.1", features = [
     "snappy",
-], default-features = false }
+], default-features = false, optional = true }
 env_logger = "0.11"
 anyhow = "1.0.56"
 
@@ -46,10 +46,11 @@ serde_json = "1.0"
 tempfile = "3.0"
 
 [features]
-default = []
-portable = ["rocksdb/portable"]
-march-native = ["rocksdb/march-native"]
+default = ["rocksdb", "ckb-light-client-lib/rocksdb"]
+portable = ["rocksdb", "rocksdb/portable", "ckb-light-client-lib/rocksdb"]
+march-native = ["rocksdb", "rocksdb/march-native", "ckb-light-client-lib/rocksdb"]
 sqlite = ["ckb-light-client-lib/sqlite"]
+rocksdb = ["dep:rocksdb"]
 
 # [profile.release]
 # overflow-checks = true

light-client-lib/Cargo.toml

@@ -12,8 +12,9 @@ repository = "https://github.com/nervosnetwork/ckb-light-client"
 crate-type = ["cdylib", "rlib"]
 
 [features]
-default = []
+default = ["rocksdb"]
 sqlite = ["rusqlite"]
+rocksdb = ["dep:rocksdb"]
 
 [dependencies]
 ckb-app-config = "1"
@@ -56,7 +57,7 @@ bincode = "1.3"
 [target.'cfg(not(target_arch = "wasm32"))'.dependencies]
 rocksdb = { package = "ckb-rocksdb", version = "=0.21.1", features = [
     "snappy",
-], default-features = false }
+], default-features = false, optional = true }
 rusqlite = { version = "0.32", optional = true, features = ["bundled"] }
 
 [target.'cfg(target_arch = "wasm32")'.dependencies]

light-client-lib/src/error.rs

@@ -11,10 +11,14 @@ pub enum Error {
     #[error("runtime error: {0}")]
     Runtime(String),
 
-    #[cfg(not(target_arch = "wasm32"))]
+    #[cfg(all(not(target_arch = "wasm32"), feature = "rocksdb"))]
     #[error("db error: {0}")]
     Db(#[from] rocksdb::Error),
 
+    #[cfg(all(not(target_arch = "wasm32"), feature = "sqlite"))]
+    #[error("db error: {0}")]
+    Sqlite(#[from] rusqlite::Error),
+
     #[cfg(target_arch = "wasm32")]
     #[error("db error: {0}")]
     Indexdb(String),

light-client-lib/src/storage/db/iterator.rs

@@ -1,6 +1,6 @@
 //! Unified iterator types for different storage backends (RocksDB, IndexedDB, SQLite)
 
-#[cfg(not(target_arch = "wasm32"))]
+#[cfg(all(not(target_arch = "wasm32"), feature = "rocksdb"))]
 use rocksdb::Direction;
 
 // On wasm32, re-export IteratorDirection and KVPair from db-common to avoid duplication
@@ -15,7 +15,7 @@ pub enum IteratorDirection {
     Reverse,
 }
 
-#[cfg(not(target_arch = "wasm32"))]
+#[cfg(all(not(target_arch = "wasm32"), feature = "rocksdb"))]
 impl From<IteratorDirection> for Direction {
     fn from(dir: IteratorDirection) -> Self {
         match dir {