Add support for an LSM-tree-based backend with Fjall

.woodpecker/debug.yaml

@@ -37,6 +37,8 @@ steps:
       - GARAGE_TEST_INTEGRATION_DB_ENGINE=lmdb ./result/bin/integration-* || (cat tmp-garage-integration/stderr.log; false)
       - nix-shell --attr ci --run "killall -9 garage" || true
       - GARAGE_TEST_INTEGRATION_DB_ENGINE=sqlite ./result/bin/integration-* || (cat tmp-garage-integration/stderr.log; false)
+      - nix-shell --attr ci --run "killall -9 garage" || true
+      - GARAGE_TEST_INTEGRATION_DB_ENGINE=fjall ./result/bin/integration-* || (cat tmp-garage-integration/stderr.log; false)
       - rm result
       - rm -rv tmp-garage-integration
 

Cargo.lock

@@ -54,9 +54,9 @@ dependencies = [
 
 [[package]]
 name = "ahash"
-version = "0.8.7"
+version = "0.8.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "77c3a9648d43b9cd48db467b3f87fdd6e146bcc88ab0180006cef2179fe11d01"
+checksum = "e89da841a80418a9b391ebaea17f5c112ffaaa96f621d2c285b5174da76b9011"
 dependencies = [
  "cfg-if",
  "getrandom",
@@ -793,7 +793,7 @@ dependencies = [
  "num-traits",
  "serde",
  "wasm-bindgen",
- "windows-targets 0.52.0",
+ "windows-targets 0.52.6",
 ]
 
 [[package]]
@@ -905,9 +905,9 @@ dependencies = [
 
 [[package]]
 name = "crc32fast"
-version = "1.4.0"
+version = "1.4.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b3855a8a784b474f333699ef2bbca9db2c4a1f6d9088a90a2d25b1eb53111eaa"
+checksum = "a97769d94ddab943e4510d138150169a2758b5ef3eb191a9ee688de3e23ef7b3"
 dependencies = [
  "cfg-if",
 ]
@@ -921,6 +921,15 @@ dependencies = [
  "crossbeam-utils",
 ]
 
+[[package]]
+name = "crossbeam-epoch"
+version = "0.9.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5b82ac4a3c2ca9c3460964f020e1402edd5753411d7737aa39c3714ad1b5420e"
+dependencies = [
+ "crossbeam-utils",
+]
+
 [[package]]
 name = "crossbeam-queue"
 version = "0.3.11"
@@ -930,6 +939,16 @@ dependencies = [
  "crossbeam-utils",
 ]
 
+[[package]]
+name = "crossbeam-skiplist"
+version = "0.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "df29de440c58ca2cc6e587ec3d22347551a32435fbde9d2bff64e78a9ffa151b"
+dependencies = [
+ "crossbeam-epoch",
+ "crossbeam-utils",
+]
+
 [[package]]
 name = "crossbeam-utils"
 version = "0.8.19"
@@ -1064,6 +1083,12 @@ dependencies = [
  "subtle",
 ]
 
+[[package]]
+name = "double-ended-peekable"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c0d05e1c0dbad51b52c38bda7adceef61b9efc2baf04acfe8726a8c4630a6f57"
+
 [[package]]
 name = "dyn-clone"
 version = "1.0.16"
@@ -1194,6 +1219,22 @@ version = "0.4.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0ce7134b9999ecaf8bcd65542e436736ef32ddca1b3e06094cb6ec5755203b80"
 
+[[package]]
+name = "fjall"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e2fd11be247941253b9861c7ca94526d092d8311ac0a1740415242e3d9efd7a5"
+dependencies = [
+ "byteorder",
+ "crc32fast",
+ "fs_extra",
+ "log",
+ "lsm-tree",
+ "path-absolutize",
+ "std-semaphore",
+ "tempfile",
+]
+
 [[package]]
 name = "fnv"
 version = "1.0.7"
@@ -1213,6 +1254,12 @@ dependencies = [
 name = "format_table"
 version = "0.1.1"
 
+[[package]]
+name = "fs_extra"
+version = "1.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "42703706b716c37f96a77aea830392ad231f44c9e9a67872fa5548707e11b11c"
+
 [[package]]
 name = "futures"
 version = "0.3.30"
@@ -1445,6 +1492,7 @@ name = "garage_db"
 version = "1.0.1"
 dependencies = [
  "err-derive",
+ "fjall",
  "heed",
  "hexdump",
  "mktemp",
@@ -1700,6 +1748,12 @@ dependencies = [
  "subtle",
 ]
 
+[[package]]
+name = "guardian"
+version = "1.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "493913a18c0d7bebb75127a26a432162c59edbe06f6cf712001e3e769345e8b5"
+
 [[package]]
 name = "h2"
 version = "0.3.24"
@@ -2462,9 +2516,37 @@ dependencies = [
 
 [[package]]
 name = "log"
-version = "0.4.20"
+version = "0.4.22"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b5e6163cb8c49088c2c36f57875e58ccd8c87c7427f7fbd50ea6710b2f3f2e8f"
+checksum = "a7a70ba024b9dc04c27ea2f0c0548feb474ec5c54bba33a7f72f873a39d07b24"
+
+[[package]]
+name = "lsm-tree"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e6b7522d314955643781c4050b48477985e61f892434e14e9e6148d27c60435d"
+dependencies = [
+ "byteorder",
+ "crc32fast",
+ "crossbeam-skiplist",
+ "double-ended-peekable",
+ "guardian",
+ "log",
+ "lz4_flex",
+ "path-absolutize",
+ "quick_cache",
+ "self_cell",
+ "tempfile",
+]
+
+[[package]]
+name = "lz4_flex"
+version = "0.11.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "75761162ae2b0e580d7e7c390558127e5f01b4194debd6221fd8c207fc80e3f5"
+dependencies = [
+ "twox-hash",
+]
 
 [[package]]
 name = "matchers"
@@ -2893,6 +2975,24 @@ version = "1.0.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "de3145af08024dea9fa9914f381a17b8fc6034dfb00f3a84013f7ff43f29ed4c"
 
+[[package]]
+name = "path-absolutize"
+version = "3.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e4af381fe79fa195b4909485d99f73a80792331df0625188e707854f0b3383f5"
+dependencies = [
+ "path-dedot",
+]
+
+[[package]]
+name = "path-dedot"
+version = "3.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "07ba0ad7e047712414213ff67533e6dd477af0a4e1d14fb52343e53d30ea9397"
+dependencies = [
+ "once_cell",
+]
+
 [[package]]
 name = "pem"
 version = "3.0.3"
@@ -3195,6 +3295,17 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "quick_cache"
+version = "0.6.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2ec0b6fed0a0ff01fa82d0c8982389375dd59c72dae84d4f8a15b1a894c273f7"
+dependencies = [
+ "ahash",
+ "equivalent",
+ "hashbrown 0.14.3",
+]
+
 [[package]]
 name = "quote"
 version = "1.0.35"
@@ -3682,6 +3793,12 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "self_cell"
+version = "1.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d369a96f978623eb3dc28807c4852d6cc617fed53da5d3c400feff1ef34a714a"
+
 [[package]]
 name = "semver"
 version = "1.0.21"
@@ -3874,6 +3991,12 @@ dependencies = [
  "der",
 ]
 
+[[package]]
+name = "static_assertions"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a2eb9349b6444b326872e140eb1cf5e7c522154d69e7a0ffb0fb81c06b37543f"
+
 [[package]]
 name = "static_init"
 version = "1.0.3"
@@ -3902,6 +4025,12 @@ dependencies = [
  "syn 1.0.109",
 ]
 
+[[package]]
+name = "std-semaphore"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "33ae9eec00137a8eed469fb4148acd9fc6ac8c3f9b110f52cd34698c8b5bfa0e"
+
 [[package]]
 name = "strsim"
 version = "0.10.0"
@@ -4021,15 +4150,15 @@ dependencies = [
 
 [[package]]
 name = "tempfile"
-version = "3.9.0"
+version = "3.12.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "01ce4141aa927a6d1bd34a041795abd0db1cccba5d5f24b009f694bdf3a1f3fa"
+checksum = "04cbcdd0c794ebb0d4cf35e88edd2f7d2c4c3e9a5a6dab322839b321c6a87a64"
 dependencies = [
  "cfg-if",
  "fastrand",
- "redox_syscall 0.4.1",
+ "once_cell",
  "rustix",
- "windows-sys 0.52.0",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -4450,6 +4579,16 @@ version = "0.2.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e421abadd41a4225275504ea4d6566923418b7f05506fbc9c0fe86ba7396114b"
 
+[[package]]
+name = "twox-hash"
+version = "1.6.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "97fee6b57c6a41524a810daee9286c02d7752c4253064d0b05472833a438f675"
+dependencies = [
+ "cfg-if",
+ "static_assertions",
+]
+
 [[package]]
 name = "typenum"
 version = "1.17.0"
@@ -4730,7 +4869,7 @@ version = "0.52.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "33ab640c8d7e35bf8ba19b884ba838ceb4fba93a4e8c65a9059d08afcfc683d9"
 dependencies = [
- "windows-targets 0.52.0",
+ "windows-targets 0.52.6",
 ]
 
 [[package]]
@@ -4748,7 +4887,16 @@ version = "0.52.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "282be5f36a8ce781fad8c8ae18fa3f9beff57ec1b52cb3de0789201425d9a33d"
 dependencies = [
- "windows-targets 0.52.0",
+ "windows-targets 0.52.6",
+]
+
+[[package]]
+name = "windows-sys"
+version = "0.59.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1e38bc4d79ed67fd075bcc251a1c39b32a1776bbe92e5bef1f0bf1f8c531853b"
+dependencies = [
+ "windows-targets 0.52.6",
 ]
 
 [[package]]
@@ -4768,17 +4916,18 @@ dependencies = [
 
 [[package]]
 name = "windows-targets"
-version = "0.52.0"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8a18201040b24831fbb9e4eb208f8892e1f50a37feb53cc7ff887feb8f50e7cd"
+checksum = "9b724f72796e036ab90c1021d4780d4d3d648aca59e491e6b98e725b84e99973"
 dependencies = [
- "windows_aarch64_gnullvm 0.52.0",
+ "windows_aarch64_gnullvm 0.52.6",
- "windows_aarch64_msvc 0.52.0",
+ "windows_aarch64_msvc 0.52.6",
- "windows_i686_gnu 0.52.0",
+ "windows_i686_gnu 0.52.6",
- "windows_i686_msvc 0.52.0",
+ "windows_i686_gnullvm",
- "windows_x86_64_gnu 0.52.0",
+ "windows_i686_msvc 0.52.6",
- "windows_x86_64_gnullvm 0.52.0",
+ "windows_x86_64_gnu 0.52.6",
- "windows_x86_64_msvc 0.52.0",
+ "windows_x86_64_gnullvm 0.52.6",
+ "windows_x86_64_msvc 0.52.6",
 ]
 
 [[package]]
@@ -4789,9 +4938,9 @@ checksum = "2b38e32f0abccf9987a4e3079dfb67dcd799fb61361e53e2882c3cbaf0d905d8"
 
 [[package]]
 name = "windows_aarch64_gnullvm"
-version = "0.52.0"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cb7764e35d4db8a7921e09562a0304bf2f93e0a51bfccee0bd0bb0b666b015ea"
+checksum = "32a4622180e7a0ec044bb555404c800bc9fd9ec262ec147edd5989ccd0c02cd3"
 
 [[package]]
 name = "windows_aarch64_msvc"
@@ -4801,9 +4950,9 @@ checksum = "dc35310971f3b2dbbf3f0690a219f40e2d9afcf64f9ab7cc1be722937c26b4bc"
 
 [[package]]
 name = "windows_aarch64_msvc"
-version = "0.52.0"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bbaa0368d4f1d2aaefc55b6fcfee13f41544ddf36801e793edbbfd7d7df075ef"
+checksum = "09ec2a7bb152e2252b53fa7803150007879548bc709c039df7627cabbd05d469"
 
 [[package]]
 name = "windows_i686_gnu"
@@ -4813,9 +4962,15 @@ checksum = "a75915e7def60c94dcef72200b9a8e58e5091744960da64ec734a6c6e9b3743e"
 
 [[package]]
 name = "windows_i686_gnu"
-version = "0.52.0"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a28637cb1fa3560a16915793afb20081aba2c92ee8af57b4d5f28e4b3e7df313"
+checksum = "8e9b5ad5ab802e97eb8e295ac6720e509ee4c243f69d781394014ebfe8bbfa0b"
+
+[[package]]
+name = "windows_i686_gnullvm"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0eee52d38c090b3caa76c563b86c3a4bd71ef1a819287c19d586d7334ae8ed66"
 
 [[package]]
 name = "windows_i686_msvc"
@@ -4825,9 +4980,9 @@ checksum = "8f55c233f70c4b27f66c523580f78f1004e8b5a8b659e05a4eb49d4166cca406"
 
 [[package]]
 name = "windows_i686_msvc"
-version = "0.52.0"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ffe5e8e31046ce6230cc7215707b816e339ff4d4d67c65dffa206fd0f7aa7b9a"
+checksum = "240948bc05c5e7c6dabba28bf89d89ffce3e303022809e73deaefe4f6ec56c66"
 
 [[package]]
 name = "windows_x86_64_gnu"
@@ -4837,9 +4992,9 @@ checksum = "53d40abd2583d23e4718fddf1ebec84dbff8381c07cae67ff7768bbf19c6718e"
 
 [[package]]
 name = "windows_x86_64_gnu"
-version = "0.52.0"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3d6fa32db2bc4a2f5abeacf2b69f7992cd09dca97498da74a151a3132c26befd"
+checksum = "147a5c80aabfbf0c7d901cb5895d1de30ef2907eb21fbbab29ca94c5b08b1a78"
 
 [[package]]
 name = "windows_x86_64_gnullvm"
@@ -4849,9 +5004,9 @@ checksum = "0b7b52767868a23d5bab768e390dc5f5c55825b6d30b86c844ff2dc7414044cc"
 
 [[package]]
 name = "windows_x86_64_gnullvm"
-version = "0.52.0"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1a657e1e9d3f514745a572a6846d3c7aa7dbe1658c056ed9c3344c4109a6949e"
+checksum = "24d5b23dc417412679681396f2b49f3de8c1473deb516bd34410872eff51ed0d"
 
 [[package]]
 name = "windows_x86_64_msvc"
@@ -4861,9 +5016,9 @@ checksum = "ed94fce61571a4006852b7389a063ab983c02eb1bb37b47f8272ce92d06d9538"
 
 [[package]]
 name = "windows_x86_64_msvc"
-version = "0.52.0"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dff9641d1cd4be8d1a070daf9e3773c5f67e78b4d9d42263020c057706765c04"
+checksum = "589f6da84c646204747d1270a2a5661ea66ed1cced2631d546fdfb155959f9ec"
 
 [[package]]
 name = "winnow"

Cargo.toml

@@ -85,6 +85,7 @@ heed = { version = "0.11", default-features = false, features = ["lmdb"] }
 rusqlite = "0.31.0"
 r2d2 = "0.8"
 r2d2_sqlite = "0.24"
+fjall = "1.5"
 
 async-compression = { version = "0.4", features = ["tokio", "zstd"] }
 zstd = { version = "0.13", default-features = false }

src/db/Cargo.toml

@@ -20,6 +20,7 @@ heed = { workspace = true, optional = true }
 rusqlite = { workspace = true, optional = true, features = ["backup"] }
 r2d2 = { workspace = true, optional = true }
 r2d2_sqlite = { workspace = true, optional = true }
+fjall = { workspace = true, optional = true }
 
 [dev-dependencies]
 mktemp.workspace = true
@@ -28,4 +29,5 @@ mktemp.workspace = true
 default = [ "lmdb", "sqlite" ]
 bundled-libs = [ "rusqlite?/bundled" ]
 lmdb = [ "heed" ]
+fjall = [ "dep:fjall" ]
 sqlite = [ "rusqlite", "r2d2", "r2d2_sqlite" ]

src/db/fjall_adapter.rs

@@ -0,0 +1,413 @@
+use core::ops::Bound;
+use core::pin::Pin;
+use core::ptr::NonNull;
+
+use std::collections::HashMap;
+use std::path::PathBuf;
+use std::sync::{Arc, RwLock};
+
+use fjall::{
+	PartitionCreateOptions, PersistMode, ReadTransaction, TransactionalKeyspace,
+	TransactionalPartitionHandle, WriteTransaction,
+};
+
+use crate::{
+	Db, Error, IDb, ITx, ITxFn, OnCommit, Result, TxError, TxFnResult, TxOpError, TxOpResult,
+	TxResult, TxValueIter, Value, ValueIter,
+};
+
+pub use fjall;
+
+// -- err
+
+impl From<fjall::Error> for Error {
+	fn from(e: fjall::Error) -> Error {
+		Error(format!("fjall: {}", e).into())
+	}
+}
+
+impl From<fjall::LsmError> for Error {
+	fn from(e: fjall::LsmError) -> Error {
+		Error(format!("fjall lsm_tree: {}", e).into())
+	}
+}
+
+impl From<fjall::Error> for TxOpError {
+	fn from(e: fjall::Error) -> TxOpError {
+		TxOpError(e.into())
+	}
+}
+
+// -- db
+
+pub struct FjallDb {
+	path: PathBuf,
+	keyspace: TransactionalKeyspace,
+	trees: RwLock<(Vec<TransactionalPartitionHandle>, HashMap<String, usize>)>,
+}
+
+type ByteRefRangeBound<'r> = (Bound<&'r [u8]>, Bound<&'r [u8]>);
+
+impl FjallDb {
+	pub fn init(path: &PathBuf, keyspace: TransactionalKeyspace) -> Db {
+		let s = Self {
+			path: path.clone(),
+			keyspace,
+			trees: RwLock::new((Vec::new(), HashMap::new())),
+		};
+		Db(Arc::new(s))
+	}
+
+	fn get_tree(&self, i: usize) -> Result<TransactionalPartitionHandle> {
+		self.trees
+			.read()
+			.unwrap()
+			.0
+			.get(i)
+			.cloned()
+			.ok_or_else(|| Error("invalid tree id".into()))
+	}
+
+	fn canonicalize(name: &str) -> String {
+		name.chars()
+			.map(|c| {
+				if c.is_alphanumeric() || c == '-' || c == '_' {
+					c
+				} else {
+					'_'
+				}
+			})
+			.collect::<String>()
+	}
+}
+
+impl IDb for FjallDb {
+	fn engine(&self) -> String {
+		"LSM trees (using Fjall crate)".into()
+	}
+
+	fn open_tree(&self, name: &str) -> Result<usize> {
+		let mut trees = self.trees.write().unwrap();
+		let canonical_name = FjallDb::canonicalize(name);
+		if let Some(i) = trees.1.get(&canonical_name) {
+			Ok(*i)
+		} else {
+			let tree = self
+				.keyspace
+				.open_partition(&canonical_name, PartitionCreateOptions::default())?;
+			let i = trees.0.len();
+			trees.0.push(tree);
+			trees.1.insert(canonical_name, i);
+			Ok(i)
+		}
+	}
+
+	fn list_trees(&self) -> Result<Vec<String>> {
+		Ok(self
+			.keyspace
+			.list_partitions()
+			.iter()
+			.map(|n| n.to_string())
+			.collect())
+	}
+
+	fn snapshot(&self, to: &PathBuf) -> Result<()> {
+		std::fs::create_dir_all(to)?;
+		let mut path = to.clone();
+		path.push("data.fjall");
+
+		let source_keyspace = fjall::Config::new(&self.path).open()?;
+		let copy_keyspace = fjall::Config::new(path).open()?;
+
+		for partition_name in source_keyspace.list_partitions() {
+			let source_partition = source_keyspace
+				.open_partition(&partition_name, PartitionCreateOptions::default())?;
+			let snapshot = source_partition.snapshot();
+			let copy_partition =
+				copy_keyspace.open_partition(&partition_name, PartitionCreateOptions::default())?;
+
+			for entry in snapshot.iter() {
+				let (key, value) = entry?;
+				copy_partition.insert(key, value)?;
+			}
+		}
+
+		copy_keyspace.persist(PersistMode::SyncAll)?;
+		Ok(())
+	}
+
+	// ----
+
+	fn get(&self, tree_idx: usize, key: &[u8]) -> Result<Option<Value>> {
+		let tree = self.get_tree(tree_idx)?;
+		let tx = self.keyspace.read_tx();
+		let val = tx.get(&tree, key)?;
+		match val {
+			None => Ok(None),
+			Some(v) => Ok(Some(v.to_vec())),
+		}
+	}
+
+	fn len(&self, tree_idx: usize) -> Result<usize> {
+		let tree = self.get_tree(tree_idx)?;
+		let tx = self.keyspace.read_tx();
+		Ok(tx.len(&tree)?)
+	}
+
+	fn insert(&self, tree_idx: usize, key: &[u8], value: &[u8]) -> Result<()> {
+		let tree = self.get_tree(tree_idx)?;
+		let mut tx = self.keyspace.write_tx();
+		tx.insert(&tree, key, value);
+		tx.commit()?;
+		Ok(())
+	}
+
+	fn remove(&self, tree_idx: usize, key: &[u8]) -> Result<()> {
+		let tree = self.get_tree(tree_idx)?;
+		let mut tx = self.keyspace.write_tx();
+		tx.remove(&tree, key);
+		tx.commit()?;
+		Ok(())
+	}
+
+	fn clear(&self, tree_idx: usize) -> Result<()> {
+		let tree = self.get_tree(tree_idx)?;
+		let tree_name = tree.inner().name.clone();
+		self.keyspace.delete_partition(tree)?;
+		let tree = self
+			.keyspace
+			.open_partition(&tree_name, PartitionCreateOptions::default())?;
+		let mut trees = self.trees.write().unwrap();
+		trees.0[tree_idx] = tree;
+		Ok(())
+	}
+
+	fn iter(&self, tree_idx: usize) -> Result<ValueIter<'_>> {
+		let tree = self.get_tree(tree_idx)?;
+		let tx = self.keyspace.read_tx();
+		TxAndIterator::make(tx, |tx| Ok(tx.iter(&tree)))
+	}
+
+	fn iter_rev(&self, tree_idx: usize) -> Result<ValueIter<'_>> {
+		let tree = self.get_tree(tree_idx)?;
+		let tx = self.keyspace.read_tx();
+		TxAndIterator::make(tx, |tx| Ok(tx.iter(&tree).rev()))
+	}
+
+	fn range<'r>(
+		&self,
+		tree_idx: usize,
+		low: Bound<&'r [u8]>,
+		high: Bound<&'r [u8]>,
+	) -> Result<ValueIter<'_>> {
+		let tree = self.get_tree(tree_idx)?;
+		let tx = self.keyspace.read_tx();
+		TxAndIterator::make(tx, |tx| {
+			Ok(tx.range::<&'r [u8], ByteRefRangeBound>(&tree, (low, high)))
+		})
+	}
+	fn range_rev<'r>(
+		&self,
+		tree_idx: usize,
+		low: Bound<&'r [u8]>,
+		high: Bound<&'r [u8]>,
+	) -> Result<ValueIter<'_>> {
+		let tree = self.get_tree(tree_idx)?;
+		let tx = self.keyspace.read_tx();
+		TxAndIterator::make(tx, |tx| {
+			Ok(tx
+				.range::<&'r [u8], ByteRefRangeBound>(&tree, (low, high))
+				.rev())
+		})
+	}
+
+	// ----
+
+	fn transaction(&self, f: &dyn ITxFn) -> TxResult<OnCommit, ()> {
+		let trees = self.trees.read().unwrap();
+		let mut tx = FjallTx {
+			trees: &trees.0[..],
+			tx: self.keyspace.write_tx(),
+		};
+
+		let res = f.try_on(&mut tx);
+		match res {
+			TxFnResult::Ok(on_commit) => {
+				tx.tx.commit().map_err(Error::from).map_err(TxError::Db)?;
+				Ok(on_commit)
+			}
+			TxFnResult::Abort => {
+				tx.tx.rollback();
+				Err(TxError::Abort(()))
+			}
+			TxFnResult::DbErr => {
+				tx.tx.rollback();
+				Err(TxError::Db(Error(
+					"(this message will be discarded)".into(),
+				)))
+			}
+		}
+	}
+}
+
+// ----
+
+struct FjallTx<'a> {
+	trees: &'a [TransactionalPartitionHandle],
+	tx: WriteTransaction<'a>,
+}
+
+impl<'a> FjallTx<'a> {
+	fn get_tree(&self, i: usize) -> TxOpResult<&TransactionalPartitionHandle> {
+		self.trees.get(i).ok_or_else(|| {
+			TxOpError(Error(
+				"invalid tree id (it might have been openned after the transaction started)".into(),
+			))
+		})
+	}
+}
+
+impl<'a> ITx for FjallTx<'a> {
+	fn get(&self, tree_idx: usize, key: &[u8]) -> TxOpResult<Option<Value>> {
+		let tree = self.get_tree(tree_idx)?;
+		match self.tx.get(tree, key)? {
+			Some(v) => Ok(Some(v.to_vec())),
+			None => Ok(None),
+		}
+	}
+	fn len(&self, tree_idx: usize) -> TxOpResult<usize> {
+		let tree = self.get_tree(tree_idx)?;
+		Ok(self.tx.len(tree)? as usize)
+	}
+
+	fn insert(&mut self, tree_idx: usize, key: &[u8], value: &[u8]) -> TxOpResult<()> {
+		let tree = self.get_tree(tree_idx)?.clone();
+		self.tx.insert(&tree, key, value);
+		Ok(())
+	}
+	fn remove(&mut self, tree_idx: usize, key: &[u8]) -> TxOpResult<()> {
+		let tree = self.get_tree(tree_idx)?.clone();
+		self.tx.remove(&tree, key);
+		Ok(())
+	}
+	fn clear(&mut self, _tree_idx: usize) -> TxOpResult<()> {
+		unimplemented!("LSM tree clearing in cross-partition transaction is not supported")
+	}
+
+	fn iter(&self, tree_idx: usize) -> TxOpResult<TxValueIter<'_>> {
+		let tree = self.get_tree(tree_idx)?.clone();
+		Ok(Box::new(self.tx.iter(&tree).map(tx_iter_item)))
+	}
+	fn iter_rev(&self, tree_idx: usize) -> TxOpResult<TxValueIter<'_>> {
+		let tree = self.get_tree(tree_idx)?.clone();
+		Ok(Box::new(self.tx.iter(&tree).rev().map(tx_iter_item)))
+	}
+
+	fn range<'r>(
+		&self,
+		tree_idx: usize,
+		low: Bound<&'r [u8]>,
+		high: Bound<&'r [u8]>,
+	) -> TxOpResult<TxValueIter<'_>> {
+		let tree = self.get_tree(tree_idx)?.clone();
+		Ok(Box::new(
+			self.tx
+				.range::<&'r [u8], ByteRefRangeBound>(&tree, (low, high))
+				.map(tx_iter_item),
+		))
+	}
+	fn range_rev<'r>(
+		&self,
+		tree_idx: usize,
+		low: Bound<&'r [u8]>,
+		high: Bound<&'r [u8]>,
+	) -> TxOpResult<TxValueIter<'_>> {
+		let tree = self.get_tree(tree_idx)?.clone();
+		Ok(Box::new(
+			self.tx
+				.range::<&'r [u8], ByteRefRangeBound>(&tree, (low, high))
+				.rev()
+				.map(tx_iter_item),
+		))
+	}
+}
+
+// ---- iterators outside transactions ----
+// complicated, they must hold the transaction object
+// therefore a bit of unsafe code (it is a self-referential struct)
+
+type IteratorItem = fjall::Result<(fjall::UserKey, fjall::UserValue)>;
+
+struct TxAndIterator<I>
+where
+	I: Iterator<Item = IteratorItem>,
+{
+	tx: ReadTransaction,
+	iter: Option<I>,
+}
+
+impl<'a, I> TxAndIterator<I>
+where
+	I: Iterator<Item = IteratorItem> + 'a,
+{
+	fn make<F>(tx: ReadTransaction, iterfun: F) -> Result<ValueIter<'a>>
+	where
+		F: FnOnce(&ReadTransaction) -> Result<I>,
+	{
+		let res = TxAndIterator { tx, iter: None };
+		let mut boxed = Box::pin(res);
+
+		// This unsafe allows us to bypass lifetime checks
+		let tx = unsafe { NonNull::from(&boxed.tx).as_ref() };
+		let iter = iterfun(tx)?;
+
+		let mut_ref = Pin::as_mut(&mut boxed);
+		// This unsafe allows us to write in a field of the pinned struct
+		unsafe {
+			Pin::get_unchecked_mut(mut_ref).iter = Some(iter);
+		}
+
+		Ok(Box::new(TxAndIteratorPin(boxed)))
+	}
+}
+
+impl<'a, I> Drop for TxAndIterator<I>
+where
+	I: Iterator<Item = IteratorItem>,
+{
+	fn drop(&mut self) {
+		// ensure the iterator is dropped before the RoTxn it references
+		drop(self.iter.take());
+	}
+}
+
+struct TxAndIteratorPin<I>(Pin<Box<TxAndIterator<I>>>)
+where
+	I: Iterator<Item = IteratorItem>;
+
+impl<I> Iterator for TxAndIteratorPin<I>
+where
+	I: Iterator<Item = IteratorItem>,
+{
+	type Item = Result<(Value, Value)>;
+
+	fn next(&mut self) -> Option<Self::Item> {
+		let mut_ref = Pin::as_mut(&mut self.0);
+		// This unsafe allows us to mutably access the iterator field
+		let next = unsafe { Pin::get_unchecked_mut(mut_ref).iter.as_mut()?.next() };
+		match next {
+			None => None,
+			Some(Err(e)) => Some(Err(e.into())),
+			Some(Ok((k, v))) => Some(Ok((k.to_vec(), v.to_vec()))),
+		}
+	}
+}
+
+// ---- iterators within transactions ----
+
+fn tx_iter_item<'a>(
+	item: std::result::Result<(Arc<[u8]>, Arc<[u8]>), fjall::Error>,
+) -> TxOpResult<(Vec<u8>, Vec<u8>)> {
+	item.map(|(k, v)| (k.to_vec(), v.to_vec()))
+		.map_err(|e| TxOpError(Error::from(e)))
+}

src/db/lib.rs

@@ -1,6 +1,8 @@
 #[macro_use]
 extern crate tracing;
 
+#[cfg(feature = "fjall")]
+pub mod fjall_adapter;
 #[cfg(feature = "lmdb")]
 pub mod lmdb_adapter;
 #[cfg(feature = "sqlite")]

src/db/open.rs

@@ -11,6 +11,7 @@ use crate::{Db, Error, Result};
 pub enum Engine {
 	Lmdb,
 	Sqlite,
+	Fjall,
 }
 
 impl Engine {
@@ -19,6 +20,7 @@ impl Engine {
 		match self {
 			Self::Lmdb => "lmdb",
 			Self::Sqlite => "sqlite",
+			Self::Fjall => "fjall",
 		}
 	}
 }
@@ -36,6 +38,7 @@ impl std::str::FromStr for Engine {
 		match text {
 			"lmdb" | "heed" => Ok(Self::Lmdb),
 			"sqlite" | "sqlite3" | "rusqlite" => Ok(Self::Sqlite),
+            "fjall" => Ok(Self::Fjall),
 			"sled" => Err(Error("Sled is no longer supported as a database engine. Converting your old metadata db can be done using an older Garage binary (e.g. v0.9.4).".into())),
 			kind => Err(Error(
 				format!(
@@ -114,6 +117,15 @@ pub fn open_db(path: &PathBuf, engine: Engine, opt: &OpenOpt) -> Result<Db> {
 			}
 		}
 
+		// ---- Fjall DB ----
+		#[cfg(feature = "fjall")]
+		Engine::Fjall => {
+			info!("Opening Fjall database at: {}", path.display());
+            let fsync_ms = opt.fsync.then(|| 1000 as u16);
+			let keyspace = fjall::Config::new(path).fsync_ms(fsync_ms).open_transactional()?;
+			Ok(crate::fjall_adapter::FjallDb::init(path, keyspace))
+		}
+
 		// Pattern is unreachable when all supported DB engines are compiled into binary. The allow
 		// attribute is added so that we won't have to change this match in case stop building
 		// support for one or more engines by default.

src/garage/Cargo.toml

@@ -89,6 +89,7 @@ k2v = [ "garage_util/k2v", "garage_api/k2v" ]
 # Database engines
 lmdb = [ "garage_model/lmdb" ]
 sqlite = [ "garage_model/sqlite" ]
+fjall = [ "garage_model/fjall" ]
 
 # Automatic registration and discovery via Consul API
 consul-discovery = [ "garage_rpc/consul-discovery" ]

src/model/Cargo.toml

@@ -47,3 +47,4 @@ default = [ "lmdb", "sqlite" ]
 k2v = [ "garage_util/k2v" ]
 lmdb = [ "garage_db/lmdb" ]
 sqlite = [ "garage_db/sqlite" ]
+fjall = [ "garage_db/fjall" ]

src/model/garage.rs

@@ -124,6 +124,9 @@ impl Garage {
 			db::Engine::Lmdb => {
 				db_path.push("db.lmdb");
 			}
+			db::Engine::Fjall => {
+				db_path.push("db.fjall");
+			}
 		}
 		let db_opt = db::OpenOpt {
 			fsync: config.metadata_fsync,