make lmdb's map_size configurable (fix #628)

src/model/Cargo.toml

@@ -23,6 +23,7 @@ garage_util.workspace = true
 async-trait = "0.1.7"
 arc-swap = "1.0"
 blake2 = "0.10"
+bytesize = "1.2"
 err-derive = "0.3"
 hex = "0.4"
 base64 = "0.21"

src/model/garage.rs

@@ -121,11 +121,22 @@ impl Garage {
 			// ---- LMDB DB ----
 			#[cfg(feature = "lmdb")]
 			"lmdb" | "heed" => {
+				use std::convert::TryInto;
 				db_path.push("db.lmdb");
 				info!("Opening LMDB database at: {}", db_path.display());
 				std::fs::create_dir_all(&db_path)
 					.ok_or_message("Unable to create LMDB data directory")?;
-				let map_size = garage_db::lmdb_adapter::recommended_map_size();
+				let map_size = match &config.lmdb_map_size {
+					None => garage_db::lmdb_adapter::recommended_map_size(),
+					Some(v) => {
+						let v: usize = v
+							.parse::<bytesize::ByteSize>()
+							.ok()
+							.and_then(|x| x.as_u64().try_into().ok())
+							.ok_or_message("invalid value for `lmdb_map_size`")?;
+						v - (v % 4096)
+					}
+				};
 
 				use db::lmdb_adapter::heed;
 				let mut env_builder = heed::EnvOpenOptions::new();
@@ -142,6 +153,7 @@ impl Garage {
 							"OutOfMemory error while trying to open LMDB database. This can happen \
 							if your operating system is not allowing you to use sufficient virtual \
 							memory address space. Please check that no limit is set (ulimit -v). \
+							You may also try to set a smaller `lmdb_map_size` configuration parameter. \
 							On 32-bit machines, you should probably switch to another database engine.".into()))
 					}
 					x => x.ok_or_message("Unable to open LMDB DB")?,

src/util/config.rs

@@ -72,6 +72,10 @@ pub struct Config {
 	#[serde(default = "default_sled_flush_every_ms")]
 	pub sled_flush_every_ms: u64,
 
+	/// LMDB map size
+	#[serde(default)]
+	pub lmdb_map_size: Option<String>,
+
 	// -- APIs
 	/// Configuration for S3 api
 	pub s3_api: S3ApiConfig,