Use LRU cache

meilisearch/src/lib.rs

@@ -45,6 +45,33 @@ use option::ScheduleSnapshot;
 
 use crate::error::MeilisearchHttpError;
 
+/// Default number of simultaneously opened indexes,
+/// lower for Windows that dedicates a smaller virtual address space to processes.
+///
+/// The value was chosen this way:
+///
+/// - Windows provides a small virtual address space of about 10TiB to processes.
+/// - The chosen value allows for indexes to reach a safe size of 1TiB.
+/// - This can accomodate an unlimited number of indexes as long as they stay below 1TiB size.
+#[cfg(windows)]
+const DEFAULT_INDEX_COUNT: usize = 10;
+/// Default number of simultaneously opened indexes.
+///
+/// The higher, the better for avoiding reopening indexes.
+///
+/// The value was chosen this way:
+///
+/// - Opening an index consumes a file descriptor.
+/// - The default on many unices is about 256 file descriptors for a process.
+/// - 100 is a little bit less than half this value.
+///
+/// In the future, this value could be computed from the dynamic number of allowed file descriptors for the current process.
+///
+/// On Unices, this value is largely irrelevant to virtual address space, because due to index resizing the indexes should take virtual memory in the same ballpark
+/// as their disk size and it is unlikely for a user to have a sum of index weighing 128TB on a single Meilisearch node.
+#[cfg(not(windows))]
+const DEFAULT_INDEX_COUNT: usize = 100;
+
 /// Check if a db is empty. It does not provide any information on the
 /// validity of the data in it.
 /// We consider a database as non empty when it's a non empty directory.
@@ -206,9 +233,11 @@ fn open_or_create_database_unchecked(
             snapshots_path: opt.snapshot_dir.clone(),
             dumps_path: opt.dump_dir.clone(),
             task_db_size: opt.max_task_db_size.get_bytes() as usize,
-            index_size: opt.max_index_size.get_bytes() as usize,
+            index_base_map_size: opt.max_index_size.get_bytes() as usize,
             indexer_config: (&opt.indexer_options).try_into()?,
             autobatching_enabled: true,
+            index_growth_amount: byte_unit::Byte::from_str("10GiB").unwrap().get_bytes() as usize,
+            index_count: DEFAULT_INDEX_COUNT,
         })?)
     };
 

meilisearch/src/option.rs

@@ -65,11 +65,10 @@ const MEILI_MAX_INDEXING_THREADS: &str = "MEILI_MAX_INDEXING_THREADS";
 const DEFAULT_LOG_EVERY_N: usize = 100_000;
 
 // Each environment (index and task-db) is taking space in the virtual address space.
-//
-// The size of the virtual address space is limited by the OS. About 100TB for Linux and about 10TB for Windows.
-// This means that the number of indexes is limited to about 200 for Linux and about 20 for Windows.
-pub const INDEX_SIZE: u64 = 536_870_912_000; // 500 GiB
-pub const TASK_DB_SIZE: u64 = 10_737_418_240; // 10 GiB
+// When creating a new environment, it starts its life with 10GiB of virtual address space.
+// It is then later resized if needs be.
+pub const INDEX_SIZE: u64 = 10 * 1024 * 1024 * 1024; // 10 GiB
+pub const TASK_DB_SIZE: u64 = 10 * 1024 * 1024 * 1024; // 10 GiB
 
 #[derive(Debug, Default, Clone, Copy, Serialize, Deserialize)]
 #[serde(rename_all = "UPPERCASE")]