Fix ignored column descriptions; enhance preservation behavior. (7320d0a40b)

Signed-off-by: Jason Volk <jason@zemos.net>

src/database/engine/cf_opts.rs

@@ -43,6 +43,7 @@ fn descriptor_cf_options(
 	opts.set_max_bytes_for_level_multiplier(1.0);
 	opts.set_max_bytes_for_level_multiplier_additional(&desc.level_shape);
 
+	opts.set_disable_auto_compactions(desc.ignored);
 	opts.set_compaction_style(desc.compaction);
 	opts.set_compaction_pri(desc.compaction_pri);
 	opts.set_universal_compaction_options(&uc_options(&desc));

src/database/engine/descriptor.rs

@@ -10,6 +10,7 @@ use super::cf_opts::SENTINEL_COMPRESSION_LEVEL;
 #[derive(Debug, Clone, Copy)]
 pub(crate) struct Descriptor {
 	pub(crate) name: &'static str,
+	pub(crate) ignored: bool,
 	pub(crate) dropped: bool,
 	pub(crate) cache_disp: CacheDisp,
 	pub(crate) key_size_hint: Option<usize>,
@@ -52,6 +53,7 @@ pub(crate) enum CacheDisp {
 /// Base descriptor supplying common defaults to all derived descriptors.
 static BASE: Descriptor = Descriptor {
 	name: EMPTY,
+	ignored: false,
 	dropped: false,
 	cache_disp: CacheDisp::Shared,
 	key_size_hint: None,
@@ -83,8 +85,14 @@ static BASE: Descriptor = Descriptor {
 	auto_readahead_max: 1024 * 1024 * 2,
 };
 
+/// Placeholder descriptor for existing columns which have no description.
+/// Automatically generated on db open; should not appear in any schema.
+pub(crate) static IGNORED: Descriptor = Descriptor { ignored: true, ..BASE };
+
 /// Tombstone descriptor for columns which have been or will be deleted.
-pub(crate) static DROPPED: Descriptor = Descriptor { dropped: true, ..BASE };
+/// Descriptors of this kind are explicitly set to delete data. Care should be
+/// taken when using this as it inhibits downgrading and other migrations.
+pub(crate) static DROPPED: Descriptor = Descriptor { dropped: true, ..IGNORED };
 
 /// Descriptor for large datasets with random updates across the keyspace.
 pub(crate) static RANDOM: Descriptor = Descriptor {

src/database/engine/open.rs

@@ -6,11 +6,11 @@ use std::{
 
 use itertools::Itertools;
 use rocksdb::{ColumnFamilyDescriptor, Options};
-use tuwunel_core::{Result, debug, debug_warn, implement, info, warn};
+use tuwunel_core::{Result, debug, debug_warn, implement, info, trace, warn};
 
 use super::{
-	Db, Engine, cf_opts::cf_options, context, db_opts::db_options, descriptor::Descriptor,
-	repair::repair,
+	Db, Engine, cf_opts::cf_options, context, db_opts::db_options, descriptor,
+	descriptor::Descriptor, repair::repair,
 };
 use crate::{Context, or_else};
 
@@ -87,6 +87,7 @@ fn configure_cfds(
 	// Found columns which are not described.
 	let missing = existing
 		.iter()
+		.map(String::as_str)
 		.filter(|&name| name != "default")
 		.filter(|&name| !desc.iter().any(|desc| desc.name == name));
 
@@ -123,13 +124,19 @@ fn configure_cfds(
 		debug_warn!("Found undescribed column {name:?} in existing database.");
 	});
 
-	dropped.map(|desc| desc.name).for_each(|name| {
-		debug!("Previously dropped column {name:?} no longer found in database.");
-	});
+	dropped
+		.clone()
+		.map(|desc| desc.name)
+		.for_each(|name| {
+			debug!("Previously dropped column {name:?} no longer found in database.");
+		});
 
-	creating.map(|desc| desc.name).for_each(|name| {
-		debug!("Creating new column {name:?} not previously found in existing database.");
-	});
+	creating
+		.clone()
+		.map(|desc| desc.name)
+		.for_each(|name| {
+			debug!("Creating new column {name:?} not previously found in existing database.");
+		});
 
 	dropping
 		.clone()
@@ -141,23 +148,44 @@ fn configure_cfds(
 			);
 		});
 
-	let dropping_names: Vec<_> = dropping
-		.clone()
+	let not_dropped = |desc: &&Descriptor| {
+		!dropped
+			.clone()
+			.any(|dropped| desc.name == dropped.name)
+	};
+
+	let dropping = dropping
 		.map(|desc| desc.name)
 		.map(ToOwned::to_owned)
 		.collect();
 
+	let cfnames = desc
+		.iter()
+		.filter(not_dropped)
+		.map(|desc| desc.name)
+		.chain(missing.clone());
+
 	let cfds: Vec<_> = desc
 		.iter()
-		.filter(|desc| !desc.dropped)
-		.chain(dropping)
+		.filter(not_dropped)
 		.copied()
-		.inspect(|desc| debug!(name = desc.name, "Described column"))
-		.map(|desc| Ok((desc.name.to_owned(), cf_options(ctx, db_opts.clone(), &desc)?)))
+		.chain(missing.map(|_| descriptor::IGNORED))
+		.zip(cfnames)
+		.inspect(|&(desc, name)| {
+			assert!(
+				desc.ignored || desc.name == name,
+				"{name:?} does not match descriptor {:?}",
+				desc.name
+			);
+		})
+		.inspect(|&(_, name)| debug!(name, "Described column"))
+		.map(|(desc, name)| (desc, name.to_owned()))
+		.map(|(desc, name)| Ok((name, cf_options(ctx, db_opts.clone(), &desc)?)))
 		.map_ok(|(name, opts)| ColumnFamilyDescriptor::new(name, opts))
 		.collect::<Result<_>>()?;
 
-	Ok((cfds, dropping_names))
+	trace!(?dropping);
+	Ok((cfds, dropping))
 }
 
 #[implement(Engine)]