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-rw-r--r--src/garage/admin.rs2
-rw-r--r--src/garage/cli/structs.rs3
-rw-r--r--src/model/block.rs228
3 files changed, 182 insertions, 51 deletions
diff --git a/src/garage/admin.rs b/src/garage/admin.rs
index b5fc9a7e..c3a83d02 100644
--- a/src/garage/admin.rs
+++ b/src/garage/admin.rs
@@ -446,7 +446,7 @@ impl AdminRpcHandler {
if opt.detailed {
writeln!(
&mut ret,
- " number of blocks: {}",
+ " number of RC entries (~= number of blocks): {}",
self.garage.block_manager.rc_len()
)
.unwrap();
diff --git a/src/garage/cli/structs.rs b/src/garage/cli/structs.rs
index 0df6ef87..b930d8a8 100644
--- a/src/garage/cli/structs.rs
+++ b/src/garage/cli/structs.rs
@@ -8,8 +8,7 @@ pub enum Command {
#[structopt(name = "server")]
Server,
- /// Print identifier (public key) of this garage node.
- /// Generates a new keypair if necessary.
+ /// Print identifier (public key) of this Garage node
#[structopt(name = "node-id")]
NodeId(NodeIdOpt),
diff --git a/src/model/block.rs b/src/model/block.rs
index 406abf7b..3f40aaab 100644
--- a/src/model/block.rs
+++ b/src/model/block.rs
@@ -31,10 +31,20 @@ pub const INLINE_THRESHOLD: usize = 3072;
pub const BACKGROUND_WORKERS: u64 = 1;
pub const BACKGROUND_TRANQUILITY: u32 = 3;
-const BLOCK_RW_TIMEOUT: Duration = Duration::from_secs(42);
-const BLOCK_GC_TIMEOUT: Duration = Duration::from_secs(60);
+// Timeout for RPCs that read and write blocks to remote nodes
+const BLOCK_RW_TIMEOUT: Duration = Duration::from_secs(30);
+// Timeout for RPCs that ask other nodes whether they need a copy
+// of a given block before we delete it locally
const NEED_BLOCK_QUERY_TIMEOUT: Duration = Duration::from_secs(5);
-const RESYNC_RETRY_TIMEOUT: Duration = Duration::from_secs(10);
+
+// The delay between the time where a resync operation fails
+// and the time when it is retried.
+const RESYNC_RETRY_DELAY: Duration = Duration::from_secs(60);
+
+// The delay between the moment when the reference counter
+// drops to zero, and the moment where we allow ourselves
+// to delete the block locally.
+const BLOCK_GC_DELAY: Duration = Duration::from_secs(600);
/// RPC messages used to share blocks of data between nodes
#[derive(Debug, Serialize, Deserialize)]
@@ -180,7 +190,7 @@ impl BlockManager {
/// that are required because of refcount > 0, and will try
/// to fix any mismatch between the two.
pub async fn repair_data_store(&self, must_exit: &watch::Receiver<bool>) -> Result<(), Error> {
- // 1. Repair blocks from RC table
+ // 1. Repair blocks from RC table.
let garage = self.garage.load_full().unwrap();
let mut last_hash = None;
for (i, entry) in garage.block_ref_table.data.store.iter().enumerate() {
@@ -245,40 +255,51 @@ impl BlockManager {
/// Increment the number of time a block is used, putting it to resynchronization if it is
/// required, but not known
pub fn block_incref(&self, hash: &Hash) -> Result<(), Error> {
- let old_rc = self.rc.fetch_and_update(&hash, |old| {
- let old_v = old.map(u64_from_be_bytes).unwrap_or(0);
- Some(u64::to_be_bytes(old_v + 1).to_vec())
- })?;
- let old_rc = old_rc.map(u64_from_be_bytes).unwrap_or(0);
- if old_rc == 0 {
- self.put_to_resync(hash, BLOCK_RW_TIMEOUT)?;
+ let old_rc = self
+ .rc
+ .fetch_and_update(&hash, |old| RcEntry::parse_opt(old).increment().serialize())?;
+ let old_rc = RcEntry::parse_opt(old_rc);
+ if old_rc.is_zero() {
+ // When the reference counter is incremented, there is
+ // normally a node that is responsible for sending us the
+ // data of the block. However that operation may fail,
+ // so in all cases we add the block here to the todo list
+ // to check later that it arrived correctly, and if not
+ // we will fecth it from someone.
+ self.put_to_resync(hash, 2 * BLOCK_RW_TIMEOUT)?;
}
Ok(())
}
/// Decrement the number of time a block is used
pub fn block_decref(&self, hash: &Hash) -> Result<(), Error> {
- let new_rc = self.rc.update_and_fetch(&hash, |old| {
- let old_v = old.map(u64_from_be_bytes).unwrap_or(0);
- if old_v > 1 {
- Some(u64::to_be_bytes(old_v - 1).to_vec())
- } else {
- None
- }
- })?;
- if new_rc.is_none() {
- self.put_to_resync(hash, BLOCK_GC_TIMEOUT)?;
+ let new_rc = self
+ .rc
+ .update_and_fetch(&hash, |old| RcEntry::parse_opt(old).decrement().serialize())?;
+ let new_rc = RcEntry::parse_opt(new_rc);
+ if let RcEntry::Deletable { .. } = new_rc {
+ self.put_to_resync(hash, BLOCK_GC_DELAY + Duration::from_secs(10))?;
}
Ok(())
}
/// Read a block's reference count
- pub fn get_block_rc(&self, hash: &Hash) -> Result<u64, Error> {
- Ok(self
- .rc
- .get(hash.as_ref())?
- .map(u64_from_be_bytes)
- .unwrap_or(0))
+ fn get_block_rc(&self, hash: &Hash) -> Result<RcEntry, Error> {
+ Ok(RcEntry::parse_opt(self.rc.get(hash.as_ref())?))
+ }
+
+ /// Delete an entry in the RC table if it is deletable and the
+ /// deletion time has passed
+ fn clear_deleted_block_rc(&self, hash: &Hash) -> Result<(), Error> {
+ let now = now_msec();
+ self.rc.update_and_fetch(&hash, |rcval| {
+ let updated = match RcEntry::parse_opt(rcval) {
+ RcEntry::Deletable { at_time } if now > at_time => RcEntry::Absent,
+ v => v,
+ };
+ updated.serialize()
+ })?;
+ Ok(())
}
// ---- Reading and writing blocks locally ----
@@ -300,7 +321,7 @@ impl BlockManager {
Ok(f) => f,
Err(e) => {
// Not found but maybe we should have had it ??
- self.put_to_resync(hash, Duration::from_millis(0))?;
+ self.put_to_resync(hash, 2 * BLOCK_RW_TIMEOUT)?;
return Err(Into::into(e));
}
};
@@ -314,6 +335,7 @@ impl BlockManager {
.await
.move_block_to_corrupted(hash, self)
.await?;
+ self.put_to_resync(hash, Duration::from_millis(0))?;
return Err(Error::CorruptData(*hash));
}
@@ -328,7 +350,7 @@ impl BlockManager {
.await
.check_block_status(hash, self)
.await?;
- Ok(needed && !exists)
+ Ok(needed.is_nonzero() && !exists)
}
/// Utility: gives the path of the directory in which a block should be found
@@ -349,7 +371,7 @@ impl BlockManager {
// ---- Resync loop ----
pub fn spawn_background_worker(self: Arc<Self>) {
- // Launch 2 simultaneous workers for background resync loop preprocessing
+ // Launch n simultaneous workers for background resync loop preprocessing
for i in 0..BACKGROUND_WORKERS {
let bm2 = self.clone();
let background = self.system.background.clone();
@@ -407,7 +429,7 @@ impl BlockManager {
let res = self.resync_block(&hash).await;
if let Err(e) = &res {
warn!("Error when resyncing {:?}: {}", hash, e);
- self.put_to_resync(&hash, RESYNC_RETRY_TIMEOUT)?;
+ self.put_to_resync(&hash, RESYNC_RETRY_DELAY)?;
}
Ok(true)
} else {
@@ -437,15 +459,18 @@ impl BlockManager {
.check_block_status(hash, self)
.await?;
- if exists != needed {
- info!(
- "Resync block {:?}: exists {}, needed {}",
- hash, exists, needed
+ if exists != needed.is_needed() || exists != needed.is_nonzero() {
+ debug!(
+ "Resync block {:?}: exists {}, nonzero rc {}, deletable {}",
+ hash,
+ exists,
+ needed.is_nonzero(),
+ needed.is_deletable(),
);
}
- if exists && !needed {
- trace!("Offloading block {:?}", hash);
+ if exists && needed.is_deletable() {
+ info!("Resync block {:?}: offloading and deleting", hash);
let mut who = self.replication.write_nodes(hash);
if who.len() < self.replication.write_quorum() {
@@ -488,7 +513,7 @@ impl BlockManager {
need_nodes.len()
);
- let put_block_message = self.read_block(hash).await.err_context("PutBlock RPC")?;
+ let put_block_message = self.read_block(hash).await?;
self.system
.rpc
.try_call_many(
@@ -499,10 +524,11 @@ impl BlockManager {
.with_quorum(need_nodes.len())
.with_timeout(BLOCK_RW_TIMEOUT),
)
- .await?;
+ .await
+ .err_context("PutBlock RPC")?;
}
info!(
- "Deleting block {:?}, offload finished ({} / {})",
+ "Deleting unneeded block {:?}, offload finished ({} / {})",
hash,
need_nodes.len(),
who.len()
@@ -513,12 +539,16 @@ impl BlockManager {
.await
.delete_if_unneeded(hash, self)
.await?;
+
+ self.clear_deleted_block_rc(hash)?;
}
- if needed && !exists {
- // TODO find a way to not do this if they are sending it to us
- // Let's suppose this isn't an issue for now with the BLOCK_RW_TIMEOUT delay
- // between the RC being incremented and this part being called.
+ if needed.is_nonzero() && !exists {
+ info!(
+ "Resync block {:?}: fetching absent but needed block (refcount > 0)",
+ hash
+ );
+
let block_data = self.rpc_get_block(hash).await?;
self.write_block(hash, &block_data[..]).await?;
}
@@ -526,6 +556,8 @@ impl BlockManager {
Ok(())
}
+ // ---- Utility: iteration on files in the data directory ----
+
async fn for_each_file<F, Fut, State>(
&self,
state: State,
@@ -608,7 +640,7 @@ impl EndpointHandler<BlockRpc> for BlockManager {
struct BlockStatus {
exists: bool,
- needed: bool,
+ needed: RcEntry,
}
impl BlockManagerLocked {
@@ -620,7 +652,7 @@ impl BlockManagerLocked {
let path = mgr.block_path(hash);
let exists = fs::metadata(&path).await.is_ok();
- let needed = mgr.get_block_rc(hash)? > 0;
+ let needed = mgr.get_block_rc(hash)?;
Ok(BlockStatus { exists, needed })
}
@@ -659,14 +691,13 @@ impl BlockManagerLocked {
let mut path2 = path.clone();
path2.set_extension("corrupted");
fs::rename(path, path2).await?;
- mgr.put_to_resync(hash, Duration::from_millis(0))?;
Ok(())
}
async fn delete_if_unneeded(&self, hash: &Hash, mgr: &BlockManager) -> Result<(), Error> {
let BlockStatus { exists, needed } = self.check_block_status(hash, mgr).await?;
- if exists && !needed {
+ if exists && needed.is_deletable() {
let path = mgr.block_path(hash);
fs::remove_file(path).await?;
}
@@ -680,3 +711,104 @@ fn u64_from_be_bytes<T: AsRef<[u8]>>(bytes: T) -> u64 {
x8.copy_from_slice(bytes.as_ref());
u64::from_be_bytes(x8)
}
+
+/// Describes the state of the reference counter for a block
+#[derive(Clone, Copy, Debug)]
+enum RcEntry {
+ /// Present: the block has `count` references, with `count` > 0.
+ ///
+ /// This is stored as u64::to_be_bytes(count)
+ Present { count: u64 },
+
+ /// Deletable: the block has zero references, and can be deleted
+ /// once time (returned by now_msec) is larger than at_time
+ /// (in millis since Unix epoch)
+ ///
+ /// This is stored as [0u8; 8] followed by u64::to_be_bytes(at_time),
+ /// (this allows for the data format to be backwards compatible with
+ /// previous Garage versions that didn't have this intermediate state)
+ Deletable { at_time: u64 },
+
+ /// Absent: the block has zero references, and can be deleted
+ /// immediately
+ Absent,
+}
+
+impl RcEntry {
+ fn parse(bytes: &[u8]) -> Self {
+ if bytes.len() == 8 {
+ RcEntry::Present {
+ count: u64::from_be_bytes(bytes.try_into().unwrap()),
+ }
+ } else if bytes.len() == 16 {
+ RcEntry::Deletable {
+ at_time: u64::from_be_bytes(bytes[8..16].try_into().unwrap()),
+ }
+ } else {
+ panic!("Invalid RC entry: {:?}, database is corrupted. This is an error Garage is currently unable to recover from. Sorry, and also please report a bug.",
+ bytes
+ )
+ }
+ }
+
+ fn parse_opt<V: AsRef<[u8]>>(bytes: Option<V>) -> Self {
+ bytes
+ .map(|b| Self::parse(b.as_ref()))
+ .unwrap_or(Self::Absent)
+ }
+
+ fn serialize(self) -> Option<Vec<u8>> {
+ match self {
+ RcEntry::Present { count } => Some(u64::to_be_bytes(count).to_vec()),
+ RcEntry::Deletable { at_time } => {
+ Some([u64::to_be_bytes(0), u64::to_be_bytes(at_time)].concat())
+ }
+ RcEntry::Absent => None,
+ }
+ }
+
+ fn increment(self) -> Self {
+ let old_count = match self {
+ RcEntry::Present { count } => count,
+ _ => 0,
+ };
+ RcEntry::Present {
+ count: old_count + 1,
+ }
+ }
+
+ fn decrement(self) -> Self {
+ match self {
+ RcEntry::Present { count } => {
+ if count > 1 {
+ RcEntry::Present { count: count - 1 }
+ } else {
+ RcEntry::Deletable {
+ at_time: now_msec() + BLOCK_GC_DELAY.as_millis() as u64,
+ }
+ }
+ }
+ del => del,
+ }
+ }
+
+ fn is_zero(&self) -> bool {
+ matches!(self, RcEntry::Deletable { .. } | RcEntry::Absent)
+ }
+
+ fn is_nonzero(&self) -> bool {
+ !self.is_zero()
+ }
+
+ fn is_deletable(&self) -> bool {
+ match self {
+ RcEntry::Present { .. } => false,
+ RcEntry::Deletable { at_time } => now_msec() > *at_time,
+ RcEntry::Absent => true,
+ }
+ }
+
+ fn is_needed(&self) -> bool {
+ !self.is_deletable()
+ }
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-02 00:20:08 +0000