Merge pull request #252 from ekexium/batch-get-for-update

Fix batch_get_for_update

Author: nrc

src/request/mod.rs

@@ -10,8 +10,9 @@ use tikv_client_store::{HasError, Request};
 
 pub use self::{
     plan::{
-        Collect, CollectError, DefaultProcessor, Dispatch, ExtractError, Merge, MergeResponse,
-        MultiRegion, Plan, Process, ProcessResponse, ResolveLock, RetryRegion,
+        Collect, CollectAndMatchKey, CollectError, DefaultProcessor, Dispatch, ExtractError,
+        HasKeys, Merge, MergeResponse, MultiRegion, Plan, PreserveKey, Process, ProcessResponse,
+        ResolveLock, RetryRegion,
     },
     plan_builder::{PlanBuilder, SingleKey},
     shard::Shardable,

src/request/plan.rs

@@ -6,11 +6,13 @@ use crate::{
     request::{KvRequest, Shardable},
     stats::tikv_stats,
     transaction::{resolve_locks, HasLocks},
-    Error, Result,
+    util::iter::FlatMapOkIterExt,
+    Error, Key, KvPair, Result, Value,
 };
 use async_trait::async_trait;
 use futures::{prelude::*, stream::StreamExt};
 use std::{marker::PhantomData, sync::Arc};
+use tikv_client_proto::kvrpcpb;
 use tikv_client_store::{HasError, HasRegionError, KvClient};
 
 /// A plan for how to execute a request. A user builds up a plan with various
@@ -55,6 +57,12 @@ impl<Req: KvRequest> Plan for Dispatch<Req> {
     }
 }
 
+impl<Req: KvRequest + HasKeys> HasKeys for Dispatch<Req> {
+    fn get_keys(&self) -> Vec<Key> {
+        self.request.get_keys()
+    }
+}
+
 pub struct MultiRegion<P: Plan, PdC: PdClient> {
     pub(super) inner: P,
     pub pd_client: Arc<PdC>,
@@ -123,6 +131,12 @@ impl<In: Clone + Send + Sync + 'static, P: Plan<Result = Vec<Result<In>>>, M: Me
 #[derive(Clone, Copy)]
 pub struct Collect;
 
+/// A merge strategy to be used with
+/// [`preserve_keys`](super::plan_builder::PlanBuilder::preserve_keys).
+/// It matches the keys preserved before and the values returned in the response.
+#[derive(Clone, Debug)]
+pub struct CollectAndMatchKey;
+
 /// A merge strategy which returns an error if any response is an error and
 /// otherwise returns a Vec of the results.
 #[derive(Clone, Copy)]
@@ -256,6 +270,17 @@ where
     }
 }
 
+impl<P: Plan + HasKeys, PdC: PdClient> HasKeys for ResolveLock<P, PdC> {
+    fn get_keys(&self) -> Vec<Key> {
+        self.inner.get_keys()
+    }
+}
+
+/// When executed, the plan extracts errors from its inner plan, and
+/// returns an `Err` wrapping the error.
+///
+/// The errors come from two places: `Err` from inner plans, and `Ok(response)`
+/// where `response` contains unresolved errors (`error` and `region_error`).
 pub struct ExtractError<P: Plan> {
     pub inner: P,
 }
@@ -268,11 +293,6 @@ impl<P: Plan> Clone for ExtractError<P> {
     }
 }
 
-/// When executed, the plan extracts errors from its inner plan, and
-/// returns an `Err` wrapping the error.
-///
-/// The errors come from two places: `Err` from inner plans, and `Ok(response)`
-/// where `response` contains unresolved errors (`error` and `region_error`).
 #[async_trait]
 impl<P: Plan> Plan for ExtractError<P>
 where
@@ -292,6 +312,98 @@ where
     }
 }
 
+/// When executed, the plan clones the keys and execute its inner plan, then
+/// returns `(keys, response)`.
+///
+/// It's useful when the information of keys are lost in the response but needed
+/// for processing.
+pub struct PreserveKey<P: Plan + HasKeys> {
+    pub inner: P,
+}
+
+impl<P: Plan + HasKeys> Clone for PreserveKey<P> {
+    fn clone(&self) -> Self {
+        PreserveKey {
+            inner: self.inner.clone(),
+        }
+    }
+}
+
+#[async_trait]
+impl<P> Plan for PreserveKey<P>
+where
+    P: Plan + HasKeys,
+{
+    type Result = ResponseAndKeys<P::Result>;
+
+    async fn execute(&self) -> Result<Self::Result> {
+        let keys = self.inner.get_keys();
+        let res = self.inner.execute().await?;
+        Ok(ResponseAndKeys(res, keys))
+    }
+}
+
+pub trait HasKeys {
+    fn get_keys(&self) -> Vec<Key>;
+}
+
+// contains a response and the corresponding keys
+// currently only used for matching keys and values in pessimistic lock requests
+#[derive(Debug, Clone)]
+pub struct ResponseAndKeys<Resp>(Resp, Vec<Key>);
+
+impl<Resp: HasError> HasError for ResponseAndKeys<Resp> {
+    fn error(&mut self) -> Option<Error> {
+        self.0.error()
+    }
+}
+
+impl<Resp: HasLocks> HasLocks for ResponseAndKeys<Resp> {
+    fn take_locks(&mut self) -> Vec<tikv_client_proto::kvrpcpb::LockInfo> {
+        self.0.take_locks()
+    }
+}
+
+impl<Resp: HasRegionError> HasRegionError for ResponseAndKeys<Resp> {
+    fn region_error(&mut self) -> Option<Error> {
+        self.0.region_error()
+    }
+}
+
+impl Merge<ResponseAndKeys<kvrpcpb::PessimisticLockResponse>> for CollectAndMatchKey {
+    type Out = Vec<KvPair>;
+
+    fn merge(
+        &self,
+        input: Vec<Result<ResponseAndKeys<kvrpcpb::PessimisticLockResponse>>>,
+    ) -> Result<Self::Out> {
+        input
+            .into_iter()
+            .flat_map_ok(|ResponseAndKeys(mut resp, keys)| {
+                let values = resp.take_values();
+                let not_founds = resp.take_not_founds();
+                let v: Vec<_> = if not_founds.is_empty() {
+                    // Legacy TiKV does not distiguish not existing key and existing key
+                    // that with empty value. We assume that key does not exist if value
+                    // is empty.
+                    let values: Vec<Value> = values.into_iter().filter(|v| v.is_empty()).collect();
+                    keys.into_iter().zip(values).map(From::from).collect()
+                } else {
+                    assert_eq!(values.len(), not_founds.len());
+                    let values: Vec<Value> = values
+                        .into_iter()
+                        .zip(not_founds.into_iter())
+                        .filter_map(|(v, not_found)| if not_found { None } else { Some(v) })
+                        .collect();
+                    keys.into_iter().zip(values).map(From::from).collect()
+                };
+                // FIXME sucks to collect and re-iterate, but the iterators have different types
+                v.into_iter()
+            })
+            .collect()
+    }
+}
+
 #[cfg(test)]
 mod test {
     use super::*;

src/request/plan_builder.rs

@@ -1,11 +1,12 @@
 // Copyright 2021 TiKV Project Authors. Licensed under Apache-2.0.
 
+use super::PreserveKey;
 use crate::{
     backoff::Backoff,
     pd::PdClient,
     request::{
-        DefaultProcessor, Dispatch, ExtractError, KvRequest, Merge, MergeResponse, MultiRegion,
-        Plan, Process, ProcessResponse, ResolveLock, RetryRegion, Shardable,
+        DefaultProcessor, Dispatch, ExtractError, HasKeys, KvRequest, Merge, MergeResponse,
+        MultiRegion, Plan, Process, ProcessResponse, ResolveLock, RetryRegion, Shardable,
     },
     store::Store,
     transaction::HasLocks,
@@ -161,6 +162,19 @@ impl<PdC: PdClient, R: KvRequest> PlanBuilder<PdC, Dispatch<R>, NoTarget> {
     }
 }
 
+impl<PdC: PdClient, P: Plan + HasKeys> PlanBuilder<PdC, P, NoTarget>
+where
+    P::Result: HasError,
+{
+    pub fn preserve_keys(self) -> PlanBuilder<PdC, PreserveKey<P>, NoTarget> {
+        PlanBuilder {
+            pd_client: self.pd_client.clone(),
+            plan: PreserveKey { inner: self.plan },
+            phantom: PhantomData,
+        }
+    }
+}
+
 impl<PdC: PdClient, P: Plan> PlanBuilder<PdC, P, Targetted>
 where
     P::Result: HasError,

src/request/shard.rs

@@ -2,13 +2,30 @@
 
 use crate::{
     pd::PdClient,
-    request::{Dispatch, KvRequest, Plan, ResolveLock, RetryRegion},
+    request::{Dispatch, HasKeys, KvRequest, Plan, PreserveKey, ResolveLock, RetryRegion},
     store::Store,
     Result,
 };
 use futures::stream::BoxStream;
 use std::sync::Arc;
 
+macro_rules! impl_inner_shardable {
+    () => {
+        type Shard = P::Shard;
+
+        fn shards(
+            &self,
+            pd_client: &Arc<impl PdClient>,
+        ) -> BoxStream<'static, Result<(Self::Shard, Store)>> {
+            self.inner.shards(pd_client)
+        }
+
+        fn apply_shard(&mut self, shard: Self::Shard, store: &Store) -> Result<()> {
+            self.inner.apply_shard(shard, store)
+        }
+    };
+}
+
 pub trait Shardable {
     type Shard: Send;
 
@@ -37,33 +54,15 @@ impl<Req: KvRequest + Shardable> Shardable for Dispatch<Req> {
 }
 
 impl<P: Plan + Shardable, PdC: PdClient> Shardable for ResolveLock<P, PdC> {
-    type Shard = P::Shard;
-
-    fn shards(
-        &self,
-        pd_client: &Arc<impl PdClient>,
-    ) -> BoxStream<'static, Result<(Self::Shard, Store)>> {
-        self.inner.shards(pd_client)
-    }
+    impl_inner_shardable!();
+}
 
-    fn apply_shard(&mut self, shard: Self::Shard, store: &Store) -> Result<()> {
-        self.inner.apply_shard(shard, store)
-    }
+impl<P: Plan + HasKeys + Shardable> Shardable for PreserveKey<P> {
+    impl_inner_shardable!();
 }
 
 impl<P: Plan + Shardable, PdC: PdClient> Shardable for RetryRegion<P, PdC> {
-    type Shard = P::Shard;
-
-    fn shards(
-        &self,
-        pd_client: &Arc<impl PdClient>,
-    ) -> BoxStream<'static, Result<(Self::Shard, Store)>> {
-        self.inner.shards(pd_client)
-    }
-
-    fn apply_shard(&mut self, shard: Self::Shard, store: &Store) -> Result<()> {
-        self.inner.apply_shard(shard, store)
-    }
+    impl_inner_shardable!();
 }
 
 #[macro_export]

src/transaction/requests.rs

@@ -2,7 +2,9 @@
 
 use crate::{
     pd::PdClient,
-    request::{Collect, DefaultProcessor, KvRequest, Merge, Process, Shardable, SingleKey},
+    request::{
+        Collect, DefaultProcessor, HasKeys, KvRequest, Merge, Process, Shardable, SingleKey,
+    },
     store::{store_stream_for_keys, store_stream_for_range_by_start_key, Store},
     timestamp::TimestampExt,
     transaction::HasLocks,
@@ -359,6 +361,15 @@ impl Shardable for kvrpcpb::PessimisticLockRequest {
     }
 }
 
+impl HasKeys for kvrpcpb::PessimisticLockRequest {
+    fn get_keys(&self) -> Vec<Key> {
+        self.mutations
+            .iter()
+            .map(|m| m.key.clone().into())
+            .collect()
+    }
+}
+
 impl Merge<kvrpcpb::PessimisticLockResponse> for Collect {
     // FIXME: PessimisticLockResponse only contains values.
     // We need to pair keys and values returned somewhere.